Background Working life factors influence patients' (life) satisfaction and well-being. Effort at work is part of a social contract that reciprocates effort by adequate reward. Components of work-related rewards matter for health. The question arises how working life factors can be operationalised. A validated measure of health-adverse psychosocial work environments is the effort-reward imbalance questionnaire (ERI) developed for comparative socioepidemiologic investigations of work-related stress . ERI has been established in “healthy” subjects, and its application to diseased cohorts is less experienced.
Objectives We tested the consistency, construct validity and the factorial structures of the ERI questionnaire in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) capable for work.
Methods A cross-sectional study applied the ERI within a set of standardized self-reported questionnaires to SLE and RA patients capable for work. Data were compared to controls not suffering from rheumatic diseases. Internal consistency was assessed by Cronbach's alpha. Confirmatory factor analysis (CFA) was applied to test construct validity and the factorial structure (Figure 1). Goodness of fit is measured in terms of root mean square error of approximation (RMSEA) and coefficient of determination. Positive ethical approval was obtained.
Results 267 RA patients (85.0% female (f)), 252 SLE patients (95.6% f) and 177 controls (90.3% f) contributed data. In RA mean age was 47.7±10.0 years, mean disease duration 9.0±8.0 years, mean HAQ 1.1±0.5. In SLE mean age was 40.1±9.4 years, mean disease duration 10.5±7.3 years, mean HAQ 0.8±0.4. Controls' mean age was 42.8±9.8 years, and mean HAQ was 0.4±0.1.
Cronbach's alphas were 0.76, 0.86, and 0.79 for the effort, reward, and overcomittment scales, respectively. The standardised regression weights in the CFA (see Figure 1) are similar to “healthy” populations . RMSEA and coefficient of determination in the CFA are 0.080 and 80.4%, respectively.
Conclusions Our study applied the ERI model to SLE and RA patients for validation for the first time. Despite the heterogeneity in the total cohort we achieved good internal consistency and very good construct and structural validity. Although developed for “healthy” subjects in socioepidemiologic investigations, our results show that the ERI questionnaire is a psychometrically useful tool for epidemiological studies in employed SLE and RA patients that focusses on the health-adverse effects of work and employment.
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Acknowledgements Unrestricted grants: Ministry of Innovation, Science, Research and Technology of the German State North Rhine-Westphalia, Deutsche Rheuma-Liga e.V., German LE Self-Help Community, Abbvie Germany, Hiller Foundation
Disclosure of Interest None declared
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