http://informahealthcare.com/mor ISSN 1439-7595 (print), 1439-7609 (online) Mod Rheumatol, 2014; 24(1): 166–171 © 2013 Japan College of Rheumatology DOI 10.3109/14397595.2013.854046
ORIGINAL ARTICLE
Quality of life and self-reported disability in patients with knee osteoarthritis
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Berat Meryem Alkan • Fatma Fidan ¨ zge Ardıc¸og˘lu Aliye Tosun • O
•
Received: 31 October 2012 / Accepted: 24 January 2013 Ó Japan College of Rheumatology 2013
Abstract Objectives Osteoarthritis (OA) is the most common degenerative joint disorder and a major public health problem throughout the world. The aims of this study are to assess quality of life (QoL) in patients with knee OA using the generic instrument Short Form-36 (SF-36) and to determine its relationships with conventional clinical measures and self-reported disability. Methods Patients with knee OA (n = 112) with median age of 60 (45–76) years and 40 sex- and age-matched healthy controls were included in the study. Age, sex, body mass index (BMI), symptom duration, and Kellgren– Lawrence scores were recorded. QoL, disability, and pain were assessed using the SF-36, the Western Ontario and McMaster (WOMAC) index, the Lequesne index, and a visual analog scale (VAS) in patients. Also, QoL was assessed using the SF-36 in controls. Results Patients with knee OA had lower scores in all subgroups of SF-36 compared with controls. In patients, the SF-36 physical function (PF) and pain areas significantly correlated with effusion, VAS pain, and Lequesne and WOMAC subgroup scores (p \ 0.05). The pain area of QoL did not show correlation with comorbidity with knee OA. We found that SF-36 and WOMAC pain scores were more severe in female patients. Conclusions Patients with knee OA had significantly poorer QoL compared with healthy controls. SF-36 is ¨ . Ardıc¸og˘lu B. M. Alkan F. Fidan A. Tosun O Atatu¨rk Education and Research Hospital Ankara, Ankara, Turkey B. M. Alkan (&) Ahmet Taner Kıs¸ lalı mah., 2875 sok no 8 C¸ayyolu, Ankara, Turkey e-mail: [email protected] Published online: 17 February 2013
related to the clinical status and functional ability of patients with OA and can be used as a sensitive health status measure for clinical evaluation. Also WOMAC can be used as a sensitive measure for disability of patients with knee OA. Keywords WOMAC SF-36 Knee osteoarthritis Lequesne index
Introduction Osteoarthritis (OA) is the most common degenerative joint disorder and a major public health problem throughout the world [1]. Cartilage degeneration and inflammation stimulate new bone (spur) formation around the joint [2]. These degenerative changes cause pain, stiffness, and swelling that result in chronic disease and disability with advanced age and seriously alter quality of life (QoL) [3]. The goal of clinical treatment is to improve the health condition of the patient. QoL is an important outcome measure for health condition and evaluation of treatments [4]. There are many instruments available to measure QoL. Some of the better known instruments are the Medical Outcome Study Short Form-36 (SF-36) brief generic instruments. SF-36 was developed by investigators at RAND Corporation in the USA to assess functional status and well-being, and is available in at least 70 language versions [5]. During the past few decades, a number of clinical tools for outcome measurement in OA patients have been developed [6, 7]. The Western Ontario and McMaster (WOMAC) index is one of the most widely used outcome measures for this purpose. WOMAC is a diseaseand joint-specific instrument, developed for evaluation of knee and/or hip OA by Bellamy et al. [8].
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The aims of this study are to assess QoL in patients with knee OA using SF-36 and to determine the relationships between SF-36 and conventional clinical measures and self-reported disability by WOMAC and Lequesne index. Our hypothesis is that pain, functional status, and disability may be related to QoL in patients with knee OA.
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Patients and methods In this study, 112 patients who were admitted to our outpatient clinic and had knee OA according to American College of Rheumatology criteria plus 40 sex- and agematched healthy controls (none having any clinical symptom of OA in the knees or pain in lower extremities during the previous 6 months) were included in the study. Exclusion criteria were as follows: concurrent systemic inflammatory rheumatic disease and medical comorbidity that would render the patient unable to participate fully in study procedures. Age, sex, and body mass index (BMI) were recorded in patients and healthy controls. Kellgren– Lawrence scores, QoL, disability, pain, and clinical measures were assessed in patients with knee OA. This study was approved by the Atatu¨rk Education and Research Hospital Ethic Committee, and written consent was obtained from each included patient and healthy control. Patients completed the following measures: 1.
2.
3.
4. 5.
Standing anteroposterior images were graded by an experienced physician using the Kellgren–Lawrence (KL) radiographic grading scale [9]. The grades for this scale are as follows: 0 = no features of OA, 1 = questionable osteophytes, 2 = definite osteophytes without joint-space narrowing, 3 = definite osteophytes with moderate joint-space narrowing, 4 = definite osteophytes with severe joint-space narrowing. Pain knee pain was evaluated by a 100-mm visual analog scale (VAS). The VAS for pain is a simple way of measuring the intensity of pain. The 100-mm VAS is a unidimensional scale that is versatile, easy to use, and has been adopted in many settings. It has been shown to be valid and reliable [10]. Range of motion (ROM): Active knee flexion ROM and restricted knee extension ROM were measured with a standard long-arm goniometer according to Norkin and White [11]. Symptom duration, presence of effusion, and crepitus were recorded. QoL was assessed using the generic instrument SF-36 to assess health-related QoL. SF-36 is a widely applied instrument for measuring health status and consists of eight dimensions: physical functioning, social functioning, physical role, emotional role, mental health,
6.
