Rheumatology Advance Access published March 22, 2015
RHEUMATOLOGY
53
Original article
doi:10.1093/rheumatology/kev014
The impact of rheumatoid arthritis on work capacity in Chinese patients: a cross-sectional study
Objective. To evaluate the impact of RA on work capacity and identify factors related to work capacity impairment in patients with RA. Methods. A cross-sectional multicentre study was performed in 21 tertiary care hospitals across China. A consecutive sample of 846 patients with RA was recruited, of which 589 patients of working age at disease onset constituted the study population. Information on the socio-demographic, clinical, working and financial conditions of the patients was collected. Logistic regression analyses were used to identify factors associated with work capacity impairment. Results. The rate of work capacity impairment was 48.0% in RA patients with a mean disease duration of 60 months (interquartile range 14134 months), including 11.7% leaving the labour force early, 33.6% working reduced hours and 2.7% changing job. Multivariable logistic regression analysis showed that reduced working hours was significantly related to current smoking [odds ratio (OR) 2.07 (95% CI 1.08, 3.97)], no insurance [OR 1.94 (95% CI 1.20, 3.12)], in manual labour [OR 2.66 (95% CI 1.68, 4.20)] and higher HAQ score [OR 2.22 (95% CI 1.36, 3.60)]. There was an association of current smoking [OR 3.75 (95% CI 1.54, 9.15)], in manual labour [OR 2.33 (95% CI 1.17, 4.64)], longer disease duration 1
Department of Rheumatology and Immunology, People’s Hospital, Peking University Health Science Center, 2Department of Rheumatology and Immunology, Peking University Shougang Hospital, 3Department of Gastroenterology, People’s Hospital, Peking University Health Science Center, Beijing, 4Department of Rheumatology and Immunology, Second Hospital of Shanxi Medical University, Taiyuan, 5Department of Rheumatology and Immunology, First Affiliated Hospital, Baotou Medical College, Baotou, 6Department of Rheumatology, China-Japan Friendship Hospital, Beijing, 7 Department of Clinical Immunology, Xijing Hospital, Fourth Military Medical University, Xi’an, 8Department of Rheumatology and Immunology, Second Hospital of Hebei Medical University, Shijiazhuang, 9Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, 10Department of Rheumatology and Immunology, Third Hospital of Hebei Medical University, Shijiazhuang, 11 Department of Rheumatology and Immunology, Affiliated Kailuan Hospital of North China Coal Medical University, Tangshan, Hebei, 12 Department of Rheumatology and Clinical Immunology, Peking University First Hospital, Beijing, 13Department of Rheumatology and Immunology, Bethune International Peace Hospital of PLA, Shijiazhuang, 14Department of Rheumatology and Immunology, Handan Central Hospital, Handan, 15Department of Rheumatology
and Immunology, People0 s Hospital of Hebei Province, Shijiazhuang, Department of Rheumatology, People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, 17Department of Rheumatology and Immunology, Beijing Shunyi Hospital, Beijing, 18 Department of Rheumatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 19 Department of Rheumatology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 20Department of Rheumatology and Immunology, Beijing Hospital, Beijing, 21Department of Rheumatology, Shandong University Qilu Hospital, Jinan and 22Deparment of Rheumatology, Second Hospital of Lanzhou University, Lanzhou, China 16
Submitted 13 February 2013; revised version accepted 27 January 2015 Correspondence to: Zhanguo Li, Department of Rheumatology, People’s Hospital, Peking University Health Science Center, No. 11 Xizhimen South Street, Western District, Beijing, China. E-mail: [email protected] Xiaoying Zhang and Rong Mu contributed equally to this study.
