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Health-related quality of life in patients with knee osteoarthritis attending two primary care clinics in Malaysia: a cross-sectional study

Health-related quality of life in patients with knee osteoarthritis attending two primary care... Background: Measurement of health-related quality of life (HRQOL) among patients with osteoarthritis (OA) helps the health care provider to understand the impact of the disease in the patients' own perspective and make health services more patient-centered. The main aim of this study was to measure the quality of life among patients with symptomatic knee OA attending primary care clinic. We also aimed to ascertain the association between socio-demographic and medical status of patients with knee OA and their quality of life. Methods: A clinic based, cross sectional study using the Short Form-36 (SF-36) questionnaire was conducted in two primary care health clinics in Hulu Langat, Selangor, Malaysia over a period of 8 months. The nurses and medical assistants were involved in recruiting the patients while the family physicians conducted the interview. Results: A total 151 respondents were recruited. The mean age was 65.6 ± 10.8 years with females constituted 119 (78.8%) of the patients. The mean duration of knee pain was 4.07 ± 2.96 years. Half of the patients were overweight and majority, 138 (91.4%), had at least one co-morbidity, the commonest being hypertension. The physical health status showed lower score as compared to mental health component. The domain concerning mental health components showed positive correlation with age. There was a significant negative correlation between age and physical functioning (p < 0.0005) which indicated the deterioration of this domain as patients became older. Male respondents had better scores in most of the QOL dimensions especially in the physical functioning domain (p = 0.03). There was no significant association between QOL with different education levels, employment status and marital status. Patients with higher body mass index (BMI) and existence co-morbidities scored lower in most of the QOL domains. Conclusions: This study has shown that patients with knee OA attending primary care clinics have relatively poor quality of life pertaining to the physical health components but less impact was seen on the patients' mental health. Page 1 of 7 (page number not for citation purposes) Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 Background Methods Health-related quality of life (HRQOL) is increasingly This was a cross-sectional study involving patients with acknowledged as a valid health indicator in many dis- symptomatic knee OA attending two different health clin- eases. HRQOL is narrowed to aspects of an individual's ics in Hulu Langat, Selangor, Malaysia. The study was con- life that is affected by health, disease and/or its treatment. ducted between 1st September 2003 and 30th April 2004. It encompasses emotional, physical, social and subjective By universal sampling, all patients aged 50 and above vis- feelings of well being that reflect an individual's subjective iting the outpatient clinic were screened by a triage nurse evaluation and reaction to his/her illness [1]. or medical assistant for knee pain. Their names and regis- tration numbers were recorded in a special registry book. Osteoarthritis (OA) is the most common type of arthritis If the patients were not seen on the same day, they were found worldwide especially in the elderly. It is a major seen at the next visit. All patients diagnosed with knee OA cause of disability in both the developed and developing based upon the American College of Rheumatology crite- world [2]. The prevalence of OA is in the region of 10-20% ria [12] and age 50 years and above were included. We of the adult population. In all populations studied so far excluded those who were illiterate and could not answer the prevalence of knee OA is higher than that of hip OA the questionnaire. Patients who needed hospital admis- but this is more marked in Asian populations [3]. The sion or those with any other forms of lower limb immo- most common form of OA in Malaysia is knee OA [4]. bility or abnormality such as paraplegia were also Although there is no exact figure of patients with knee OA, excluded. the Community Orientated Program for Control of Rheu- matic Diseases (COPCORD) study showed that 9.3% of The medical outcome study 36-item short form (SF-36) adult Malaysians complained of knee pain with a sharp was used to measure the HRQOL in this study. The SF-36 increase in pain rate to 23% in those over 55 years of age is a 36-item instrument designed to measure generic and 39% in those over 65 years [5,6]. health concepts relevant across age, disease and treatment groups. It is a reliable and validated generic instrument Most patients with OA are assessed and treated within pri- that has been used extensively to measure HRQOL in mary care settings [7] but there seems to be a discrepancy diverse groups [13]. Through the International Quality of between how doctors and patient define the importance Life assessment Project, 15 countries including Malaysia of an illness. Furthermore, OA of the knee is often ignored have participated in translating and adapting the SF-36. by doctors until the disease is very advanced because it is often considered as part of the 'normal' ageing process Socio-demographic and medical characteristics of the [7,8]. As OA and other rheumatic conditions seldom patients were recorded and the Malay language version of cause death but have a substantial impact on health, SF-36 form was either self-administered or led by an inter- HRQOL measures are better indicators of their impact viewer (face-to-face). This version had been translated and than related mortality rates [9]. validated and was used in the Malaysian National Quality of Life Survey 2000 [14]. It measured eight domains con- Review of medical literature revealed 15 studies on sisted of physical functioning, role-physical, bodily