vitality, bodily pain, and general health perceptions. Scores range from 0 (worst) to 100 (best) with higher scores indicating better health status [12, 13]. Also, QoL was assessed using the SF-36 in control groups. Self-reported disability was assessed using the WOMAC and Lequesne index. WOMAC is a validated instrument for measuring disease-specific outcome in patients with OA of the hip or knee and is recommended by the Outcome Measures for Arthritis Clinical Trials (OMERACT) for measurement of functional dimensions [14]. Transcultural adaptation into Turkish was done by Tu¨zu¨n et al. [15]. WOMAC has three subscales, i.e., pain, stiffness (stiff), and physical functional disability (function), and an overall score. The instrument consists of 24 items on three subscales: pain (5 items), stiffness (2 items), and physical function (17 items). There are five response options for every question (0 = none, 1 = mild, 2 = moderate, 3 = severe, 4 = extreme) in Likert form. The algofunctional Lequesne index is one of the instruments used to measure severity of knee OA [6]. It also comprises three dimensions, including pain (5 items), maximum walking distance (2 items), and activities of daily living (ADL) (8 items). Each dimension has a maximum total score of 8; therefore, the total score ranges from 0 to 24. Severity of symptoms is classified according to the index scores into severe (score 8–10), very severe (score 11–13), and extremely severe (score C14) [16].
Statistics Data were analyzed using SPSS version 17.0 for Windows. Descriptive statistics were used to describe demographic characteristics. Comparative analyses of demographic characteristics between patients and controls were computed using either the Mann–Whitney U test or the chisquared test depending on the levels of measurement. Mean group scores were compared using the Mann–Whitney U test between patients and controls. Spearman correlation tests were used to determine the relationships between variables. The level of significance was set at p \ 0.05.
Results One hundred and twelve patients with knee OA (85 female, 27 male) and forty healthy controls (30 female, 10 male) were included in the study. The ages of the knee OA patients were between 45 and 76 years (mean 59.90 ± 9.89 years, median 60 years), and disease duration was
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between 5 and 300 months (median 48 months). Table 1 presents the main clinical data, and disability scores in patients with knee OA. The ages of the healthy controls were between 47 and 74 years (mean 58.35 ± 7.0 years, median 57 years). There were no statistically significant differences in gender, age or BMI between the patients with knee OA and controls (p [ 0.05). Comparison between patients with knee OA and healthy controls showed that patients with knee OA had lower scores in all subgroups of SF-36 than controls. There were statistically significant differences in SF-36 physical function (PF), role physical (RP), bodily pain (BP), vitality (VT), social function (SF), and mental health (MH) subgroup scores. The results are summarized in Table 2. Table 3 presents a comparison of the mean scores of SF-36 subgroups, disability scores, and clinical variables in patients with knee OA with respect to gender. There were statistically significant differences in the WOMAC
Table 1 Clinical data, and disability scores in patients with knee osteoarthritis (n = 112) Educational level Low, n (%)
10 (8.9)
Medium, n (%)
69 (61.6)
High, n (%)
33 (29.5)
subscore for pain (WOMAC-A) and SF-36 BP, general health (GH), and role emotional (RE) subgroup scores between female and male patients (p \ 0.05). Table 2 Comparison of scores of SF-36 subgroups, and demographic data in patients with knee osteoarthritis and healthy controls Median (min–max)
Patients (n = 112)
Controls (n = 40)
p value
Age (years)
60 (45–76)
57 (47–74)
0.326
Males/females, n (%)
27 (24.1)/85 (75.9)
10 (25)/30 (75)
0.910
Body mass index (kg/ m2)
30 (24.46–45.88)
29.08 (24–40)
0.059
Physical function (PF)
50 (0–100)
77.50 (50–100)
0.000*
Role physical (RP) Bodily pain (BP)
25 (0–100) 41 (0–100)
100 (0–100) 72 (40–100)
0.000* 0.000*
SF-36 subgroups
General health (GH)
57 (0–97)
59.50 (25–82)
0.772
Vitality (VT)
25 (0–90)
55 (20–75)
0.000*
Social function (SF)
50 (0–100)
87.50 (50–100)
0.000*
Role emotional (RE)
100 (0–100)
100 (0–100)
0.237
Mental health (MH)
52 (4–92)
62 (36–100)
0.001*
* p B 0.001
Symptom duration (months), median (min–max)
48 (5–300)
VAS-pain (0–10), median (min–max)