! The Author 2015. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: [email protected]
1
CLINICAL SCIENCE
Abstract
Downloaded from http://rheumatology.oxfordjournals.org/ at University of Pennsylvania Library on August 19, 2015
Xiaoying Zhang1, Rong Mu1, Xiuru Wang2, Chuanhui Xu1, Tianjiao Duan3, Yuan An1, Shuling Han2, Xiaofeng Li4, Lizhi Wang4, Caihong Wang4, Yongfu Wang5, Rong Yang5, Guochun Wang6, Xin Lu6, Ping Zhu7, Lina Chen7, Jinting Liu8, Hongtao Jin8, Xiangyuan Liu9, Lin Sun9, Ping Wei10, Junxiang Wang10, Haiying Chen10, Liufu Cui11, Rong Shu11, Bailu Liu11, Zhuoli Zhang12, Guangtao Li12, Zhenbin Li13, Jing Yang13, Junfang Li14, Bin Jia14, Fengxiao Zhang15, Jiemei Tao15, Jinying Lin16, Meiqiu Wei16, Xiaomin Liu17, Dan Ke17, Shaoxian Hu18, Cong Ye18, Xiuyan Yang19, Hao Li19, Cibo Huang20, Ming Gao20, Pei Lai20, Xingfu Li21, Lijun Song21, Yi Wang22, Xiaoyuan Wang22, Yin Su1 and Zhanguo Li1
Xiaoying Zhang et al.
[OR 1.01 (95% CI 1.00, 1.01)] and lower BMI [OR 0.90 (95% CI 0.82, 0.99)] with leaving the labour force early. Conclusion. There is a substantial impact of RA on the work capacity of patients in China. Socialdemographic, disease- and work-related factors are all associated with work capacity impairment. Key words: rheumatoid arthritis, work capacity, cross-sectional study.
Rheumatology key messages This is the first large-scale cross-sectional study to evaluate the impact of RA on work ability in China. Socio-demographic, disease- and work-related factors are associated with work capacity impairment in Chinese RA patients. . We emphasize that not only rheumatologists, but also society should make efforts to improve the work ability of RA patients. . .
RA is an immune-mediated inflammatory disease characterized by symmetrical polyarthritis usually involving the small joints of the hands and feet [1]. A decline in work capacity is an important outcome of the disease. Much attention has been paid to this issue because of its high prevalence rate and the considerable impact on patients’ lives, family income and societal costs [29]. The majority of previous studies have focused on work disability in RA patients, frequently defined as work cessation. The results have shown that as many as 2040% of RA patients become permanently work disabled within 23 years of diagnosis [10, 11]. Data from 32 countries in the Quantitative Patient Questionnaires in Standard Monitoring of Patients with Rheumatoid Arthritis (QUEST-RA) study indicate that more than one-third of working patients reported subsequent work disability because of RA [6]. However, when evaluating the impact of RA on work capacity, it is a narrow view that work disability has been equated with cessation from paid work. Investigators have examined different aspects, e.g. sick leave, job changes, etc., to fully assess the outcomes of the disease [4, 10, 1215]. According to the populationbased study by Olofsson et al. [16], during treatment with TNF antagonist the rate of sick leave dropped from 38.6% to 28.5%. It is noteworthy that differences in systems of health provision and social security influence definitions of work capacity impairment. Multiple factors may contribute to the decline in work capacity, including disease severity, structural damage and psychological and socio-economic factors, which are indispensable issues of treatment in RA patients [27, 1214]. The information on work capacity impairment has come mostly from studies in the USA and Europe. To our knowledge, there has been no study on work capacity impairment of RA patients in China. The prevalence of RA in China ranges from 0.2% to 0.93% according to epidemiological studies from different regions [17, 18]. Therefore it is important to investigate the influence of RA on the work ability of Chinese patients work ability. In this study evaluating work capacity impairment, we examined three categories of work transition: leaving
2
the labour force, job change and reduced working hours. The present study was carried out to assess the prevalence of self-reported work capacity impairment in China and evaluate related factors in terms of socio-demographic, disease-related and occupational variables.
Methods Subjects We performed a cross-sectional hospital-based study. Eight hundred and forty-six Chinese RA patients were recruited from outpatient rheumatology clinics of 21 tertiary care hospitals in 10 provinces of China between July 2009 and July 2010. All patients fulfilled the 1987 ACR revised criteria for RA [19]. These 846 patients with RA were on average 53.1 years old (S.D. 13.7) and median disease duration was 48 months [interquartile range (IQR) 12118]. The male:female ratio was 1:4. Data were collected by structured questionnaires, including socio-demographic data, work-related information and disease-related variables, under the direction of trained recruiters. All the patients were confirmed to understand the questionnaires. Ethical approval was obtained from the ethical committee of Peking University People’s Hospital and informed consent was obtained in accordance with the Declaration of Helsinki.
