|Year : 2013 | Volume
| Issue : 1 | Page : 10-16
Impact of knee osteoarthritis on the quality of life among Saudi elders: A comparative study
Asma Saad Alrushud1, Salwa B El-Sobkey1, Ashraf Ramadan Hafez1, Abdulaziz Al-Ahaideb2
1 Departments of Rehabilitation Health Sciences, College of Applied Medical Sciences, Riyadh, Saudi Arabia
2 Department of Orthopedics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
|Date of Web Publication||28-May-2013|
11 Abu Firas Alhamdani Street, Riyadh
Background: The population sector of elders is progressively increasing, and it is estimated that it will reach almost one third of the total population in 2025. Large number of elders is suffering from knee osteoarthritis (OA) as the most prevalent rheumatic diseases worldwide. Recently there is a growing concern among researchers and health professionals regarding the impact of knee OA on elders and their quality of life (QOL). Objectives: To explore the impact of knee OA on QOL among Saudi elders aged between 60-70 years and to define which of the Short from survey (SF-36) domain (s) and which component, physical or mental, are mostly affected by this knee OA. In addition to study the presence of correlation between scores of SF-36 domains and components and the following factors; patient's age, gender, weight, height, body mass index (BMI), disease duration and severity, educational level, stability of the income source, income, housing type, housing ownership, and care giver. Subjects and Methods: This study was carried out during (December/ 2010 - March/ 2011). One hundred and twenty Saudi elders, (58, 48.3% male), aged between 60-70 years with mean± SD (64.5 ± 3.03) participated in this comparative study. Half of them had severe knee OA, as defined by knee society score (KSS), they were recruited from King Saud Medical City. The other half were without knee OA, were recruited from Prince Salman Social Center and the Saudi association for the Cooperative Retirees. Arabic version of Short Form -36 questionnaire was used to measure participants QOL domains scores as well as the overall scores of the physical and mental components of the questionnaire. Data collected were statistically treated and presented in tables. Results: Current study showed a better significant scores for Saudi elders without knee OA on all SF-36 domains (p = 0.0001). Calculating the patients' domain's scores as percentage from the maximum domain's scores which showed that, the mental health component of elders patients was more affected than physical health component and that role limitation due to emotional problems domain (RLEP) was the most affected domain (22.7%). Physical component showed positive correlation with income (r= 0.320, P= 0.013). While mental component showed negative correlation with disease duration (r = -0.341, P=0.008). Conclusion: Knee OA has negative impact on Saudi elders' QOL. Mental health component was more affected than physical health component. Consequently RLEP domain was the most affected domain. Patients' QOL was positively correlated to income and negatively correlated to disease duration.
Keywords: Age-related changes, knee osteoarthritis, knee society score, quality of life, Saudi elders, short form-36 questionnaire
|How to cite this article:|
Alrushud AS, El-Sobkey SB, Hafez AR, Al-Ahaideb A. Impact of knee osteoarthritis on the quality of life among Saudi elders: A comparative study. Saudi J Sports Med 2013;13:10-6
|How to cite this URL:|
Alrushud AS, El-Sobkey SB, Hafez AR, Al-Ahaideb A. Impact of knee osteoarthritis on the quality of life among Saudi elders: A comparative study. Saudi J Sports Med [serial online] 2013 [cited 2014 Mar 12];13:10-6. Available from: http://www.sjosm.org/text.asp?2013/13/1/10/112207
| Introduction|| |
The rate of aged persons in the world is rapidly rising, and it is estimated that it will reach 27.4% of the total population in 2025. A large number of elders are suffering from knee osteoarthritis (OA) as the most prevalent rheumatic disease worldwide. Recently, a growing concern from researchers and health professionals is regarding the impact of knee OA of elders and its impact on their quality of life (QOL).
This study was conducted to explore the impact of knee OA on QOL among Saudi elders aged between 60 and 70 years and to define which of the short form survey (SF-36) domain (s) and which component, physical or mental, is mostly affected by this knee OA. In addition, this study also aimed to determine the presence of correlation between scores of SF-36 domains and the following factors: Patient's age, gender, weight, height, body mass index (BMI), disease duration and severity, educational level, stability of the income source, income, housing type, housing ownership and care giver.
| Materials and Methods|| |
This study was carried out during December 2010 to March 2011. It aimed to explore the impact of knee OA on QOL among Saudi elders aged between 60 and 70 years and to define which of the SF-36 domain (s) and which component, physical or mental, is mostly affected by this knee OA. In addition, this study also aimed to determine the presence of correlation between scores of SF-36 domains and the following factors: Patient's age, gender, weight, height, BMI, disease duration and severity, educational level, stability of the income source, income, housing type, housing ownership and care giver.