7 (3–10)
Table 3 Comparison of mean scores of SF-36 subgroups, disability scores, and clinical variables in patients with knee osteoarthritis with respect to gender (Mann–Whitney tests)
Grade 1, n (%)
7 (6.26)
Median (min–max)
Grade 2, n (%)
40 (35.71)
Grade 3, n (%) Grade 4, n (%)
47 (41.96) 18 (16.07)
Kellgren–Lawrence scale
ROM, mean ± SD
Females (n = 85)
Males (n = 27)
p value
Age (years)
60 (45–75)
64 (45–76)
0.425
VAS pain
7 (3–10)
6 (4–10)
0.070
WOMAC-A
9 (2–17)
7 (1–10)
0.015*
Knee flexion
117.99 ± 6.89
WOMAC-B
2 (0–6)
2 (0–4)
0.129
Restricted knee extension
1.38 ± 2.21
WOMAC-C
23 (2–47)
21 (0–41)
0.193
Diabetes, n (%)
31 (27.9)
SF-36 subgroups
Hypertension, n (%)
51 (45.9)
50 (20–100)
0.161
17 (15.3)
Physical function (PF)
45 (0–90)
Heart failure, n (%) WOMAC-A
8 (0–17)
Role physical (RP) Bodily pain (BP)
25 (0–100) 41 (0–74)
50 (20–100) 51 (22–100)
0.881 0.017*
WOMAC-B
2 (0–6)
General health (GH)
52 (0–97)
72 (0–92)
0.000*
WOMAC-C
22 (0–47)
Vitality (VT)
25 (0–85)
35 (0–90)
0.541
Social function (SF)
50 (0–100)
62.5 (12.5–100)
0.278
WOMAC subgroups, median (min–max)
Lequesne subgroups, median (min-max) Pain
4 (0–8)
Distance
1 (0–7)
Role emotional (RE)
66 (0–100)
100 (0–100)
0.026*
4.5 (0–10)
Mental health (MH)
52 (8–92)
52 (4–80)
0.854
Function
ROM range of motion, VAS visual analog scale, WOMAC Western Ontario and McMaster Universities Osteoarthritis Index, WOMAC-A WOMAC subscore for pain, WOMAC-B WOMAC subscore for joint stiffness, WOMAC-C WOMAC subscore for daily living activities, SD standard deviation
VAS visual analog scale, WOMAC Western Ontario and McMaster Universities Osteoarthritis Index, WOMAC-A WOMAC subscore for pain, WOMAC-B WOMAC subscore for joint stiffness, WOMAC-C WOMAC subscore for daily living activities * p \ 0.05
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Table 4 Correlation between SF-36 subgroups and disability scores, clinical variables, and demographic data in patients with knee osteoarthritis
R value
PF
RP
BP
-0.141
-0.271
-0.037
0.068
0.099
-0.092
0.127
0.134
0.698
0.478
0.298
0.336
0.184
0.158
Age, p values
0.138
Gender
0.133
-0.014
0.162
0.881
0.096
-0.003
-0.143
0.313
0.977
0.134
Symptom duration
-0.160
-0.265
-0.098
KL scale
-0.178
BMI
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0.092
0.004*
0.005* -0.268
GH
VT
SF
RE
MH
0.228
0.339
0.058
0.103
0.211
0.017
0.016*
0.000**
0.544
0.280
0.025*
0.855
-0.121
-0.053
-0.104
-0.024
-0.092
0.203
0.577
0.277
0.802
0.334
0.014
0.084
-0.210
0.051
0.077
0.596
0.419
0.304
0.885
0.377
-0.152
-0.053
-0.025
-0.164
0.026*
-0.008
0.050
0.060
0.004*
0.111
0.579
0.790
0.085
0.934
0.602
Knee flexion
0.082 0.391
0.156 0.100
0.144 0.129
0.188 0.047*
0.075 0.433
0.229 0.015*
0.081 0.396
0.032 0.735
Crepitus
0.043
0.329
0.162
0.069
0.078
0.192
0.005
0.019
0.652
0.000**
0.088
0.468
0.413
0.043*
0.956
0.845
0.229
0.170
0.255
0.207
0.161
0.313
0.133
0.173
0.015*
0.073
0.007*
0.029*
0.090
0.001**
0.163
0.068
-0.022
-0.021
0.819
0.824
-0.054
-0.214
Effusion VAS pain
-0.358 0.000**
WOMAC-A
-0.526 0.000**
WOMAC-B
-0.295
WOMAC-C
-0.593
0.002** 0.000**
-0.349 0.000** -0.450 0.000** -0.259 0.006* -0.521 0.000**
-0.542 0.000** -0.461 0.000** -0.337 0.000** -0.478 0.000**
-0.209 0.027* -0.195 0.039* -0.191 0.044* -0.179 0.059
-0.137 0.148 -0.200 0.034* -0.084 0.379 -0.218 0.021*
-0.266 0.005** -0.327 0.000** -0.266 0.005** -0.403 0.000**
0.571 -0.121
0.024* -0.139
0.205
0.144
-0.032
-0.160
0.737
0.093
Lequesne Pain
-0.525
-0.383
-0.564
-0.305
-0.108
-0.324
-0.189
-0.176
Distance
0.000** -0.527
0.000** -0.343
0.000* -0.456
0.000** -0.220
0.258 -0.052
0.000** -0.338
0.046* -0.077
0.063 -0.21
0.000**
0.000**
0.046*
0.731
Function
-0.516 0.000**
-0.378 0.000**
0.000** -0.404 0.000**
0.108
0.067
-0.153
-0.174
0.108
0.067
-0.189 0.046*
0.054
-0.033
0.183
0.731
0.054
BMI body mass index, KL Kellgren–Lawrence scale, PF physical function, RP role physical, BP bodily pain, GH general health, VT vitality, SF social function, RE role emotional, MH mental health, VAS visual analog scale, WOMAC Western Ontario and McMaster Universities Osteoarthritis Index, WOMAC-A WOMAC subscore for pain, WOMAC-B WOMAC subscore for joint stiffness, WOMAC-C WOMAC subscore for daily living activities * p \ 0.05, ** p \ 0.001
Table 4 shows that SF-36 physical function significantly correlated with effusion, VAS pain, and Lequesne and WOMAC subgroup scores in patients (p \ 0.05). There were no correlations between the SF-36 PF score and age, gender, BMI, symptom duration, Kellgren–Lawrence score or knee flexion range ROM in patients.