Work capacity assessment Work capacity impairment was defined as reduced working hours, job change or leaving the labour force early due to RA [4, 15]. We defined reduced working hours as missing workdays or a reduction in routine working time because of RA. Job change referred to work transition as the result of RA contrary to the individual’s wishes and adversely affecting individual work circumstances. Leaving the labour force early was defined as leaving the labour force before official retirement age due to RA. According to China’s New Labour Contract Law, the retirement age is 60 years for men and 55 years for women [20], therefore RA patients who stopped working before these ages because of RA were considered to
www.rheumatology.oxfordjournals.org
Downloaded from http://rheumatology.oxfordjournals.org/ at University of Pennsylvania Library on August 19, 2015
Introduction
The impact of RA on work capacity in China
Measurement of variables Socio-demographic variables Socio-demographic variables, including age, sex, marital status, smoking habit, BMI, educational level, monthly income and medical insurance were derived from the questionnaires. BMI [weight (kg)/height (m2)] was treated as a continuous variable in the statistical analysis. The categories of educational level were divided into low (maximum primary school), moderate (maximum higher secondary school) and high (obtained a certificate of higher education) [14]. The categories of monthly income were divided into five groups: ¥1000, ¥10003000, ¥30005000, ¥500010 000, >¥10 000 (4£99.5, £99.5298.5, £298.5497.5, £497.5995.0, >£995.0). The source of income included retirement pension, salary, alimony, financial support from family, etc. The types of medical insurance included medical service at state expense, urban employee basic medical insurance, new cooperative medical scheme and no insurance. Disease-related variables Disease duration referred to the duration between the onset of RA and recruitment in the study. A Chinese edition of the HAQ was used to assess physical function in activities of daily life [21]. Visual analogue scales (0 = best to 10 = worst) were used to evaluate the level of pain, patient global assessment and physician global assessment. Work-related variables Employment status at the time of recruitment was divided into the following categories: gainfully employed, unemployed (including unemployed individuals and homemakers), not working (on sickness benefit) and retired. Patients’ jobs were classified into manual and sedentary
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jobs according to job titles and job categories based on the International Standard Classification of Occupations (1988) [22]. Categories of legislators, senior officials and managers, professionals, technicians and associate professionals and clerks were classified as sedentary jobs and those of service workers, shop and market sales workers, skilled agricultural and fishery workers, craft and related workers, plant and machine operators and assemblers, elementary occupations and armed forces were manual jobs. Data for patients who had never been employed or whose jobs were hard to classify were excluded from the statistical analysis and the type of job was set as other.
Statistical analysis Descriptive statistics were conducted for socio-demographic and clinical variables, including frequency, percentage, mean (S.D.) and median (IQR), depending on the characteristic and distribution of the data. t-test and the MannWhitney U-test were used to compare the differences in continuous variables and Pearson or Fisher’s exact chi-square analysis was conducted to determine differences in categorical variables of patients with or without impaired work capacity. A multivariable analysis (multinomial logistic regression, stepwise selection model with entry level P = 0.05 and stay level P = 0.1) was performed to detect the variables associated with work capacity impairment. The result of the stepwise selection model showed only statistically significant variables. We separately compared different groups with work capacity adversely impacted by RA with the nonwork capacity impairment group. Independent variables were selected for a multivariable analysis because of their clinical relevance and/or statistical significance in the univariate analysis. Due to multicollinearity with the HAQ, we removed pain, patient global assessment and physician global assessment from the multivariable analysis. For all analyses, P < 0.05 was considered statistically significant. Statistical analysis was conducted with the statistical software package SPSS 17.0 (SPSS, Chicago, IL, USA).
Results Characteristics of RA patients Of the 846 patients, 238 patients had retired at diagnosis, 19 were under working age and 589 were of working age, which were further analysed for change of work status (Fig. 1). The ratio of male to female patients was approximately 1:5. Mean age of the 589 patients at disease onset was 41.5 years (S.D. 10.6) and median disease duration was 60 months (IQR 14134; range 0520). The median of the visual analogue scales to evaluate the level of pain (patient global assessment) was 5. Only 36.8% (217/589) of RA patients were currently gainfully employed. More than half of the participants [54.7% (322/589)] were occupied in manual labour. Table 1 summarizes the sociodemographics, clinical characteristics and work-related information of the patients of working age.
