Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Epidemiology of allergic rhinitis and associated risk factors in Asia

Epidemiology of allergic rhinitis and associated risk factors in Asia This review article aims to present the epidemiology and associated risk factors of allergic rhinitis (AR) in Asia. AR-related literature published on Asia was systematically reviewed and the associated risk factors were investigated. The prevalence of AR in Asia varied considerably depending on the geographical location, study design and population involved. Several risk factors were observed to have strong association with disease presentation across multiple studies. Among these, family income, family size, daily personal computer usage time, personal and parental education attainment, and stress level have shown some level of biological gradient influence when multiple risk levels were analyzed. This suggests that AR manifestation and presentation possibly might be strongly affected by various personal and family factors. These findings are beneficial as they may provide insights into modifiable factors that may influence AR presentation. In addition, these results indicate that strategies to reduce personal and family-related risk factors have to be developed in order to alleviate the odds of AR expression. Keywords: Allergic rhinitis, Risk factor, Asia, Systematic review Background Risk factors affecting the presentation of allergic rhinitis Allergic rhinitis epidemiology and symptoms Apart from the demographic factors, smoking and drink- According to the Phase III International Study of Asthma ing habits, pet adoption, education attainment, and fam- and Allergies in Childhood (ISAAC), the prevalence of AR ily history were the risk factors of AR, commonly varied between 0.8 to 14.9% in 6-7 years old and 1.4 to studied in Asian countries [7–11]. Conversely, Western 39.7% in 13-14 years old worldwide [1]. In Asia, this countries focus more on the effects of pollens, drugs, disease affects a large population, ranging from 27% in pets, and family history on the presentation of AR South Korea [2] to 32% in the United Arab Emirates [3]. [12–14]. The differences between the risk factors ana- It is a prevalent yet underappreciated atopic disorder lyzed could be culturally induced or due to the climatic which is commonly characterized by the presence of at least differences between Asian and Western countries. one of the following clinical symptoms: persistent nasal ob- However, it was observed that pet adoption and family struction and mucous discharge, sneezing, and itching [4]. history are the common risk factors studied in both re- Although AR is commonly regarded as a mild and gions, suggesting their pervasiveness in inducing AR seasonal nuisance, it can trigger persistent mucosal inflam- manifestation worldwide. mation which may synergize with other infective inflamma- tion, resulting in severe outcomes including hospitalization Disease diagnosis [5]. As such, the odds of hospital admission for children While AR is influenced by genetic predisposition, the with the allergic disease have been reported to increase by symptom presentation also depends on environmental 19 times with the co-infection of rhinoviral diseases, allergic exposures [15]. In addition, the disease can co-present sensitization, and allergen exposure [6]. with other diseases, such as asthma and other infectious diseases, which could further complicate the disease * Correspondence: dbscft@nus.edu.sg diagnosis. A robust association of rhinitis was found Department of Biological Sciences, Faculty of Science, Allergy and Molecular among individuals with allergic and non-allergic asthma Immunology Laboratory, Lee Hiok Kwee Functional Genomics Laboratories, [16]. Among patients with persistent and severe rhinitis, National University of Singapore, Block S2, Level 5, Science Drive 4, Lower Kent Ridge Rd, Singapore 117543, Singapore asthma was found prevailing [17]. © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 2 of 21 Moreover, patients can experience adverse effects on AR manifestation were evaluated using several important social life, productivity at work and performance in criteria established in literature. These criteria include the school, especially for those who suffer from a more se- strength of association, consistency of the observed associ- vere form of AR [16]. The use of suboptimum pharma- ation, specificity, biologic gradient, biologic plausibility, cotherapy and antihistamines with sedative effects can coherence, analogy, and temporality. In addition, meta-ana- further exacerbate the situation. This incurs a financial lysis was conducted using the software/program-Stata/SE burden from both direct and indirect costs which 11.2 with random effects model to evaluate the influence of adversely affects society [18]. Therefore, a prompt and modifiable risk factors with replicative results reported in at accurate diagnosis, followed by appropriate disease man- least three independent AR publications. agement and awareness of the exacerbation risk factors, would be crucial to ease this burden. Results and discussion Diagnosis of the disease is usually based on medical his- AR epidemiology in Asia tory of the patient in addition to skin prick test or blood Based on the methodology described, different articles test. However, misinterpretation can occasionally occur published in Asia were reviewed. The reviewed arti- and this delays the golden treatment period which can cles have variable study design, disease definition and result in other unexpected consequences, such as paying adopt different analysis parameters as shown in unnecessary medical expenditure and missing work [18]. Table 1. The population size also varies from study to study, ranging from 200 in Kidoni et al. [19]to The aim of the study 30,000 in An et al. [2] This review article aims to study the epidemiology of AR Though similar parameters were used to study the in Asia and identify significant modifiable risk factors as- epidemiology of AR, a larger population group will help sociated with disease presentation. Several criteria have to furtherestablish theprevalenceof the diseaseasit been employed to establish association between trigger- better represents the targeted population. In addition, ing factors and disease manifestation. apart from the country of study, the disease prevalence differs depending on the disease definition and the Methods studypopulation. In thestudy conducted by Min et al. Search strategy and selection criteria [20], AR prevalence is 1.14% among Korean residents; The epidemiology and potential factors associated with while in a retrospective study published by Alsowaidi et AR manifestation were obtained from the Web of al., 2010 [3], 32% of United Arab Emirates residents are Science using the search terms of ‘rhinitis’, ‘risk’ and AR patients. Asian countries. The list of Asian countries and inde- pendent territories used in the search is listed in Additional file 1. ‘Rhinitis’ is used as it represents a Risk factors and co-morbidities of AR general form of the disease which serves to capture as Apart from the general demographic factors, many modi- many risk factors, including both modifiable and fiable risk factors for allergic diseases, such as smoking non-modifiable, as possible. As Asian and Western and drinking habits were investigated as summarised in countries are known to have different cultural and social Table 1. Furthermore, cultural- or socioeconomic-related backgrounds, our study only evaluated articles published factors specific to an individual country have been ex- on Asia and this articles serves to provide a detailed list plored in some studies to identify their association with of triggering risk factors associated with AR in Asia. AR presentation. For instance, heavy traffic and individual Using these search terms, 56 articles were first identi- stress level are two factors investigated in a Singapore [21] fied. The articles were carefully reviewed and those with and Korea [2] study, respectively. These factors were iden- unclear study design or disease definition or which were tified worrying elements in the respective countries, thus conducted in a narrow pool of individuals were ex- finding their association with AR presentation is crucial. cluded. Apart from these 14 articles, additional 6 We further classified these factors into a potential risk cross-referencing articles were also included. These 20 factors or co-morbidities category based on the following articles, published between 1994 and 2017, were evalu- definitions. A typical risk factor is a demographical, phys- ated closely for their study design, disease prevalence, ical, sociological or environmental component which po- disease definition, and the AR risk factor analyzed. tentially increases the risk of presenting a disease or is protective against the expression of an illness. On the Establishing the association link other hand, if AR manifestation is linked to another dis- The factors investigated in the 20 articles were further clas- ease occurrence, it will be known as a co-morbid of AR. sified either as a potential risk factor or a co-morbidity. The As listed in Table 2, most of the factors analysed are in the association between potential modifiable risk factors and risk factor category. However, diseases such as asthma are Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 3 of 21 Table 1 Summaries of allergic rhinitis-specific articles published in year 1994-2017 in Asia Country, No. of sample Study design Prevalence Definition of the disease stage Parameters analyzed Reference, date location Singapore 2868 adults aged Cross-sectional population-based 4.5% Allergic rhinitis: self-reported presence, in the Significant parameters Ng & Tan, 20-74 years study previous year, of usual nasal blockage and ➢ Age 1994 [36] discharge apart from colds or the flu, ➢ Fume exposure provoked by allergens, with or without ➢ Housing estate conjunctivitis. ➢ Insect ➢ Occupational exposure ➢ Race ➢ Smoking Insignificant parameters ➢ Air pollution ➢ Carpet ➢ Gender ➢ Pet Korea 10,054 residents Cross-sectional interview based 1.14% Perennial allergic rhinitis in this study was Significant parameters Min et al., study with Physical examination defined as the presence of typical nasal ➢ Educational attainment 1997 [20] symptoms including watery rhinorrhea, ➢ Residency sneezing, itching and nasal obstruction during Insignificant parameters a period greater than 12 months, positive ➢ Marital status history of known allergen or triggering factors, ➢ Occupational exposure and the physical finding of pale nasal mucosa ➢ Smoking on endoscopic examination. ➢ Social class Thailand, 3124 residents Cross-sectional questionnaire 13.15% (95% CI = 13.13-13.17) Rhinitis is defined as inflammation of the Significant parameters Bunnag Bangkok based study with Chronic rhinitis (CR) lining of the nose, characterized by one or ➢ Associated allergic et al., 2000 more of the following symptoms, i.e. itching, diseases [37] sneezing, rhinorrhea and nasal obstruction ➢ Drinking (International Rhinitis Management Working ➢ Family history of atopy Group, 1994). CR is diagnosed when one ➢ Household income frequently has rhinitis symptoms without fever ➢ Smoking for a period of more than one year. Insignificant parameter ➢ Gender Israel 10,057 Cross-sectional questionnaire 41.6% with Ever AR, Ever AR: Children who reported having rhinitis Significant parameters Graif et al., schoolchildren, based study 9.4% with Current AR and sneezing without flu ever ➢ Asthma 2004 [38] aged 13-14 years Current AR: Answer ‘Yes’ to the question, ➢ Family history of allergic “Do you have allergic rhinitis?” diseases ➢ Gender ➢ Race ➢ Residency Singapore 202 patients aged Retrospective analysis with 33% (AR + asthma), 13% Confirmation from a specialist in Pediatric Significant parameter Kidoni 2-14 years medical records from allergic (AR + AD) & 7% (AR + Otolaryngology ➢ Mold et al., 2004 rhinitis patients undergo SPT test asthma + AD) [19]. in KK Children’s hospital (Jul 2001 − 44% hospitalization rate to June 2002) Laos, 536 (included Cross-sectional questionnaire 21.0% (6-7 years) & 22.3% Had a problem with sneezing, runny, or Significant parameters Phathammavong Vientiane students aged based study from Dec 2006 to (13-14 years) blocked nose when did not have cold or the ➢ Household income et al., 2008 [9] 6-7 years and Feb 2007 with stool examination flu in the past 12 months (ISAAC definition) ➢ Parasitic infection 13-14 years) ➢ Past respiratory infection Insignificant parameters Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 4 of 21 Table 1 Summaries of allergic rhinitis-specific articles published in year 1994-2017 in Asia (Continued) Country, No. of sample Study design Prevalence Definition of the disease stage Parameters analyzed Reference, date location ➢ Age ➢ Air conditioning ➢ Birth order ➢ Family history of allergic diseases ➢ Food ➢ Gender ➢ Parity ➢ Past measles infection ➢ Pet ➢ Sharing bed ➢ Smoking ➢ Time on road Singapore 6794 children Cross-sectional questionnaire 25.6 (Rhinitis) N.A. Significant parameter Zuraimi attending 120 based study ➢ Smoking et al., 2008 randomly selected [39] child care centres Taiwan, 1368 elementary Cross-sectional questionnaire 50.1% The presence of typical nasal symptoms Significant parameters Hsu et al., Taipei school children based study with multi-stage including watery rhinorrhea, sneezing, and ➢ Air pollution 2009 [10] clustered-stratified random nasal obstruction of more than 12 months’ ➢ Carpet method, physical examination duration, positive history of known allergen ➢ Gender or triggering factors, and pale nasal mucosa. ➢ Parity Insignificant parameters ➢ Age of gestation ➢ Gestational complication ➢ Maternal education ➢ Mold ➢ Pet ➢ Smoking United Arab 7550 residents Cross-sectional questionnaire 32% The definition of AR used in this study was Significant parameters Alsowaidi Emirates, ≥13 years based study having had AR symptoms of (nasal blockage, ➢ Age et al., 2010 Al-Ain City rhinorrhoea, sneezing and irritation), in the ➢ Education attainment [3] past 12 months. ➢ Family history of allergic diseases ➢ Gender ➢ Nationality Singapore 2994 children living Cross-sectional questionnaire 24% (Rhinitis) N.A. Significant parameter Zuraimi in homes without based study ➢ Traffic et al., 2011 any indoor risk Insignificant parameter [21] factors ➢ Air conditioning China, 9899 citizens Cross-sectional questionnaire 6.24% According to the diagnostic criteria of AR in Significant parameters Li et al., Guangzhou based study with stratified the ARIA 2001 Guideline, the ENT specialists ➢ Computer usage 2014 [7] City multistage cluster sampling verified the screening questionnaires and ➢ Family history of allergic method made the diagnosis based on the typical AR diseases symptoms within the last 12 months. ➢ Home renovation Intermittent AR was determined when the ➢ Pet Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 5 of 21 Table 1 Summaries of allergic rhinitis-specific articles published in year 1994-2017 in Asia (Continued) Country, No. of sample Study design Prevalence Definition of the disease stage Parameters analyzed Reference, date location symptoms occur, 4 days/week or, 4 ➢ Residency consecutive weeks/year; while persistent AR ➢ Smoking was determined when symptoms last 4 days/ Insignificant parameters week or 4 consecutive weeks/year. ➢ Age ➢ Breastfeeding ➢ Car ownership ➢ Hair coloring ➢ Household income Korea 31,217 subjects Cross-sectional study, data from 27% N.A. Significant parameters An et al., aged 6-97 years Korea National Health and ➢ Marital status 2015 [2] Nutrition Examination Survey ➢ Occupational exposure ➢ Sleep time ➢ Stress level Insignificant parameters ➢ BMI ➢ Drinking ➢ Education attainment ➢ Family size ➢ Household income ➢ Residency ➢ Smoking China 20,803 elementary Cross-sectional questionnaire 9.8% AR: yes for “Has your child had allergic rhinitis Significant parameters Li et al., school students based study in the past 12 months?” ➢ Age 2015 [22] ➢ Age of gestation ➢ Breastfeeding ➢ Family size ➢ Gender ➢ Household income ➢ Housing estate ➢ Maternal education ➢ Mode of delivery ➢ Maternal pre- or postnatal depression ➢ Paternal education Insignificant parameters ➢ Drinking ➢ Smoking Malaysia 695 Malaysia office Cross-sectional questionnaire 53% with current rhinitis Doctor diagnosis Significant parameters Lim et al., works aged based study, SPT test, building ➢ Age 2015 [11] 18-60 years inspection ➢ House dust mite Insignificant parameters ➢ Gender ➢ Pet ➢ Smoking China, 3327 Cross-sectional questionnaire 17.67% Doctor diagnosis Significant parameter Lei, Yang & Zhen, Wuhan based study, physical examination ➢ Gender 2016 [40] Insignificant parameter Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 6 of 21 Table 1 Summaries of allergic rhinitis-specific articles published in year 1994-2017 in Asia (Continued) Country, No. of sample Study design Prevalence Definition of the disease stage Parameters analyzed Reference, date location ➢ BMI Malaysia, 462 students from Cross-sectional questionnaire 18.8% for students from N.A. Significant parameter Norbäck Johor Bahru 8 random schools based study, building inspections junior high schools ➢ Fungi et al., 2016 (1) [41] Malaysia, 462 students from Cross-sectional questionnaire 18.8% for students from N.A. Significant parameters Norbäck Johor Bahru 8 random schools based study, building inspections junior high schools ➢ Atopy et al., 2016 ➢ Family history of allergic (2) [35] disease ➢ Fungi ➢ House dust mite ➢ Race Insignificant parameters ➢ Gender ➢ Smoking China, 13,335 children, Cross-sectional questionnaire 12.6% Answer yes for “Has your child ever had a Significant parameters Huang Shanghai aged 4-6 years based study problem with sneezing, or a runny, or blocked ➢ Breastfeeding et al., 2017 nose when he/she did not have a cold or the ➢ Gruel introduction [34] flu in the past years” Taiwan 1497 newborns Birth cohort follow-up, Non-atopic parents & one Doctor diagnosis Significant parameters Lee et al., questionnaire survey, physician- atopic parent & atopic ➢ Age of gestation 2017 [42] verified and serological testing parents ➢ Gender : 30.8% vs 39.9% vs 54.7% ➢ Residency Kuwait 1154 students, aged Cross-sectional questionnaire 20.4% (95% Cl- 18.1-22.9) Current rhinitis: “ever doctor-diagnosed Significant parameters Ziyab, 18-26 years based study rhinitis” plus “having problems with sneezing, ➢ Age 2017 [8] attending Kuwait runny, or blocked nose in the absence of cold ➢ Family history of allergic University or flu in the last 12 months” diseases ➢ Pet Insignificant parameters ➢ Birth order ➢ Gender ➢ Mode of delivery ➢ Smoking Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 7 of 21 Table 2 The list of risk factors analyzed in the literature reviewed Table 2 The list of risk factors analyzed in the literature reviewed (Continued) No. Risk Factors No. Risk Factors 1 Age 45 Sleep time 2 Age of gestation 46 Smoking (self/parent) 3 Air conditioning 47 Social class 4 Air pollution 48 Stress level 5 Alcohol consumption (self/parent) 49 Time on road 6 Birth order 50 Traffic 7 BMI 8 Breastfeeding co-morbidities which can possibly induce AR expression 9 Car ownership as shown in Table 3.In this article, onlythe modifiable 10 Carpet risk factors were evaluated for their relationship with AR 11 Computer usage manifestation. 