pain, HRQOL in OA but there were only two studies that specif- general health, vitality/energy, social functioning, role- ically looked at HRQOL in patients with OA in the pri- emotional and mental health. Scores on each scale ranged mary care setting [10,11]. HRQOL studies in patients with from a minimum of 0 to a maximum of 100, with higher knee OA attending primary care have never been done in scores indicative of better health. Proxy respondents from Malaysia. Our study specifically aims to look at the either family or friends were not entertained as the valid- HRQOL of patients with symptomatic knee OA in pri- ity of SF-36 will be compromised. If there was problem in mary care setting. The findings will help the care provider understanding the questionnaire, the investigator would especially in the primary care to understand the impact of re-read it without re-phrase or explanation. All respond- the disease on the patients and offer an insight into the ents were asked to answer based on what they understood need for early treatment and interventions. of the question. We documented the socio-demographic, medical and Information for computation of scores was provided by non-medical related characteristics of these patients and the manual produced by the Medical Outcomes Trust ascertained their association with HRQOL. We have (1994). Statistical Package for Social Sciences, version found that patient with knee OA attending primary care 12.0 (SPSS Inc, Chicago, IL) was used for data analysis. have relatively poor quality of life pertaining to the phys- Age, body mass index and duration of knee pain were ical health components but there was less impact on the entered as continuous variables. Other variables were mental health of the patients. entered as binary categorical. The association between continuous quantitative variable and QOL scores was ana- Page 2 of 7 (page number not for citation purposes) Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 lyzed using Pearson Correlation Test. Independent sam- disease in the last one year. The mean body mass index ples T-Test was used to analyzed association between (BMI) was 28.23 ± 4.97 with majority (n = 76, 50.3%), dichotomous qualitative variables and QOL scores. The were in the overweight category. association of polinomial qualitative variables and QOL scores were analyzed with One-way Analysis of Variance The profile of SF-36 quality of life dimensions scores are (ANOVA). The p value significance was taken as < 0.05. shown in Table 3. A wide range of scores were reported for Ethnicity was analyzed as dichotomous variable (Malay all dimensions. A full range of scores (0-100) was and non-Malay) due to small proportion of other ethnics. observed on two of the dimensions: role limitations due Results with showed statistical significance were re-ana- to role-physical (RP) and role-emotional (RE). Although lysed using the multiple linear regression models to con- the overall mean scores were above 50.00 in all domains, trol the confounding factors. domains related to the physical health status showed rel- atively lower score as compared to mental health compo- nent. Results There were a total of 213 patients with knee pain during the study period and only 154 were eligible. Out of this, There was a significant negative correlation between phys- only 151 (98%) completed the study. The patients' base- ical functioning (PF) and age (r = -0.337, p < 0.0005) and line and socio-demographic characteristics are shown in there were better scores for males in most of the QOL Table 1. dimensions, especially in the PF domain (p = 0.03). QOL scores were also better pertaining to mental health com- Thirteen (8.6%) patients were not known to have any of ponent for patients with no formal education, where sig- the surveyed medical illnesses and 4 (2.6%) had more nificant differences were found in the vitality (VT) and RE than four. The most common was hypertension and the with p = 0.017 and p = 0.007 respectively. There was no other medical characteristics are shown in Table 2. The significant difference in the marital and employment sta- mean duration of knee pain was 4.07 ± 2.96 years and tus. only eight (5.3%) patients had been hospitalized for the Patients with co-morbidities scored lower than those without in most of the QOL domains and a significant dif- Table 1: Patients baseline and socio-demographic ference was seen in the social functioning (SF) domain (p characteristics = 0.001). The association with other medical characteris- Patient characteristics Number of patients, N = 151 tics showed negative correlation between duration of knee pain and all the QOL domains (except RE) with signifi- Age, yr (mean ± SD) 65.6 ± 10.8 cant negative correlation was found in the RP domain (r Gender = -0.287, p < 0.005). There were lower QOL scores for Male 32 (21.2%) patients with higher BMI except in SF, and significant dif- Female 119 (78.8%) ference was found in the bodily pain (BP) domain (p = Race 0.044). A post-hoc analysis showed the significant differ- Malay 119 (78.8%) ence was between normal BMI and obese patient (p = Chinese 16 (10.6%) 0.013). Indian 9 (6%) Factors which were significant in the bivariate analysis Marital status were then re-analyzed using multiple linear regression Married 114 (75.5%) analysis. The association between PF scores with age and Single/Widowed/Divorce 37 (24.5%) gender remained significant. Similar results were seen Social support between VT and RE scores with education levels. Living alone 5 (3.3%) Living with relatives 146 (96.7%) Discussions The mean age of respondents in our study and the range Level of education received were similar to a study done previously on mainly Chi- No formal education 20 (13.3%) nese descendents [11]. Majority of our respondents had Primary 100 (66.2%) Secondary 31 (20.5%) hypertension followed by diabetes (30.5%). This finding Tertiary 0 (0%) reflected the prevalence of these two diseases among the elderly in Malaysia. A study conducted by the Public Employment status