One hundred and twenty Saudi elders (58, 48.3% males) aged between 60 and 70 years (mean and standard deviation (SD) is 64.5 ± 3.03 years) participated in this comparative study. Their BMI ranged from 18.5 to 29.9%. They were free from psychological diagnosis and could answer the researcher's questions. Half of them were with knee OA, as diagnosed by the referring rheumatologist. They were recruited from King Saud Medical City. They continued their medications as prescribed by the rheumatologist, but they did not receive physiotherapy sessions in the last 3 months and they did not take steroid injections or hyaluronic acid injections in the last 6 months. Patients were excluded if they had knee surgery, had low back pain, painful hip or painful ankle, with traumatic injuries or with associated chronic rheumatic diseases other than knee OA, with congenital or hereditary deformity or needed hospital admission. The other half were without knee OA and were recruited from Prince Salman Social Center and the Saudi Association for the Cooperative Retirees.
This study was reviewed and approved by the Department of Rehabilitation Health Sciences, College of Applied Medical Sciences, King Saud University, ethical committee of Prince Salman Social Center and ethical committee of King Saud Medical City. A written consent form signed by the participant was obtained before starting the study.
The current work was designed as a comparative study to explore the impact of knee OA on the QOL among Saudi elders aged between 60 and 70 years.
Instruments (measurement tools)
- Digital weight and height scale to measure the height and weight for each participant, BMI calculated automatically by the scale.
- Plastic goniometer to measure knee joint range of motion to be used in Knee Society Score (KSS).
- Data collection sheet including the consent form, demographic data (name, age, height, weight and BMI, items about the social level and finance).
- Arabic version of the SF-36 was used to measure all aspects of QOL during the previous 30 days. This survey contains eight domains and 36 items.
On the day of examination of patients with knee OA
- The researcher welcomed the patient and fully explained the aim and procedure of the study to him/her.
- Measurement of the vital signs.
- Patient weight and height were measured by the digital weight-height scale and recorded in the data collection sheet.
- The BMI was calculated automatically by the scale and it was recorded in the sheet.
- Subject with BMI ranging from 18.5% to 29.9% and fitting the study›s criteria was eligible to participate in the study after signing the consent form.
- Personal data and information related to social level and financial and educational levels were recorded.
- SF-36 was fulfilled by the researcher through interviewing the patient.
- The right and left knee joints were assessed by the KSS.
- Same procedure (steps from 1 to 7) was done for participants without knee OA.
- Data were analyzed using version 15.0 of the statistical package for social sciences (SPSS). Descriptive statistics in the form of mean and standard deviation of continuous data, including participant's age, weight, height, BMI and disease duration, and in the form of frequency and percentage for categorical data as gender, educational level, stability of income source, income, housing type, housing ownership and care giver were calculated.
- Comparison between Saudi elders without and with knee OA regarding demographical data was done by using the independent t-test for continuous variables and Chi-square test for categorical variables.
- Independent t-tests were used to compare the scores of the eight domains of SF-36 between Saudi elders without and with knee OA as well as the scores of the physical and mental components.
- Pearson correlation coefficients were used to study the relationship between the eight domains of SF-36 as well as the two components and the continuous variables (patient's age, disease duration), while Spearman correlation coefficients were used to study the relation between the eighth domains of SF-36 as well as the two components and the patients' income. Findings were represented in suitable tables.
| Results|| |
One hundred and twenty Saudi elders (58, 48.3% males) participated in this study. Their age ranged from 60 to 70 years (mean and SD is 64 ± 3.03 years). Other demographic characteristics are presented in [Table 1], which also shows that there is no significant difference between the two groups except in their age (P = 0.029) and income (P = 0.007).
|Table 1: Comparison of demographic characteristics among saudi elders without and with knee osteoarthritis|
Click here to view
[Table 2] shows better QOL scores of elders without knee OA than patients with knee OA. These higher scores were significant for the two components of the scale including physical and mental components (P = 0.0001).
