Qual Life Res DOI 10.1007/s11136-010-9820-4
BRIEF COMMUNICATION
Measuring health-related quality of life in Kashin–Beck disease using EQ-5D Umer Farooq • Xiong Guo • Ling-Hsiang Chuang Hua Fang • Guihua Zhuang • Chuantao Xia
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Accepted: 7 December 2010 Ó Springer Science+Business Media B.V. 2010
Abstract Purpose To assess health-related quality of life in patients with Kashin–Beck disease (KBD) in China. Methods A total of 684 participants from endemic areas of the Shaanxi province in China were recruited through a multistage stratified random sampling. Amongst those, 368 participants were diagnosed with KBD while the rest of 316 were non-KBD participants. Differences between KBD and non-KBD groups were analysed for the percentage of reporting any problems in each of EQ-5D five dimensions, EQ-5D index scores and visual analogue scale (VAS) scores. Results KBD patients have a higher percentage of reporting any problems in each of EQ-5D dimension than non-KBD participants and a general population in Beijing. The most affected dimension is pain/discomfort, followed by mobility, anxiety/depression, and usual activities, and self-care being the last. The mean EQ-5D index and VAS
U. Farooq X. Guo (&) C. Xia School of Public Health, Medicine College, Key Laboratory of Environment and Gene Related Diseases of Ministry of Education, Xi’an Jiaotong University, Xi’an, Shaanxi, China e-mail:
[email protected] L.-H. Chuang Center for Health Economics, The University of York, Heslington York, UK H. Fang School of Nursing, Medicine College, Xi’an Jiaotong University, Xi’an, Shaanxi, China G. Zhuang Department of Epidemiology and Biostatistics, School of Public Health, Medicine College, Xi’an Jiaotong University, Xi’an, Shaanxi, China
scores for KBD patients are significantly lower than those of non-KBD participants. Conclusion This study is the first attempt to measure the health-related quality of life in KBD patients. The results of the study show that KBD has a severe impact on patients’ health-related quality of life as measured by EQ5D. It particularly causes great problems in the dimensions of pain/discomfort, mobility and anxiety/depression. Keywords Quality of life Endemic diseases Musculoskeletal diseases Osteoarthropathy Abbreviations KBD Kashin–Beck disease HRQOL Health-related quality of life VAS Visual analogue scale OA Osteoarthritis RA Rheumatoid arthritis
Introduction Kashin–Beck disease (KBD) is an osteoarthropathy. This debilitating disease attacks the growth of joint cartilage, with the worst forms resulting in dwarfism, very short upper limbs and deformed, painful joints with limited mobility. Kashin–Beck disease starts in childhood with symptoms occurring from the age of 4 years [1–3].This is an endemic disease prevalent in eastern Siberia, North Korea and the diagonal broad belt extending from the north-eastern to the south-western China [4]. KBD is known locally as ‘‘big bone disease’’ in China with an estimated prevalence of 0.69 million KBD
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patients amongst a total population of 10.58 million in 366 KBD endemic counties [5]. There is no permanent cure so prevalence can be as high as 50% in small communities [6]. Most of the affected counties in China are rural with a majority of population involved in agriculture, consuming locally produced grain. The joints most frequently affected by KBD are ankles, knees, wrists and elbows, leading to atrophied muscles; it makes manual farming work difficult and painful, causing greater economic and social difficulties for the population [1–3]. KBD interferes with the continuation of education, learning skills, daily life and professions; thus, it is expected to have a profound effect on an individual’s health-related quality of life (HRQOL). Unlike other musculoskeletal diseases where their specific and substantial impacts on HRQOL have been studied [7, 8], most of the studies on KBD have so far focused on aetiology, distribution and treatment. Therefore, the current study aims to measure the health-related quality of life of patients with KBD in China.