Discussion Osteoarthritis (OA) represents a significant public health problem and disease burden globally, resulting in major disability and pain in affected individuals and significant
healthcare costs for associated disease management [17]. Patients with lower-extremity OA exhibit deterioration in functions concerning mobility, transfer, and ADL [18]. In this study, health-related QoL was evaluated by SF-36 in patients diagnosed with OA and healthy controls. According to the results of the current study, there was a statistically significant impairment in all subscales of QoL, except general health and role emotional subscores. As reported by other studies [19, 20], our results reveal that patients with knee OA had significantly poorer QoL compared with healthy controls. Domains related to physical health status show relatively lower scores as compared with mental health components in patients with OA. The
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lower scores in physical health components compared with mental components are consistent with other studies [21, 22]. Authors have consistently shown that people with OA of the knee had poor QoL pertaining to physical activities and overall health compared with general population. In this study, we investigated the possible causative factors associated with QoL in patients diagnosed with OA of the knee. We observed a direct correlation between pain intensity and QoL as assessed by SF-36. In this study, disease-specific disability functional assessment was performed using the WOMAC questionnaire and Lequesne index. According to our results, a statistically significant correlation was found between pain, stiffness, function scores of WOMAC, and physical function and pain areas of QoL (p \ 0.05). Also subscores of the Lequesne index were significantly correlated with SF-36 physical function and pain subscores. Both SF-36 and WOMAC are valuable instruments that can give information about the health status of the patient with knee OA [23]. We found that, although there was a strong correlation between radiological severity and the SF-36 role physical subscore, radiological severity was not correlated with the pain subscore. Similarly, in a recent study, health-related QoL was assessed by the Nottingham Health Profile (NHP) in a group of patients with knee OA and the physical mobility subscore was found to be correlated with radiological severity whereas the pain subscore was not [20]. The discordance between radiographic OA and the occurrence of knee pain is well documented [24, 25]. It was shown in a recent study that Kellgren–Lawrence score is not related to the VAS or WOMAC score but that it is important for followup of disease progress [26]. We found that, although swelling was correlated with the SF-36 physical function and pain subscores, knee flexion ROM and crepitus were not. The American College of Rheumatology has provided criteria for diagnosis of OA, which do not include swelling. However, similarly Avasthi et al. [28] found that swelling is the only variable which, amongst all, is significantly associated with severity of disease in OA. In the same study, presence of suprapatellar pouch effusion was underlined as increasing the risk of pain [27]. Crepitus and deformity were not found to be significantly associated with disease severity. Pain is a major symptom of knee OA, and although gender differences in pain experience have been previously examined, results remain unclear. Some studies indicate that females report more severe clinical pain than males, while other studies have not found differences in pain levels between genders [29, 30]. We found that SF-36 and WOMAC pain scores were more severe in female patients. SF-36 general health and role emotional were also lower in females. Other SF-36 subscores and WOMAC subscores for joint stiffness and daily living activities were not different between genders.
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In the present study, there was not a significant correlation between age and any subscale of QoL, except the role physical subscore. It has been shown in recent studies that there is a significant negative correlation between age and physical functioning, indicating deterioration of this domain as patients become older [30, 31]. In this study, QoL did not show correlation with BMI in knee OA. The association between BMI and the risk of developing knee OA was demonstrable in various other studies too [32, 33]. However, its relation to pain is not certain. Weight loss has been shown to reduce the incidence of knee OA in a cohort study, and high weight is one of the most important preventable risk factors for knee OA [34]. A limitation of this study is the lack of evaluation of the relationship between depression and QoL. Also we did not evaluate the physical component summary (PCS) and mental component summary (MCS) of SF-36 in our study. Our results could be affected by differences of country, culture, and race. Conclusions Patients with knee OA had significantly poorer QoL compared with healthy controls. SF-36 physical function and pain scores were significant correlated with effusion, VAS pain, and all WOMAC and Lequesne subgroup scales in patients with knee OA. We found that SF-36 and WOMAC pain scores were more severe in female patients. SF-36 is related to the clinical status and functional ability of patients with knee OA, and it can be used as a sensitive health status measure for clinical evaluation. Also WOMAC can be used as a sensitive measure for disability of patients with knee OA. Conflict of interest
None.