|Table 2: Comparison between saudi elders without and with knee osteoarthritis regarding scores of the two components of SF-36|
Click here to view
The eight domains of SF-36 for elders without knee OA have scores of more than 90% of the maximum score except for general health domain, which is 73% [Table 3]. On the other hand, patients with knee OA have QOL percentage of the maximum scores ranging from 22.7% to 53%. Role limitations due to emotional problems domain shows the lowest percentage of 22.7%, and it is the most affected domain by the disease, followed by the general health domain (37.7%), pain domain (44%), emotional well being domain (46.8%), SF domain (51%), energy domain (52.3%) and physical functioning domain (53%).
|Table 3: Percentages from the maximum scores of the SF-36 domains in saudi elders without and with knee osteoarthritis|
Click here to view
In addition, the two components of SF-36 for elders without knee OA have percentages of more than 90% of the maximum score. On the other hand, patients with knee OA have QOL percentage of the maximum scores less than 50%. The mental component of patients with knee OA is more affected by the disease, with 44% of the maximum score, than the physical component, with 49% of the maximum score.
The KSS has been used to evaluate patient's knee joints and their functional level; the total score shows that all patients have poor knee joints. All patients with knee OA (100%) get scores below 60.
The study reveals correlations between the patients' age, disease duration and income as independent factors and the scores of the eight domains of SF-36 as dependent ones. There is no significant correlation between age factor and the eight domains of SF- 36, while there is a negative significant correlation between disease duration factor and physical functioning domain (P = 0.035), the emotional well-being domain (P = 0.007), social functioning domain (P = 0.001), pain domain (P = 0.000) and general health domain (P = 0.012). Income factor shows a positive significant correlation with physical functioning domain (P = 0.016) and role limitations due to emotional problems domain (P = 0.023).
The study reveals correlations between the patients' age, disease duration and income as independent factors and the 2 components of SF-36 as dependent ones. There is no correlation between patients' age and the two components. There is moderate negative significant correlation between the disease duration and the mental component (P = 0.008) and moderate positive significant correlation between income and physical component of QOL (P = 0.013).
| Discussion|| |
Researchers investigated some demographic factors that may affect patients' QOL. Those factors include patient's age, gender, weight, height, BMI, disease duration and severity. Those factors were commonly mentioned in the literature. In addition, extra social factors such as stability of the income source, income, housing type, housing ownership and care giver had been collected to adopt the study to the Saudi community.
Results of the current study showed a significant negative impact of knee OA on QOL of Saudi elders compared with elders without knee OA. All domains of SF-36 of patients with knee OA are affected by the disease as they had lower scores than the scores of elders without knee OA (P = 0.001 for all domains). Moreover, they had lower scores for both physical and mental components of the SF-36 questionnaire (P = 0.0001 for both). However, Dominick et al.,  who compared QOL responses among elder's subjects with OA, rheumatoid arthritis and no arthritis diagnosis, found that there were no statistically significant differences in QOL scores between subjects with OA and those without arthritis.
The negative impact of knee OA among Saudi elders is consistent with other research studies conducted in different countries such as Cock et al., (2007) in the U.S., who found that elders with knee OA are more likely to report lower levels of QOL even with controlling the confounding variables of age, gender, race, education and income.  Zakaria et al., (2009) in Malaysia, who measured the elder patients' QOL by using SF-36 and stated that patients with knee OA attending primary care clinics have relatively poor QOL.  Chacon et al., in Venezuela, had measured QOL using the arthritis impact measurement scales in a version translated to Spanish, and they found that the perception of QOL is negatively affected by increasing the level of joint pain, old age and low socioeconomic status in elderly patients with knee OA.  Yildiz et al., in Nottingham, concluded that elderly patients with knee OA undergo a significant impact on multiple dimensions of QOL compared with healthy controls.  Salafi et al., in Italy, stated that elderly patients with knee OA had significant lower scores of SF-36.  Another study was done by Muaraki et al. in Japan, who found that knee OA was significantly associated with lower QOL scores among the elder women.  Boonsin et al., in Thailand, stated that knee OA has a negative impact on QOL. 
