Socioeconomic determinants of disability and depression in patients with rheumatoid arthritis

Objective. To examine the relationship between functional limitation, socioeconomic inequality, and depression in a diverse cohort of patients with rheumatoid arthritis (RA). Methods. The study design was cross-sectional and subjects were from the University of California, San Francisco RA Cohort. Patients were enrolled from 2 rheumatology clinics, an urban county public hospital and a university tertiary care medical center. Age, sex, race/ethnicity, disease activity, functional limitation, and medications were variables collected at clinical visits. The patient's clinic site was used as a proxy for his or her socioeconomic status. The outcome variable was depressive symptom severity measured by the Patient Health Questionnaire 9. Differences in characteristics between depressed and nondepressed patients were calculated using 2-sided t-tests or the Pearson's chi-square test. For the multivariate analysis, repeated measures with generalized estimating equations were used. Results. There were statistically significant differences between depressed and nondepressed patients related to race/ethnicity, public versus tertiary care hospital rheumatology clinic, disability, and medications. In the multivariate analysis, increased functional limitation and public clinic site remained significantly associated with increased depression scores. A significant interaction existed between clinic site and disability. Mean depression scores rose more precipitously as functional limitation increased at the public hospital rheumatology clinic. Conclusion. There are disparities in both physical and mental health among individuals with low socioeconomic status. The psychological effects of disability vary in patients with RA such that a vulnerable population with functional limitations is at higher risk of developing depressive symptoms.