The impact of patient global assessment in the definition of remission as a predictor of long-term radiographic damage in patients with rheumatoid arthritis: protocol for an individual patient data meta-analysis

BACKGROUND: Remission is the target for management of rheumatoid arthritis (RA) and intensification of immunosuppressive therapy is recommended for those that do not achieve this status. Patient global assessment (PGA) is the single patient reported outcome considered in the American College of Rheumatology/European League Against Rheumatism remission criteria, but its use as target has been questioned. The primary aim of this study is to assess whether excluding PGA from the definition of disease remission changes the association of disease remission with long-term radiographic damage and physical function in patients with RA. METHODS: Individual Patient Data Meta-analysis using data from randomized controlled trials of biological and targeted synthetic agents, identified through ClinicalTrials.gov and PubMed. Different remission states will be defined: (i) 4v-remission [tender (TJC28) and swollen 28-joint counts (SJC28) both≤1, C-reactive protein (CRP)≤1 (mg/dl), and PGA≤1 (0-10 scale)], (ii) 4v-near-remission (TJC28≤1, SJC28≤1, CRP≤1, and PGA>1), (iii) non-remission (TJC28>1 or SJC28>1 or CRP>1), all mutually exclusive, and (iv) 3v-remission (TJC28≤1, SJC28≤1, CRP≤1). Likelihood ratios will be used to descriptively compare whether meeting the 3v and 4v-remission criteria in a single visit (at 6 or 12 months) predicts good outcome in the second year (1-2y). Differences in the predictive value of PGA in the definition of remission will be assessed by comparing the three mutually exclusive disease states using logistic regression analysis. Good outcome is defined primarily by radiographic damage (no deterioration in radiographic scores, whatever the instrument used in each trial), and secondarily by functional disability (Health Assessment Questionnaire consistently ≤0.5 and no deterioration), and their combination ("overall good outcome"). Additional analyses will consider longer periods over which to (concurrently) define remission status and outcome (between 1-5y and 1-10y), different cut-offs to define good radiographic outcome (change ≤0.5, ≤3 and ≤5 in radiographic score), sustained remission and the influence of treatment and other clinical factors. DISCUSSION: If 4v-remission and 4v-near-remission are associated with a similar probability of good outcomes, particularly regarding structural damage, the 3v-remission (excluding PGA) could be adopted as the target for immunosuppressive therapy. Patients' perspectives would remain essential, but assessed separately from disease activity, using instruments adequate to guide adjunctive therapies. Systematic review registration: PROSPERO, CRD42017057099.