QOL decreased in patients with knee OA as demonstrated by low scores in all domains of SF-36, and these low scores can be referred to the disease itself. This is justified by participant's sample, which was a homogenous one. This homogeneity between the two groups of participants gives rise to the assumption that any difference between SF-36 scores is fairly referred to knee OA. Moreover, patients with knee OA were younger (with mean age of 63.22 years) than elders without knee OA (with mean age of 65.12 years). This gives rise to the concept that elders with knee OA who had lower scores of SF-36 can be fairly referred to the disease mechanism but not to age-related changes. , If the knee changes are age related, the older subjects would have lower scores than the younger patients. Nevertheless, aging is not inevitably associated with OA. In fact, several pathophysiologic changes that occur in osteoarthritic cartilage differ from those associated with age-related changes in cartilage. 
Income was significantly different between the two groups (P = 0.007). This difference may be referred to the placement of the study as it was conducted in three different places in Riyadh city, with socio-economic diversity. Patients were recruited from King Saud Medical City, the place that is considered as being of modest social level compared with the places of Prince Salman Social Center and the Saudi Association for Co-operative Retirees, which are considered as the highest social places in Riyadh city.
The present study results showed that patients with knee OA experience higher scores of pain than elders without knee OA, and that was evidenced by the scores of pain domain of SF-36. Patients got only 44% of the maximum score while elders without knee OA got 97.5%. Knee OA is considered as the major cause of disability in both the developed and the developing world, and this disability affects QOL in a negative way.  Roland and Moskwitz  stated that among people 65-74 years of age, OA was found to be the fifth largest cause of disability. People with arthritis are more likely to self-identify as "disabled" compared with those with other chronic conditions.  This may be due to the nature of arthritis symptoms and their effect on social, occupational and physical activities. 
Pain was considered as a major determinant of loss of function in individuals with OA. They limit their functional activities to avoid movements that exacerbate pain.  This pain was exacerbated during activities of daily living; when pain level of patients was assessed by the KSS, 16.7% of patients were complaining of moderate continual pain. Results of the present study confirmed that the knee OA symptoms, especially pain, decreased patient's QOL.
In the Saudi community, as documented by this study, patients with knee OA suffer mostly from pain that prevents them from usual daily activities such as praying in the usual authentic way, sitting on ground and using Arabic toilet. , This pain is agreed to be directly related to subject's QOL, and led to lower its score. The study by Hopman-Rock et al.  in Netherlands is in consistence with the current study results; they examined the QOL of community living elderly people and found significantly lower values of QOL in people with more chronic pain compared with a reference group without pain.
Diminished knee function (range of motion) is another main symptom of knee OA; patients with knee OA try to avoid pain by limiting their range of motion. All patients in this study had lost ≥15° of the maximum range of knee flexion; 125°, this range limitation led to activities' restriction and impacted their QOL negatively.  Watenabe et al.  compared patients with knee OA with a control group without knee OA, and they found a significant decrease of knee extension and knee flexion range of motion with P = 0.01 and P = 0.064, respectively.
Patient's dependency also had been affected by knee OA as they became more dependent.  This truly applied to the current study; 61% of the patients had a general servant to help them during daily activities, while only 1.7% of them used a special servant, and this could be referred to the difference in their income. It should be remembered that there was a lower significant difference in the income of elders with knee OA as the largest percent of patients (36.7%) had income ranging from 4000 SR to 6000 SR monthly; this level of income may restrict them from hiring a special servant or using assistive aids, and this would affect their QOL negatively.
Domain of role limitations due to physical health was markedly affected by the disease. Saudi patients got 48.8% of the maximum score of this domain while Saudi elders without knee OA had 98.3% of the domain maximum score. These higher scores among Saudi elders without knee OA could be explained by the fact that 50% of the participants without knee OA were females who were recruited from Prince Salman Social Center, and they were active elder women.
Psychological reactions, like depression, helplessness and anxiety, in patients with knee OA are not surprising given the amount and persistence of pain and disability they experience and the uncertainty about what the future might hold for them.  It has been reported that 10% of the people with OA are depressed, which is affecting their activities of daily living and restricting their lives. ,, Depression or anxiety are frequently expressed when a person fails to cope with the pain and disability resulting from OA.  This concept explains why the role limitation due to emotional problems domain was the most affected domain by knee OA, with only 22.7% of the maximum percentage of the score. Role limitation due to emotional problems includes three items related to the psychological health. Participants were asked about the effect of their psychological state on their activity and activity time, amount and quality.
This study was conducted in Riyadh city, which may limit generalization of the findings to Saudi elders with knee OA. Limiting the study to Riyadh city was due to applicability issues.