12 Drinking (self/parent) Demographical factors affecting the AR presentation 13 Education attainment Multiple papers have suggested the importance of age, 14 Family history of allergic diseases gender, race, and nationality in affecting AR presentation 15 Family history of atopy (Table 4). The association of race and nationality on the 16 Family size disease expression could signify the difference in social 17 Food and cultural backgrounds, as well as genetics, which can 18 Fume exposure potentially influence the presentation of AR. However, as these factors are non-modifiable, they are only useful 19 Fungi in evaluating the risk of presenting AR, but not for 20 Gender prevention. 21 Gestational complication In Li et al. [22], the odds of AR have shown to increase 22 Gruel introduction period with the rise of household income when different house- 23 Hair coloring hold income groups are compared. For the household 24 Home renovation with an income of > 2500 RMB/month, the odds of AR is 2.88 times of those with an income of 800 RMB/ 25 House dust mite month. A similar trend is observed in another two inde- 26 Household income pendent studies. A pooled odds ratio of 2.75 has been 27 Housing estate obtained which suggests the significant role of house- 28 Insect hold income in affecting AR expression (Fig. 1). 29 Marital status Moreover, being married, a large number of members 30 Maternal education in the household, and parity were indicated to be benefi- cial for protecting one against AR. However, their 31 Maternal pre- or postnatal depression influences towards protection of AR are likely to be in- 32 Mode of delivery terrelated as married individuals are usually with chil- 33 Mold dren and are therefore likely to report an increased 34 Nationality parity number and household members. 35 Occupational exposure 36 Parasitic infection Personal risk factors affecting AR presentation Apart from the demographical factors that are usually 37 Parity non-changeable to an individual, one’s behaviours, atti- 38 Past measles infection tude, and encounters might have direct and indirect 39 Past respiratory infection 40 Paternal education Table 3 The list of co-morbidities analyzed in the literature reviewed 41 Pet No. Co-morbidities 42 Race 1 Atopy 43 Residency 2 Associated allergy 44 Sharing bed 3 Current asthma Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 8 of 21 Table 4 Strength of association of demographic factors with AR manifestation Study Study OR/PR Values (95% CI) p-value References population, N Age Alsowaidiet al., 2010 [3] 7550 OR 0.66 (0.54 - 0.81) < 0.0005 > 19 years in ref. to 13-19 years: OR adjusted for nationality, gender, family history of AR, and education Li et al., 2015 [22] 20,803 OR 1.05 (1.02-1.07) < 0.05 Continuous variable, 1 year increase (elementary school student) Lim et al., 2015 [11] 695 OR 0.72 (0.58 - 0.88) < 0.01 Continuous variable, 10 year increase (18 - 60 years): OR adjusted for gender, smoking, house dust mite allergy, cat allergy, home dampness, and home renovation Ng & Tan, 1994 [36] 2868 OR 0.19 (0.10 – 0.35) < 0.0001 60-74 years in ref. to 20-39 years: OR adjusted for race, flat size, housing estate, smoking, insect exposure, occupational exposure, and fume Ziyab, 2017 [8] 1154 PR 1.04 (1.01 - 1.07) < 0.01 Continuous variable (18-26 years): PR adjusted for gender, cat exposure, maternal AR, and paternal AR Gender Alsowaidi et al., 2010 [3] 7550 OR 0.75 (0.63 - 0.88) < 0.005 Male in ref. to female: OR adjusted for nationality, age, family history of AR, and education Graif et al., 2004 [38] 10,057 OR 0.85 (0.74 – 0.97) – Male in ref. to female: OR adjusted for current asthma, family history of asthma, race, residency, and smoking Hsu et al., 2009 [10] 1368 OR 0.58 (0.47 – 0.72) < 0.001 Male in ref. to female: OR adjusted for birth weight, parity, gestational age, maternal education, gestational complications, smoking, pets, carpets, molds, and air pollutions Lee et al., 2017 [42] 1497 OR 1.57 < 0.01 Male in ref. to female Lei, Yang & Zhen, 3327 OR 0.68 (0.46 - 1.00) < 0.05 Male in ref. to female 2016 [40] Li et al., 2015 [22] 20,803 OR 1.55 (1.41 - 1.70) < 0.001 Male in ref. to female Race Graif et al., 2004 [38] 10,057 OR 1.75 (1.45 - 2.13) – Jews in ref. to Arabs: OR adjusted for current asthma, family history of asthma, gender, residency, and smoking Ng & Tan, 1994 [36] 2, 868 OR 2.02 (1.29 - 3.14) < 0.005 Indian in ref. to Malay: OR adjusted for age, flat size, housing estate, smoking, insect exposure, occupational exposure, and fume Norbäck et al., 462 OR 0.33 (0.13 - 0.88) < 0.05 Indian in ref. to Malay: OR adjusted for gender, smoking, atopy, 2016 (2) [35] and family history of allergic diseases Nationality Alsowaidi et al., 2010 [3] 7550 OR 0.48 (0.34 - 0.68) < 0.005 Others in ref. to Arabs: OR adjusted for age, gender, family history of AR, and education Residency Graif et al., 2004 [38] 10,057 OR 0.84 (0.90 - 1.40) – Urban in ref. to rural: OR adjusted for current asthma, family history of asthma, gender, gender, and smoking Lee et al., 2017 [42] 1497 OR 0.71 < 0.05 Townhouse in ref. to others Li et al., 2014 [7] 9899 OR 1.91 (1.37 - 2.68) < 0.001 Urban in ref. to rural Min et al., 1997 [20] 10,054 OR 5.26 (2.27 - 12.50) < 0.05 Urban in ref. to rural: OR adjusted for age Housing estate Li et al., 2015 [22] 20,803 OR 2.19 (1.97 - 2.43) < 0.001 Cities SH, GZ, WH, CD in ref. to XA, HA, HO, UR Ng & Tan, 1994 [36] 2868 OR 1.92 (1.07 - 3.46) < 0.05 Toa Payoh in ref. to Yishun : OR adjusted for age, flat size, race, smoking, insect exposure, occupational exposure, and fume Household income Bunnag et al., 2000 [37] 3124 OR 1.97 (1.23 - 3.16) < 0.05 High income in ref. to medium income: adjusted OR Li et al., 2015 [22] 20,803 OR 1.42 (1.21 - 1.68) < 0.001 800-1500 RMB/month in ref. to 800 RMB/month 1.93 (1.64 - 2.27) < 0.001 1500-2500 RMB/month in ref. to 800 RMB/month 2.88 (2.47 - 3.37) < 0.001 > 2500 RMB/month in ref. to 800RMB/month Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 9 of 21 Table 4 Strength of association of demographic factors with AR manifestation (Continued) Study Study OR/PR Values (95% CI) p-value References population, N Phathammavong et al., 536 OR 2.23 (1.04 - 4.81) < 0.05 High income in ref. to low income: OR adjusted for gender, 2008 [9] age, parity, parents education, pets ownership, sharing bed, air conditioning, measles infection, respiratory infection, time on road, meat, fish, vegetables, cow milk, fast food and eggs consumptions, and intestinal parasitic infestation Parity Hsu et al., 2009 [10] 1368 OR 1.42 (1.02 - 1.97) < 0.025 N = 1 in ref. to N ≥ 3 : OR adjusted for birth weight, gender, gestational age, maternal education, gestational complications, smoking, pets, carpets, molds, and air pollutions 1.43 (1.01 - 2.01) < 0.025 N = 2 in ref. to N ≥ 3: OR adjusted for birth weight, gender, gestational age, maternal education, gestational complications, smoking, pets, carpets, molds, and air pollutions Family size Li et al., 2015 [22] 20,803 OR 1.26 (1.05 - 1.51) < 0.005 N < 3 in ref. to N ≥ 4 1.18 (1.0 - 1.30) < 0.005 N = 3 in ref. to N ≥ 4 Marital status An et al., 2015 [2] 31,217 OR 0.85 (0.74 - 0.97) < 0.05 Married in ref. to unmarried: OR adjusted for age, gender, family size, residency, educational, Household income, and occupation OR odds ratio, PR prevalence ratio influences to the disease presentation. These factors are allergic responses and enhance AR expression (Table 8) highly varied from one person to another and are often [28]. In addition, literature has suggested the possibility of affected by their background and the social group they dust trapped on the computer [7] and higher indoor aller- interact with. gen exposure [2]to explain thehigher oddsofAR mani- As stated in Table 5, like the case with many other in- festation among office workers who usually have higher fectious diseases [23, 24], alcohol consumption and education qualifications. Dose-response effects were also smoking habits have shown to increase the odds of pre- observed in computer usage, education attainment and senting AR. This is especially true for the smoking habit; stress level as odds of AR increase with higher level of risk which shows higher odds of expressing AR among exposure, with the exception for AR odds of college stu- present smokers, past smokers, and even passive dents to illiterate individuals in Min et al. [20]. smokers as compared to non-smokers and those who In contrast, people with parasitic or past respiratory are not exposed to passive smoking. The result is con- infections were reported to have higher odds of AR pres- sistent across four independent articles and a pooled entation. The results are contradictory with biological odds ratio of 1.34 was obtained indicating smoking habit plausibility discussed in other literature. Phathamma- does associate with the increased AR manifestation vong et al. [9], proposed that AR and other respiratory (Fig. 2). infections compete for immune responses, resulting in a Coincidentally, people with more computer usage, higher odds of presenting AR among the respiratory in- higher education, higher stress level and lesser sleeping fection patients. This hypothesis is supported by the re- time were presented with higher AR susceptibility. ported odds of AR for individuals with either parasitic Though several pathways were speculated for such asso- infection or past respiratory infection are exceptionally ciation, the effects of confounders and bias could not be high (3.41 and 4.06 respectively). However, this factor ruled out and further study is required to establish the has only been studied in Phathmmavong et al. among direct association link between these factors. the articles reviewed and further analysis is essential to Stress might be one of the critical risk factors for AR confirm the effects of these infections on AR presenta- presentation. Studies have shown the association be- tion, which could be one of the most important factors tween the level of stress in individuals with more fre- in predicting AR risk. quent drinking and smoking habits, having higher daily computer usage, and higher education levels but with Family risk factors affecting AR presentation less sleeping time [25–27]. Being in a stressful situation In Table 6, mother depression and cesarean delivery are can trigger the expression of cortisol which can induce positively correlated with the odds of AR presentation. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 10 of 21 Fig. 1 Individual and combined odds ratio and 95% confidence intervals for higher income group in association with Allergic Rhinitis presentation As stated in Li et al. [22], pre- and postnatal depression Environmental risk factors affecting AR presentation stimulates the production of cortisol, and this secretion af- As suggested in multiple studies investigated, environ- fects the immune development of a fetus and increases mental factors are highly important in triggering AR. For the odds of presenting AR. Apart from this, cesarean de- instance, Table 7 has shown that the presence of allergens livery might further exacerbate this situation as unlike va- such as fungi, molds, insects and house dust mites could ginal delivery, the infants are not exposed to the mother’s increase the odds of presenting AR. Among the allergens birth canal microflora, which has shown to be protective studied, the presence of fungi and molds were reported to against AR expression [29] as illustrated in Table 8. have very high odds of association to AR with 3.44 for Conversely, inconsistent results are observed for the asso- fungi in Norbäck et al. [35] and 9.40 for molds in Kidoni ciation of breastfeeding with AR presentation across mul- et al. [19] Moreover, insect exposure and house dust mite tiple studies [30, 31]. This refutes the commonly accepted have been identified as two of the most important risk fac- hypothesis which states breastfeeding as protective through tors for AR as indicated in Table 7. These common indoor the antibodies present in the milk and the additional nutri- allergens, such as mold and fungal spores, insect wastes ents from the mother’s diet transferred to the milk [32, 33]. and house dust mite fecal proteins can induce Type I In contrast, parental education and awareness encourages a hypersensitivity reaction by promoting the expression of a hygienic environment which is unfavorable for AR protec- range of allergic-causing mediators, thus increasing the tion as this reduces the chance of exposing their children to odds of expressing AR (Table 8). In addition, the a larger variety of allergens in early life. Similarly, for gruel utilization of carpets, which trap dust, and home renova- consumption, the subtle protection might be due to the ef- tion, which introduces a variety of allergic-causing renova- fect of gruel to stimulate inflammatory cytokines which tion materials, further exacerbate the situation. suppress the allergic reaction [34]. Similarly, outdoor exposures to heavy traffic, air pollu- On the other hand, genetic factor is long established to tion, and fume exposure were also reported to be posi- play an influential role in AR presentation [15]and afam- tively correlated with AR manifestation. These factors are ily history of atopy and allergic diseases might predispose especially crucial for those whose occupations expose children to AR. Multiple studies have shown that family them to the allergens [36]. Constant outdoor encounters history is a key risk factor associated with the increased with pollutants released from motor vehicles and heavy risk of AR expression. This is particularly true for children fumes during work promote AR presentation by changing with a family history of AR as high odds ratios of 6.08 and aperson’s susceptibility towards allergens [2, 10, 21, 36]. 3.51 have been reported in studies conducted by Also- waidi et al. [3] and Li et al. [7], respectively. However, gen- Evaluation of risk factors associated with AR manifestation etic factor is non-modifiable and hence, it needs to be using several criteria complemented with other preventive measures in order to Various risk factors have shown strong association with reduce the risk of presenting the disease. AR presentation. Results are consistent for several risk Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 11 of 21 Table 5 Strength of association of personal risk factor with AR manifestation Study Study OR Values (95% CI) p-value References population, N Alcohol Bunnag et al., 2000 [37] 3124 OR 1.46 (1.15 - 1.86) < 0.05 Drinker in ref. to non-drinker: adjusted OR Smoking Bunnag et al., 2000 [37] 3124 OR 1.39 (1.05 - 1.83) < 0.05 Smoker in ref. to non-smoker: adjusted OR Li et al., 2014 [7] 9899 OR 1.44 (1.10 - 1.88) < 0.01 Smoker in ref. to non-smoker Ng & Tan, 1994 [36] 2868 OR 1.75 (1.01 – 3.04) < 0.05 Past smoker in ref. to non- smoker: OR adjusted for age, flat size, housing estate, race, insect exposure, occupational exposure, and fume Zuraimi et al., 2008 [39] 6794 OR 1.23 (1.01 - 1.50) – Passive smoker in ref. to non-passive smoker: OR adjusted for age, gender, race, socioeconomic status, housing type, family atopy, breastfeeding, food allergy, respiratory infections, home dampness, air conditioning, home wall paper, carpet, home traffic density, childcare centre ventilation and dampness Computer usage Li et al., 2014 [7] 9899 OR 1.45 (1.10 - 1.91) < 0.01 Occasionally in ref. to never 1.46 (1.10 - 1.93) < 0.01 < 2 h daily in ref. to never 1.58 (1.14 - 2.19) < 0.01 2-4 h daily in ref. to never Education Alsowaidi et al., 7550 OR 1.42 (1.05 - 1.93) < 0.05 University in ref. to illiterate and primary school: 2010 [3] OR adjusted for nationality, gender, family history of AR, and age Min et al., 1997 [20] 10,054 OR 1.83 (0.82 - 4.02) < 0.05 Elementary in ref. to illiterate: OR adjusted for age 2.11 (0.93 - 4.79) < 0.05 Junior in ref. to illiterate: OR adjusted for age 2.81 (1.34 - 5.86) < 0.05 Senior in ref. to illiterate: OR adjusted for age 2.54 (1.08 - 5.96) < 0.05 College in ref. to illiterate: OR adjusted for age Stress An et al., 2015 [2] 31,217 OR 1.14 (1.01 - 1.28) < 0.001 A little in ref. to little: OR adjusted for age, gender, height, weight, body mass index, smoking status, sleep time and drinking 1.46 (1.28 - 1.66) < 0.001 Moderate in ref. to little : OR adjusted for age, gender, height, weight, body mass index, smoking status, sleep time and drinking 1.47 (1.21 - 1.79) < 0.001 Severe in ref. to little : OR adjusted for age, gender, height, weight, body mass index, smoking status, sleep time and drinking Sleep time An et al., 2015 [2] 31,217 OR 0.92 (0.84 - 1.00) < 0.05 > 7 h in ref. to ≤7h : OR adjusted for age, gender, height, weight, body mass index, smoking status, stress and drinking Parasitic infection Phathammavong 536 OR 3.41 (1.03 - 11.29) < 0.05 With parasitic infection in ref. to without et al., 2008 [9] : OR adjusted for gender, age, parity, parents education, pets ownership, sharing bed, air conditioning, measles infection, respiratory infection, time on road, meat, fish, vegetables, cow milk, fast food and eggs consumptions, and family income Past respiratory infection Phathammavong 536 OR 4.06 (1.83 - 9.01) < 0.05 With past respiratory infection in ref. to without et al., 2008 [9] : OR adjusted for gender, age, parity, parents education, pets ownership, sharing bed, air conditioning, Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 12 of 21 Table 5 Strength of association of personal risk factor with AR manifestation (Continued) Study Study OR Values (95% CI) p-value References population, N measles infection, family income, time on road, meat, fish, vegetables, cow milk, fast food and eggs consumptions, and intestinal parasitic infestation OR odds ratio factors across studies with different experimental setups Last but not least, with reference to Fig. 3, the two risk and countries. factors, family income and smoking, analyzed using In addition to the ORs, criteria such as biological gra- meta-analysis are consistently being identified as signifi- dient, biological plausibility and temporality are import- cant AR risk factor before and after 2010. In addition, ant in evaluating the association between risk factors education attainment and occupational exposure are two and AR. The biological gradient of the factor can be other significant modifiable risks that appeared in AR established especially when it is studied in a continuous publications before and after 2010 in Asia. In contrast, it manner or in multiple exposure levels. This was demon- was observed that after the year 2010, more strated in various demographical factors such as in fam- family-related risks were analyzed and shown to be sig- ily income, family size, personal factors like computer nificant AR risk factors, such as the age of gestation and usage, education attainment, stress levels and even in breastfeeding. This suggests a shift in focus to consider parental education attainment. Moreover, the association more family-related risk factors among the Asian between the risk factors and AR manifestation are fur- population. ther strengthened when factors with similar roles in AR presentation, such as the common allergens like house Limitations and conclusion dust mites, fungi, and molds, display comparable results. The studies chosen for this review are limited to articles Furthermore, the listed factors can only be considered published in Asia. Thus, the result might not be relevant as a potential risk if its exposure is reasonably affected and applicable to other nations outside Asia. In addition, or altered the risk of AR development. Its biologic the analysis might still be biased though several criteria plausibility must also be coherent to the study results have been used in establishing the significance of the po- found. However, with reference to Table 7, breastfeeding, tential AR risk factor in triggering or protecting parasitic infection and past respiratory infections show against AR presentation. The analysed data could be contradictory results as to what is hypothesized and fur- affected by personal viewpoints in addition to errors ther analysis and interpretation is thus needed. occurred when translating data from primary Fig. 2 Individual and combined odds ratio and 95% confidence intervals for smokers/past-smokers in association with Allergic Rhinitis presentation Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 13 of 21 Table 6 Strength of association of family factor with AR manifestation Study Study OR/PR Values (95% CI) p-value References population, N Age of gestation Lee et al., 2017 [42] 1497 OR 0.51 < 0.05 Preterm in ref. to term Li et al., 2015 [22] 20,803 OR 1.07 (0.88 - 1.30) < 0.001 Preterm in ref. to term 1.42 (1.20 - 1.69) < 0.001 Post-term in ref. to term Mother depression Li et al., 2015 [22] 20,803 OR 1.16 (1.05 - 1.29) < 0.05 Mother with pre- or postnatal depression in ref. to without Mode of delivery Li et al., 2015 [22] 20,803 OR 1.36 (1.23 - 1.49) < 0.001 Cesarean in ref. to vaginal delivery Breastfeeding Huang et al., 13,335 OR 0.97 (0.94 - 0.99) < 0.05 With exclusive for > 6 months breastfeeding in ref. to never 2017 [34] breastfeeding : OR adjusted for family atopy, gender, age, district of the current residence, home ownership, early pet-keeping, parental smoking, and home dampness Li et al., 2015 [22] 20,803 OR 0.67 (0.61 – 0.73) < 0.001 With exclusive breastfeeding in the first 4 months in ref. to without Maternal education Li et al., 2015 [22] 20,803 OR 1.55 (1.36 - 1.77) < 0.001 High school in ref. to middle school or below 2.11 (1.86 - 2.39) < 0.001 College or above in ref. to middle school or below Paternal education Li et al., 2015 [22] 20,803 OR 1.52 (1.32 - 1.74) < 0.001 High school in ref. to middle school or below 2.02 (1.77 - 2.30) < 0.001 College or above in ref. to middle school or below Gruel introduction Huang et al., 2017 [34] 13,335 OR 0.95 (0.90 - 1.00) < 0.05 For > 6 months-old in ref. to < 3 months-old : OR adjusted for family atopy, gender, age, district of the current residence, home ownership, early pet-keeping, parental smoking, and home dampness Family history of atopy Bunnag et al., 3124 OR 1.96 (1.56 - 2.46) < 0.05 With family history of atopy in ref. to without: adjusted OR 2000 [37] Family history of allergic diseases Alsowaidi et al., 7550 OR 6.08 (4.93 - 7.50) < 0.0005 With family history of AR in ref. to without 2010 [3] : OR adjusted for nationality, gender, age, and education Li et al., 2014 [7] 9899 OR 3.51 (2.65 - 4.64) < 0.001 With family history of AR in ref. to without Graif et al., 2004 [38] 10,057 OR 1.30 (1.02 - 1.66) – With family history of asthma in ref. to without: OR adjusted for current asthma, gender, gender, gender, and smoking Norbäck et al., 462 OR 3.49 (1.97 - 6.20) < 0.001 With family history of allergic reactions in ref. to without: OR 2016 (2) [35] adjusted for gender, smoking, atopy, and race Ziyab, 2017 [8] 1154 PR 1.82 (1.39 - 2.39) < 0.001 With maternal allergy in ref. to without: PR adjusted for gender, cat exposure, and age 1.87 (1.25 - 2.77) < 0.005 With paternal allergy in ref. to without: PR adjusted for gender, cat exposure, and age OR odds ratio, PR prevalence ratio literature to the review summaries, such as misrepre- association of a particular risk factor with the disease sentation and misinterpretation of the original data. presentation might not be as straightforward as what Thus, it is highly recommended for readers to refer is illustrated here. to the original articles before extracting any informa- From the articles reviewed, family income, family size, tion from this article. Furthermore, as most of the computer usage, personal and parental education attain- studies used in this review are observational studies, ment and stress level are identified as risk factors with confounding effects cannot be ruled out and the the greatest potential to influence AR presentation, and Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 14 of 21 Table 7 Strength of association of environmental risk factors with AR manifestation Study Study OR/PR Values (95% CI) p-value References population, N Fungi Norbäck et al., 462 OR 0.76 (0.58 - 0.99) < 0.05 With fungi in ref. to without: OR adjusted for gender, ethnicity, 2016 (1) [41] smoking, atopy and heredity Norbäck et al., 462 OR 3.44 (1.81 - 6.59) < 0.001 With fungal endotoxin C14 3-OH FA in ref. to without: OR adjusted 2016 (2) [35] for classroom level Mold Kidoni et al., 202 OR 9.40 (3.80 - 22.90) – With mold sensitization vs without 2004 [19] Insect Ng & Tan, 1994 [36] 2868 OR 2.08 (1.29 – 3.35) < 0.005 Once every day in ref. to once every few months : OR adjusted for age, flat size, housing estate, race, race, occupational exposure, and fume House dust mite Lim et al., 2015 [11] 695 OR 1.66 (1.08 - 2.56) < 0.05 With house dust mite allergy in ref. to without : OR adjusted for gender, current smoking status, age, cat allergy, home dampness, and indoor home painting in last 12 months Norbäck et al., 462 OR 2.91 (1.35 - 6.24) < 0.01 Continuous variable, 1000 mg increase in fine dust 2016 (2) [35] : OR adjusted for classroom level Carpet Hsu et al., 2009 [35] 1368 OR 1.60 (1.09 - 2.35) < 0.025 With carpets in ref. to without : OR adjusted for birth weight, gender, gestational age, maternal education, gestational complications, smoking, pets, parity, molds, and air pollutions Home renovation Li et al., 2014 [7] 9899 OR 1.39 (1.06 - 1.81) < 0.05 With home renovation in ref. to without Air pollution Hsu et al., 2009 [10] 1368 OR 1.44 (1.10 - 1.88) < 0.01 With air pollution in ref. to without : OR adjusted for birth weight, gender, gestational age, maternal education, gestational complications, smoking, pets, carpets, molds, and parity Fume exposure Ng & Tan, 1994 [36] 2868 OR 2.29 (1.32 - 3.99) < 0.005 Often in ref. to rarely: OR adjusted for age, flat size, housing estate, race, race, occupational exposure, and race Traffic Zuraimi et al., 2994 PR 1.58 (1.04 - 2.39) < 0.05 Heavy traffic in ref. to low traffic for all children 2011 [21] : PR adjusted for gender, age, race, socioeconomic status, housing type, parental atopy, breastfeeding, food allergy, and resident height 1.73 (1.00 - 2.99) < 0.05 Heavy traffic in ref. to low traffic for all lifetime residents : PR adjusted for gender, age, race, socioeconomic status, housing type, parental atopy, breastfeeding, food allergy, and resident height Occupational exposure An et al., 2015 [2] 31,217 OR 1.28 (1.11 - 1.47) < 0.01 Unemployed in ref. to engineer : OR adjusted for age, gender, family size, residency, educational, household income, and marriage 1.29 (1.09 - 1.52) < 0.01 Manager, expert, specialist & clerks in ref. to engineer : OR adjusted for age, gender, family size, residency, educational, household income, and marriage 1.18 (1.01 - 1.39) < 0.01 Service worker & seller in ref. to engineer : OR adjusted for age, gender, family size residency, educational, household income, and marriage 1.32 (1.11 - 1.58) < 0.01 Technician, mechanics & production worker in ref. to engineer : OR adjusted for age, gender, family size, residency, educational, household income, and marriage Ng & Tan 1994 [36] 2868 OR 1.95 (1.36 - 2.80) < 0.0005 Wth occupational exposure vs without: OR adjusted for age, flat size, housing estate, race, race, fume, and race OR odds ratio, PR prevalence ratio Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 15 of 21 Table 8 Collated potential risk factors for AR presentation No Potential risk factor No. of studies No. of studies with Possible explanations Sources significant results 1 Age 7 5 The allergic condition is highest in young adults, declining with age [43]. However, the Alsowaidi et al., reason remains unclear. 2010 [3] Li et al., 2015 [22] Lim et al., 2015 [11] Ng & Tan, 1994 [36] Ziyab, 2017 [8] Li et al., 2014 [7] Phathammavong et al., 2008 [9] 2 Age of gestation 3 2 Preterm baby, who is characterized by lower birth weight and earlier exposure to the Lee et al., 2017 [42] mother microflora, have prematurity protection against AR [42]. In contrast, successful Li et al., 2015 [22] pregnancy shifted the T lymphocytes production to Th2 which increases the risk of Hsu et al., 2009 [10] atopy and AR [22]. 3 Air conditioning 2 0 Home dampness has been shown to be related to allergic rhinitis exacerbations [44], Phathammavong et al., 2008 [9] probably in relation to the development of mold or mildew. As air-conditional areas Zuraimi et al., usually have higher dampness, it may lead to increase in AR 2011 [21] expression [45]. 4 Air pollution 2 1 The pollutants might provoke and exacerbate the allergic conditions of the current Hsu et al., 2009 [10] patients. Besides, it might also make a person more susceptible to certain allergens [45]. Ng & Tan, 1994 [36] 5 Alcohol consumption 3 1 Alcohol consumption is related to increased stress level which is one of the provoking Bunnag C et al., 2000 [37] (self/parent) factors potentially enhancing AR presentation [2]. An et al., 2015 [2] Li et al., 2015 [22] 6 Birth order 2 0 An allergic mother might be more prone to provide low-exposure environment for Phathammavong et al., 2008 [9] the next children [29]. Ziyab, 2017 [8] 7 BMI 2 0 Higher BMI and greater weight-to-height ratio is associated with higher atopic and An et al., 2015 [2] higher allergic diseases incidence Lei, Yang & Zhen, 2016 [40] regardless of gender and age [43]. 8 Breastfeeding 3 2 Breastfeeding for more than 6 months has shown to enhance the presentation of Huang et al., 2017 [34] AR [30, 31], but the reason remains unknown. Contrary plausibility has also shown that Li et al., 2015 [22] food proteins consumed by the mother [32] or breastfeeding might help to reduce the Li et al., 2014 [7] inflammatory responses by destroying microbes [33] and is thus protective against AR presentation. 9 Car ownership 1 0 Car owners spend more time outdoor and are thus exposed to higher levels of outdoor Li et al., 2014 [7] pollutants [46]. 10 Carpet 2 1 Having carpets at home increases the risk of accumulating mite allergens, thus Hsu et al., 2009 [10] resulting in more AR cases [47]. Ng & Tan, 1994 [36] 11 Computer usage 1 1 Studies suggested that when the computer is not properly cleaned, prolong usage of Li et al., 2014 [7] the computer will likely result in higher allergen exposure and thus an increase in AR cases [7]. 12 Drinking (self/parent) 3 1 Alcohol consumption is related to increased stress level which is one of the provoking Bunnag C et al., 2000 [37] factors potentially enhancing AR presentation [2]. An et al., 2015 [2] Li et al., 2015 [22] 13 Education attainment 3 2 People with higher education usually work in an indoor environment, thus exposing Alsowaidi et al., 2010 [3] them to indoor allergens [2]. Min et al., 1997 [20] Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 16 of 21 Table 8 Collated potential risk factors for AR presentation (Continued) No Potential risk factor No. of studies No. of studies with Possible explanations Sources significant results An et al., 2015 [2] 14 Family history of 6 5 Allergic diseases can be hereditary, with incomplete genetic penetrance [48]. Alsowaidi et al., 2010 [3] allergic diseases Li et al., 2014 [7] Graif et al., 2004 [38] Norbäck et al., 2016 (2) [35] Ziyab, 2017 [8] Phathammavong et al., 2008 [9] 15 Family history of 1 1 Atopy is usually used as a marker for other allergic diseases, and genetic factors Bunnag et al., 2000 [37] atopy usually play a role in allergic disease presentation. As such, higher family history of atopy usually suggests higher chance of contracting allergic diseases [43]. 16 Family size 2 1 Crowding increases the contact of an individual with allergens and is thus Li et al., 2015 [22] protective against manifestation of allergic reaction [47]. An et al., 2015 [2] 17 Food 1 0 Some foods are protective against AR, most likely through shifting the macromolecules Phathammavong et al., 2008 [9] production, such as fatty acid balance, which later results in the reduction of inflammatory mediators required for disease presentation [30]. 18 Fume exposure 1 1 Fume released into the air by various means is also one of the potential triggering Ng & Tan, 1994 [36] factors in AR presentation [45]. 19 Fungi 2 2 Airborne fungi spores induce type I hypersensitivity and hence AR presentation [49]. Norbäck et al., 2016 (1) [41] Norbäck et al., 2016 (2) [35] 20 Gender 12 7 The allergic diseases appear more frequently in males at infant age, but with equal Alsowaidi et al., 2010 [3] burden as females at mid-teens, and then become more frequent in females with Graif et al., 2004 [38] the reason remain largely unknown [43]. Hsu et al., 2009 [10] Lee et al., 2017 [42] Lei, Yang & Zhen, 2016 [40] Li et al., 2015 [22] Bunnag et al., 2000 [37] Lim et al., 2015 [11] Ng & Tan, 1994 [36] Norbäck et al., 2016 (2) [35] Phathammavong et al., 2008 [9] Ziyab, 2017 [8] 21 Gestational complication 1 0 Uterus complication during gestation periods affects the immune system development Hsu et al., 2009 [10] of the fetus and increases the risk of atopy-related diseases [29]. 22 Gruel introduction 1 1 Study shows that gruel introduction between 4 to 6 months, in complementary with Huang et al., 2017 [34] period breastfeeding, induces IL-10 and TGFβ production which is protective against AR [34]. 23 Hair coloring 1 0 Oxidative hair dye can induce hypersensitivity reactions, thus increasing the risk of Li et al., 2014 [7] expressing AR [50]. 24 Home renovation 1 1 The materials used during the home renovation, such as formaldehyde might have an Li et al., 2014 [7] impact in causing cell sensitization and later AR presentation [7, 31]. 25 House dust mite 2 2 Long term exposure to threshold concentrations of dust mite fecal proteins causes the Lim et al., 2015 [11] presentation of allergens by antigen presenting cells (APC) to CD4+ T lymphocytes, Norbäck et al., 2016 (2) [35] leading to the production of downstream mediators and manifestation of AR symptoms [49]. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 17 of 21 Table 8 Collated potential risk factors for AR presentation (Continued) No Potential risk factor No. of studies No. of studies with Possible explanations Sources significant results 26 Household income 5 3 Higher income is associated with better living conditions and hygiene behavior, thus Bunnag et al., 2000 [37] reducing the exposure to a variety of allergens, which possibly increases their odds Li et al., 2015 [22] of AR [42]. Phathammavong et al., 2008 [9] An et al., 2015 [2] Li et al., 2014 [7] 27 Housing estate 2 2 Living in a housing estate with poor environmental conditions has resulted in more Li et al., 2015 [22] allergic cases [47]. Ng & Tan, 1994 [36] 28 Insect 1 1 Prolonged exposure to insects, which is one of the common allergens may trigger Ng & Tan, 1994 [36] hypersensitivity reactions with production of mediators and hence, the expression of AR symptoms [49]. 29 Marital status 2 1 Being married is hypothesized to be associated with positive physical and mental An et al., 2015 [2] outcomes and is therefore protective against AR [2]. Min et al., 1997 [20] 30 Maternal education 2 1 Educated parents will have higher awareness of their children health status, and thus Li et al., 2015 [22] adopt protective measures to combat against AR starting from a young age [45]. Hsu et al., 2009 [10] 31 Maternal pre- or 1 1 Pre- or postnatal depression results in excessive cortisol expression, which will affect Li et al., 2015 [22] postnatal depression the immune system development of the fetus [22]. 