Health Department, Universiti Kebangsaan Malaysia Employed/Self-employed 17 (11.2%) reported that the prevalence of hypertension in Hulu Lan- Unemployed/Retired 134 (88.8%) gat, Selangor, Malaysia population increased from 5% Page 3 of 7 (page number not for citation purposes) Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 Table 2: Patients Medical Characteristics Number of patients(%) Comorbidities Yes 138 (91.4) No 13 (8.6) No of comorbidities 0 13 (8.6) 1 71 (47) 2 54 (35.8) 39 (6) ≥ 4 4 (2.6) Medical conditions Diabetes mellitus 46 (30.5) Hypertension 128 (84.8) Gouty arthritis 7 (4.6) Bronchial asthma 6 (4) Other illnesses 34 (22.5) Duration of knee pain < 1 y 23 (15.2) 1 - 5 y 87 (57.6) 6 - 10 y 40 (26.5) > 10 y 1 (0.7) Hospitalization for knee pain for the past 1 year Yes 8 (5.3) No 143 (94.7) Body Mass Index (BMI) 18.5 - 24.9 (Normal) 32 (21.2) 25.0 - 29.9 (Overweight) 76 (50.3) > 30.0 (Obese) 43 (28.5) among patients between 45-54 years old to 11.6% in Profile). One study used the Sickness Impact Profile (SIP) those aged 55 - 64 years old. Similar finding was reported to assess patients in 40 family practices in Netherlands in diabetes, 9% rising to 15.8% in older age group [15]. [10]. The other study from Hong Kong, assessed 760 adult Chinese patients of a family medicine clinic with each Domains related to the physical health status show rela- subject answered the COOP/WONCA charts and a stand- tively lower score as compared to mental health compo- ard questionnaire on demographic and morbidity data nent. The lower score in physical health component [11]. The authors consistently showed that people with compared to the mental component were consistent with OA of the knee had poor quality of life pertaining to the other studies [10,11], although they had used different physical activities and overall health compared to the gen- instruments (COOP/WONCA charts and Sickness Impact eral population. Table 3: Overall scores of SF-36 quality of life dimensions Physical Health Status Mental Health Status Physical Role- Bodily Pain General Vitality Social Role- Mental Functioning Physical Health Functioning Emotional Health (PF) (RP) (BP) (GH) (VT) (SF) (RE) (MH) Mean 51.88 67.54 56.01 53.29 77.84 93.62 84.10 84.95 Standard 24.11 46.16 18.30 17.17 16.33 15.06 36.27 14.79 deviation (SD) Minimum 5.00 0.00 22.00 5.00 25.00 37.50 0.00 20.00 Maximum 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 * Scores range from 0 to 100 with higher scores indicating better functioning. Page 4 of 7 (page number not for citation purposes) Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 As there was no Malaysian study on QOL of patients with activities downward to the level at which they can func- knee OA, a US norm for patients with osteoarthritis and tion [19]. hypertension was used for comparison (Figure 1). This norm was provided in the SF-36 interpretation manual In our study, age was found to be a predictor for declining [16]. It represented a quality of life of the population age of PF. A significant negative correlation was found 55 years and above in US with these two medical condi- between age and PF (p < 0.0005), even after adjustment tions. While the physical health component showed virtu- for other confounders. This finding was contrary to previ- ally identical scores except for RP, the population in our ous studies [17,20] where the authors reported an insig- study scored better in the mental health component. A nificant negative correlation with age. One study looked large deficit in RP and VT were seen where the US norm at factors that were associated with physical functioning in scored much lower compared to the population in this symptomatic knee OA and the other analyzed factors study. In other words, the US population with OA per- influencing physical function in patients with knee and ceived to have more problems with work or other daily hip OA attending outpatient clinics. activities as a result of physical health and felt tired and worn-out most of the time. This could be due to the dif- Female respondents with knee OA were found to have ference in coping mechanism, cultural as well as socio- lower scores in most of the QOL dimensions with a signif- demographic background between the two populations as icant difference seen in physical functioning (p = 0.03) demonstrated in a few QOL studies amongst Asian popu- even after adjusting for other factors (p = 0.024). This is lation [11,17]. similar to other studies [20,21] and because of the higher prevalence of knee OA in women, this finding is of partic- A relatively higher score in the mental component in our ular importance to the overall management of patients study showed that mental health was less affected by knee with knee OA. It has also been shown that being female OA. This could be due to better coping mechanism and and having joint stiffness were significant independent adaptation to this chronic disease. Affleck et al [18] stud- predictors of total patient expenditures related to OA [22]. ied the coping styles and mood changes in patient with knee OA and rheumatoid arthritis (RA). They found that Background education was found to be an important fac- patients with knee OA used various coping mechanism tor associated with VT and RE domains after controlling and resulted in less pain and better mood as compared to for confounders. Patient with higher education have patients with RA. Furthermore OA might be considered as lower scores in these two domains. The mechanism by normal ageing process, hence it was easily accepted. The which education influenced mental health is unclear but affective and cognitive meaning of information that ini- this could be due to a higher expectation among patients tially was experienced as threatening may be changed to with higher education group. Although there were studies make the present situation more acceptable. Thus patients reported that more years of education were associated may have adjusted their expectations for their health or with better physical function, none of the studies reviewed reported any association between education lev- els with mental health [11,17,20,23]. Education was also found to have a significant association in PF but disap- peared after adjustment. However a small percentage of respondents with higher education in this study limited the generalizability of the results. There was no signifi- cance association found when comparing QOL with dif- ferent employment and marital status which was in PF RP BP GH VT SF RE MH agreement with the finding of other studies [17,24]. 