Active foot synovitis in patients with rheumatoid arthritis: unstable remission status, radiographic progression, and worse functional outcomes in patients with foot synovitis in apparent remission

Abstract

To determine whether foot synovitis is associated with adverse radiographic and functional outcomes after 3 years in an inception rheumatoid arthritis (RA) cohort receiving treat-to-target combination DMARD therapy.Disease activity (DA) was assessed in early RA patients (n=266) using DAS28, clinical disease activity index (CDAI) and simplified disease activity index (SDAI). Radiographic outcomes were assessed with annual hand and feet radiographs and quality of life by SF-36. Prevalence of remission and foot synovitis was calculated using marginal binomial generalised estimating equations, transition between remission and non-remission states by a multi-state Markov model and changes in radiographic scores by a negative binomial mixed regression log-link model. Population matched SF-36 data were analysed by mixed-effects linear regression.DA scores that omit foot joints were modest in their ability to capture foot synovitis. Despite relative stringency of SDAI and CDAI for remission, 25-36% of patients in remission had foot synovitis. In patients in remission, foot synovitis predicted transition from remission into relapse by up to 2-fold. Sustainability of remission markedly influenced progression of erosion scores (p=0.006). After adjusting for DA, foot synovitis was associated with worse SF-36 physical functioning (p=0.025).DA measures that omit foot joints capture foot synovitis poorly. When used to define remission, a substantial proportion have foot synovitis which predicts relapse and worse physical function. Foot synovitis influences sustainability of remission which in turn markedly influences radiographic progression. Regardless of remission status, persistent foot synovitis should prompt therapy escalation to improve long-term outcomes. This article is protected by copyright. All rights reserved.