32 Mode of delivery 2 1 Exposure of the fetus to the mother microflora during birth is an advantage to Li et al., 2015 [22] protect them against allergic sensitization [29, 51]. In contrast, cesarean birth is Ziyab, 2017 [8] associated with higher AR risk [51]. 33 Mold 2 1 Mold spores induce type I hypersensitivity and hence, AR presentation [49]. Kidoni et al., 2004 [19] Hsu et al., 2009 [10] 34 Nationality 1 1 AR prevalence is especially high in Asia probably due to the higher humidity, more Alsowaidi et al., 2010 [3] extensive smoking and vaccination habits [43]. 35 Occupational 3 2 Some occupations have higher risk of exposure to allergens, thus increasing their risk An et al., 2015 [2] exposure of expressing AR [50]. Ng & Tan, 1994 [36] Min et al., 1997 [20] 36 Parasitic infection 1 1 Parasitic infection might have some effects to a person’s gut microbiota, which could Phathammavong et al., 2008 [9] later offer some protection against allergic sensitization as stated in hygiene hypothesis [52]. However, some literature also show that parasitic infection influences the allergy development due to its competition with human immune response [9]. 37 Parity 2 1 Being allergic might cause reduced reproductivity in females, resulting in a lower Hsu et al., 2009 [10] parity which is associated with AR presentation [29]. Phathammavong et al., 2008 [9] 38 Past measles infection 1 0 The association of measles with AR is not clear, but it was hypothesized that measles Phathammavong et al., 2008 [9] infection might protect against AR development or could promote allergic sensitization [52]. 39 Past respiratory infection 1 1 Evidence shows that past respiratory infection, such as tuberculosis caused by Phathammavong et al., 2008 [9] Mycobacterium tuberculosis could be protective against AR, possibly through reduction of allergy sensitization [52]. In contrast, some studies have shown that past respiratory infection is directly associated with AR development [9]. 40 Paternal education 1 1 Educated parents are more likely to keep a hygienic living environment, thus possibly Li et al., 2015 [22] increasing the incidence of allergic conditions in their children [45]. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 18 of 21 Table 8 Collated potential risk factors for AR presentation (Continued) No Potential risk factor No. of studies No. of studies with Possible explanations Sources significant results 41 Pet 6 3 For individuals sensitive to pet furs, long term exposure to the pet induces Li et al., 2014 [7] hypersensitivity reaction and could later result in AR presentation [49]. Ziyab, 2017 [8] Phathammavong et al., 2008 [9] Hsu et al., 2009 [10] Lim et al., 2015 [11] Ng & Tan, 1994 [36] 42 Race 3 3 Cultural differences between the races probably have some effects on AR presentation; Graif et al., 2004 [38] however, there is currently no specific research addressing the impact of races on AR Ng & Tan, 1994 [36] disease presentation. Norbäck et al., 2016 (2) [35] 43 Residency 5 4 For people who lived in urban areas, they are more prevalent in developing allergic Graif et al., 2004 [38] reaction [47], probably due to a poorer housing or environmental conditions. Modern Lee et al., 2017 [42] building techniques increase indoor humidity and temperature, facilitates mold Li et al., 2014 [7] development and hence, contributes to AR presentation [2]. Min et al., 1997 [20] An et al., 2015 [2] 44 Sharing bed 1 0 Sharing bed is hypothesized as one of the potential risk factors for AR [9], probably Phathammavong et al., 2008 [9] due to increased risk of getting infections from other people. 45 Sleep time 1 1 People with lesser sleep are usually with higher levels of stress, which is a potential An et al., 2015 [2] trigger factor for AR expression [2]. 46 Smoking (self/parent) 12 4 Tobacco smoke is one of the trigger factors which precipitates the hypersensitivity Bunnag et al., 2000 [37] reactions, thus exacerbating the AR conditions [47]. On the other hand, parents with Li et al., 2014 [7] AR children will also try to reduce their children exposure to external allergic stimuli Ng & Tan, 1994 [36] through changing their smoking habits, thus explaining the negative association of Zuraimi et al., 2008 [39] AR and smoking habit [45]. An et al., 2015 [2] Hsu et al., 2009 [10] Li et al., 2015 [22] Lim et al., 2015 [11] Min et al., 1997 [20] Norbäck et al., 2016 (2) [35] Phathammavong et al., 2008 [9] Ziyab, 2017 [8] 47 Social class 1 0 As stated in hygiene hypothesis, people in lower social class are likely to have a Min et al., 1997 [20] greater exposure to infections. This may have direct and indirect impacts to their gut microbiota, which might offer protection against allergic sensitization [45, 52]. 48 Stress level 1 1 Stress can trigger the production of cortisol, and later induce allergic responses [28]. An et al., 2015 [2] 49 Time on road 1 0 Longer time spent on road is associated with higher AR risk, probably due to Phathammavong et al., 2008 [9] prolonged exposure to air contaminant [9]. 50 Traffic 1 1 The release of motor vehicles such as NO and CO provokes and exacerbates the Zuraimi et al., 2011 [21] conditions of the current AR patients, and might have consequences on changes in susceptibility towards allergens, thus affecting AR presentation [45]. Depending on the outdoor environmental pollution, long term exposure to heavy traffic might lead to allergic sensitization and resulted in AR expression [21]. Indicates the publication with insignificant results Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 19 of 21 Fig. 3 Years in which significant AR risk factors were identified Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 20 of 21 when compared to other factors, they fulfill most of the 5. Murray CS. Allergens, viruses, and asthma exacerbations. Proc Am Thorac Soc. 2004;1:99–104. https://doi.org/10.1513/pats.2306027. criteria listed. In contrast, more considerations are re- 6. Cookson W. The alliance of genes and environment in asthma and allergy. quired in interpreting the effects of breastfeeding, para- Nature 1999;402 November:B5–11. sitic infections and past respiratory infections to AR 7. Li CW, De Chen H, Zhong JT, Bin LZ, Peng H, Lu HG, et al. Epidemiological characterization and risk factors of allergic rhinitis in the general population presentation. These factors show incoherent biological in Guangzhou City in China. PLoS One. 2014;9:1–16. plausibility and more in-depth investigation and analysis 8. Ziyab AH. Prevalence and risk factors of asthma, rhinitis, and eczema and is thus required. their multimorbidity among young adults in Kuwait: a cross-sectional study. Biomed Res Int. 2017;2017:2184193. https://doi.org/10.1155/2017/2184193. The results obtained from this review article can be 9. Phathammavong O, Ali M, Phengsavanh A, Xaysomphou D, Odajima H, used to improve the diagnosis of AR in clinical settings Nishima S, et al. Prevalence and potential risk factors of rhinitis and atopic by identifying patients with risk factors strongly associ- eczema among schoolchildren in Vientiane capital, Lao PDR: ISAAC questionnaire. Biosci Trends 2008;2:193–199. ated with AR manifestation. In addition, as personal and 10. Hsu S-P, Lin K-N, Tan C-T, Lee F-P, Huang H-M. Prenatal risk factors and occurrence family-related modifiable factors are found to be strong of allergic rhinitis among elementary school children in an urban city. Int J Pediatr AR triggering factors, strategies to alleviate personal Otorhinolaryngol. 2009;73:807–10. https://doi.org/10.1016/j.ijporl.2009.02.023. 11. Lim FL, Hashim Z, LTL T, Said SM, Hashim JH, Norbäck D. Asthma, airway stress levels and increase the awareness of allergy risk in symptoms and rhinitis in office workers in Malaysia: associations with house a hygienic environment have to be developed. dust mite (HDM) allergy, cat allergy and levels of house dust mite allergens in office dust. PLoS One. 2015;10:1–21. 12. Tamay Z, Akcay A, Ones U, Guler N, Kilic G, Zencir M. Prevalence and risk Additional file factors for allergic rhinitis in primary school children. Int J Pediatr Otorhinolaryngol. 2007;71:463–71. Additional file 1: List of countries and dependent territories used in the 13. Sultész M, Katona G, Hirschberg A, Gálffy G. Prevalence and risk factors for literature review search. (PDF 322 kb) allergic rhinitis in primary schoolchildren in Budapest. Int J Pediatr Otorhinolaryngol. 2010;74:503–9. 14. Kuyucu S, Saraclar Y, Tuncer A, Geyik PO, Adalioglu G, Akpinarli A, et al. Abbreviations Epidemiologic characteristics of rhinitis in Turkish children: the international AR: Allergic rhinitis; OR: Odds ratio; PR: Prevalence ratio study of asthma and allergies in childhood (ISAAC) phase 2. Pediatr Allergy Immunol. 2006;17:269–77. https://doi.org/10.1111/j.1399-3038.2006.00407.x. Acknowledgements 15. Magnan A, Meunier JP, Saugnac C, Gasteau J, Neukirch F. Frequency and The authors would like to thank all authors involved in the studies reviewed impact of allergic rhinitis in asthma patients in everyday general medical above as well as the individuals that volunteered in these studies. In addition, practice: a French observational cross-sectional study. Allergy Eur J Allergy we also would like to express my special thanks of gratitude to Ng Yu Ting, Sri Clin Immunol. 2008;63:292–8. Anusha Matta, and Sio Yang Yie for language editing of this manuscript. 16. Cirillo I, Marseglia G, Klersy C, Ciprandi G. Allergic patients have more numerous and prolonged respiratory infections than nonallergic subjects. Authors’ contributions Allergy Eur J Allergy Clin Immunol. 2007;62:1087–90. FTC supported and guided the literature review process. SNC carried out the 17. Cardell LO, Olsson P, Andersson M, Welin KO, Svensson J, Tennvall GR, et al. literature review and translated the information into the manuscript. Both TOTALL: high cost of allergic rhinitis - a national Swedish population-based authors read and approved the final version of the article. questionnaire study. npj Prim Care Respir Med 2016;26. 18. Weiss KB, Sullivan SD. The health economics of asthma and rhinitis. I. Assess Ethics approval and consent to participate Econ Impact. J Allergy Clin Immunol. 2001;107:3–8. Not applicable. 19. Kidoni MI, See Y, Goh A, Chay OM, Balakrishnan A. Aeroallergen sensitization in pediatric allergic rhinitis in Singapore: is air-conditioning a factor in the Consent for publication tropics? Pediatr Allergy Immunol. 2004;15:340–3. Not applicable. 20. Min YG, Jung HW, Kim HS, Park SK, Yoo KY. Prevalence and risk factors for perennial allergic rhinitis in Korea: results of a nationwide survey. Competing interests Clin Otolaryngol Allied Sci. 1997;22:139–44. The authors declare that they have no competing interests. 21. Zuraimi MS, Tham KW, Chew FT, Ooi PL, Koh D. Home air-conditioning, traffic exposure, and asthma and allergic symptoms among preschool children. Pediatr Allergy Immunol. 2011;22(1 PART 2):112–8. Publisher’sNote 22. Li Y, Jiang Y, Li S, Shen X, Liu J, Jiang F. Pre-and postnatal risk factors in relation Springer Nature remains neutral with regard to jurisdictional claims in published to allergic rhinitis in school-aged children in China. PLoS One. 2015;10:1–11. maps and institutional affiliations. 23. Talamini G, Bassi C, Falconi M, Sartori N, Salvia R, Rigo L, et al. Alcohol and Received: 10 January 2018 Accepted: 11 July 2018 smoking as risk factors in chronic pancreatitis and pancreatic cancer. Dig Dis Sci. 1999;44:1303–11. 24. Poikolainen K, Karvonen J, Pukkala E. Excess mortality related to alcohol and smoking among hospital-treated patients with psoriasis. Arch Dermatol. References 1999;135:1490–3. https://doi.org/10.1001/archderm.135.12.1490. 1. Strachan D, Sibbald B, Weiland S, Aït-Khaled N, Anabwani G, Anderson HR, 25. Conway TL, Vickers RR, Ward HW, Rahe RH. Occupational stress and et al. Worldwide variations in prevalence of symptoms of allergic variation in cigarette, coffee, and alcohol consumption. J Health Soc Behav. rhinoconjunctivitis in children: the international study of asthma and 1981;22:155. https://doi.org/10.2307/2136291. allergies in childhood (ISAAC). Pediatr Allergy Immunol. 1997;8:161–76. 26. Robotham D, Julian C. Stress and the higher education student: a critical 2. An S-Y. Analysis of various risk factors predisposing subjects to allergic review of the literature. J Furth High Educ. 2006;30:107–17. https://doi.org/ rhinitis. Asian Pacific J Allergy Immunol. 2015;:143–52. doi:https://doi.org/10. 10.1080/03098770600617513. 12932/AP0554.33.2.2015. 3. Alsowaidi S, Abdulle A, Shehab A, Zuberbier T, Bernsen R. Allergic rhinitis: 27. Jacobsen LK, Southwick SM, Kosten TR. Substance use disorders in patients prevalence and possible risk factors in a gulf Arab population. Allergy Eur J with posttraumatic stress disorder : a review of the literature. Am J Allergy Clin Immunol. 2010;65:208–12. Psychiatry. 2001;158:1184–90. https://doi.org/10.1176/appi.ajp.158.8.1184. 4. Bousquet J. Allergic rhinitis and its impact on asthma (ARIA) 2008. Allergy. 28. Osman M. Therapeutic implications of sex differences in asthma and atopy. 2008;63:1052–5. https://doi.org/10.1111/j.1398-9995.2007.01620.x. Arch Dis Child. 2003;88:587–90. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 21 of 21 29. Nafstad P, Magnus P, Jaakkola JJ. Risk of childhood asthma and allergic rhinitis in relation to pregnancy complications. J Allergy Clin Immunol. 2000;106:867–73. 30. NafstadP,NystadW,MagnusP,Jaakkola JJK. Asthma andallergic rhinitis at 4 years of age in relation to fish consumption in infancy. J Asthma. 2003;40:343–8. 31. Wang X, Liu W, Hu Y, Zou Z, Shen L, Huang C. Home environment, lifestyles behaviors, and rhinitis in childhood. Int J Hyg Environ Health. 2016;219:220–31. 32. Spiekermann GM, Walker WA. Oral tolerance and its role in clinical disease. J Pediatr Gastroenterol Nutr. 2001;32:237–55. 33. Hanson LÅ. Session 1: feeding and infant development breast-feeding and immune function. Proc Nutr Soc. 2007;66:384–96. https://doi.org/10.1017/S0029665107005654. 34. Huang C, Liu W, Cai J, Weschler LB, Wang X, Hu Y, et al. Breastfeeding and timing of first dietary introduction in relation to childhood asthma, allergies, and airway diseases: a cross-sectional study. J Asthma. 2017;54:488–97. 35. Norbäck D, Hashim JH, Markowicz P, Cai GH, Hashim Z, Ali F, et al. Endotoxin, ergosterol, muramic acid and fungal DNA in dust from schools in Johor Bahru, Malaysia - associations with rhinitis and sick building syndrome (SBS) in junior high school students. Sci Total Environ. 2016;545– 546:95–103. https://doi.org/10.1016/j.scitotenv.2015.12.072. 36. Ng TP, Tan WC. Epidemiology of allergic rhinitis and its associated risk- factors in Singapore. Int J Epidemiol. 1994;23:553–8. 37. Bunnag C, Jareoncharsri P, Voraprayoon S, Kongpatanakul S. Epidemiology of rhinitis in Thais : characteristics and risk factors. Asian Pacific J Allergy Immunol. 2000;18:1. 38. Graif Y, Garty B-Z, Livne I, Green MS, Shohat T. Prevalence and risk factors for allergic rhinitis and atopic eczema among schoolchildren in Israel: results from a national study. Ann Allergy Asthma Immunol. 2004;92:245–9. https://doi.org/10.1016/S1081-1206(10)61555-4. 39. Zuraimi MS, Tham KW, Chew FT, Ooi PL, David K. Home exposures to environmental tobacco smoke and allergic symptoms among young children in Singapore. Int Arch Allergy Immunol. 2008;146:57–65. 40. Lei Y, Yang H, Zhen L. Obesity is a risk factor for allergic rhinitis in children of Wuhan (China). Asia Pac Allergy. 2016;6:101–4. https://doi.org/10.5415/ apallergy.2016.6.2.101. 41. Norbäck D, Hashim JH, Cai GH, Hashim Z, Ali F, Bloom E, et al. Rhinitis, ocular, throat and dermal symptoms, headache and tiredness among students in schools from Johor Bahru, Malaysia: associations with fungal DNA and mycotoxins in classroom dust. PLoS One. 2016;11:1–15. 42. Lee M-T, Wu C-C, Ou C-Y, Chang J-C, Liu C-A, Wang C-L, et al. A prospective birth cohort study of different risk factors for development of allergic diseases in offspring of non-atopic parents. Oncotarget. 2017;8:10858–70. https://doi.org/10.18632/oncotarget.14565. 43. Yao TC, Ou LS, Yeh KW, Lee WI, Chen LC, Huang JL. Associations of age, gender, and BMI with prevalence of allergic diseases in children: PATCH study. J Asthma. 2011;48:503–10. 44. Kilpeläinen M, Terho EO, Helenius H, Koskenvuo M. Home dampness, current allergic diseases, and respiratory infections among young adults. Thorax. 2001;56:462–7. 45. Lee YL, Shaw CK, Su HJ, Lai JS, Ko YC, Huang SL, et al. Climate, traffic-related air pollutants and allergic rhinitis prevalence in middle-school children in Taiwan. Eur Respir J. 2003;21:964–70. 46. Duggan EM, Sturley J, Fitzgerald AP, Perry IJ, Hourihane JOB. The 2002-2007 trends of prevalence of asthma, allergic rhinitis and eczema in Irish schoolchildren. Pediatr Allergy Immunol. 2012;23:464–71. 47. Gelber LE, Seltzer LH, Bouzoukis JK, Pollart SM, Chapman MD, Platts- Mills T a. Sensitization and exposure to indoor allergens as risk factors for asthma among patients presenting to hospital. Am Rev Respir Dis. 1993;147:573–8. 48. Dold S, Wjst M, von Mutius E, Reitmeir P, Stiepel E. Genetic risk for asthma, allergic rhinitis, and atopic dermatitis. Arch Dis Child. 1992;67:1018–22. https://doi.org/10.1136/adc.67.8.1018. 49. Skoner DP. Allergic rhinitis: definition, epidemiology, pathophysiology, detection, and diagnosis. J Allergy Clin Immunol. 2001;108(1 SUPPL):S2–8. 50. Helaskoski E, Suojalehto H, Virtanen H, Airaksinen L, Kuuliala O, Aalto-Korte K, et al. Occupational asthma, rhinitis, and contact urticaria caused by oxidative hair dyes in hairdressers. Ann Allergy Asthma Immunol. 2014;112:46–52. 51. Pistiner M, Gold DR, Abdulkerim H, Hoffman E, Celedón JC. Birth by cesarean section, allergic rhinitis, and allergic sensitization among children with a parental history of atopy. J Allergy Clin Immunol. 2008;122:274–9. 52. Strachan DP. Family size, infection and atopy: the first decade of the “hygiene hypothesis”. Thorax. 2000;55(Suppl 1):S2–10. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png World Allergy Organization Journal Springer Journals

Epidemiology of allergic rhinitis and associated risk factors in Asia

World Allergy Organization Journal , Volume 11 (1) – Aug 6, 2018

Loading next page...
 
/lp/springer-journals/epidemiology-of-allergic-rhinitis-and-associated-risk-factors-in-asia-CCCW2I0Fz4
Publisher
Springer Journals
Copyright
Copyright © 2018 by The Author(s).