51.88 67.54 56.01 53.29 77.84 93.62 84.1 84.95 This Study 57.44 38.17 55.04 58.96 49.54 79.74 74.84 78.01 US norm for patients with OA and Hypertension Despite high prevalence of co-morbidity among respond- QOL Domains ents in this study, there was no significant association between the presence of co-morbidity and QOL dimen- Compar (Q oar Figure 1 OL thrit ) di is and Hypertension ison b mensi eo tween n with the overa US no ll mean SF rm for p -36 qu atients with Oste- ality of life sions except for social functioning domain but the latter Comparison between overall mean SF-36 quality of disappeared after adjustment for confounders. This is in life (QOL) dimension with the US norm for patients agreement with a previous study [17] that showed co- with Osteoarthritis and Hypertension. PF = Physical morbidity had no association with pain or physical func- functioning, RP = Role limitations due to physical health, BP = tioning. Bodily pain, GH = General health perceptions, VT = Vitality, SF = Social functioning, RE = Role limitations due to emo- tional problems, MH = General mental health. Respondents with BMI ≥ 30 have lower QOL score in all domains except SF. A significant difference was found in Page 5 of 7 (page number not for citation purposes) Score Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 the bodily pain domain even after adjustment for con- Lists of Abbreviations founders (p = 0.044, p = 0.008 respectively). The associa- BMI: Body mass index; BP: Bodily pain; COOP/WONCA: tion between BMI and the risk of developing knee OA was Dartmouth Primary Care Cooperative Information demonstrable in various other studies too [25-27]. How- Project/World Organization of National Colleges; Acade- ever its relation to pain is less certain. The study by mies, and Academic Associations of General Practice/ Creamer et al [28] reported a strong correlation between Family Physicians; HRQOL: Health related quality of life; BMI and pain severity. Using WOMAC questionnaire they OA: Osteoarthritis; PF: Physical health; QOL: Quality of found that higher BMI was associated with pain on walk- life; RA: Rheumatoid arthritis; RE: Role-emotion; RP: ing, climbing stairs and standing that suggest a direct Role-physical; SF: Social functioning; SF-36: 36-item short mechanical role in pain production. Overweight and form; SIP: Sickness impact profile; VP: Vitality function; obesity either lead to an excessive load increase or a WOMAC: Western Ontario and McMaster Osteoarthritis medial displacement of the resultant force, depending on Index. the strength of the counteracting lateral muscles. In com- bination with the observed age-dependent reduction in Competing interests The authors declare that they have no competing interests. quadriceps strength and weakening of the lateral muscu- lar tension band, the latter effect could lead to an increased susceptibility of the knee joint [29]. Weight loss Authors' contributions has been shown to reduce the incidence of knee OA in a AAB and SYAK participated in the design of the study and cohort study and is one of the most important preventable performed the statistical analysis. MHH and MFAR risk factors for the knee OA [30]. involved in the drafting and revising of the manuscript and re-analyzing the data. ZFZ conceived of the study, and They were a few limitations in our studies. Chinese and participated in its design and coordination and helped to Indian were under represented because of the language draft the manuscript. All authors read and approved the difficulty. A validated translation in both languages final manuscript. should be developed in the future to overcome this prob- lem. Small number of male subject limited further extrap- Acknowledgements The authors would like to thank Dr Mohd Rizal of Public Health Depart- olation of the results. Almost all of the study subjects were ment, Universiti Kebangsaan Malaysia Medical Centre and all staff in Batu 9 elderly and therefore some information might have been and Batu 14 Health Clinic, Hulu Langat, Selangor, Malaysia. The study was erroneous due to poor recall. approved by the Medical Research and Ethics Committee of the Faculty of Medicine, Universiti Kebangsaan Malaysia (Ethics Committee Approval Conclusions Code: FF-082-2003). A royalty free license has been obtained from the This study has shown that patient with knee OA attending Quality Metric Inc. (US). 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Bagge E, Bjelle A, Eden S, Svanborg A: Factors associated with available free of charge to the entire biomedical community radiographic OA: results from the population study 70-year- old people in Goteborg. J Rheumatol 1991, 18(8):1218-1222. peer reviewed and published immediately upon acceptance 28. Creamer P, Lethbridge-Cejku M, Hochberg MC: Determinants of cited in PubMed and archived on PubMed Central pain severity in knee OA of demographic and psychosocial variables using 3 pain measures. J Rheumatol 1999, yours — you keep the copyright 26(8):1785-1792. BioMedcentral Submit your manuscript here: http://www.biomedcentral.com/info/publishing_adv.asp Page 7 of 7 (page number not for citation purposes) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Asia Pacific Family Medicine Springer Journals

Health-related quality of life in patients with knee osteoarthritis attending two primary care clinics in Malaysia: a cross-sectional study

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Copyright © 2009 by Zakaria et al; licensee BioMed Central Ltd.