3
Downloaded from http://rheumatology.oxfordjournals.org/ at University of Pennsylvania Library on August 19, 2015
have left the labour force early. Making a work transition or not during the disease was the outcome variable for the analysis. Based on sex and age at the onset of RA, we divided the whole cohort into patients of working age, under working age and retired (who had retired at disease onset). Patients of working age at disease onset constituted the study population. To specify whether working age patients had work capacity adversely impacted by RA during the disease, recruiters asked all patients if they had changed their work status ever because of RA: (i) Yes, I had to reduce working hours; (ii) Yes, I had to stop working before official retirement age because of RA; (iii) I retired before symptoms of RA; (iv) Yes, I had to change my job because of the disease; (v) No, I have not changed work or I have changed my work due to reasons other than RA. The patients in our study could choose only one option. Patients whose answers were (i), (ii) and (iv) were categorized as reduced working hours, leaving the labour force early and job change, respectively, and those with (v) were defined as nonwork capacity impairment.
Xiaoying Zhang et al.
FIG. 1 Flow chart of the study population
Five hundred and eighty-nine patients were of working age at diagnosis. bWork status at the time of recruitment was categorized as gainfully employed, not working, unemployed or retired.
Prevalence of work capacity impairment Forty-eight per cent (283/589) of the patients suffered impaired work capacity, namely, reduced their working hours [198/589 (33.6%)], changed job [16/589 (2.7%)] and left the labour force early [69/589 (11.7%)], while 52.0% (306/589) of the patients were classified as nonwork capacity impaired (including those whose work status had not changed or had changed but not due to RA). Among 217 RA patients gainfully employed at the time of recruitment, there were 67 patients who had reduced their working hours during the disease. Of the 306 patients who had no change in work status because of RA, 146 were gainfully employed, 102 were retired, 51 were unemployed and for 7 data were missing. In patients with disease duration 10 000, n (%) Medical security Total, n No insurance, n (%) Medical service at state expense, n (%) Urban employee basic medical insurance, n (%) New cooperative medical scheme, n (%) Clinical characteristics Age at disease onset, mean (S.D.) , years Disease duration, median (IQR), months VAS pain (010 cm), median (IQR) VAS patient global assessment (010 cm), median (IQR) VAS physician global assessment (010 cm), median (IQR) Functional status (HAQ score) (03), median (IQR) Work status at recruitmentb Total, n Gainfully employed, n (%) Unemployed, n (%) Not working, n (%) Retired, n (%) Type of employment Total, n Sedentary, n (%) Manual, n (%) Othersc, n (%) Work transition due to RA Total, n Reduced working hours, n (%) Changed jobs, n (%) Left the labour force early,d n (%) Had no change, n (%)
Patients of working age (n = 589)
2 7
571 232 (39.4) 268 (45.5) 47 (8.0) 20 (3.4) 4 (0.7)
18
571 161 (27.3) 34 (5.8) 301 (51.1) 75 (12.7)
18
41.5 (10.6) 60 (14134) 5.0 (2.57.0) 5.0 (2.57.0) 4.5 (2.06.0) 0.75 (0.001.5)
15 15 4 4 9 29
581 217 (36.8) 146 (24.8) 22 (3.7) 196 (33.2)
8
586 193 (32.8) 322 (54.7) 71(12.1)
3
589 198 (33.6) 16 (2.7) 69 (11.7) 306 (52.0)
a
Missing data are due to item non-response. bUnemployed (including unemployed individuals and homemakers); not working (on sickness benefit). cOthers (patients have never been employed or jobs are hard to classify). dLeft the labour force early (patients stop working before retirement age due to RA). e1 CNY = £0.0913 in 2009. CNY: China Yuan; IQR: interquartile range; VAS: visual analogue scale.
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5
Xiaoying Zhang et al.