Subject
Medicine & Public Health; Allergology; Immunology
eISSN
1939-4551
DOI
10.1186/s40413-018-0198-z
Publisher site
See Article on Publisher Site

Abstract

This review article aims to present the epidemiology and associated risk factors of allergic rhinitis (AR) in Asia. AR-related literature published on Asia was systematically reviewed and the associated risk factors were investigated. The prevalence of AR in Asia varied considerably depending on the geographical location, study design and population involved. Several risk factors were observed to have strong association with disease presentation across multiple studies. Among these, family income, family size, daily personal computer usage time, personal and parental education attainment, and stress level have shown some level of biological gradient influence when multiple risk levels were analyzed. This suggests that AR manifestation and presentation possibly might be strongly affected by various personal and family factors. These findings are beneficial as they may provide insights into modifiable factors that may influence AR presentation. In addition, these results indicate that strategies to reduce personal and family-related risk factors have to be developed in order to alleviate the odds of AR expression. Keywords: Allergic rhinitis, Risk factor, Asia, Systematic review Background Risk factors affecting the presentation of allergic rhinitis Allergic rhinitis epidemiology and symptoms Apart from the demographic factors, smoking and drink- According to the Phase III International Study of Asthma ing habits, pet adoption, education attainment, and fam- and Allergies in Childhood (ISAAC), the prevalence of AR ily history were the risk factors of AR, commonly varied between 0.8 to 14.9% in 6-7 years old and 1.4 to studied in Asian countries [7–11]. Conversely, Western 39.7% in 13-14 years old worldwide [1]. In Asia, this countries focus more on the effects of pollens, drugs, disease affects a large population, ranging from 27% in pets, and family history on the presentation of AR South Korea [2] to 32% in the United Arab Emirates [3]. [12–14]. The differences between the risk factors ana- It is a prevalent yet underappreciated atopic disorder lyzed could be culturally induced or due to the climatic which is commonly characterized by the presence of at least differences between Asian and Western countries. one of the following clinical symptoms: persistent nasal ob- However, it was observed that pet adoption and family struction and mucous discharge, sneezing, and itching [4]. history are the common risk factors studied in both re- Although AR is commonly regarded as a mild and gions, suggesting their pervasiveness in inducing AR seasonal nuisance, it can trigger persistent mucosal inflam- manifestation worldwide. mation which may synergize with other infective inflamma- tion, resulting in severe outcomes including hospitalization Disease diagnosis [5]. As such, the odds of hospital admission for children While AR is influenced by genetic predisposition, the with the allergic disease have been reported to increase by symptom presentation also depends on environmental 19 times with the co-infection of rhinoviral diseases, allergic exposures [15]. In addition, the disease can co-present sensitization, and allergen exposure [6]. with other diseases, such as asthma and other infectious diseases, which could further complicate the disease * Correspondence: dbscft@nus.edu.sg diagnosis. A robust association of rhinitis was found Department of Biological Sciences, Faculty of Science, Allergy and Molecular among individuals with allergic and non-allergic asthma Immunology Laboratory, Lee Hiok Kwee Functional Genomics Laboratories, [16]. Among patients with persistent and severe rhinitis, National University of Singapore, Block S2, Level 5, Science Drive 4, Lower Kent Ridge Rd, Singapore 117543, Singapore asthma was found prevailing [17]. © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 2 of 21 Moreover, patients can experience adverse effects on AR manifestation were evaluated using several important social life, productivity at work and performance in criteria established in literature. These criteria include the school, especially for those who suffer from a more se- strength of association, consistency of the observed associ- vere form of AR [16]. The use of suboptimum pharma- ation, specificity, biologic gradient, biologic plausibility, cotherapy and antihistamines with sedative effects can coherence, analogy, and temporality. In addition, meta-ana- further exacerbate the situation. This incurs a financial lysis was conducted using the software/program-Stata/SE burden from both direct and indirect costs which 11.2 with random effects model to evaluate the influence of adversely affects society [18]. Therefore, a prompt and modifiable risk factors with replicative results reported in at accurate diagnosis, followed by appropriate disease man- least three independent AR publications. agement and awareness of the exacerbation risk factors, would be crucial to ease this burden. Results and discussion Diagnosis of the disease is usually based on medical his- AR epidemiology in Asia tory of the patient in addition to skin prick test or blood Based on the methodology described, different articles test. However, misinterpretation can occasionally occur published in Asia were reviewed. The reviewed arti- and this delays the golden treatment period which can cles have variable study design, disease definition and result in other unexpected consequences, such as paying adopt different analysis parameters as shown in unnecessary medical expenditure and missing work [18]. Table 1. The population size also varies from study to study, ranging from 200 in Kidoni et al. [19]to The aim of the study 30,000 in An et al. [2] This review article aims to study the epidemiology of AR Though similar parameters were used to study the in Asia and identify significant modifiable risk factors as- epidemiology of AR, a larger population group will help sociated with disease presentation. Several criteria have to furtherestablish theprevalenceof the diseaseasit been employed to establish association between trigger- better represents the targeted population. In addition, ing factors and disease manifestation. apart from the country of study, the disease prevalence differs depending on the disease definition and the Methods studypopulation. In thestudy conducted by Min et al. Search strategy and selection criteria [20], AR prevalence is 1.14% among Korean residents; The epidemiology and potential factors associated with while in a retrospective study published by Alsowaidi et AR manifestation were obtained from the Web of al., 2010 [3], 32% of United Arab Emirates residents are Science using the search terms of ‘rhinitis’, ‘risk’ and AR patients. Asian countries. The list of Asian countries and inde- pendent territories used in the search is listed in Additional file 1. ‘Rhinitis’ is used as it represents a Risk factors and co-morbidities of AR general form of the disease which serves to capture as Apart from the general demographic factors, many modi- many risk factors, including both modifiable and fiable risk factors for allergic diseases, such as smoking non-modifiable, as possible. As Asian and Western and drinking habits were investigated as summarised in countries are known to have different cultural and social Table 1. Furthermore, cultural- or socioeconomic-related backgrounds, our study only evaluated articles published factors specific to an individual country have been ex- on Asia and this articles serves to provide a detailed list plored in some studies to identify their association with of triggering risk factors associated with AR in Asia. AR presentation. For instance, heavy traffic and individual Using these search terms, 56 articles were first identi- stress level are two factors investigated in a Singapore [21] fied. The articles were carefully reviewed and those with and Korea [2] study, respectively. These factors were iden- unclear study design or disease definition or which were tified worrying elements in the respective countries, thus conducted in a narrow pool of individuals were ex- finding their association with AR presentation is crucial. cluded. Apart from these 14 articles, additional 6 We further classified these factors into a potential risk cross-referencing articles were also included. These 20 factors or co-morbidities category based on the following articles, published between 1994 and 2017, were evalu- definitions. A typical risk factor is a demographical, phys- ated closely for their study design, disease prevalence, ical, sociological or environmental component which po- disease definition, and the AR risk factor analyzed. tentially increases the risk of presenting a disease or is protective against the expression of an illness. On the Establishing the association link other hand, if AR manifestation is linked to another dis- The factors investigated in the 20 articles were further clas- ease occurrence, it will be known as a co-morbid of AR. sified either as a potential risk factor or a co-morbidity. The As listed in Table 2, most of the factors analysed are in the association between potential modifiable risk factors and risk factor category. However, diseases such as asthma are Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 3 of 21 Table 1 Summaries of allergic rhinitis-specific articles published in year 1994-2017 in Asia Country, No. of sample Study design Prevalence Definition of the disease stage Parameters analyzed Reference, date location Singapore 2868 adults aged Cross-sectional population-based 4.5% Allergic rhinitis: self-reported presence, in the Significant parameters Ng & Tan, 20-74 years study previous year, of usual nasal blockage and ➢ Age 1994 [36] discharge apart from colds or the flu, ➢ Fume exposure provoked by allergens, with or without ➢ Housing estate conjunctivitis. ➢ Insect ➢ Occupational exposure ➢ Race ➢ Smoking Insignificant parameters ➢ Air pollution ➢ Carpet ➢ Gender ➢ Pet Korea 10,054 residents Cross-sectional interview based 1.14% Perennial allergic rhinitis in this study was Significant parameters Min et al., study with Physical examination defined as the presence of typical nasal ➢ Educational attainment 1997 [20] symptoms including watery rhinorrhea, ➢ Residency sneezing, itching and nasal obstruction during Insignificant parameters a period greater than 12 months, positive ➢ Marital status history of known allergen or triggering factors, ➢ Occupational exposure and the physical finding of pale nasal mucosa ➢ Smoking on endoscopic examination. ➢ Social class Thailand, 3124 residents Cross-sectional questionnaire 13.15% (95% CI = 13.13-13.17) Rhinitis is defined as inflammation of the Significant parameters Bunnag Bangkok based study with Chronic rhinitis (CR) lining of the nose, characterized by one or ➢ Associated allergic et al., 2000 more of the following symptoms, i.e. itching, diseases [37] sneezing, rhinorrhea and nasal obstruction ➢ Drinking (International Rhinitis Management Working ➢ Family history of atopy Group, 1994). CR is diagnosed when one ➢ Household income frequently has rhinitis symptoms without fever ➢ Smoking for a period of more than one year. Insignificant parameter ➢ Gender Israel 10,057 Cross-sectional questionnaire 41.6% with Ever AR, Ever AR: Children who reported having rhinitis Significant parameters Graif et al., schoolchildren, based study 9.4% with Current AR and sneezing without flu ever ➢ Asthma 2004 [38] aged 13-14 years Current AR: Answer ‘Yes’ to the question, ➢ Family history of allergic “Do you have allergic rhinitis?” diseases ➢ Gender ➢ Race ➢ Residency Singapore 202 patients aged Retrospective analysis with 33% (AR + asthma), 13% Confirmation from a specialist in Pediatric Significant parameter Kidoni 2-14 years medical records from allergic (AR + AD) & 7% (AR + Otolaryngology ➢ Mold et al., 2004 rhinitis patients undergo SPT test asthma + AD) [19]. in KK Children’s hospital (Jul 2001 − 44% hospitalization rate to June 2002) Laos, 536 (included Cross-sectional questionnaire 21.0% (6-7 years) & 22.3% Had a problem with sneezing, runny, or Significant parameters Phathammavong Vientiane students aged based study from Dec 2006 to (13-14 years) blocked nose when did not have cold or the ➢ Household income et al., 2008 [9] 6-7 years and Feb 2007 with stool examination flu in the past 12 months (ISAAC definition) ➢ Parasitic infection 13-14 years) ➢ Past respiratory infection Insignificant parameters Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 4 of 21 Table 1 Summaries of allergic rhinitis-specific articles published in year 1994-2017 in Asia (Continued) Country, No. of sample Study design Prevalence Definition of the disease stage Parameters analyzed Reference, date location ➢ Age ➢ Air conditioning ➢ Birth order ➢ Family history of allergic diseases ➢ Food ➢ Gender ➢ Parity ➢ Past measles infection ➢ Pet ➢ Sharing bed ➢ Smoking ➢ Time on road Singapore 6794 children Cross-sectional questionnaire 25.6 (Rhinitis) N.A. Significant parameter Zuraimi attending 120 based study ➢ Smoking et al., 2008 randomly selected [39] child care centres Taiwan, 1368 elementary Cross-sectional questionnaire 50.1% The presence of typical nasal symptoms Significant parameters Hsu et al., Taipei school children based study with multi-stage including watery rhinorrhea, sneezing, and ➢ Air pollution 2009 [10] clustered-stratified random nasal obstruction of more than 12 months’ ➢ Carpet method, physical examination duration, positive history of known allergen ➢ Gender or triggering factors, and pale nasal mucosa. ➢ Parity Insignificant parameters ➢ Age of gestation ➢ Gestational complication ➢ Maternal education ➢ Mold ➢ Pet ➢ Smoking United Arab 7550 residents Cross-sectional questionnaire 32% The definition of AR used in this study was Significant parameters Alsowaidi Emirates, ≥13 years based study having had AR symptoms of (nasal blockage, ➢ Age et al., 2010 Al-Ain City rhinorrhoea, sneezing and irritation), in the ➢ Education attainment [3] past 12 months. ➢ Family history of allergic diseases ➢ Gender ➢ Nationality Singapore 2994 children living Cross-sectional questionnaire 24% (Rhinitis) N.A. Significant parameter Zuraimi in homes without based study ➢ Traffic et al., 2011 any indoor risk Insignificant parameter [21] factors ➢ Air conditioning China, 9899 citizens Cross-sectional questionnaire 6.24% According to the diagnostic criteria of AR in Significant parameters Li et al., Guangzhou based study with stratified the ARIA 2001 Guideline, the ENT specialists ➢ Computer usage 2014 [7] City multistage cluster sampling verified the screening questionnaires and ➢ Family history of allergic method made the diagnosis based on the typical AR diseases symptoms within the last 12 months. ➢ Home renovation Intermittent AR was determined when the ➢ Pet Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 5 of 21 Table 1 Summaries of allergic rhinitis-specific articles published in year 1994-2017 in Asia (Continued) Country, No. of sample Study design Prevalence Definition of the disease stage Parameters analyzed Reference, date location symptoms occur, 4 days/week or, 4 ➢ Residency consecutive weeks/year; while persistent AR ➢ Smoking was determined when symptoms last 4 days/ Insignificant parameters week or 4 consecutive weeks/year. ➢ Age ➢ Breastfeeding ➢ Car ownership ➢ Hair coloring ➢ Household income Korea 31,217 subjects Cross-sectional study, data from 27% N.A. Significant parameters An et al., aged 6-97 years Korea National Health and ➢ Marital status 2015 [2] Nutrition Examination Survey ➢ Occupational exposure ➢ Sleep time ➢ Stress level Insignificant parameters ➢ BMI ➢ Drinking ➢ Education attainment ➢ Family size ➢ Household income ➢ Residency ➢ Smoking China 20,803 elementary Cross-sectional questionnaire 9.8% AR: yes for “Has your child had allergic rhinitis Significant parameters Li et al., school students based study in the past 12 months?” ➢ Age 2015 [22] ➢ Age of gestation ➢ Breastfeeding ➢ Family size ➢ Gender ➢ Household income ➢ Housing estate ➢ Maternal education ➢ Mode of delivery ➢ Maternal pre- or postnatal depression ➢ Paternal education Insignificant parameters ➢ Drinking ➢ Smoking Malaysia 695 Malaysia office Cross-sectional questionnaire 53% with current rhinitis Doctor diagnosis Significant parameters Lim et al., works aged based study, SPT test, building ➢ Age 2015 [11] 18-60 years inspection ➢ House dust mite Insignificant parameters ➢ Gender ➢ Pet ➢ Smoking China, 3327 Cross-sectional questionnaire 17.67% Doctor diagnosis Significant parameter Lei, Yang & Zhen, Wuhan based study, physical examination ➢ Gender 2016 [40] Insignificant parameter Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 6 of 21 Table 1 Summaries of allergic rhinitis-specific articles published in year 1994-2017 in Asia (Continued) Country, No. of sample Study design Prevalence Definition of the disease stage Parameters analyzed Reference, date location ➢ BMI Malaysia, 462 students from Cross-sectional questionnaire 18.8% for students from N.A. Significant parameter Norbäck Johor Bahru 8 random schools based study, building inspections junior high schools ➢ Fungi et al., 2016 (1) [41] Malaysia, 462 students from Cross-sectional questionnaire 18.8% for students from N.A. Significant parameters Norbäck Johor Bahru 8 random schools based study, building inspections junior high schools ➢ Atopy et al., 2016 ➢ Family history of allergic (2) [35] disease ➢ Fungi ➢ House dust mite ➢ Race Insignificant parameters ➢ Gender ➢ Smoking China, 13,335 children, Cross-sectional questionnaire 12.6% Answer yes for “Has your child ever had a Significant parameters Huang Shanghai aged 4-6 years based study problem with sneezing, or a runny, or blocked ➢ Breastfeeding et al., 2017 nose when he/she did not have a cold or the ➢ Gruel introduction [34] flu in the past years” Taiwan 1497 newborns Birth cohort follow-up, Non-atopic parents & one Doctor diagnosis Significant parameters Lee et al., questionnaire survey, physician- atopic parent & atopic ➢ Age of gestation 2017 [42] verified and serological testing parents ➢ Gender : 30.8% vs 39.9% vs 54.7% ➢ Residency Kuwait 1154 students, aged Cross-sectional questionnaire 20.4% (95% Cl- 18.1-22.9) Current rhinitis: “ever doctor-diagnosed Significant parameters Ziyab, 18-26 years based study rhinitis” plus “having problems with sneezing, ➢ Age 2017 [8] attending Kuwait runny, or blocked nose in the absence of cold ➢ Family history of allergic University or flu in the last 12 months” diseases ➢ Pet Insignificant parameters ➢ Birth order ➢ Gender ➢ Mode of delivery ➢ Smoking Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 7 of 21 Table 2 The list of risk factors analyzed in the literature reviewed Table 2 The list of risk factors analyzed in the literature reviewed (Continued) No. Risk Factors No. Risk Factors 1 Age 45 Sleep time 2 Age of gestation 46 Smoking (self/parent) 3 Air conditioning 47 Social class 4 Air pollution 48 Stress level 5 Alcohol consumption (self/parent) 49 Time on road 6 Birth order 50 Traffic 7 BMI 8 Breastfeeding co-morbidities which can possibly induce AR expression 9 Car ownership as shown in Table 3.In this article, onlythe modifiable 10 Carpet risk factors were evaluated for their relationship with AR 11 Computer usage manifestation. 