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22. Lam CL, Lauder IJ. The impact of chronic diseases on the healthrelated quality of life (HRQOL) of Chinese patients in primary care. Fam Pract. 2000;17(2):159–66. 23. Brazier JE, Harper R, Munro J, et al. Generic and conditionspecific outcome measures for people with osteoarthritis of the knee. Rheumatology. 1999;38:870–7. 24. Hannan MT, Felson DT, Pincus T. Analysis of the discordance between radiographic changes and knee pain in osteoarthritis of the knee. J Rheumatol. 2000;27:1513–7. 25. Cicuttini FM, Baker J, Hart DJ, et al. Association of pain with radiological changes in different compartments and views of the knee joint. Osteoarthr Cartil. 1996;4:143–7. 26. Rupprecht TN, Oczipka F, Lu¨ring C, et al. Is there a correlation between the clinical, radiological and intrasurgical findings of osteoarthritis of the knee? A prospective study on 103 patients. Z Orthop Unfall. 2007;145:430–5. 27. Creamer P, Lethbridge-Cejku M, Hochberg MC. Factors associated with functional impairment in symptomatic knee osteoarthritis. Rheumatology (Oxford). 2000;39:490–6. 28. Avasthi S, Sanghi D, Singh A, et al. Significance of clinical parameters and role of clinical scoring systems in predicting severity of primary osteoarthritis knee. Internet J Orthop Surg. 2009;13(1). doi:10.5580/aaa. 29. Keefe FJ, Lefebvre JC, Egert JR, et al. The relationship of gender to pain, pain behavior, and disability in osteoarthritis: the role of catastrophizing. J Pain. 2000;87:325–34. 30. Robinson ME, Gagnon CM, Riley JL, et al. Altering gender role expectations: effects of pain tolerance, pain threshold, and pain rating. J Pain. 2003;4:284–8. 31. Zakaria ZF, Bakar AA, Hasmoni HM, et al. 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):10. 32. Felson DT, Zhang Y, Hannan MT, et al. Risk factors for incident radiographic knee osteoarthritis in the elderly: the Framingham Study. Arthritis Rheum. 1997;40(4):728–33. 33. Mili F, Helmick CJ, Zack MM. Prevalence of arthritis: analysis of data from US Behavioral Risk Factor Surveillance System, 1996–99. J Rheumatol. 2002;29(9):1981–8. 34. Felson DT, Zhang Y, Anthony JM, et al. Weight loss reduces the risk for symptomatic knee osteoarthritis in women. The Framingham Study. Ann Intern Med. 1992;116(7):535–9.
ORIGINAL ARTICLE
Quality of life and self-reported disability in patients with knee osteoarthritis
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Berat Meryem Alkan • Fatma Fidan ¨ zge Ardıc¸og˘lu Aliye Tosun • O
•
Received: 31 October 2012 / Accepted: 24 January 2013 Ó Japan College of Rheumatology 2013
Abstract Objectives Osteoarthritis (OA) is the most common degenerative joint disorder and a major public health problem throughout the world. The aims of this study are to assess quality of life (QoL) in patients with knee OA using the generic instrument Short Form-36 (SF-36) and to determine its relationships with conventional clinical measures and self-reported disability. Methods Patients with knee OA (n = 112) with median age of 60 (45–76) years and 40 sex- and age-matched healthy controls were included in the study. Age, sex, body mass index (BMI), symptom duration, and Kellgren– Lawrence scores were recorded. QoL, disability, and pain were assessed using the SF-36, the Western Ontario and McMaster (WOMAC) index, the Lequesne index, and a visual analog scale (VAS) in patients. Also, QoL was assessed using the SF-36 in controls. Results Patients with knee OA had lower scores in all subgroups of SF-36 compared with controls. In patients, the SF-36 physical function (PF) and pain areas significantly correlated with effusion, VAS pain, and Lequesne and WOMAC subgroup scores (p \ 0.05). The pain area of QoL did not show correlation with comorbidity with knee OA. We found that SF-36 and WOMAC pain scores were more severe in female patients. Conclusions Patients with knee OA had significantly poorer QoL compared with healthy controls. SF-36 is ¨ . Ardıc¸og˘lu B. M. Alkan F. Fidan A. Tosun O Atatu¨rk Education and Research Hospital Ankara, Ankara, Turkey B. M. Alkan (&) Ahmet Taner Kıs¸ lalı mah., 2875 sok no 8 C¸ayyolu, Ankara, Turkey e-mail: [email protected] Published online: 17 February 2013
related to the clinical status and functional ability of patients with OA and can be used as a sensitive health status measure for clinical evaluation. Also WOMAC can be used as a sensitive measure for disability of patients with knee OA. Keywords WOMAC SF-36 Knee osteoarthritis Lequesne index
Introduction Osteoarthritis (OA) is the most common degenerative joint disorder and a major public health problem throughout the world [1]. Cartilage degeneration and inflammation stimulate new bone (spur) formation around the joint [2]. These degenerative changes cause pain, stiffness, and swelling that result in chronic disease and disability with advanced age and seriously alter quality of life (QoL) [3]. The goal of clinical treatment is to improve the health condition of the patient. QoL is an important outcome measure for health condition and evaluation of treatments [4]. There are many instruments available to measure QoL. Some of the better known instruments are the Medical Outcome Study Short Form-36 (SF-36) brief generic instruments. SF-36 was developed by investigators at RAND Corporation in the USA to assess functional status and well-being, and is available in at least 70 language versions [5]. During the past few decades, a number of clinical tools for outcome measurement in OA patients have been developed [6, 7]. The Western Ontario and McMaster (WOMAC) index is one of the most widely used outcome measures for this purpose. WOMAC is a diseaseand joint-specific instrument, developed for evaluation of knee and/or hip OA by Bellamy et al. [8].
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The aims of this study are to assess QoL in patients with knee OA using SF-36 and to determine the relationships between SF-36 and conventional clinical measures and self-reported disability by WOMAC and Lequesne index. Our hypothesis is that pain, functional status, and disability may be related to QoL in patients with knee OA.
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Patients and methods In this study, 112 patients who were admitted to our outpatient clinic and had knee OA according to American College of Rheumatology criteria plus 40 sex- and agematched healthy controls (none having any clinical symptom of OA in the knees or pain in lower extremities during the previous 6 months) were included in the study. Exclusion criteria were as follows: concurrent systemic inflammatory rheumatic disease and medical comorbidity that would render the patient unable to participate fully in study procedures. Age, sex, and body mass index (BMI) were recorded in patients and healthy controls. Kellgren– Lawrence scores, QoL, disability, pain, and clinical measures were assessed in patients with knee OA. This study was approved by the Atatu¨rk Education and Research Hospital Ethic Committee, and written consent was obtained from each included patient and healthy control. Patients completed the following measures: 1.