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Medicine & Public Health; General Practice / Family Medicine; Primary Care Medicine
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1447-056X
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10.1186/1447-056X-8-10
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20084190
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Abstract

Background: Measurement of health-related quality of life (HRQOL) among patients with osteoarthritis (OA) helps the health care provider to understand the impact of the disease in the patients' own perspective and make health services more patient-centered. The main aim of this study was to measure the quality of life among patients with symptomatic knee OA attending primary care clinic. We also aimed to ascertain the association between socio-demographic and medical status of patients with knee OA and their quality of life. Methods: A clinic based, cross sectional study using the Short Form-36 (SF-36) questionnaire was conducted in two primary care health clinics in Hulu Langat, Selangor, Malaysia over a period of 8 months. The nurses and medical assistants were involved in recruiting the patients while the family physicians conducted the interview. Results: A total 151 respondents were recruited. The mean age was 65.6 ± 10.8 years with females constituted 119 (78.8%) of the patients. The mean duration of knee pain was 4.07 ± 2.96 years. Half of the patients were overweight and majority, 138 (91.4%), had at least one co-morbidity, the commonest being hypertension. The physical health status showed lower score as compared to mental health component. The domain concerning mental health components showed positive correlation with age. There was a significant negative correlation between age and physical functioning (p < 0.0005) which indicated the deterioration of this domain as patients became older. Male respondents had better scores in most of the QOL dimensions especially in the physical functioning domain (p = 0.03). There was no significant association between QOL with different education levels, employment status and marital status. Patients with higher body mass index (BMI) and existence co-morbidities scored lower in most of the QOL domains. Conclusions: This study has shown that patients with knee OA attending primary care clinics have relatively poor quality of life pertaining to the physical health components but less impact was seen on the patients' mental health. Page 1 of 7 (page number not for citation purposes) Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 Background Methods Health-related quality of life (HRQOL) is increasingly This was a cross-sectional study involving patients with acknowledged as a valid health indicator in many dis- symptomatic knee OA attending two different health clin- eases. HRQOL is narrowed to aspects of an individual's ics in Hulu Langat, Selangor, Malaysia. The study was con- life that is affected by health, disease and/or its treatment. ducted between 1st September 2003 and 30th April 2004. It encompasses emotional, physical, social and subjective By universal sampling, all patients aged 50 and above vis- feelings of well being that reflect an individual's subjective iting the outpatient clinic were screened by a triage nurse evaluation and reaction to his/her illness [1]. or medical assistant for knee pain. Their names and regis- tration numbers were recorded in a special registry book. Osteoarthritis (OA) is the most common type of arthritis If the patients were not seen on the same day, they were found worldwide especially in the elderly. It is a major seen at the next visit. All patients diagnosed with knee OA cause of disability in both the developed and developing based upon the American College of Rheumatology crite- world [2]. The prevalence of OA is in the region of 10-20% ria [12] and age 50 years and above were included. We of the adult population. In all populations studied so far excluded those who were illiterate and could not answer the prevalence of knee OA is higher than that of hip OA the questionnaire. Patients who needed hospital admis- but this is more marked in Asian populations [3]. The sion or those with any other forms of lower limb immo- most common form of OA in Malaysia is knee OA [4]. bility or abnormality such as paraplegia were also Although there is no exact figure of patients with knee OA, excluded. the Community Orientated Program for Control of Rheu- matic Diseases (COPCORD) study showed that 9.3% of The medical outcome study 36-item short form (SF-36) adult Malaysians complained of knee pain with a sharp was used to measure the HRQOL in this study. The SF-36 increase in pain rate to 23% in those over 55 years of age is a 36-item instrument designed to measure generic and 39% in those over 65 years [5,6]. health concepts relevant across age, disease and treatment groups. It is a reliable and validated generic instrument Most patients with OA are assessed and treated within pri- that has been used extensively to measure HRQOL in mary care settings [7] but there seems to be a discrepancy diverse groups [13]. Through the International Quality of between how doctors and patient define the importance Life assessment Project, 15 countries including Malaysia of an illness. Furthermore, OA of the knee is often ignored have participated in translating and adapting the SF-36. by doctors until the disease is very advanced because it is often considered as part of the 'normal' ageing process Socio-demographic and medical characteristics of the [7,8]. As OA and other rheumatic conditions seldom patients were recorded and the Malay language version of cause death but have a substantial impact on health, SF-36 form was either self-administered or led by an inter- HRQOL measures are better indicators of their