12 Drinking (self/parent) Demographical factors affecting the AR presentation 13 Education attainment Multiple papers have suggested the importance of age, 14 Family history of allergic diseases gender, race, and nationality in affecting AR presentation 15 Family history of atopy (Table 4). The association of race and nationality on the 16 Family size disease expression could signify the difference in social 17 Food and cultural backgrounds, as well as genetics, which can 18 Fume exposure potentially influence the presentation of AR. However, as these factors are non-modifiable, they are only useful 19 Fungi in evaluating the risk of presenting AR, but not for 20 Gender prevention. 21 Gestational complication In Li et al. [22], the odds of AR have shown to increase 22 Gruel introduction period with the rise of household income when different house- 23 Hair coloring hold income groups are compared. For the household 24 Home renovation with an income of > 2500 RMB/month, the odds of AR is 2.88 times of those with an income of 800 RMB/ 25 House dust mite month. A similar trend is observed in another two inde- 26 Household income pendent studies. A pooled odds ratio of 2.75 has been 27 Housing estate obtained which suggests the significant role of house- 28 Insect hold income in affecting AR expression (Fig. 1). 29 Marital status Moreover, being married, a large number of members 30 Maternal education in the household, and parity were indicated to be benefi- cial for protecting one against AR. However, their 31 Maternal pre- or postnatal depression influences towards protection of AR are likely to be in- 32 Mode of delivery terrelated as married individuals are usually with chil- 33 Mold dren and are therefore likely to report an increased 34 Nationality parity number and household members. 35 Occupational exposure 36 Parasitic infection Personal risk factors affecting AR presentation Apart from the demographical factors that are usually 37 Parity non-changeable to an individual, one’s behaviours, atti- 38 Past measles infection tude, and encounters might have direct and indirect 39 Past respiratory infection 40 Paternal education Table 3 The list of co-morbidities analyzed in the literature reviewed 41 Pet No. Co-morbidities 42 Race 1 Atopy 43 Residency 2 Associated allergy 44 Sharing bed 3 Current asthma Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 8 of 21 Table 4 Strength of association of demographic factors with AR manifestation Study Study OR/PR Values (95% CI) p-value References population, N Age Alsowaidiet al., 2010 [3] 7550 OR 0.66 (0.54 - 0.81) < 0.0005 > 19 years in ref. to 13-19 years: OR adjusted for nationality, gender, family history of AR, and education Li et al., 2015 [22] 20,803 OR 1.05 (1.02-1.07) < 0.05 Continuous variable, 1 year increase (elementary school student) Lim et al., 2015 [11] 695 OR 0.72 (0.58 - 0.88) < 0.01 Continuous variable, 10 year increase (18 - 60 years): OR adjusted for gender, smoking, house dust mite allergy, cat allergy, home dampness, and home renovation Ng & Tan, 1994 [36] 2868 OR 0.19 (0.10 – 0.35) < 0.0001 60-74 years in ref. to 20-39 years: OR adjusted for race, flat size, housing estate, smoking, insect exposure, occupational exposure, and fume Ziyab, 2017 [8] 1154 PR 1.04 (1.01 - 1.07) < 0.01 Continuous variable (18-26 years): PR adjusted for gender, cat exposure, maternal AR, and paternal AR Gender Alsowaidi et al., 2010 [3] 7550 OR 0.75 (0.63 - 0.88) < 0.005 Male in ref. to female: OR adjusted for nationality, age, family history of AR, and education Graif et al., 2004 [38] 10,057 OR 0.85 (0.74 – 0.97) – Male in ref. to female: OR adjusted for current asthma, family history of asthma, race, residency, and smoking Hsu et al., 2009 [10] 1368 OR 0.58 (0.47 – 0.72) < 0.001 Male in ref. to female: OR adjusted for birth weight, parity, gestational age, maternal education, gestational complications, smoking, pets, carpets, molds, and air pollutions Lee et al., 2017 [42] 1497 OR 1.57 < 0.01 Male in ref. to female Lei, Yang & Zhen, 3327 OR 0.68 (0.46 - 1.00) < 0.05 Male in ref. to female 2016 [40] Li et al., 2015 [22] 20,803 OR 1.55 (1.41 - 1.70) < 0.001 Male in ref. to female Race Graif et al., 2004 [38] 10,057 OR 1.75 (1.45 - 2.13) – Jews in ref. to Arabs: OR adjusted for current asthma, family history of asthma, gender, residency, and smoking Ng & Tan, 1994 [36] 2, 868 OR 2.02 (1.29 - 3.14) < 0.005 Indian in ref. to Malay: OR adjusted for age, flat size, housing estate, smoking, insect exposure, occupational exposure, and fume Norbäck et al., 462 OR 0.33 (0.13 - 0.88) < 0.05 Indian in ref. to Malay: OR adjusted for gender, smoking, atopy, 2016 (2) [35] and family history of allergic diseases Nationality Alsowaidi et al., 2010 [3] 7550 OR 0.48 (0.34 - 0.68) < 0.005 Others in ref. to Arabs: OR adjusted for age, gender, family history of AR, and education Residency Graif et al., 2004 [38] 10,057 OR 0.84 (0.90 - 1.40) – Urban in ref. to rural: OR adjusted for current asthma, family history of asthma, gender, gender, and smoking Lee et al., 2017 [42] 1497 OR 0.71 < 0.05 Townhouse in ref. to others Li et al., 2014 [7] 9899 OR 1.91 (1.37 - 2.68) < 0.001 Urban in ref. to rural Min et al., 1997 [20] 10,054 OR 5.26 (2.27 - 12.50) < 0.05 Urban in ref. to rural: OR adjusted for age Housing estate Li et al., 2015 [22] 20,803 OR 2.19 (1.97 - 2.43) < 0.001 Cities SH, GZ, WH, CD in ref. to XA, HA, HO, UR Ng & Tan, 1994 [36] 2868 OR 1.92 (1.07 - 3.46) < 0.05 Toa Payoh in ref. to Yishun : OR adjusted for age, flat size, race, smoking, insect exposure, occupational exposure, and fume Household income Bunnag et al., 2000 [37] 3124 OR 1.97 (1.23 - 3.16) < 0.05 High income in ref. to medium income: adjusted OR Li et al., 2015 [22] 20,803 OR 1.42 (1.21 - 1.68) < 0.001 800-1500 RMB/month in ref. to 800 RMB/month 1.93 (1.64 - 2.27) < 0.001 1500-2500 RMB/month in ref. to 800 RMB/month 2.88 (2.47 - 3.37) < 0.001 > 2500 RMB/month in ref. to 800RMB/month Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 9 of 21 Table 4 Strength of association of demographic factors with AR manifestation (Continued) Study Study OR/PR Values (95% CI) p-value References population, N Phathammavong et al., 536 OR 2.23 (1.04 - 4.81) < 0.05 High income in ref. to low income: OR adjusted for gender, 2008 [9] age, parity, parents education, pets ownership, sharing bed, air conditioning, measles infection, respiratory infection, time on road, meat, fish, vegetables, cow milk, fast food and eggs consumptions, and intestinal parasitic infestation Parity Hsu et al., 2009 [10] 1368 OR 1.42 (1.02 - 1.97) < 0.025 N = 1 in ref. to N ≥ 3 : OR adjusted for birth weight, gender, gestational age, maternal education, gestational complications, smoking, pets, carpets, molds, and air pollutions 1.43 (1.01 - 2.01) < 0.025 N = 2 in ref. to N ≥ 3: OR adjusted for birth weight, gender, gestational age, maternal education, gestational complications, smoking, pets, carpets, molds, and air pollutions Family size Li et al., 2015 [22] 20,803 OR 1.26 (1.05 - 1.51) < 0.005 N < 3 in ref. to N ≥ 4 1.18 (1.0 - 1.30) < 0.005 N = 3 in ref. to N ≥ 4 Marital status An et al., 2015 [2] 31,217 OR 0.85 (0.74 - 0.97) < 0.05 Married in ref. to unmarried: OR adjusted for age, gender, family size, residency, educational, Household income, and occupation OR odds ratio, PR prevalence ratio influences to the disease presentation. These factors are allergic responses and enhance AR expression (Table 8) highly varied from one person to another and are often [28]. In addition, literature has suggested the possibility of affected by their background and the social group they dust trapped on the computer [7] and higher indoor aller- interact with. gen exposure [2]to explain thehigher oddsofAR mani- As stated in Table 5, like the case with many other in- festation among office workers who usually have higher fectious diseases [23, 24], alcohol consumption and education qualifications. Dose-response effects were also smoking habits have shown to increase the odds of pre- observed in computer usage, education attainment and senting AR. This is especially true for the smoking habit; stress level as odds of AR increase with higher level of risk which shows higher odds of expressing AR among exposure, with the exception for AR odds of college stu- present smokers, past smokers, and even passive dents to illiterate individuals in Min et al. [20]. smokers as compared to non-smokers and those who In contrast, people with parasitic or past respiratory are not exposed to passive smoking. The result is con- infections were reported to have higher odds of AR pres- sistent across four independent articles and a pooled entation. The results are contradictory with biological odds ratio of 1.34 was obtained indicating smoking habit plausibility discussed in other literature. Phathamma- does associate with the increased AR manifestation vong et al. [9], proposed that AR and other respiratory (Fig. 2). infections compete for immune responses, resulting in a Coincidentally, people with more computer usage, higher odds of presenting AR among the respiratory in- higher education, higher stress level and lesser sleeping fection patients. This hypothesis is supported by the re- time were presented with higher AR susceptibility. ported odds of AR for individuals with either parasitic Though several pathways were speculated for such asso- infection or past respiratory infection are exceptionally ciation, the effects of confounders and bias could not be high (3.41 and 4.06 respectively). However, this factor ruled out and further study is required to establish the has only been studied in Phathmmavong et al. among direct association link between these factors. the articles reviewed and further analysis is essential to Stress might be one of the critical risk factors for AR confirm the effects of these infections on AR presenta- presentation. Studies have shown the association be- tion, which could be one of the most important factors tween the level of stress in individuals with more fre- in predicting AR risk. quent drinking and smoking habits, having higher daily computer usage, and higher education levels but with Family risk factors affecting AR presentation less sleeping time [25–27]. Being in a stressful situation In Table 6, mother depression and cesarean delivery are can trigger the expression of cortisol which can induce positively correlated with the odds of AR presentation. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 10 of 21 Fig. 1 Individual and combined odds ratio and 95% confidence intervals for higher income group in association with Allergic Rhinitis presentation As stated in Li et al. [22], pre- and postnatal depression Environmental risk factors affecting AR presentation stimulates the production of cortisol, and this secretion af- As suggested in multiple studies investigated, environ- fects the immune development of a fetus and increases mental factors are highly important in triggering AR. For the odds of presenting AR. Apart from this, cesarean de- instance, Table 7 has shown that the presence of allergens livery might further exacerbate this situation as unlike va- such as fungi, molds, insects and house dust mites could ginal delivery, the infants are not exposed to the mother’s increase the odds of presenting AR. Among the allergens birth canal microflora, which has shown to be protective studied, the presence of fungi and molds were reported to against AR expression [29] as illustrated in Table 8. have very high odds of association to AR with 3.44 for Conversely, inconsistent results are observed for the asso- fungi in Norbäck et al. [35] and 9.40 for molds in Kidoni ciation of breastfeeding with AR presentation across mul- et al. [19] Moreover, insect exposure and house dust mite tiple studies [30, 31]. This refutes the commonly accepted have been identified as two of the most important risk fac- hypothesis which states breastfeeding as protective through tors for AR as indicated in Table 7. These common indoor the antibodies present in the milk and the additional nutri- allergens, such as mold and fungal spores, insect wastes ents from the mother’s diet transferred to the milk [32, 33]. and house dust mite fecal proteins can induce Type I In contrast, parental education and awareness encourages a hypersensitivity reaction by promoting the expression of a hygienic environment which is unfavorable for AR protec- range of allergic-causing mediators, thus increasing the tion as this reduces the chance of exposing their children to odds of expressing AR (Table 8). In addition, the a larger variety of allergens in early life. Similarly, for gruel utilization of carpets, which trap dust, and home renova- consumption, the subtle protection might be due to the ef- tion, which introduces a variety of allergic-causing renova- fect of gruel to stimulate inflammatory cytokines which tion materials, further exacerbate the situation. suppress the allergic reaction [34]. Similarly, outdoor exposures to heavy traffic, air pollu- On the other hand, genetic factor is long established to tion, and fume exposure were also reported to be posi- play an influential role in AR presentation [15]and afam- tively correlated with AR manifestation. These factors are ily history of atopy and allergic diseases might predispose especially crucial for those whose occupations expose children to AR. Multiple studies have shown that family them to the allergens [36]. Constant outdoor encounters history is a key risk factor associated with the increased with pollutants released from motor vehicles and heavy risk of AR expression. This is particularly true for children fumes during work promote AR presentation by changing with a family history of AR as high odds ratios of 6.08 and aperson’s susceptibility towards allergens [2, 10, 21, 36]. 3.51 have been reported in studies conducted by Also- waidi et al. [3] and Li et al. [7], respectively. However, gen- Evaluation of risk factors associated with AR manifestation etic factor is non-modifiable and hence, it needs to be using several criteria complemented with other preventive measures in order to Various risk factors have shown strong association with reduce the risk of presenting the disease. AR presentation. Results are consistent for several risk Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 11 of 21 Table 5 Strength of association of personal risk factor with AR manifestation Study Study OR Values (95% CI) p-value References population, N Alcohol Bunnag et al., 2000 [37] 3124 OR 1.46 (1.15 - 1.86) < 0.05 Drinker in ref. to non-drinker: adjusted OR Smoking Bunnag et al., 2000 [37] 3124 OR 1.39 (1.05 - 1.83) < 0.05 Smoker in ref. to non-smoker: adjusted OR Li et al., 2014 [7] 9899 OR 1.44 (1.10 - 1.88) < 0.01 Smoker in ref. to non-smoker Ng & Tan, 1994 [36] 2868 OR 1.75 (1.01 – 3.04) < 0.05 Past smoker in ref. to non- smoker: OR adjusted for age, flat size, housing estate, race, insect exposure, occupational exposure, and fume Zuraimi et al., 2008 [39] 6794 OR 1.23 (1.01 - 1.50) – Passive smoker in ref. to non-passive smoker: OR adjusted for age, gender, race, socioeconomic status, housing type, family atopy, breastfeeding, food allergy, respiratory infections, home dampness, air conditioning, home wall paper, carpet, home traffic density, childcare centre ventilation and dampness Computer usage Li et al., 2014 [7] 9899 OR 1.45 (1.10 - 1.91) < 0.01 Occasionally in ref. to never 1.46 (1.10 - 1.93) < 0.01 < 2 h daily in ref. to never 1.58 (1.14 - 2.19) < 0.01 2-4 h daily in ref. to never Education Alsowaidi et al., 7550 OR 1.42 (1.05 - 1.93) < 0.05 University in ref. to illiterate and primary school: 2010 [3] OR adjusted for nationality, gender, family history of AR, and age Min et al., 1997 [20] 10,054 OR 1.83 (0.82 - 4.02) < 0.05 Elementary in ref. to illiterate: OR adjusted for age 2.11 (0.93 - 4.79) < 0.05 Junior in ref. to illiterate: OR adjusted for age 2.81 (1.34 - 5.86) < 0.05 Senior in ref. to illiterate: OR adjusted for age 2.54 (1.08 - 5.96) < 0.05 College in ref. to illiterate: OR adjusted for age Stress An et al., 2015 [2] 31,217 OR 1.14 (1.01 - 1.28) < 0.001 A little in ref. to little: OR adjusted for age, gender, height, weight, body mass index, smoking status, sleep time and drinking 1.46 (1.28 - 1.66) < 0.001 Moderate in ref. to little : OR adjusted for age, gender, height, weight, body mass index, smoking status, sleep time and drinking 1.47 (1.21 - 1.79) < 0.001 Severe in ref. to little : OR adjusted for age, gender, height, weight, body mass index, smoking status, sleep time and drinking Sleep time An et al., 2015 [2] 31,217 OR 0.92 (0.84 - 1.00) < 0.05 > 7 h in ref. to ≤7h : OR adjusted for age, gender, height, weight, body mass index, smoking status, stress and drinking Parasitic infection Phathammavong 536 OR 3.41 (1.03 - 11.29) < 0.05 With parasitic infection in ref. to without et al., 2008 [9] : OR adjusted for gender, age, parity, parents education, pets ownership, sharing bed, air conditioning, measles infection, respiratory infection, time on road, meat, fish, vegetables, cow milk, fast food and eggs consumptions, and family