Methods Study design The data used in this paper were extracted from a crosssectional survey conducted in the KBD endemic areas of Shaanxi province in China. Shaanxi province, located in the north-west of the country, has a population of 37.2 million with 63% living in the rural areas [9]. With a prevalence of 14–21%, Shaanxi has one of the highest rates of KBD in China [10, 11]. The target population of the survey was those above 13 years living in endemic areas in Shaanxi province. The age criteria were set to ensure the better understanding and responsiveness of adults towards HRQOL issues and precision of KBD diagnosis by clinical criteria in adults. The selected participants were interviewed with a battery of questionnaires. Sampling The sample unit was a village in Shaanxi province. Through a multistage stratified random sampling strategy, two counties (Linyou and Yongshou) from endemic areas of Shaanxi province were randomly selected for the first stage, and then the villages of each selected county were divided into three strata based on the prevalence of KBD: low (\10%)-, middle (10–20%)- and high-prevalence ([20%) villages. One village was selected from each stratum, and all individuals above 13 years in the selected villages were invited to participate. A total of 684 participants were recruited in the study in which 368 participants
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were diagnosed with KBD and 316 participants without KBD as assessed by the clinical criteria [1–3, 12]. (Hereafter, the former refers to KBD group and the latter as nonKBD group.) The response rate was 100% amongst the recruited participants. The survey was conducted between June 2009 and December 2009. Study tools The simplified Chinese version of EQ-5D validated for the general population [13] in mainland China was employed after permission from the EuroQoL Group. Due to the lack of a domestic EQ-5D value set for mainland China, the UK value set [14] has been applied as a substitute. EQ-5D is a well-established and widely used generic instrument for assessing HRQOL. It has been used for back disorders [15], osteoarthritis (OA) of the knee [16], rheumatoid arthritis(RA) [17–20] and several musculoskeletal diseases [21] and is one of the most commonly used generic instruments for assessing the HRQOL in musculoskeletal diseases [22]. Statistical analysis Descriptive statistics are used to present the basic characteristics of participants in both the KBD and non-KBD groups. To compare the difference between the two groups, the categorical variables are analysed using a chi-square test. For continuous variables, the Mann–Whitney test is used to account for the non-normal distribution of the variables. The percentage of reporting any problems (by combining some and extreme problem responses) in each of EQ5D five dimensions is summarized. The difference in reporting any problem in each dimension between two groups is compared using chi-square test. The EQ-5D index and VAS scores are described by using mean, median and standard deviation (SD), and the differences between these scores of both groups are assessed using the Mann–Whitney test. Data were analysed using SPSS version 16 and STATA 10, and the significance was assessed at the level of 0.01.
Results Patient profile The basic characteristics of participants in KBD and nonKBD groups are shown in Table 1. There is no statistically significant difference between the two groups in any of the characteristics examined.
Qual Life Res Table 1 Characteristics of both KBD and non-KBD groups
Characteristic
Total sample [N = 684 (%)]
KBD group (%)
Non-KBD group (%)
P-value
0.211
Gender Male
315 (46.1)
179 (48.6)
136 (43.0)
Female
369 (53.9)
189 (51.4)
180 (57.0)
Age (mean ± SD)
52.42 ± 12.23
55.99 ± 10.08
51.70 ± 10.23
0.671 0.068
Education level No schooling
253 (37)
147 (39.9)
106 (33.5)
Primary
209 (30.6)
118 (32.1)
91 (28.9)
Middle
169 (24.7)
81 (22.0)
88 (27.8)
52 (7.6)
22 (6.0)
30 (9.5)
1 (0.1)
0 (0)
1 (0.3)
656 (95.9)
356 (96.7)
300 (94.9)
12 (1.8)
3 (0.8)
9 (2.8)
Business
6 (0.9)
2 (0.5)
4 (1.3)
Technician
7 (1.0)
6 (1.6)
1 (0.3)
Others
3 (0.4)
1 (0.3)
2 (0.6)
18 (2.6)
9 (2.4)
9 (2.8)
High school University Profession Farmer Factory worker
0.076
Marital status Single Widow
70 (10.2)
43 (11.7)
27 (8.5)
Married
596 (87.1)
316 (85.9)
280 (88.6)
0.389
Housing Cave
61 (8.9)
House
620 (90.6)
Flat Table 2 Comparison of five domains of EQ-5D in KBD and non-KBD groups
a
Hong et al. [13]
* P-value \0.001
EQ-5D
36 (9.8)
3 (0.4)
1 (0.3)
Chi square Chinese norma
Non KBD Some/ No extreme problem problem (%) (%)
0.622
290 (91.8)
2 (0.5)
KBD No problem (%)
25 (7.9)
33027 (89.7)
Some/extreme problem (%)
Some/extreme problem (%)
Mobility
88 (23.9) 280 (76.1)
248 (78.5)
68 (21.5)
202.55*
4.9
Self-care
158 (42.9) 210 (57.1)
277 (87.7)
39 (12.3)
146.88*
2.0
Usual activities Pain/discomfort
113 (30.7) 255 (69.3) 37 (10.1) 331 (89.9)
257 (81.3) 59 (18.7) 209 (66.1) 107 (33.9)
175.44* 232.2*
3.3 18.0
89 (24.2) 279 (75.8)
206 (65.2) 110 (34.8)
116.5*
6.1
Anxiety/depression
EQ-5D descriptive system The percentage of reporting any problems in each EQ-5D dimension is shown in Table 2. For the purpose of comparison, a norm from the general population in Beijing [13] is also listed. As Table 2 shows, KBD patients have a higher percentage of reporting ‘any problems’ in each EQ5D dimension when compared with non-KBD participants and the general population. The data also suggest that the most affected dimension is pain/discomfort, followed by mobility, anxiety/depression, and usual activities, and selfcare being the last. Furthermore, the difference between
KBD and non-KBD groups in reporting ‘any problems’ for each dimension is statistically significant. Note that participants without KBD but living in KBD endemic areas (non-KBD) also have higher rates of reporting any problems in each dimension than the general population in Beijing. EQ-5D index score and VAS score As expected, the KBD group has lower mean scores of VAS and EQ-5D index than those of the non-KBD group (P \ 0.001), shown in Table 3.