2.
3.
4. 5.
Standing anteroposterior images were graded by an experienced physician using the Kellgren–Lawrence (KL) radiographic grading scale [9]. The grades for this scale are as follows: 0 = no features of OA, 1 = questionable osteophytes, 2 = definite osteophytes without joint-space narrowing, 3 = definite osteophytes with moderate joint-space narrowing, 4 = definite osteophytes with severe joint-space narrowing. Pain knee pain was evaluated by a 100-mm visual analog scale (VAS). The VAS for pain is a simple way of measuring the intensity of pain. The 100-mm VAS is a unidimensional scale that is versatile, easy to use, and has been adopted in many settings. It has been shown to be valid and reliable [10]. Range of motion (ROM): Active knee flexion ROM and restricted knee extension ROM were measured with a standard long-arm goniometer according to Norkin and White [11]. Symptom duration, presence of effusion, and crepitus were recorded. QoL was assessed using the generic instrument SF-36 to assess health-related QoL. SF-36 is a widely applied instrument for measuring health status and consists of eight dimensions: physical functioning, social functioning, physical role, emotional role, mental health,
6.
vitality, bodily pain, and general health perceptions. Scores range from 0 (worst) to 100 (best) with higher scores indicating better health status [12, 13]. Also, QoL was assessed using the SF-36 in control groups. Self-reported disability was assessed using the WOMAC and Lequesne index. WOMAC is a validated instrument for measuring disease-specific outcome in patients with OA of the hip or knee and is recommended by the Outcome Measures for Arthritis Clinical Trials (OMERACT) for measurement of functional dimensions [14]. Transcultural adaptation into Turkish was done by Tu¨zu¨n et al. [15]. WOMAC has three subscales, i.e., pain, stiffness (stiff), and physical functional disability (function), and an overall score. The instrument consists of 24 items on three subscales: pain (5 items), stiffness (2 items), and physical function (17 items). There are five response options for every question (0 = none, 1 = mild, 2 = moderate, 3 = severe, 4 = extreme) in Likert form. The algofunctional Lequesne index is one of the instruments used to measure severity of knee OA [6]. It also comprises three dimensions, including pain (5 items), maximum walking distance (2 items), and activities of daily living (ADL) (8 items). Each dimension has a maximum total score of 8; therefore, the total score ranges from 0 to 24. Severity of symptoms is classified according to the index scores into severe (score 8–10), very severe (score 11–13), and extremely severe (score C14) [16].
Statistics Data were analyzed using SPSS version 17.0 for Windows. Descriptive statistics were used to describe demographic characteristics. Comparative analyses of demographic characteristics between patients and controls were computed using either the Mann–Whitney U test or the chisquared test depending on the levels of measurement. Mean group scores were compared using the Mann–Whitney U test between patients and controls. Spearman correlation tests were used to determine the relationships between variables. The level of significance was set at p \ 0.05.
Results One hundred and twelve patients with knee OA (85 female, 27 male) and forty healthy controls (30 female, 10 male) were included in the study. The ages of the knee OA patients were between 45 and 76 years (mean 59.90 ± 9.89 years, median 60 years), and disease duration was
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between 5 and 300 months (median 48 months). Table 1 presents the main clinical data, and disability scores in patients with knee OA. The ages of the healthy controls were between 47 and 74 years (mean 58.35 ± 7.0 years, median 57 years). There were no statistically significant differences in gender, age or BMI between the patients with knee OA and controls (p [ 0.05). Comparison between patients with knee OA and healthy controls showed that patients with knee OA had lower scores in all subgroups of SF-36 than controls. There were statistically significant differences in SF-36 physical function (PF), role physical (RP), bodily pain (BP), vitality (VT), social function (SF), and mental health (MH) subgroup scores. The results are summarized in Table 2. Table 3 presents a comparison of the mean scores of SF-36 subgroups, disability scores, and clinical variables in patients with knee OA with respect to gender. There were statistically significant differences in the WOMAC
Table 1 Clinical data, and disability scores in patients with knee osteoarthritis (n = 112) Educational level Low, n (%)
10 (8.9)
Medium, n (%)
69 (61.6)
High, n (%)
33 (29.5)
subscore for pain (WOMAC-A) and SF-36 BP, general health (GH), and role emotional (RE) subgroup scores between female and male patients (p \ 0.05). Table 2 Comparison of scores of SF-36 subgroups, and demographic data in patients with knee osteoarthritis and healthy controls Median (min–max)
Patients (n = 112)
Controls (n = 40)
p value
Age (years)
60 (45–76)
57 (47–74)
0.326
Males/females, n (%)