TABLE 2 Univariate analysis for socio-demographic, clinical and work-related characteristics of patients with and without work capacity impairment
Variable
Patients with work capacity impairment (n = 283)a Patients Reduced Left the without labour work capacity working Job change hours force early impairment (n = 16) P-valueb, (n = 198) P-valueb, c (n = 69) P-valueb, d (n = 306)a
0.541 0.219 0.419 0.013
50.5 (9.4) 13 (18.8) 21.9 (3.2) 11 (15.9)
0.260 0.460 0.029 0.067
43.0 (15.3) 1 (6.3) 22.8 (3.7) 1 (6.3)
0.140 0.485 0.867 1.000
0.002f
18 (26.0) 44 (63.8) 7 (10.1)
0.345f
7 (43.8) 9 (56.2) 0 (0.0)
0.998f
RHEUMATOLOGY
53
Original article
doi:10.1093/rheumatology/kev014
The impact of rheumatoid arthritis on work capacity in Chinese patients: a cross-sectional study
Objective. To evaluate the impact of RA on work capacity and identify factors related to work capacity impairment in patients with RA. Methods. A cross-sectional multicentre study was performed in 21 tertiary care hospitals across China. A consecutive sample of 846 patients with RA was recruited, of which 589 patients of working age at disease onset constituted the study population. Information on the socio-demographic, clinical, working and financial conditions of the patients was collected. Logistic regression analyses were used to identify factors associated with work capacity impairment. Results. The rate of work capacity impairment was 48.0% in RA patients with a mean disease duration of 60 months (interquartile range 14134 months), including 11.7% leaving the labour force early, 33.6% working reduced hours and 2.7% changing job. Multivariable logistic regression analysis showed that reduced working hours was significantly related to current smoking [odds ratio (OR) 2.07 (95% CI 1.08, 3.97)], no insurance [OR 1.94 (95% CI 1.20, 3.12)], in manual labour [OR 2.66 (95% CI 1.68, 4.20)] and higher HAQ score [OR 2.22 (95% CI 1.36, 3.60)]. There was an association of current smoking [OR 3.75 (95% CI 1.54, 9.15)], in manual labour [OR 2.33 (95% CI 1.17, 4.64)], longer disease duration 1
Department of Rheumatology and Immunology, People’s Hospital, Peking University Health Science Center, 2Department of Rheumatology and Immunology, Peking University Shougang Hospital, 3Department of Gastroenterology, People’s Hospital, Peking University Health Science Center, Beijing, 4Department of Rheumatology and Immunology, Second Hospital of Shanxi Medical University, Taiyuan, 5Department of Rheumatology and Immunology, First Affiliated Hospital, Baotou Medical College, Baotou, 6Department of Rheumatology, China-Japan Friendship Hospital, Beijing, 7 Department of Clinical Immunology, Xijing Hospital, Fourth Military Medical University, Xi’an, 8Department of Rheumatology and Immunology, Second Hospital of Hebei Medical University, Shijiazhuang, 9Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, 10Department of Rheumatology and Immunology, Third Hospital of Hebei Medical University, Shijiazhuang, 11 Department of Rheumatology and Immunology, Affiliated Kailuan Hospital of North China Coal Medical University, Tangshan, Hebei, 12 Department of Rheumatology and Clinical Immunology, Peking University First Hospital, Beijing, 13Department of Rheumatology and Immunology, Bethune International Peace Hospital of PLA, Shijiazhuang, 14Department of Rheumatology and Immunology, Handan Central Hospital, Handan, 15Department of Rheumatology
and Immunology, People0 s Hospital of Hebei Province, Shijiazhuang, Department of Rheumatology, People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, 17Department of Rheumatology and Immunology, Beijing Shunyi Hospital, Beijing, 18 Department of Rheumatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 19 Department of Rheumatology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 20Department of Rheumatology and Immunology, Beijing Hospital, Beijing, 21Department of Rheumatology, Shandong University Qilu Hospital, Jinan and 22Deparment of Rheumatology, Second Hospital of Lanzhou University, Lanzhou, China 16
Submitted 13 February 2013; revised version accepted 27 January 2015 Correspondence to: Zhanguo Li, Department of Rheumatology, People’s Hospital, Peking University Health Science Center, No. 11 Xizhimen South Street, Western District, Beijing, China. E-mail: [email protected] Xiaoying Zhang and Rong Mu contributed equally to this study.