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Qual Life Res Table 3 Descriptive statistics of EQ-5D VAS and index scores Total sample (n = 684)
KBD group (n = 368)
Non-KBD group (n = 316)
Mean (SD)
Median (range)
Mean (SD)
Mean (SD)
Median (range)
VAS
66.3 (18.9)
70.0 (0–100)
60.5 (18.0)
73.0 (15.0)
80 (20–100)
EQ-5D index scores based on UK value set
0.64 (0.33)
0.65 (-0.59 to 1.00)
0.45 (0.30)
Median (range) 60 (0–100) 0.51 (-0.59 to 1)
0.85 (0.20)
1 (-0.31 to 1)
P-value*
\0.001 \0.001
* Asymp. Sig. (2-tailed), Mann–Whitney test
Discussion The results of this study suggest that KBD has had a severe impact on the patients’ HRQOL. The comparisons between KBD patients and non-patient participants living in the same endemic areas provide evidence of the impact of the disease: KBD caused worse HRQOL as measured by EQ5D. As Table 2 suggests, the greatest difference between KBD and non-KBD participants is in the pain/discomfort dimension followed by the mobility dimensions. If we look at the signs and symptoms of KBD [1, 12, 23, 24], it is quite evident that the affected joints usually caused pain and consequently resulted in the loss of mobility. KBD has also had a significant influence on the psychological aspects of patients’ lives. Probably because of the chronic and permanent effects like dwarfism in severe cases or limitations in daily economic and social activities, a greater proportion of the patients show anxiety and depression problems. The study also suggests that participants without KBD but living in the same endemic areas also had lower HRQOL than those of the general population in Beijing. This can be explained by family aggregation [25]; a family with a KBD-affected member can have a lower quality of life when compared to families that do not suffer from KBD. However, these HRQOL differences can also be attributed to the socioeconomic differences between the two study populations. Beijing, the capital of China, is a predominantly urban area, and the health and related social indictors of Beijing are the best in China. The birth and death rates of Beijing are 8.17 and 4.75, respectively, when compared to 10.29 and 6.21 in Shaanxi. In Beijing, 99.4% of the population has access to safe drinking water when compared to only 55% in Shaanxi. When compared to only 40.9% of Shaanxi, 85.5% of the Beijing population has proper hygienic conditions or toilets [9]. This difference in these health and social indicators might explain the HRQOL discrepancies between the general population in Beijing and non-KBD population living in KBD endemic areas. However, in the current study, we cannot disentangle the effect of KBD and the socioeconomic factors.
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A few studies in the literature have examined the HRQOL of patients with musculoskeletal disorders using EQ-5D. For instance, Picavet and Hoeymans compared the percentage of patients reporting any problems amongst EQ-5D dimensions for different musculoskeletal disorders [22]. The study found that in Gout, the percentage of patients reporting any problems in five dimensions were 31.9, 3.6, 32.8, 59.2 and 22.8%, respectively, while in RA, these were 52.1, 15.6, 54.3, 80.6 and 28.5% and other chronic arthritic diseases as 42.5, 16.3, 49.8, 78.1 and 33.1%. Similarly to the pattern we found in KBD, it was observed here that there was a higher percentage of reporting any problems in the pain/discomfort dimension and the least problems in the self-care dimension. In the context of KBD, the least problems in the self-care dimension can probably be explained by the fact that KBD starts in childhood so most of the patients adapt themselves and learn how to live with the disease. However, KBD patients still have highest percentages in reporting any problems in all EQ-5D dimensions (Table 2). Furthermore, a study by Wolfe and Hawley reported that the EQ-5D index scores and VAS scores amongst osteoarthritis diseases were 0.57 and 67 for RA and 0.56 and 68 for OA, respectively [21]. Comparing these scores with our findings, KBD patients still have the lowest EQ-5D index and VAS scores (Table 3). Conclusion This study is the first attempt to measure the health-related quality of life in KBD patients. The results of the study show that KBD has a severe impact on patients’ healthrelated quality of life as measured by EQ-5D. It particularly causes great problems in the dimensions of pain/discomfort, mobility and anxiety/depression. Acknowledgments We are thankful to the CDC staff of Linyou and Yongshou counties for providing the background information and support in data collection. We are also thankful to National Natural Scientific Foundation of China (30630058), the Specialized Research Fund for the Doctoral Program of Higher Education of China (20090201110049) and Ayub Medical College, Pakistan for supporting the research study and PhD fellowship.
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