Socioeconomic gradient in work disability in diabetes: evidence from three occupational cohorts

Background The role of socioeconomic status in work disability among employees with diabetes is not well known. We examined the association between socioeconomic status and work disability among employees with and without diabetes taking into account comorbid conditions. Methods We used individual participant data from three occupational cohorts from Finland, France and the UK (employees with diabetes, n=2170, age-matched and sex-matched controls without diabetes, n=4340). In all cohorts, survey data were linked with register data and the employees were followed up on average for 4.4 years. Socioeconomic status was based on occupational titles. Work disability (sickness absence and disability pension) was indexed as the numbers of disability days and episodes. The study-specific estimates were pooled using meta-analysis and effect modifications were studied with meta-regression. Results The average numbers of disability days and episodes per year were 1.5-3.5 times higher for persons with diabetes compared to those without. Among persons with diabetes, the risk of work disability was almost four times higher in the lowest compared to the highest occupational position (relative index of inequality (RII) for days 3.82; 95% CI 2.77 to 5.56; RII for episodes 3.80; 95% CI 3.13 to 4.61). This association was consistent in both sexes and regardless of comorbid conditions. In relative terms, the association of socioeconomic status and work disability was similar among those free of diabetes. Conclusions A strong socioeconomic gradient in work disability was observed among people with and without diabetes.