Mediators and Moderators of two online interventions for managing pain, fear of progression and functional ability in rheumatoid arthritis

Abstract

This is a secondary analysis of a trial comparing online mindfulness-based stress reduction with cognitive-behaviour therapy for people with rheumatoid arthritis. Both interventions were administered over eight weeks with five lessons and accompanied by weekly therapist contact. For the purposes of this study, we investigated the pain severity, fear of progression and functional ability as the outcome variables because the treatments had differential effects on these three outcomes but had equivalent effects on other variables. We examined mediators and moderators of relative treatment efficacy of mindfulness based stress reduction (n = 91) versus cognitive-behaviour therapy (n = 103) for these outcomes. For pain severity, no significant mediators or moderators were identified. However, amongst those with low pain severity, mindfulness-based stress reduction was more efficacious than cognitive-behaviour therapy for fears of progression. Furthermore, mindfulness-based stress reduction was more efficacious than cognitive-behaviour therapy for functional ability for those with high trait mindfulness at baseline. Changes in fear of progression during treatment fully mediated the effect of treatment group on functional ability over follow-up. While both online mindfulness-based stress reduction and cognitive-behaviour therapy were efficacious for people with rheumatoid arthritis, mindfulness-based stress reduction was more effective in reducing fears of progression and improving functional ability for those with low levels of pain severity and high levels of mindfulness at baseline, respectively. These results highlight the importance of treating fear of progression for people with rheumatoid arthritis as reductions in fears of progression over treatment led to improvements in functional ability six months later.