Depending on the current results, Saudi elders with knee OA had poor physical and mental health, with 49% and 44% of the maximum scores, respectively, compared with Saudi elders without knee OA (92% and 95%). The current study showed that the responsiveness of the mental health component of SF-36 is relatively low when compared with the physical health component. This could be referred to two reasons. Firstly, to the previously discussed concept that knee OA causes pain and disability, leading to depression and anxiety. Secondly, it may be referred to poor adaptation to this chronic disease. This was observed by the researchers during the interview with the patients. The patients were complaining of pain and how this pain restricts their lives and prevents them from having a normal life, as expressed by them.
The lower scores in the mental health component compared with the physical component were consistent with other studies. Cock et al. found that individuals with OA are more likely to report mental health problems.  Tangtrakulwanice et al. proved that responsiveness of the mental health component of SF-36 is relatively low when compared with the physical component. 
Zakaria et al., in their study to measure the QOL among patients with symptomatic knee OA, attending primary care clinic and to ascertain the association between socio-demographic and medical status of patients with knee OA and their QOL, found that the physical health showed better score compared with mental health.  They referred that to better coping mechanism and adaptation to this chronic disease. Muraki et al., who measured QOL among elders with knee OA, found that subjects with symptomatic knee OA had significantly lower physical QOL. 
The present results showed a moderate negative significant correlation between the disease duration and the mental component of SF-36 (P = 0.008, r = −0.341). The longer the disease duration, the lower the mental component score. The mean disease duration in this study was 11.32 years, which was considered a longer duration compared with the disease duration in many other studies in which the disease duration ranged from 1 to 7 years. ,,, This long time of suffering pain, disability could affect patients negatively. Laborde and Powers found that subjects with OA viewed their past life as more satisfying than their present lives and lack of education about the disease strategy and the right ways of coping with the disease.  These results agreed with results found by Zakaria et al., which showed negative correlation between duration of knee pain and all the QOL domains.  In Zakaria's study, the disease duration was 4.07 ± 2.96 years, 151 respondents were recruited and the mean age was 65.6 ± 10.8 years with females constituting 119 (78.8%) of the patients. In contrast, a study done by Yilidiz et al. found no significant correlation between disease duration (4.88 ± 4.73 years) and QOL scores.  This may be due to shorter disease duration and younger participants age (59.39 ± 7.62 years). Moreover, they used different outcome measures: Nottingham Health Profile, Western Ontario and McMaster Universities Osteoarthritis Index and visual analog scale.
The present study results also showed a moderate positive significant correlation between income and physical component of QOL (P = 0.013, r = 0.320). More income resulted in higher scores of physical component. This can be interpreted by the fact that patients with more financial support might have a better opportunity to cope with their disease and they would have better facilities by purchasing aids and treatment modalities. In addition, they have a chance of more advanced treatment that makes their life easier and promotes their independence. Moreover, they might be able to hire people to help them carry out most of their daily activities as a house keeper, servant housemaid and driver.
- Physiotherapists should acknowledge that knee OA affects the mental health of elderly patients more than their physical health.
- Comprehensive rehabilitation programs should be carried out during treatment of elders with knee OA and improving the mental health of patients should be considered one aim of the program.
- Saudi elders with knee OA should be educated well about their conditions and the right ways of coping with their disability.
- The Standing X-rays of the knees would be of utmost importance to evaluate the severity of the disease.
| Conclusion|| |
There is a negative impact of knee OA on the eight domains as well as the physical and emotional component scores of the SF-36 questionnaire compared with the healthy elders' scores.
Role limitations due to emotional problems components is the most affected domain by the disease. We believe that there is a marked need for further studies that include a larger number of participants and involve different areas of Saudi Arabia to make the results more generalized.