27 (24.1)/85 (75.9)
10 (25)/30 (75)
0.910
Body mass index (kg/ m2)
30 (24.46–45.88)
29.08 (24–40)
0.059
Physical function (PF)
50 (0–100)
77.50 (50–100)
0.000*
Role physical (RP) Bodily pain (BP)
25 (0–100) 41 (0–100)
100 (0–100) 72 (40–100)
0.000* 0.000*
SF-36 subgroups
General health (GH)
57 (0–97)
59.50 (25–82)
0.772
Vitality (VT)
25 (0–90)
55 (20–75)
0.000*
Social function (SF)
50 (0–100)
87.50 (50–100)
0.000*
Role emotional (RE)
100 (0–100)
100 (0–100)
0.237
Mental health (MH)
52 (4–92)
62 (36–100)
0.001*
* p B 0.001
Symptom duration (months), median (min–max)
48 (5–300)
VAS-pain (0–10), median (min–max)
7 (3–10)
Table 3 Comparison of mean scores of SF-36 subgroups, disability scores, and clinical variables in patients with knee osteoarthritis with respect to gender (Mann–Whitney tests)
Grade 1, n (%)
7 (6.26)
Median (min–max)
Grade 2, n (%)
40 (35.71)
Grade 3, n (%) Grade 4, n (%)
47 (41.96) 18 (16.07)
Kellgren–Lawrence scale
ROM, mean ± SD
Females (n = 85)
Males (n = 27)
p value
Age (years)
60 (45–75)
64 (45–76)
0.425
VAS pain
7 (3–10)
6 (4–10)
0.070
WOMAC-A
9 (2–17)
7 (1–10)
0.015*
Knee flexion
117.99 ± 6.89
WOMAC-B
2 (0–6)
2 (0–4)
0.129
Restricted knee extension
1.38 ± 2.21
WOMAC-C
23 (2–47)
21 (0–41)
0.193
Diabetes, n (%)
31 (27.9)
SF-36 subgroups
Hypertension, n (%)
51 (45.9)
50 (20–100)
0.161
17 (15.3)
Physical function (PF)
45 (0–90)
Heart failure, n (%) WOMAC-A
8 (0–17)
Role physical (RP) Bodily pain (BP)
25 (0–100) 41 (0–74)
50 (20–100) 51 (22–100)
0.881 0.017*
WOMAC-B
2 (0–6)
General health (GH)
52 (0–97)
72 (0–92)
0.000*
WOMAC-C
22 (0–47)
Vitality (VT)
25 (0–85)
35 (0–90)
0.541
Social function (SF)
50 (0–100)
62.5 (12.5–100)
0.278
WOMAC subgroups, median (min–max)
Lequesne subgroups, median (min-max) Pain
4 (0–8)
Distance
1 (0–7)
Role emotional (RE)
66 (0–100)
100 (0–100)
0.026*
4.5 (0–10)
Mental health (MH)
52 (8–92)
52 (4–80)
0.854
Function
ROM range of motion, VAS visual analog scale, WOMAC Western Ontario and McMaster Universities Osteoarthritis Index, WOMAC-A WOMAC subscore for pain, WOMAC-B WOMAC subscore for joint stiffness, WOMAC-C WOMAC subscore for daily living activities, SD standard deviation
VAS visual analog scale, WOMAC Western Ontario and McMaster Universities Osteoarthritis Index, WOMAC-A WOMAC subscore for pain, WOMAC-B WOMAC subscore for joint stiffness, WOMAC-C WOMAC subscore for daily living activities * p \ 0.05
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Table 4 Correlation between SF-36 subgroups and disability scores, clinical variables, and demographic data in patients with knee osteoarthritis
R value
PF
RP
BP
-0.141
-0.271
-0.037
0.068
0.099
-0.092
0.127
0.134
0.698
0.478
0.298
0.336
0.184
0.158
Age, p values
0.138
Gender
0.133
-0.014
0.162
0.881
0.096
-0.003
-0.143
0.313
0.977
0.134
Symptom duration
-0.160
-0.265
-0.098
KL scale
-0.178
BMI
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0.092
0.004*
0.005* -0.268
GH
VT
SF
RE
MH
0.228
0.339
0.058
0.103
0.211
0.017
0.016*
0.000**
0.544
0.280
0.025*
0.855
-0.121
-0.053
-0.104
-0.024
-0.092
0.203
0.577
0.277
0.802
0.334
0.014
0.084
-0.210
0.051
0.077
0.596
0.419
0.304
0.885
0.377
-0.152
-0.053
-0.025
-0.164
0.026*
-0.008
0.050
0.060
0.004*
0.111
0.579
0.790
0.085
0.934
0.602
Knee flexion
0.082 0.391
0.156 0.100
0.144 0.129
0.188 0.047*
0.075 0.433
0.229 0.015*
0.081 0.396
0.032 0.735
Crepitus
0.043
0.329
0.162
0.069
0.078
0.192
0.005
0.019
0.652
0.000**
0.088
0.468
0.413
0.043*
0.956
0.845
0.229
0.170
0.255
0.207
0.161
0.313
0.133
0.173
0.015*
0.073
0.007*
0.029*
0.090
0.001**
0.163
0.068
-0.022
-0.021
0.819
0.824
-0.054
-0.214
Effusion VAS pain
-0.358 0.000**
WOMAC-A
-0.526 0.000**
WOMAC-B
-0.295
WOMAC-C
-0.593
0.002** 0.000**
-0.349 0.000** -0.450 0.000** -0.259 0.006* -0.521 0.000**
-0.542 0.000** -0.461 0.000** -0.337 0.000** -0.478 0.000**
-0.209 0.027* -0.195 0.039* -0.191 0.044* -0.179 0.059
-0.137 0.148 -0.200 0.034* -0.084 0.379 -0.218 0.021*
-0.266 0.005** -0.327 0.000** -0.266 0.005** -0.403 0.000**
0.571 -0.121
0.024* -0.139
0.205
0.144
-0.032
-0.160
0.737
0.093
Lequesne Pain
-0.525
-0.383
-0.564
-0.305
-0.108
-0.324
-0.189
-0.176
Distance
0.000** -0.527
0.000** -0.343
0.000* -0.456
0.000** -0.220
0.258 -0.052
0.000** -0.338
0.046* -0.077
0.063 -0.21
0.000**
0.000**
0.046*
0.731
Function
-0.516 0.000**
-0.378 0.000**
0.000** -0.404 0.000**
0.108
0.067
-0.153
-0.174
0.108
0.067
-0.189 0.046*
0.054
-0.033
0.183
0.731
0.054
BMI body mass index, KL Kellgren–Lawrence scale, PF physical function, RP role physical, BP bodily pain, GH general health, VT vitality, SF social function, RE role emotional, MH mental health, VAS visual analog scale, WOMAC Western Ontario and McMaster Universities Osteoarthritis Index, WOMAC-A WOMAC subscore for pain, WOMAC-B WOMAC subscore for joint stiffness, WOMAC-C WOMAC subscore for daily living activities * p \ 0.05, ** p \ 0.001
Table 4 shows that SF-36 physical function significantly correlated with effusion, VAS pain, and Lequesne and WOMAC subgroup scores in patients (p \ 0.05). There were no correlations between the SF-36 PF score and age, gender, BMI, symptom duration, Kellgren–Lawrence score or knee flexion range ROM in patients.