income Past respiratory infection Phathammavong 536 OR 4.06 (1.83 - 9.01) < 0.05 With past respiratory infection in ref. to without et al., 2008 [9] : OR adjusted for gender, age, parity, parents education, pets ownership, sharing bed, air conditioning, Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 12 of 21 Table 5 Strength of association of personal risk factor with AR manifestation (Continued) Study Study OR Values (95% CI) p-value References population, N measles infection, family income, time on road, meat, fish, vegetables, cow milk, fast food and eggs consumptions, and intestinal parasitic infestation OR odds ratio factors across studies with different experimental setups Last but not least, with reference to Fig. 3, the two risk and countries. factors, family income and smoking, analyzed using In addition to the ORs, criteria such as biological gra- meta-analysis are consistently being identified as signifi- dient, biological plausibility and temporality are import- cant AR risk factor before and after 2010. In addition, ant in evaluating the association between risk factors education attainment and occupational exposure are two and AR. The biological gradient of the factor can be other significant modifiable risks that appeared in AR established especially when it is studied in a continuous publications before and after 2010 in Asia. In contrast, it manner or in multiple exposure levels. This was demon- was observed that after the year 2010, more strated in various demographical factors such as in fam- family-related risks were analyzed and shown to be sig- ily income, family size, personal factors like computer nificant AR risk factors, such as the age of gestation and usage, education attainment, stress levels and even in breastfeeding. This suggests a shift in focus to consider parental education attainment. Moreover, the association more family-related risk factors among the Asian between the risk factors and AR manifestation are fur- population. ther strengthened when factors with similar roles in AR presentation, such as the common allergens like house Limitations and conclusion dust mites, fungi, and molds, display comparable results. The studies chosen for this review are limited to articles Furthermore, the listed factors can only be considered published in Asia. Thus, the result might not be relevant as a potential risk if its exposure is reasonably affected and applicable to other nations outside Asia. In addition, or altered the risk of AR development. Its biologic the analysis might still be biased though several criteria plausibility must also be coherent to the study results have been used in establishing the significance of the po- found. However, with reference to Table 7, breastfeeding, tential AR risk factor in triggering or protecting parasitic infection and past respiratory infections show against AR presentation. The analysed data could be contradictory results as to what is hypothesized and fur- affected by personal viewpoints in addition to errors ther analysis and interpretation is thus needed. occurred when translating data from primary Fig. 2 Individual and combined odds ratio and 95% confidence intervals for smokers/past-smokers in association with Allergic Rhinitis presentation Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 13 of 21 Table 6 Strength of association of family factor with AR manifestation Study Study OR/PR Values (95% CI) p-value References population, N Age of gestation Lee et al., 2017 [42] 1497 OR 0.51 < 0.05 Preterm in ref. to term Li et al., 2015 [22] 20,803 OR 1.07 (0.88 - 1.30) < 0.001 Preterm in ref. to term 1.42 (1.20 - 1.69) < 0.001 Post-term in ref. to term Mother depression Li et al., 2015 [22] 20,803 OR 1.16 (1.05 - 1.29) < 0.05 Mother with pre- or postnatal depression in ref. to without Mode of delivery Li et al., 2015 [22] 20,803 OR 1.36 (1.23 - 1.49) < 0.001 Cesarean in ref. to vaginal delivery Breastfeeding Huang et al., 13,335 OR 0.97 (0.94 - 0.99) < 0.05 With exclusive for > 6 months breastfeeding in ref. to never 2017 [34] breastfeeding : OR adjusted for family atopy, gender, age, district of the current residence, home ownership, early pet-keeping, parental smoking, and home dampness Li et al., 2015 [22] 20,803 OR 0.67 (0.61 – 0.73) < 0.001 With exclusive breastfeeding in the first 4 months in ref. to without Maternal education Li et al., 2015 [22] 20,803 OR 1.55 (1.36 - 1.77) < 0.001 High school in ref. to middle school or below 2.11 (1.86 - 2.39) < 0.001 College or above in ref. to middle school or below Paternal education Li et al., 2015 [22] 20,803 OR 1.52 (1.32 - 1.74) < 0.001 High school in ref. to middle school or below 2.02 (1.77 - 2.30) < 0.001 College or above in ref. to middle school or below Gruel introduction Huang et al., 2017 [34] 13,335 OR 0.95 (0.90 - 1.00) < 0.05 For > 6 months-old in ref. to < 3 months-old : OR adjusted for family atopy, gender, age, district of the current residence, home ownership, early pet-keeping, parental smoking, and home dampness Family history of atopy Bunnag et al., 3124 OR 1.96 (1.56 - 2.46) < 0.05 With family history of atopy in ref. to without: adjusted OR 2000 [37] Family history of allergic diseases Alsowaidi et al., 7550 OR 6.08 (4.93 - 7.50) < 0.0005 With family history of AR in ref. to without 2010 [3] : OR adjusted for nationality, gender, age, and education Li et al., 2014 [7] 9899 OR 3.51 (2.65 - 4.64) < 0.001 With family history of AR in ref. to without Graif et al., 2004 [38] 10,057 OR 1.30 (1.02 - 1.66) – With family history of asthma in ref. to without: OR adjusted for current asthma, gender, gender, gender, and smoking Norbäck et al., 462 OR 3.49 (1.97 - 6.20) < 0.001 With family history of allergic reactions in ref. to without: OR 2016 (2) [35] adjusted for gender, smoking, atopy, and race Ziyab, 2017 [8] 1154 PR 1.82 (1.39 - 2.39) < 0.001 With maternal allergy in ref. to without: PR adjusted for gender, cat exposure, and age 1.87 (1.25 - 2.77) < 0.005 With paternal allergy in ref. to without: PR adjusted for gender, cat exposure, and age OR odds ratio, PR prevalence ratio literature to the review summaries, such as misrepre- association of a particular risk factor with the disease sentation and misinterpretation of the original data. presentation might not be as straightforward as what Thus, it is highly recommended for readers to refer is illustrated here. to the original articles before extracting any informa- From the articles reviewed, family income, family size, tion from this article. Furthermore, as most of the computer usage, personal and parental education attain- studies used in this review are observational studies, ment and stress level are identified as risk factors with confounding effects cannot be ruled out and the the greatest potential to influence AR presentation, and Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 14 of 21 Table 7 Strength of association of environmental risk factors with AR manifestation Study Study OR/PR Values (95% CI) p-value References population, N Fungi Norbäck et al., 462 OR 0.76 (0.58 - 0.99) < 0.05 With fungi in ref. to without: OR adjusted for gender, ethnicity, 2016 (1) [41] smoking, atopy and heredity Norbäck et al., 462 OR 3.44 (1.81 - 6.59) < 0.001 With fungal endotoxin C14 3-OH FA in ref. to without: OR adjusted 2016 (2) [35] for classroom level Mold Kidoni et al., 202 OR 9.40 (3.80 - 22.90) – With mold sensitization vs without 2004 [19] Insect Ng & Tan, 1994 [36] 2868 OR 2.08 (1.29 – 3.35) < 0.005 Once every day in ref. to once every few months : OR adjusted for age, flat size, housing estate, race, race, occupational exposure, and fume House dust mite Lim et al., 2015 [11] 695 OR 1.66 (1.08 - 2.56) < 0.05 With house dust mite allergy in ref. to without : OR adjusted for gender, current smoking status, age, cat allergy, home dampness, and indoor home painting in last 12 months Norbäck et al., 462 OR 2.91 (1.35 - 6.24) < 0.01 Continuous variable, 1000 mg increase in fine dust 2016 (2) [35] : OR adjusted for classroom level Carpet Hsu et al., 2009 [35] 1368 OR 1.60 (1.09 - 2.35) < 0.025 With carpets in ref. to without : OR adjusted for birth weight, gender, gestational age, maternal education, gestational complications, smoking, pets, parity, molds, and air pollutions Home renovation Li et al., 2014 [7] 9899 OR 1.39 (1.06 - 1.81) < 0.05 With home renovation in ref. to without Air pollution Hsu et al., 2009 [10] 1368 OR 1.44 (1.10 - 1.88) < 0.01 With air pollution in ref. to without : OR adjusted for birth weight, gender, gestational age, maternal education, gestational complications, smoking, pets, carpets, molds, and parity Fume exposure Ng & Tan, 1994 [36] 2868 OR 2.29 (1.32 - 3.99) < 0.005 Often in ref. to rarely: OR adjusted for age, flat size, housing estate, race, race, occupational exposure, and race Traffic Zuraimi et al., 2994 PR 1.58 (1.04 - 2.39) < 0.05 Heavy traffic in ref. to low traffic for all children 2011 [21] : PR adjusted for gender, age, race, socioeconomic status, housing type, parental atopy, breastfeeding, food allergy, and resident height 1.73 (1.00 - 2.99) < 0.05 Heavy traffic in ref. to low traffic for all lifetime residents : PR adjusted for gender, age, race, socioeconomic status, housing type, parental atopy, breastfeeding, food allergy, and resident height Occupational exposure An et al., 2015 [2] 31,217 OR 1.28 (1.11 - 1.47) < 0.01 Unemployed in ref. to engineer : OR adjusted for age, gender, family size, residency, educational, household income, and marriage 1.29 (1.09 - 1.52) < 0.01 Manager, expert, specialist & clerks in ref. to engineer : OR adjusted for age, gender, family size, residency, educational, household income, and marriage 1.18 (1.01 - 1.39) < 0.01 Service worker & seller in ref. to engineer : OR adjusted for age, gender, family size residency, educational, household income, and marriage 1.32 (1.11 - 1.58) < 0.01 Technician, mechanics & production worker in ref. to engineer : OR adjusted for age, gender, family size, residency, educational, household income, and marriage Ng & Tan 1994 [36] 2868 OR 1.95 (1.36 - 2.80) < 0.0005 Wth occupational exposure vs without: OR adjusted for age, flat size, housing estate, race, race, fume, and race OR odds ratio, PR prevalence ratio Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 15 of 21 Table 8 Collated potential risk factors for AR presentation No Potential risk factor No. of studies No. of studies with Possible explanations Sources significant results 1 Age 7 5 The allergic condition is highest in young adults, declining with age [43]. However, the Alsowaidi et al., reason remains unclear. 2010 [3] Li et al., 2015 [22] Lim et al., 2015 [11] Ng & Tan, 1994 [36] Ziyab, 2017 [8] Li et al., 2014 [7] Phathammavong et al., 2008 [9] 2 Age of gestation 3 2 Preterm baby, who is characterized by lower birth weight and earlier exposure to the Lee et al., 2017 [42] mother microflora, have prematurity protection against AR [42]. In contrast, successful Li et al., 2015 [22] pregnancy shifted the T lymphocytes production to Th2 which increases the risk of Hsu et al., 2009 [10] atopy and AR [22]. 3 Air conditioning 2 0 Home dampness has been shown to be related to allergic rhinitis exacerbations [44], Phathammavong et al., 2008 [9] probably in relation to the development of mold or mildew. As air-conditional areas Zuraimi et al., usually have higher dampness, it may lead to increase in AR 2011 [21] expression [45]. 4 Air pollution 2 1 The pollutants might provoke and exacerbate the allergic conditions of the current Hsu et al., 2009 [10] patients. Besides, it might also make a person more susceptible to certain allergens [45]. Ng & Tan, 1994 [36] 5 Alcohol consumption 3 1 Alcohol consumption is related to increased stress level which is one of the provoking Bunnag C et al., 2000 [37] (self/parent) factors potentially enhancing AR presentation [2]. An et al., 2015 [2] Li et al., 2015 [22] 6 Birth order 2 0 An allergic mother might be more prone to provide low-exposure environment for Phathammavong et al., 2008 [9] the next children [29]. Ziyab, 2017 [8] 7 BMI 2 0 Higher BMI and greater weight-to-height ratio is associated with higher atopic and An et al., 2015 [2] higher allergic diseases incidence Lei, Yang & Zhen, 2016 [40] regardless of gender and age [43]. 8 Breastfeeding 3 2 Breastfeeding for more than 6 months has shown to enhance the presentation of Huang et al., 2017 [34] AR [30, 31], but the reason remains unknown. Contrary plausibility has also shown that Li et al., 2015 [22] food proteins consumed by the mother [32] or breastfeeding might help to reduce the Li et al., 2014 [7] inflammatory responses by destroying microbes [33] and is thus protective against AR presentation. 9 Car ownership 1 0 Car owners spend more time outdoor and are thus exposed to higher levels of outdoor Li et al., 2014 [7] pollutants [46]. 10 Carpet 2 1 Having carpets at home increases the risk of accumulating mite allergens, thus Hsu et al., 2009 [10] resulting in more AR cases [47]. Ng & Tan, 1994 [36] 11 Computer usage 1 1 Studies suggested that when the computer is not properly cleaned, prolong usage of Li et al., 2014 [7] the computer will likely result in higher allergen exposure and thus an increase in AR cases [7]. 12 Drinking (self/parent) 3 1 Alcohol consumption is related to increased stress level which is one of the provoking Bunnag C et al., 2000 [37] factors potentially enhancing AR presentation [2]. An et al., 2015 [2] Li et al., 2015 [22] 13 Education attainment 3 2 People with higher education usually work in an indoor environment, thus exposing Alsowaidi et al., 2010 [3] them to indoor allergens [2]. Min et al., 1997 [20] Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 16 of 21 Table 8 Collated potential risk factors for AR presentation (Continued) No Potential risk factor No. of studies No. of studies with Possible explanations Sources significant results An et al., 2015 [2] 14 Family history of 6 5 Allergic diseases can be hereditary, with incomplete genetic penetrance [48]. Alsowaidi et al., 2010 [3] allergic diseases Li et al., 2014 [7] Graif et al., 2004 [38] Norbäck et al., 2016 (2) [35] Ziyab, 2017 [8] Phathammavong et al., 2008 [9] 15 Family history of 1 1 Atopy is usually used as a marker for other allergic diseases, and genetic factors Bunnag et al., 2000 [37] atopy usually play a role in allergic disease presentation. As such, higher family history of atopy usually suggests higher chance of contracting allergic diseases [43]. 16 Family size 2 1 Crowding increases the contact of an individual with allergens and is thus Li et al., 2015 [22] protective against manifestation of allergic reaction [47]. An et al., 2015 [2] 17 Food 1 0 Some foods are protective against AR, most likely through shifting the macromolecules Phathammavong et al., 2008 [9] production, such as fatty acid balance, which later results in the reduction of inflammatory mediators required for disease presentation [30]. 18 Fume exposure 1 1 Fume released into the air by various means is also one of the potential triggering Ng & Tan, 1994 [36] factors in AR presentation [45]. 19 Fungi 2 2 Airborne fungi spores induce type I hypersensitivity and hence AR presentation [49]. Norbäck et al., 2016 (1) [41] Norbäck et al., 2016 (2) [35] 20 Gender 12 7 The allergic diseases appear more frequently in males at infant age, but with equal Alsowaidi et al., 2010 [3] burden as females at mid-teens, and then become more frequent in females with Graif et al., 2004 [38] the reason remain largely unknown [43]. Hsu et al., 2009 [10] Lee et al., 2017 [42] Lei, Yang & Zhen, 2016 [40] Li et al., 2015 [22] Bunnag et al., 2000 [37] Lim et al., 2015 [11] Ng & Tan, 1994 [36] Norbäck et al., 2016 (2) [35] Phathammavong et al., 2008 [9] Ziyab, 2017 [8] 21 Gestational complication 1 0 Uterus complication during gestation periods affects the immune system development Hsu et al., 2009 [10] of the fetus and increases the risk of atopy-related diseases [29]. 22 Gruel introduction 1 1 Study shows that gruel introduction between 4 to 6 months, in complementary with Huang et al., 2017 [34] period breastfeeding, induces IL-10 and TGFβ production which is protective against AR [34]. 23 Hair coloring 1 0 Oxidative hair dye can induce hypersensitivity reactions, thus increasing the risk of Li et al., 2014 [7] expressing AR [50]. 24 Home renovation 1 1 The materials used during the home renovation, such as formaldehyde might have an Li et al., 2014 [7] impact in causing cell sensitization and later AR presentation [7, 31]. 25 House dust mite 2 2 Long term exposure to threshold concentrations of dust mite fecal proteins causes the Lim et al., 2015 [11] presentation of allergens by antigen presenting cells (APC) to CD4+ T lymphocytes, Norbäck et al., 2016 (2) [35] leading to the production of downstream mediators and manifestation of AR symptoms [49]. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 17 of 21 Table 8 Collated potential risk factors for AR presentation (Continued) No Potential risk factor No. of studies No. of studies with Possible explanations Sources significant results 26 Household income 5 3 Higher income is associated with better living conditions and hygiene behavior, thus Bunnag et al., 2000 [37] reducing the exposure to a variety of allergens, which possibly increases their odds Li et al., 2015 [22] of AR [42]. Phathammavong et al., 2008 [9] An et al., 2015 [2] Li et al., 2014 [7] 27 Housing estate 2 2 Living in a housing estate with poor environmental conditions has resulted in more Li et al., 2015 [22] allergic cases [47]. Ng & Tan, 1994 [36] 28 Insect 1 1 Prolonged exposure to insects, which is one of the common allergens may trigger Ng & Tan, 1994 [36] hypersensitivity reactions with production of mediators and hence, the expression of AR symptoms [49]. 29 Marital status 2 1 Being married is hypothesized to be associated with positive physical and mental An et al., 2015 [2] outcomes and is therefore protective against AR [2]. Min et al., 1997 [20] 30 Maternal education 2 1 Educated parents will have higher awareness of their children health status, and thus Li et al., 2015 [22] adopt protective measures to combat against AR starting from a young age [45]. Hsu et al., 2009 [10] 31 Maternal pre- or 1 1 Pre- or postnatal depression results in excessive cortisol expression, which will affect Li et al., 2015 [22] postnatal depression the immune system development of the fetus [22]. 