! The Author 2015. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: [email protected]
1
CLINICAL SCIENCE
Abstract
Downloaded from http://rheumatology.oxfordjournals.org/ at University of Pennsylvania Library on August 19, 2015
Xiaoying Zhang1, Rong Mu1, Xiuru Wang2, Chuanhui Xu1, Tianjiao Duan3, Yuan An1, Shuling Han2, Xiaofeng Li4, Lizhi Wang4, Caihong Wang4, Yongfu Wang5, Rong Yang5, Guochun Wang6, Xin Lu6, Ping Zhu7, Lina Chen7, Jinting Liu8, Hongtao Jin8, Xiangyuan Liu9, Lin Sun9, Ping Wei10, Junxiang Wang10, Haiying Chen10, Liufu Cui11, Rong Shu11, Bailu Liu11, Zhuoli Zhang12, Guangtao Li12, Zhenbin Li13, Jing Yang13, Junfang Li14, Bin Jia14, Fengxiao Zhang15, Jiemei Tao15, Jinying Lin16, Meiqiu Wei16, Xiaomin Liu17, Dan Ke17, Shaoxian Hu18, Cong Ye18, Xiuyan Yang19, Hao Li19, Cibo Huang20, Ming Gao20, Pei Lai20, Xingfu Li21, Lijun Song21, Yi Wang22, Xiaoyuan Wang22, Yin Su1 and Zhanguo Li1
Xiaoying Zhang et al.
[OR 1.01 (95% CI 1.00, 1.01)] and lower BMI [OR 0.90 (95% CI 0.82, 0.99)] with leaving the labour force early. Conclusion. There is a substantial impact of RA on the work capacity of patients in China. Socialdemographic, disease- and work-related factors are all associated with work capacity impairment. Key words: rheumatoid arthritis, work capacity, cross-sectional study.
Rheumatology key messages This is the first large-scale cross-sectional study to evaluate the impact of RA on work ability in China. Socio-demographic, disease- and work-related factors are associated with work capacity impairment in Chinese RA patients. . We emphasize that not only rheumatologists, but also society should make efforts to improve the work ability of RA patients. . .
RA is an immune-mediated inflammatory disease characterized by symmetrical polyarthritis usually involving the small joints of the hands and feet [1]. A decline in work capacity is an important outcome of the disease. Much attention has been paid to this issue because of its high prevalence rate and the considerable impact on patients’ lives, family income and societal costs [29]. The majority of previous studies have focused on work disability in RA patients, frequently defined as work cessation. The results have shown that as many as 2040% of RA patients become permanently work disabled within 23 years of diagnosis [10, 11]. Data from 32 countries in the Quantitative Patient Questionnaires in Standard Monitoring of Patients with Rheumatoid Arthritis (QUEST-RA) study indicate that more than one-third of working patients reported subsequent work disability because of RA [6]. However, when evaluating the impact of RA on work capacity, it is a narrow view that work disability has been equated with cessation from paid work. Investigators have examined different aspects, e.g. sick leave, job changes, etc., to fully assess the outcomes of the disease [4, 10, 1215]. According to the populationbased study by Olofsson et al. [16], during treatment with TNF antagonist the rate of sick leave dropped from 38.6% to 28.5%. It is noteworthy that differences in systems of health provision and social security influence definitions of work capacity impairment. Multiple factors may contribute to the decline in work capacity, including disease severity, structural damage and psychological and socio-economic factors, which are indispensable issues of treatment in RA patients [27, 1214]. The information on work capacity impairment has come mostly from studies in the USA and Europe. To our knowledge, there has been no study on work capacity impairment of RA patients in China. The prevalence of RA in China ranges from 0.2% to 0.93% according to epidemiological studies from different regions [17, 18]. Therefore it is important to investigate the influence of RA on the work ability of Chinese patients work ability. In this study evaluating work capacity impairment, we examined three categories of work transition: leaving
2
the labour force, job change and reduced working hours. The present study was carried out to assess the prevalence of self-reported work capacity impairment in China and evaluate related factors in terms of socio-demographic, disease-related and occupational variables.
Methods Subjects We performed a cross-sectional hospital-based study. Eight hundred and forty-six Chinese RA patients were recruited from outpatient rheumatology clinics of 21 tertiary care hospitals in 10 provinces of China between July 2009 and July 2010. All patients fulfilled the 1987 ACR revised criteria for RA [19]. These 846 patients with RA were on average 53.1 years old (S.D. 13.7) and median disease duration was 48 months [interquartile range (IQR) 12118]. The male:female ratio was 1:4. Data were collected by structured questionnaires, including socio-demographic data, work-related information and disease-related variables, under the direction of trained recruiters. All the patients were confirmed to understand the questionnaires. Ethical approval was obtained from the ethical committee of Peking University People’s Hospital and informed consent was obtained in accordance with the Declaration of Helsinki.
