Differential effects of age and illness duration on pain-depression and disability-depression relationships in rheumatoid arthritis

We examined the differential effects of age and illness duration on pain—depression and disability—depression relationships in a sample of patients diagnosed with rheumatoid arthritis (RA). Consistent with existing literature, main effect results indicated that shorter illness duration and greater perceived pain and functional disability all related to increased levels of depression. More importantly, multiple regression analyses revealed that illness duration moderated the observed disability—depression relationship. Specifically, perceived functional disability exerted a greater negative impact on levels of depression in patients with relatively shorter illness durations compared to patients with longer illness durations. Neither age nor illness duration moderated the association between pain and depression. In general, our findings suggest that age and illness duration differentially influence pain—depression and disability—depression relationships in RA. We conclude the paper with a discussion of treatment implications of our findings for persons with RA.