impact viewer (face-to-face). This version had been translated and than related mortality rates [9]. validated and was used in the Malaysian National Quality of Life Survey 2000 [14]. It measured eight domains con- Review of medical literature revealed 15 studies on sisted of physical functioning, role-physical, bodily pain, HRQOL in OA but there were only two studies that specif- general health, vitality/energy, social functioning, role- ically looked at HRQOL in patients with OA in the pri- emotional and mental health. Scores on each scale ranged mary care setting [10,11]. HRQOL studies in patients with from a minimum of 0 to a maximum of 100, with higher knee OA attending primary care have never been done in scores indicative of better health. Proxy respondents from Malaysia. Our study specifically aims to look at the either family or friends were not entertained as the valid- HRQOL of patients with symptomatic knee OA in pri- ity of SF-36 will be compromised. If there was problem in mary care setting. The findings will help the care provider understanding the questionnaire, the investigator would especially in the primary care to understand the impact of re-read it without re-phrase or explanation. All respond- the disease on the patients and offer an insight into the ents were asked to answer based on what they understood need for early treatment and interventions. of the question. We documented the socio-demographic, medical and Information for computation of scores was provided by non-medical related characteristics of these patients and the manual produced by the Medical Outcomes Trust ascertained their association with HRQOL. We have (1994). Statistical Package for Social Sciences, version found that patient with knee OA attending primary care 12.0 (SPSS Inc, Chicago, IL) was used for data analysis. have relatively poor quality of life pertaining to the phys- Age, body mass index and duration of knee pain were ical health components but there was less impact on the entered as continuous variables. Other variables were mental health of the patients. entered as binary categorical. The association between continuous quantitative variable and QOL scores was ana- Page 2 of 7 (page number not for citation purposes) Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 lyzed using Pearson Correlation Test. Independent sam- disease in the last one year. The mean body mass index ples T-Test was used to analyzed association between (BMI) was 28.23 ± 4.97 with majority (n = 76, 50.3%), dichotomous qualitative variables and QOL scores. The were in the overweight category. association of polinomial qualitative variables and QOL scores were analyzed with One-way Analysis of Variance The profile of SF-36 quality of life dimensions scores are (ANOVA). The p value significance was taken as < 0.05. shown in Table 3. A wide range of scores were reported for Ethnicity was analyzed as dichotomous variable (Malay all dimensions. A full range of scores (0-100) was and non-Malay) due to small proportion of other ethnics. observed on two of the dimensions: role limitations due Results with showed statistical significance were re-ana- to role-physical (RP) and role-emotional (RE). Although lysed using the multiple linear regression models to con- the overall mean scores were above 50.00 in all domains, trol the confounding factors. domains related to the physical health status showed rel- atively lower score as compared to mental health compo- nent. Results There were a total of 213 patients with knee pain during the study period and only 154 were eligible. Out of this, There was a significant negative correlation between phys- only 151 (98%) completed the study. The patients' base- ical functioning (PF) and age (r = -0.337, p < 0.0005) and line and socio-demographic characteristics are shown in there were better scores for males in most of the QOL Table 1. dimensions, especially in the PF domain (p = 0.03). QOL scores were also better pertaining to mental health com- Thirteen (8.6%) patients were not known to have any of ponent for patients with no formal education, where sig- the surveyed medical illnesses and 4 (2.6%) had more nificant differences were found in the vitality (VT) and RE than four. The most common was hypertension and the with p = 0.017 and p = 0.007 respectively. There was no other medical characteristics are shown in Table 2. The significant difference in the marital and employment sta- mean duration of knee pain was 4.07 ± 2.96 years and tus. only eight (5.3%) patients had been hospitalized for the Patients with co-morbidities scored lower than those without in most of the QOL domains and a significant dif- Table 1: Patients baseline and socio-demographic ference was seen in the social functioning (SF) domain (p characteristics = 0.001). The association with other medical characteris- Patient characteristics Number of patients, N = 151 tics showed negative correlation between duration of knee pain and all the QOL domains (except RE) with signifi- Age, yr (mean ± SD) 65.6 ± 10.8 cant negative correlation was found in the RP domain (r Gender = -0.287, p < 0.005). There were lower QOL scores for Male 32 (21.2%) patients with higher BMI except in SF, and significant dif- Female 119 (78.8%) ference was found in the bodily pain (BP) domain (p = Race 0.044). A post-hoc analysis showed the significant differ- Malay 119 (78.8%) ence was between normal BMI and obese patient (p = Chinese 16 (10.6%) 0.013). Indian 9 (6%) Factors which were significant in the bivariate analysis Marital status were then re-analyzed using multiple linear regression Married 114 (75.5%) analysis. The association between PF scores with age and Single/Widowed/Divorce 37 (24.5%) gender remained significant. Similar results were seen Social support between VT and RE scores with education levels. Living alone 5 (3.3%) Living with relatives 146 (96.7%) Discussions The mean age of respondents in our study and the range Level of education received were similar to a study done previously on mainly Chi- No formal education 20 (13.3%) nese descendents [11]. Majority of our respondents had Primary 100 (66.2%) Secondary 31 (20.5%) hypertension followed by diabetes (30.5%). This finding Tertiary 0 (0%) reflected the prevalence of these two diseases among the elderly in Malaysia. A study conducted by the Public Employment status Health Department, Universiti Kebangsaan Malaysia Employed/Self-employed 17 (11.2%) reported that the prevalence of hypertension in Hulu Lan- Unemployed/Retired 134 (88.8%) gat, Selangor, Malaysia population increased from 5% Page 3 of 7 (page number not for citation purposes) Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 Table 2: Patients Medical Characteristics Number of patients(%) Comorbidities Yes 138 (91.4) No 13 (8.6) No of comorbidities 0 13 (8.6) 1 71 (47) 2 54 (35.8) 39 (6) ≥ 4 4 (2.6) Medical conditions Diabetes mellitus 46 (30.5) Hypertension 128 (84.8) Gouty arthritis 7 (4.6) Bronchial asthma 6 (4) Other illnesses 34 (22.5) Duration of knee pain < 1 y 23 (15.2) 1 - 5 y 87 (57.6) 6 - 10 y 40 (26.5) > 10 y 1 (0.7) Hospitalization for knee pain for the past 1 year Yes 8 (5.3) No 143 (94.7) Body Mass Index (BMI) 18.5 - 24.9 (Normal) 32 (21.2) 25.0 - 29.9 (Overweight) 76 (50.3) > 30.0 (Obese) 43 (28.5) among patients between 45-54 years old to 11.6% in Profile). One study used the Sickness Impact Profile (SIP) those aged 55 - 64 years old. Similar finding was reported to assess patients in 40 family practices in Netherlands in diabetes, 9% rising to 15.8% in older age group [15]. [10]. The other study from Hong Kong, assessed 760 adult Chinese patients of a family medicine clinic with each Domains related to the physical health status show rela- subject answered the COOP/WONCA charts and a stand- tively lower score as compared to mental health compo- ard questionnaire on demographic and morbidity data nent. The lower score in physical health component [11]. The authors consistently showed that people with compared to the mental component were consistent with OA of the knee had poor quality of life pertaining to the other studies [10,11], although they had used different physical activities and overall health compared to the gen- instruments (COOP/WONCA charts and Sickness Impact eral population. Table 3: Overall scores of SF-36 quality of life dimensions Physical Health Status Mental Health Status Physical Role- Bodily Pain General Vitality Social Role- Mental Functioning Physical Health Functioning Emotional Health (PF) (RP) (BP) (GH) (VT) (SF) (RE) (MH) Mean 51.88 67.54 56.01 53.29 77.84 93.62 84.10 84.95 Standard 24.11 46.16 18.30 17.17 16.33 15.06 36.27 14.79 deviation (SD) Minimum 5.00 0.00 22.00 5.00 25.00 37.50 0.00 20.00 Maximum 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 * Scores range from 0 to 100 with higher scores indicating better functioning. Page 4 of 7 (page number not for citation purposes) Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 As there was no Malaysian study on QOL of patients with activities downward to the level at which they can func- knee OA, a US norm for patients with osteoarthritis and tion [19]. hypertension was used for comparison (Figure 1). This norm was provided in the SF-36 interpretation manual In our study, age was found to be a predictor for declining [16]. It represented a quality of life of the population age of PF. A significant negative correlation was found 55 years and above in US with these two medical condi- between age and PF (p < 0.0005), even after adjustment tions. While the physical health component showed virtu- for other confounders. This finding was contrary to previ- ally identical scores except for RP, the population in our ous studies [17,20] where the authors reported an insig- study scored better in the mental health component. A nificant negative correlation with age. One study looked large deficit in RP and VT were seen where the US norm at factors that were associated with physical functioning in scored much lower compared to the population in this symptomatic knee OA and the other analyzed factors study. In other words, the US population with OA per- influencing physical function in patients with knee and ceived to have more problems with work or other daily hip OA attending outpatient clinics. activities as a result of physical health and felt tired and worn-out most of the time. This could be due to the dif- Female respondents with knee OA were found to have ference in coping mechanism, cultural as well as socio- lower scores in most of the QOL dimensions with a signif- demographic background between the two populations as icant difference seen in physical functioning (p = 0.03) demonstrated in a few QOL studies amongst Asian popu- even after adjusting for other factors (p = 0.024). This is lation [11,17]. similar to other studies [20,21] and because of the higher prevalence of knee OA in women, this finding is of partic- A relatively higher score in the mental component in our ular importance to the overall management of patients study showed that mental health was less affected by knee with knee OA. It has also been shown that being female OA. This could be due to better coping mechanism and and having joint stiffness were significant independent adaptation to this chronic disease. Affleck et al [18] stud- predictors of total patient expenditures related to OA [22]. ied the coping styles and mood changes in patient with knee OA and rheumatoid arthritis (RA). They found that Background education was found to be an important fac- patients with knee OA used various coping mechanism tor associated with VT and RE domains after controlling and resulted in less pain and better