Work capacity assessment Work capacity impairment was defined as reduced working hours, job change or leaving the labour force early due to RA [4, 15]. We defined reduced working hours as missing workdays or a reduction in routine working time because of RA. Job change referred to work transition as the result of RA contrary to the individual’s wishes and adversely affecting individual work circumstances. Leaving the labour force early was defined as leaving the labour force before official retirement age due to RA. According to China’s New Labour Contract Law, the retirement age is 60 years for men and 55 years for women [20], therefore RA patients who stopped working before these ages because of RA were considered to
www.rheumatology.oxfordjournals.org
Downloaded from http://rheumatology.oxfordjournals.org/ at University of Pennsylvania Library on August 19, 2015
Introduction
The impact of RA on work capacity in China
Measurement of variables Socio-demographic variables Socio-demographic variables, including age, sex, marital status, smoking habit, BMI, educational level, monthly income and medical insurance were derived from the questionnaires. BMI [weight (kg)/height (m2)] was treated as a continuous variable in the statistical analysis. The categories of educational level were divided into low (maximum primary school), moderate (maximum higher secondary school) and high (obtained a certificate of higher education) [14]. The categories of monthly income were divided into five groups: ¥1000, ¥10003000, ¥30005000, ¥500010 000, >¥10 000 (4£99.5, £99.5298.5, £298.5497.5, £497.5995.0, >£995.0). The source of income included retirement pension, salary, alimony, financial support from family, etc. The types of medical insurance included medical service at state expense, urban employee basic medical insurance, new cooperative medical scheme and no insurance. Disease-related variables Disease duration referred to the duration between the onset of RA and recruitment in the study. A Chinese edition of the HAQ was used to assess physical function in activities of daily life [21]. Visual analogue scales (0 = best to 10 = worst) were used to evaluate the level of pain, patient global assessment and physician global assessment. Work-related variables Employment status at the time of recruitment was divided into the following categories: gainfully employed, unemployed (including unemployed individuals and homemakers), not working (on sickness benefit) and retired. Patients’ jobs were classified into manual and sedentary
www.rheumatology.oxfordjournals.org
jobs according to job titles and job categories based on the International Standard Classification of Occupations (1988) [22]. Categories of legislators, senior officials and managers, professionals, technicians and associate professionals and clerks were classified as sedentary jobs and those of service workers, shop and market sales workers, skilled agricultural and fishery workers, craft and related workers, plant and machine operators and assemblers, elementary occupations and armed forces were manual jobs. Data for patients who had never been employed or whose jobs were hard to classify were excluded from the statistical analysis and the type of job was set as other.
Statistical analysis Descriptive statistics were conducted for socio-demographic and clinical variables, including frequency, percentage, mean (S.D.) and median (IQR), depending on the characteristic and distribution of the data. t-test and the MannWhitney U-test were used to compare the differences in continuous variables and Pearson or Fisher’s exact chi-square analysis was conducted to determine differences in categorical variables of patients with or without impaired work capacity. A multivariable analysis (multinomial logistic regression, stepwise selection model with entry level P = 0.05 and stay level P = 0.1) was performed to detect the variables associated with work capacity impairment. The result of the stepwise selection model showed only statistically significant variables. We separately compared different groups with work capacity adversely impacted by RA with the nonwork capacity impairment group. Independent variables were selected for a multivariable analysis because of their clinical relevance and/or statistical significance in the univariate analysis. Due to multicollinearity with the HAQ, we removed pain, patient global assessment and physician global assessment from the multivariable analysis. For all analyses, P < 0.05 was considered statistically significant. Statistical analysis was conducted with the statistical software package SPSS 17.0 (SPSS, Chicago, IL, USA).
Results Characteristics of RA patients Of the 846 patients, 238 patients had retired at diagnosis, 19 were under working age and 589 were of working age, which were further analysed for change of work status (Fig. 1). The ratio of male to female patients was approximately 1:5. Mean age of the 589 patients at disease onset was 41.5 years (S.D. 10.6) and median disease duration was 60 months (IQR 14134; range 0520). The median of the visual analogue scales to evaluate the level of pain (patient global assessment) was 5. Only 36.8% (217/589) of RA patients were currently gainfully employed. More than half of the participants [54.7% (322/589)] were occupied in manual labour. Table 1 summarizes the sociodemographics, clinical characteristics and work-related information of the patients of working age.