| References|| |
|1.||Vlak T. Patophysiology of osteoarthritis. Reumatizam 2005;52:30-5. |
|2.||Cook C, Pietrobon R, Hegedus E. Osteoarthritis and the impact on quality of life health indicators. Rheumatol Int 2007;27:315-21. |
|3.||Zakaria ZF, Bakar AA, Hasmoni HM, Rani FA, Kadir SA. Health-related quality of life in patients with knee osteoarthritis attending two primary care clinics in Malaysia: A cross-sectional study. Asia Pac Fam Med 2009;8:1. |
|4.||Chacón JG, González NE, Véliz A, Losada BR, Paul H, Santiago LG, et al. Effect of knee osteoarthritis on the perception of quality of life in Venezuelan patients. Arthritis Rheum 2004;51:377-82. |
|5.||Yildiz N, Topuz O, Gungen G, Deniz S, Alan H, Ardic F. Health-related quality of life (Nottingham Health ProWle) in knee osteoarthritis: correlation with clinical variables and self-reported disability. Rheumatol Int 2009;10:296-301. |
|6.||Sallafi F, Carotti M, Grassi W. Health related quality of life in patients with hip or knee oasteoarthritis: Comparison of generic and disease-specific instruments. Clin Rheumatol 2005;24:29-37. |
|7.||Muraki SH, Akune T, Oka H, En-yo T, Yosshida, M. Impact of knee and low back pain on health related quality of life in Japanese women: The research on osteoarthritis against disability (ROAD). Mod Rheumatol 2010;20:444-51. |
|8.||Boonsin, T. Comparing quality of life among people with different patterns and severities of knee osteoarthritis. J Musculoskelet Res 2006;10:47-55. |
|9.||Moskowitz RW. The burden of osteoarthritis: Clinical and quality-of-life issues. Am J Manag Care 2009;15:S223-9. |
|10.||Brooks JA, Kesler KA, Johnson CS, Ciaccia D, Brown JW. Prospective analysis of quality of life after surgical resection for esophageal cancer: Preliminary results. J Surg Oncol 2002;81:185-94. |
|11.||Verbrugge LM, Juarez L. Profile of arthritis disability. Public Health Rep 2001;116:157-79. |
|12.||Løyland B, Miaskowski C, Paul SM, Dahl E, Rustøen T. The relationship between chronic pain and health-related quality of life in long-term social assistance recipients in Norway. Qual Life Res 2010;19:1457-65. |
|13.||Al-Sharkawi MS. A multicentre study of diclofenac sodium slow-release (Voltaren Retard) in the treatment of rheumatic disorders in the Kingdom of Saudi Arabia. J Int Med Res 1984;12:244-9. |
|14.||Al-Arfaj AS, Alballa SR, Al-Saleh SS, Al-Dalaan AM, Bahabry SA, Mousa MA, et al. Knee osteoarthritis in Al-Qaseem, Saudi Arabia. Saudi Med J 2003;24:291-3. |
|15.||Hopman-Rock M, Kraaimaat FW, Bijlsma JW. Quality of life in elderly subjects with pain in the hip or knee. Qual Life Res 1997;6:67-76. |
|16.||Dominick KL, Ahern FM, Gold CH, Heller DA. Health-related quality of life among older adults with arthritis. Health Qual Life Outcomes 2004;13;2:5. |
|17.||Watanabe H, Urabe K, Takahira N, Ikeda N, Fujita M, Obara S, et al. Quality of life, knee function, and physical activity in Japanese elderly women with early-stage knee osteoarthritis. J Orthop Surg (Hong Kong) 2010;18:31-4. |
|18.||Keefe FJ, Smith SJ, Buffington AL, Gibson J, Studts JL, Caldwell DS. Recent advances and future directions in the biopsychosocial assessment and treatment of arthritis. J Consult Clin Psychol 2002;70:640-55. |
|19.||Abdel-Nasser AM, Abd El-Azim S, Taal E, El-Badawy SA, Rasker JJ, Valkenburg HA. Depression and depressive symptoms in rheumatoid arthritis patients: An analysis of their occurrence and determinants. Br J Rheumatol 1998;37:391-7. |
|20.||van der Waal JM, Terwee CB, van der Windt DA, Bouter LM, Dekker J. The impact of non-traumatic hip and knee disorders on health-related quality of life as measured with the SF-36 or SF-12. A systematic review. Qual Life Res 2005;14:1141-55. |
|21.||Bradley LA, Alberts KR. Psychological and behavioral approaches to pain management for patients with rheumatic disease. Rheum Dis Clin North Am 1999;25:215-32. |
|22.||Tangtrakulwanich B, Wiwatwongwana S, Chongsuvivatwong V, Geater AF. Comparison of validity, and responsiveness between general and disease-specific quality of life instruments (Thai version) in knee osteoarthritis. J Med Assoc Thai 2006;89:1454-9. |
|23.||Laborde JM, Powers MJ. Life satisfaction, health control orientation, and illness-related factors in persons with osteoarthritis. Res Nurs Health 1985;8:183-90. |
[Table 1], [Table 2], [Table 3]