Mindfulness-Based Stress Reduction with Individuals Who Have Rheumatoid Arthritis: Evaluating Depression and Anxiety as Mediators of Change in Disease Activity

Although the current randomized controlled trial has previously reported an effect of mindfulness-based stress reduction (MBSR) on improving disease activity in rheumatoid arthritis (RA), the possible mechanisms underlying this relationship remain unknown. This report presents secondary analyses examining anxiety and depression as potential mediators of the effect of MBSR on changes in RA disease activity. Fifty-one RA patients were randomized to either MBSR or to a wait-list control group. Depression and anxiety (Hospital and Anxiety Depression Scale) and RA disease activity (DAS28-CRP) were assessed at baseline (T1), post-treatment (T2), and at two (T3) and four (T4) months’ follow-up. Intention to treat (ITT) and per protocol (PP) analyses using multivariate analyses of variance showed that depression was lower in the MBSR than in the control group, post-treatment and at both follow-up time points. PP analyses suggested that anxiety was lower in the MBSR than in the control group post-treatment. In partial support of expectation, mediation analyses showed that a reduction in depression across the intervention (T2-T1) mediated the effect of MBSR on improvements in RA disease activity at both follow-up time points (T3-T1; T4-T1). This effect held across ITT and PP analyses. PP analyses also suggested an indirect effect of MBSR on RA disease activity via increased anxiety at T3, but not at T4. Together, findings suggest that improvements in depression (rather than anxiety) may mediate the effect of MBSR on RA disease activity. Screening for, and treating depression in RA with MBSR, may have downstream benefits for RA disease activity.