3
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have left the labour force early. Making a work transition or not during the disease was the outcome variable for the analysis. Based on sex and age at the onset of RA, we divided the whole cohort into patients of working age, under working age and retired (who had retired at disease onset). Patients of working age at disease onset constituted the study population. To specify whether working age patients had work capacity adversely impacted by RA during the disease, recruiters asked all patients if they had changed their work status ever because of RA: (i) Yes, I had to reduce working hours; (ii) Yes, I had to stop working before official retirement age because of RA; (iii) I retired before symptoms of RA; (iv) Yes, I had to change my job because of the disease; (v) No, I have not changed work or I have changed my work due to reasons other than RA. The patients in our study could choose only one option. Patients whose answers were (i), (ii) and (iv) were categorized as reduced working hours, leaving the labour force early and job change, respectively, and those with (v) were defined as nonwork capacity impairment.
Xiaoying Zhang et al.
FIG. 1 Flow chart of the study population
Five hundred and eighty-nine patients were of working age at diagnosis. bWork status at the time of recruitment was categorized as gainfully employed, not working, unemployed or retired.
Prevalence of work capacity impairment Forty-eight per cent (283/589) of the patients suffered impaired work capacity, namely, reduced their working hours [198/589 (33.6%)], changed job [16/589 (2.7%)] and left the labour force early [69/589 (11.7%)], while 52.0% (306/589) of the patients were classified as nonwork capacity impaired (including those whose work status had not changed or had changed but not due to RA). Among 217 RA patients gainfully employed at the time of recruitment, there were 67 patients who had reduced their working hours during the disease. Of the 306 patients who had no change in work status because of RA, 146 were gainfully employed, 102 were retired, 51 were unemployed and for 7 data were missing. In patients with disease duration 10 000, n (%) Medical security Total, n No insurance, n (%) Medical service at state expense, n (%) Urban employee basic medical insurance, n (%) New cooperative medical scheme, n (%) Clinical characteristics Age at disease onset, mean (S.D.) , years Disease duration, median (IQR), months VAS pain (010 cm), median (IQR) VAS patient global assessment (010 cm), median (IQR) VAS physician global assessment (010 cm), median (IQR) Functional status (HAQ score) (03), median (IQR) Work status at recruitmentb Total, n Gainfully employed, n (%) Unemployed, n (%) Not working, n (%) Retired, n (%) Type of employment Total, n Sedentary, n (%) Manual, n (%) Othersc, n (%) Work transition due to RA Total, n Reduced working hours, n (%) Changed jobs, n (%) Left the labour force early,d n (%) Had no change, n (%)
Patients of working age (n = 589)
2 7
571 232 (39.4) 268 (45.5) 47 (8.0) 20 (3.4) 4 (0.7)
18
571 161 (27.3) 34 (5.8) 301 (51.1) 75 (12.7)
18
41.5 (10.6) 60 (14134) 5.0 (2.57.0) 5.0 (2.57.0) 4.5 (2.06.0) 0.75 (0.001.5)
15 15 4 4 9 29
581 217 (36.8) 146 (24.8) 22 (3.7) 196 (33.2)
8
586 193 (32.8) 322 (54.7) 71(12.1)
3
589 198 (33.6) 16 (2.7) 69 (11.7) 306 (52.0)
a
Missing data are due to item non-response. bUnemployed (including unemployed individuals and homemakers); not working (on sickness benefit). cOthers (patients have never been employed or jobs are hard to classify). dLeft the labour force early (patients stop working before retirement age due to RA). e1 CNY = £0.0913 in 2009. CNY: China Yuan; IQR: interquartile range; VAS: visual analogue scale.
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Xiaoying Zhang et al.
TABLE 2 Univariate analysis for socio-demographic, clinical and work-related characteristics of patients with and without work capacity impairment
Variable
Patients with work capacity impairment (n = 283)a Patients Reduced Left the without labour work capacity working Job change hours force early impairment (n = 16) P-valueb, (n = 198) P-valueb, c (n = 69) P-valueb, d (n = 306)a
0.541 0.219 0.419 0.013
50.5 (9.4) 13 (18.8) 21.9 (3.2) 11 (15.9)
0.260 0.460 0.029 0.067
43.0 (15.3) 1 (6.3) 22.8 (3.7) 1 (6.3)
0.140 0.485 0.867 1.000
0.002f
18 (26.0) 44 (63.8) 7 (10.1)
0.345f
7 (43.8) 9 (56.2) 0 (0.0)
0.998f