mood as compared to for confounders. Patient with higher education have patients with RA. Furthermore OA might be considered as lower scores in these two domains. The mechanism by normal ageing process, hence it was easily accepted. The which education influenced mental health is unclear but affective and cognitive meaning of information that ini- this could be due to a higher expectation among patients tially was experienced as threatening may be changed to with higher education group. Although there were studies make the present situation more acceptable. Thus patients reported that more years of education were associated may have adjusted their expectations for their health or with better physical function, none of the studies reviewed reported any association between education lev- els with mental health [11,17,20,23]. Education was also found to have a significant association in PF but disap- peared after adjustment. However a small percentage of respondents with higher education in this study limited the generalizability of the results. There was no signifi- cance association found when comparing QOL with dif- ferent employment and marital status which was in PF RP BP GH VT SF RE MH agreement with the finding of other studies [17,24]. 51.88 67.54 56.01 53.29 77.84 93.62 84.1 84.95 This Study 57.44 38.17 55.04 58.96 49.54 79.74 74.84 78.01 US norm for patients with OA and Hypertension Despite high prevalence of co-morbidity among respond- QOL Domains ents in this study, there was no significant association between the presence of co-morbidity and QOL dimen- Compar (Q oar Figure 1 OL thrit ) di is and Hypertension ison b mensi eo tween n with the overa US no ll mean SF rm for p -36 qu atients with Oste- ality of life sions except for social functioning domain but the latter Comparison between overall mean SF-36 quality of disappeared after adjustment for confounders. This is in life (QOL) dimension with the US norm for patients agreement with a previous study [17] that showed co- with Osteoarthritis and Hypertension. PF = Physical morbidity had no association with pain or physical func- functioning, RP = Role limitations due to physical health, BP = tioning. Bodily pain, GH = General health perceptions, VT = Vitality, SF = Social functioning, RE = Role limitations due to emo- tional problems, MH = General mental health. Respondents with BMI ≥ 30 have lower QOL score in all domains except SF. A significant difference was found in Page 5 of 7 (page number not for citation purposes) Score Asia Pacific Family Medicine 2009, 8:10 http://www.apfmj.com/content/8/1/10 the bodily pain domain even after adjustment for con- Lists of Abbreviations founders (p = 0.044, p = 0.008 respectively). The associa- BMI: Body mass index; BP: Bodily pain; COOP/WONCA: tion between BMI and the risk of developing knee OA was Dartmouth Primary Care Cooperative Information demonstrable in various other studies too [25-27]. How- Project/World Organization of National Colleges; Acade- ever its relation to pain is less certain. The study by mies, and Academic Associations of General Practice/ Creamer et al [28] reported a strong correlation between Family Physicians; HRQOL: Health related quality of life; BMI and pain severity. Using WOMAC questionnaire they OA: Osteoarthritis; PF: Physical health; QOL: Quality of found that higher BMI was associated with pain on walk- life; RA: Rheumatoid arthritis; RE: Role-emotion; RP: ing, climbing stairs and standing that suggest a direct Role-physical; SF: Social functioning; SF-36: 36-item short mechanical role in pain production. Overweight and form; SIP: Sickness impact profile; VP: Vitality function; obesity either lead to an excessive load increase or a WOMAC: Western Ontario and McMaster Osteoarthritis medial displacement of the resultant force, depending on Index. the strength of the counteracting lateral muscles. In com- bination with the observed age-dependent reduction in Competing interests The authors declare that they have no competing interests. quadriceps strength and weakening of the lateral muscu- lar tension band, the latter effect could lead to an increased susceptibility of the knee joint [29]. Weight loss Authors' contributions has been shown to reduce the incidence of knee OA in a AAB and SYAK participated in the design of the study and cohort study and is one of the most important preventable performed the statistical analysis. MHH and MFAR risk factors for the knee OA [30]. involved in the drafting and revising of the manuscript and re-analyzing the data. ZFZ conceived of the study, and They were a few limitations in our studies. Chinese and participated in its design and coordination and helped to Indian were under represented because of the language draft the manuscript. All authors read and approved the difficulty. A validated translation in both languages final manuscript. should be developed in the future to overcome this prob- lem. Small number of male subject limited further extrap- Acknowledgements The authors would like to thank Dr Mohd Rizal of Public Health Depart- olation of the results. Almost all of the study subjects were ment, Universiti Kebangsaan Malaysia Medical Centre and all staff in Batu 9 elderly and therefore some information might have been and Batu 14 Health Clinic, Hulu Langat, Selangor, Malaysia. The study was erroneous due to poor recall. approved by the Medical Research and Ethics Committee of the Faculty of Medicine, Universiti Kebangsaan Malaysia (Ethics Committee Approval Conclusions Code: FF-082-2003). A royalty free license has been obtained from the This study has shown that patient with knee OA attending Quality Metric Inc. (US). 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Asia Pacific Family MedicineSpringer Journals

Published: Dec 31, 2009

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