Objectives To determine the baseline factors predictive of significant radiographic progression (SRP) in patients with moderately active rheumatoid arthritis (RA) despite receiving methotrexate (MTX).

Methods Patients from the MTX arm of the Trial of Etanercept and Methotrexate with Radiographic Patient Outcomes (TEMPO) trial with sustained moderate RA (defined as ≥3.2 mean disease activity score in 28 joints ≤5.1 during the last 6 months of the first year) were analysed for SRP (mTSS >3.0 overall) after 2 and 3 years. Baseline predictors for SRP were identified by univariate and multivariate analyses. All variables shown to be significantly associated with SRP were categorised based on clinically relevant cut-offs and tertiles and were included in a matrix risk model.

Results 228 patients were assigned MTX treatment, 210 patients were in the radiographic intention-to-treat population, and 96 of these had sustained moderate RA. SRP occurred in 25 (26%) and 33 (34%) patients after 2 and 3 years of MTX treatment, respectively. Univariate and multivariate analyses found that C reactive protein (CRP) and rheumatoid factor (RF) positivity at baseline were predictive of SRP after 2 and 3 years (p<0.05 for all). The matrix risk model showed that RF positivity and CRP levels >40 mg/L at baseline were significantly associated with SRP after 2 (p<0.05 for both; R²=0.24) and 3 years (p<0.05 for both; R²=0.22). The baseline erosion score was not found to be predictive of SRP.

Conclusions Patients with sustained moderate RA despite receiving MTX treatment are at risk of SRP, with both RF positivity and high CRP levels shown to be predictive of this.