Discussion Osteoarthritis (OA) represents a significant public health problem and disease burden globally, resulting in major disability and pain in affected individuals and significant
healthcare costs for associated disease management [17]. Patients with lower-extremity OA exhibit deterioration in functions concerning mobility, transfer, and ADL [18]. In this study, health-related QoL was evaluated by SF-36 in patients diagnosed with OA and healthy controls. According to the results of the current study, there was a statistically significant impairment in all subscales of QoL, except general health and role emotional subscores. As reported by other studies [19, 20], our results reveal that patients with knee OA had significantly poorer QoL compared with healthy controls. Domains related to physical health status show relatively lower scores as compared with mental health components in patients with OA. The
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lower scores in physical health components compared with mental components are consistent with other studies [21, 22]. Authors have consistently shown that people with OA of the knee had poor QoL pertaining to physical activities and overall health compared with general population. In this study, we investigated the possible causative factors associated with QoL in patients diagnosed with OA of the knee. We observed a direct correlation between pain intensity and QoL as assessed by SF-36. In this study, disease-specific disability functional assessment was performed using the WOMAC questionnaire and Lequesne index. According to our results, a statistically significant correlation was found between pain, stiffness, function scores of WOMAC, and physical function and pain areas of QoL (p \ 0.05). Also subscores of the Lequesne index were significantly correlated with SF-36 physical function and pain subscores. Both SF-36 and WOMAC are valuable instruments that can give information about the health status of the patient with knee OA [23]. We found that, although there was a strong correlation between radiological severity and the SF-36 role physical subscore, radiological severity was not correlated with the pain subscore. Similarly, in a recent study, health-related QoL was assessed by the Nottingham Health Profile (NHP) in a group of patients with knee OA and the physical mobility subscore was found to be correlated with radiological severity whereas the pain subscore was not [20]. The discordance between radiographic OA and the occurrence of knee pain is well documented [24, 25]. It was shown in a recent study that Kellgren–Lawrence score is not related to the VAS or WOMAC score but that it is important for followup of disease progress [26]. We found that, although swelling was correlated with the SF-36 physical function and pain subscores, knee flexion ROM and crepitus were not. The American College of Rheumatology has provided criteria for diagnosis of OA, which do not include swelling. However, similarly Avasthi et al. [28] found that swelling is the only variable which, amongst all, is significantly associated with severity of disease in OA. In the same study, presence of suprapatellar pouch effusion was underlined as increasing the risk of pain [27]. Crepitus and deformity were not found to be significantly associated with disease severity. Pain is a major symptom of knee OA, and although gender differences in pain experience have been previously examined, results remain unclear. Some studies indicate that females report more severe clinical pain than males, while other studies have not found differences in pain levels between genders [29, 30]. We found that SF-36 and WOMAC pain scores were more severe in female patients. SF-36 general health and role emotional were also lower in females. Other SF-36 subscores and WOMAC subscores for joint stiffness and daily living activities were not different between genders.
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In the present study, there was not a significant correlation between age and any subscale of QoL, except the role physical subscore. It has been shown in recent studies that there is a significant negative correlation between age and physical functioning, indicating deterioration of this domain as patients become older [30, 31]. In this study, QoL did not show correlation with BMI in knee OA. The association between BMI and the risk of developing knee OA was demonstrable in various other studies too [32, 33]. However, its relation to pain is not certain. Weight loss has been shown to reduce the incidence of knee OA in a cohort study, and high weight is one of the most important preventable risk factors for knee OA [34]. A limitation of this study is the lack of evaluation of the relationship between depression and QoL. Also we did not evaluate the physical component summary (PCS) and mental component summary (MCS) of SF-36 in our study. Our results could be affected by differences of country, culture, and race. Conclusions Patients with knee OA had significantly poorer QoL compared with healthy controls. SF-36 physical function and pain scores were significant correlated with effusion, VAS pain, and all WOMAC and Lequesne subgroup scales in patients with knee OA. We found that SF-36 and WOMAC pain scores were more severe in female patients. SF-36 is related to the clinical status and functional ability of patients with knee OA, and it can be used as a sensitive health status measure for clinical evaluation. Also WOMAC can be used as a sensitive measure for disability of patients with knee OA. Conflict of interest
None.
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DOI 10.3109/14397595.2013.854046
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