32 Mode of delivery 2 1 Exposure of the fetus to the mother microflora during birth is an advantage to Li et al., 2015 [22] protect them against allergic sensitization [29, 51]. In contrast, cesarean birth is Ziyab, 2017 [8] associated with higher AR risk [51]. 33 Mold 2 1 Mold spores induce type I hypersensitivity and hence, AR presentation [49]. Kidoni et al., 2004 [19] Hsu et al., 2009 [10] 34 Nationality 1 1 AR prevalence is especially high in Asia probably due to the higher humidity, more Alsowaidi et al., 2010 [3] extensive smoking and vaccination habits [43]. 35 Occupational 3 2 Some occupations have higher risk of exposure to allergens, thus increasing their risk An et al., 2015 [2] exposure of expressing AR [50]. Ng & Tan, 1994 [36] Min et al., 1997 [20] 36 Parasitic infection 1 1 Parasitic infection might have some effects to a person’s gut microbiota, which could Phathammavong et al., 2008 [9] later offer some protection against allergic sensitization as stated in hygiene hypothesis [52]. However, some literature also show that parasitic infection influences the allergy development due to its competition with human immune response [9]. 37 Parity 2 1 Being allergic might cause reduced reproductivity in females, resulting in a lower Hsu et al., 2009 [10] parity which is associated with AR presentation [29]. Phathammavong et al., 2008 [9] 38 Past measles infection 1 0 The association of measles with AR is not clear, but it was hypothesized that measles Phathammavong et al., 2008 [9] infection might protect against AR development or could promote allergic sensitization [52]. 39 Past respiratory infection 1 1 Evidence shows that past respiratory infection, such as tuberculosis caused by Phathammavong et al., 2008 [9] Mycobacterium tuberculosis could be protective against AR, possibly through reduction of allergy sensitization [52]. In contrast, some studies have shown that past respiratory infection is directly associated with AR development [9]. 40 Paternal education 1 1 Educated parents are more likely to keep a hygienic living environment, thus possibly Li et al., 2015 [22] increasing the incidence of allergic conditions in their children [45]. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 18 of 21 Table 8 Collated potential risk factors for AR presentation (Continued) No Potential risk factor No. of studies No. of studies with Possible explanations Sources significant results 41 Pet 6 3 For individuals sensitive to pet furs, long term exposure to the pet induces Li et al., 2014 [7] hypersensitivity reaction and could later result in AR presentation [49]. Ziyab, 2017 [8] Phathammavong et al., 2008 [9] Hsu et al., 2009 [10] Lim et al., 2015 [11] Ng & Tan, 1994 [36] 42 Race 3 3 Cultural differences between the races probably have some effects on AR presentation; Graif et al., 2004 [38] however, there is currently no specific research addressing the impact of races on AR Ng & Tan, 1994 [36] disease presentation. Norbäck et al., 2016 (2) [35] 43 Residency 5 4 For people who lived in urban areas, they are more prevalent in developing allergic Graif et al., 2004 [38] reaction [47], probably due to a poorer housing or environmental conditions. Modern Lee et al., 2017 [42] building techniques increase indoor humidity and temperature, facilitates mold Li et al., 2014 [7] development and hence, contributes to AR presentation [2]. Min et al., 1997 [20] An et al., 2015 [2] 44 Sharing bed 1 0 Sharing bed is hypothesized as one of the potential risk factors for AR [9], probably Phathammavong et al., 2008 [9] due to increased risk of getting infections from other people. 45 Sleep time 1 1 People with lesser sleep are usually with higher levels of stress, which is a potential An et al., 2015 [2] trigger factor for AR expression [2]. 46 Smoking (self/parent) 12 4 Tobacco smoke is one of the trigger factors which precipitates the hypersensitivity Bunnag et al., 2000 [37] reactions, thus exacerbating the AR conditions [47]. On the other hand, parents with Li et al., 2014 [7] AR children will also try to reduce their children exposure to external allergic stimuli Ng & Tan, 1994 [36] through changing their smoking habits, thus explaining the negative association of Zuraimi et al., 2008 [39] AR and smoking habit [45]. An et al., 2015 [2] Hsu et al., 2009 [10] Li et al., 2015 [22] Lim et al., 2015 [11] Min et al., 1997 [20] Norbäck et al., 2016 (2) [35] Phathammavong et al., 2008 [9] Ziyab, 2017 [8] 47 Social class 1 0 As stated in hygiene hypothesis, people in lower social class are likely to have a Min et al., 1997 [20] greater exposure to infections. This may have direct and indirect impacts to their gut microbiota, which might offer protection against allergic sensitization [45, 52]. 48 Stress level 1 1 Stress can trigger the production of cortisol, and later induce allergic responses [28]. An et al., 2015 [2] 49 Time on road 1 0 Longer time spent on road is associated with higher AR risk, probably due to Phathammavong et al., 2008 [9] prolonged exposure to air contaminant [9]. 50 Traffic 1 1 The release of motor vehicles such as NO and CO provokes and exacerbates the Zuraimi et al., 2011 [21] conditions of the current AR patients, and might have consequences on changes in susceptibility towards allergens, thus affecting AR presentation [45]. Depending on the outdoor environmental pollution, long term exposure to heavy traffic might lead to allergic sensitization and resulted in AR expression [21]. Indicates the publication with insignificant results Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 19 of 21 Fig. 3 Years in which significant AR risk factors were identified Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 20 of 21 when compared to other factors, they fulfill most of the 5. Murray CS. Allergens, viruses, and asthma exacerbations. Proc Am Thorac Soc. 2004;1:99–104. https://doi.org/10.1513/pats.2306027. criteria listed. In contrast, more considerations are re- 6. Cookson W. The alliance of genes and environment in asthma and allergy. quired in interpreting the effects of breastfeeding, para- Nature 1999;402 November:B5–11. sitic infections and past respiratory infections to AR 7. Li CW, De Chen H, Zhong JT, Bin LZ, Peng H, Lu HG, et al. Epidemiological characterization and risk factors of allergic rhinitis in the general population presentation. These factors show incoherent biological in Guangzhou City in China. PLoS One. 2014;9:1–16. plausibility and more in-depth investigation and analysis 8. Ziyab AH. Prevalence and risk factors of asthma, rhinitis, and eczema and is thus required. their multimorbidity among young adults in Kuwait: a cross-sectional study. Biomed Res Int. 2017;2017:2184193. https://doi.org/10.1155/2017/2184193. The results obtained from this review article can be 9. Phathammavong O, Ali M, Phengsavanh A, Xaysomphou D, Odajima H, used to improve the diagnosis of AR in clinical settings Nishima S, et al. Prevalence and potential risk factors of rhinitis and atopic by identifying patients with risk factors strongly associ- eczema among schoolchildren in Vientiane capital, Lao PDR: ISAAC questionnaire. Biosci Trends 2008;2:193–199. ated with AR manifestation. In addition, as personal and 10. Hsu S-P, Lin K-N, Tan C-T, Lee F-P, Huang H-M. Prenatal risk factors and occurrence family-related modifiable factors are found to be strong of allergic rhinitis among elementary school children in an urban city. Int J Pediatr AR triggering factors, strategies to alleviate personal Otorhinolaryngol. 2009;73:807–10. https://doi.org/10.1016/j.ijporl.2009.02.023. 11. Lim FL, Hashim Z, LTL T, Said SM, Hashim JH, Norbäck D. Asthma, airway stress levels and increase the awareness of allergy risk in symptoms and rhinitis in office workers in Malaysia: associations with house a hygienic environment have to be developed. dust mite (HDM) allergy, cat allergy and levels of house dust mite allergens in office dust. PLoS One. 2015;10:1–21. 12. Tamay Z, Akcay A, Ones U, Guler N, Kilic G, Zencir M. Prevalence and risk Additional file factors for allergic rhinitis in primary school children. Int J Pediatr Otorhinolaryngol. 2007;71:463–71. Additional file 1: List of countries and dependent territories used in the 13. Sultész M, Katona G, Hirschberg A, Gálffy G. Prevalence and risk factors for literature review search. (PDF 322 kb) allergic rhinitis in primary schoolchildren in Budapest. Int J Pediatr Otorhinolaryngol. 2010;74:503–9. 14. Kuyucu S, Saraclar Y, Tuncer A, Geyik PO, Adalioglu G, Akpinarli A, et al. Abbreviations Epidemiologic characteristics of rhinitis in Turkish children: the international AR: Allergic rhinitis; OR: Odds ratio; PR: Prevalence ratio study of asthma and allergies in childhood (ISAAC) phase 2. Pediatr Allergy Immunol. 2006;17:269–77. https://doi.org/10.1111/j.1399-3038.2006.00407.x. Acknowledgements 15. Magnan A, Meunier JP, Saugnac C, Gasteau J, Neukirch F. Frequency and The authors would like to thank all authors involved in the studies reviewed impact of allergic rhinitis in asthma patients in everyday general medical above as well as the individuals that volunteered in these studies. In addition, practice: a French observational cross-sectional study. Allergy Eur J Allergy we also would like to express my special thanks of gratitude to Ng Yu Ting, Sri Clin Immunol. 2008;63:292–8. Anusha Matta, and Sio Yang Yie for language editing of this manuscript. 16. Cirillo I, Marseglia G, Klersy C, Ciprandi G. Allergic patients have more numerous and prolonged respiratory infections than nonallergic subjects. Authors’ contributions Allergy Eur J Allergy Clin Immunol. 2007;62:1087–90. FTC supported and guided the literature review process. SNC carried out the 17. Cardell LO, Olsson P, Andersson M, Welin KO, Svensson J, Tennvall GR, et al. literature review and translated the information into the manuscript. Both TOTALL: high cost of allergic rhinitis - a national Swedish population-based authors read and approved the final version of the article. questionnaire study. npj Prim Care Respir Med 2016;26. 18. Weiss KB, Sullivan SD. The health economics of asthma and rhinitis. I. Assess Ethics approval and consent to participate Econ Impact. J Allergy Clin Immunol. 2001;107:3–8. Not applicable. 19. Kidoni MI, See Y, Goh A, Chay OM, Balakrishnan A. Aeroallergen sensitization in pediatric allergic rhinitis in Singapore: is air-conditioning a factor in the Consent for publication tropics? Pediatr Allergy Immunol. 2004;15:340–3. Not applicable. 20. Min YG, Jung HW, Kim HS, Park SK, Yoo KY. Prevalence and risk factors for perennial allergic rhinitis in Korea: results of a nationwide survey. Competing interests Clin Otolaryngol Allied Sci. 1997;22:139–44. The authors declare that they have no competing interests. 21. Zuraimi MS, Tham KW, Chew FT, Ooi PL, Koh D. Home air-conditioning, traffic exposure, and asthma and allergic symptoms among preschool children. Pediatr Allergy Immunol. 2011;22(1 PART 2):112–8. Publisher’sNote 22. Li Y, Jiang Y, Li S, Shen X, Liu J, Jiang F. Pre-and postnatal risk factors in relation Springer Nature remains neutral with regard to jurisdictional claims in published to allergic rhinitis in school-aged children in China. PLoS One. 2015;10:1–11. maps and institutional affiliations. 23. Talamini G, Bassi C, Falconi M, Sartori N, Salvia R, Rigo L, et al. Alcohol and Received: 10 January 2018 Accepted: 11 July 2018 smoking as risk factors in chronic pancreatitis and pancreatic cancer. Dig Dis Sci. 1999;44:1303–11. 24. Poikolainen K, Karvonen J, Pukkala E. Excess mortality related to alcohol and smoking among hospital-treated patients with psoriasis. Arch Dermatol. References 1999;135:1490–3. https://doi.org/10.1001/archderm.135.12.1490. 1. Strachan D, Sibbald B, Weiland S, Aït-Khaled N, Anabwani G, Anderson HR, 25. Conway TL, Vickers RR, Ward HW, Rahe RH. Occupational stress and et al. Worldwide variations in prevalence of symptoms of allergic variation in cigarette, coffee, and alcohol consumption. J Health Soc Behav. rhinoconjunctivitis in children: the international study of asthma and 1981;22:155. https://doi.org/10.2307/2136291. allergies in childhood (ISAAC). Pediatr Allergy Immunol. 1997;8:161–76. 26. Robotham D, Julian C. Stress and the higher education student: a critical 2. An S-Y. Analysis of various risk factors predisposing subjects to allergic review of the literature. J Furth High Educ. 2006;30:107–17. https://doi.org/ rhinitis. Asian Pacific J Allergy Immunol. 2015;:143–52. doi:https://doi.org/10. 10.1080/03098770600617513. 12932/AP0554.33.2.2015. 3. Alsowaidi S, Abdulle A, Shehab A, Zuberbier T, Bernsen R. Allergic rhinitis: 27. Jacobsen LK, Southwick SM, Kosten TR. Substance use disorders in patients prevalence and possible risk factors in a gulf Arab population. Allergy Eur J with posttraumatic stress disorder : a review of the literature. Am J Allergy Clin Immunol. 2010;65:208–12. Psychiatry. 2001;158:1184–90. https://doi.org/10.1176/appi.ajp.158.8.1184. 4. Bousquet J. Allergic rhinitis and its impact on asthma (ARIA) 2008. Allergy. 28. Osman M. Therapeutic implications of sex differences in asthma and atopy. 2008;63:1052–5. https://doi.org/10.1111/j.1398-9995.2007.01620.x. Arch Dis Child. 2003;88:587–90. Chong and Chew World Allergy Organization Journal (2018) 11:17 Page 21 of 21 29. Nafstad P, Magnus P, Jaakkola JJ. Risk of childhood asthma and allergic rhinitis in relation to pregnancy complications. J Allergy Clin Immunol. 2000;106:867–73. 30. NafstadP,NystadW,MagnusP,Jaakkola JJK. Asthma andallergic rhinitis at 4 years of age in relation to fish consumption in infancy. J Asthma. 2003;40:343–8. 31. Wang X, Liu W, Hu Y, Zou Z, Shen L, Huang C. Home environment, lifestyles behaviors, and rhinitis in childhood. Int J Hyg Environ Health. 2016;219:220–31. 32. Spiekermann GM, Walker WA. Oral tolerance and its role in clinical disease. J Pediatr Gastroenterol Nutr. 2001;32:237–55. 33. Hanson LÅ. Session 1: feeding and infant development breast-feeding and immune function. Proc Nutr Soc. 2007;66:384–96. https://doi.org/10.1017/S0029665107005654. 34. Huang C, Liu W, Cai J, Weschler LB, Wang X, Hu Y, et al. Breastfeeding and timing of first dietary introduction in relation to childhood asthma, allergies, and airway diseases: a cross-sectional study. J Asthma. 2017;54:488–97. 35. Norbäck D, Hashim JH, Markowicz P, Cai GH, Hashim Z, Ali F, et al. Endotoxin, ergosterol, muramic acid and fungal DNA in dust from schools in Johor Bahru, Malaysia - associations with rhinitis and sick building syndrome (SBS) in junior high school students. Sci Total Environ. 2016;545– 546:95–103. https://doi.org/10.1016/j.scitotenv.2015.12.072. 36. Ng TP, Tan WC. Epidemiology of allergic rhinitis and its associated risk- factors in Singapore. Int J Epidemiol. 1994;23:553–8. 37. Bunnag C, Jareoncharsri P, Voraprayoon S, Kongpatanakul S. Epidemiology of rhinitis in Thais : characteristics and risk factors. Asian Pacific J Allergy Immunol. 2000;18:1. 38. Graif Y, Garty B-Z, Livne I, Green MS, Shohat T. Prevalence and risk factors for allergic rhinitis and atopic eczema among schoolchildren in Israel: results from a national study. Ann Allergy Asthma Immunol. 2004;92:245–9. https://doi.org/10.1016/S1081-1206(10)61555-4. 39. Zuraimi MS, Tham KW, Chew FT, Ooi PL, David K. Home exposures to environmental tobacco smoke and allergic symptoms among young children in Singapore. Int Arch Allergy Immunol. 2008;146:57–65. 40. Lei Y, Yang H, Zhen L. Obesity is a risk factor for allergic rhinitis in children of Wuhan (China). Asia Pac Allergy. 2016;6:101–4. https://doi.org/10.5415/ apallergy.2016.6.2.101. 41. Norbäck D, Hashim JH, Cai GH, Hashim Z, Ali F, Bloom E, et al. Rhinitis, ocular, throat and dermal symptoms, headache and tiredness among students in schools from Johor Bahru, Malaysia: associations with fungal DNA and mycotoxins in classroom dust. PLoS One. 2016;11:1–15. 42. Lee M-T, Wu C-C, Ou C-Y, Chang J-C, Liu C-A, Wang C-L, et al. A prospective birth cohort study of different risk factors for development of allergic diseases in offspring of non-atopic parents. Oncotarget. 2017;8:10858–70. https://doi.org/10.18632/oncotarget.14565. 43. Yao TC, Ou LS, Yeh KW, Lee WI, Chen LC, Huang JL. Associations of age, gender, and BMI with prevalence of allergic diseases in children: PATCH study. J Asthma. 2011;48:503–10. 44. Kilpeläinen M, Terho EO, Helenius H, Koskenvuo M. Home dampness, current allergic diseases, and respiratory infections among young adults. Thorax. 2001;56:462–7. 45. Lee YL, Shaw CK, Su HJ, Lai JS, Ko YC, Huang SL, et al. Climate, traffic-related air pollutants and allergic rhinitis prevalence in middle-school children in Taiwan. Eur Respir J. 2003;21:964–70. 46. Duggan EM, Sturley J, Fitzgerald AP, Perry IJ, Hourihane JOB. The 2002-2007 trends of prevalence of asthma, allergic rhinitis and eczema in Irish schoolchildren. Pediatr Allergy Immunol. 2012;23:464–71. 47. Gelber LE, Seltzer LH, Bouzoukis JK, Pollart SM, Chapman MD, Platts- Mills T a. Sensitization and exposure to indoor allergens as risk factors for asthma among patients presenting to hospital. Am Rev Respir Dis. 1993;147:573–8. 48. Dold S, Wjst M, von Mutius E, Reitmeir P, Stiepel E. Genetic risk for asthma, allergic rhinitis, and atopic dermatitis. Arch Dis Child. 1992;67:1018–22. https://doi.org/10.1136/adc.67.8.1018. 49. Skoner DP. Allergic rhinitis: definition, epidemiology, pathophysiology, detection, and diagnosis. J Allergy Clin Immunol. 2001;108(1 SUPPL):S2–8. 50. Helaskoski E, Suojalehto H, Virtanen H, Airaksinen L, Kuuliala O, Aalto-Korte K, et al. Occupational asthma, rhinitis, and contact urticaria caused by oxidative hair dyes in hairdressers. Ann Allergy Asthma Immunol. 2014;112:46–52. 51. Pistiner M, Gold DR, Abdulkerim H, Hoffman E, Celedón JC. Birth by cesarean section, allergic rhinitis, and allergic sensitization among children with a parental history of atopy. J Allergy Clin Immunol. 2008;122:274–9. 52. Strachan DP. Family size, infection and atopy: the first decade of the “hygiene hypothesis”. Thorax. 2000;55(Suppl 1):S2–10.

Journal

World Allergy Organization JournalSpringer Journals

Published: Aug 6, 2018

References