Comparative effectiveness and predictors of response to tumour necrosis factor inhibitor therapies in rheumatoid arthritis

Abstract

Adalimumab, etanercept and infliximab are effective TNF inhibitors (TNFis) in the treatment of RA, but no randomized clinical trials have compared the three agents. Prior observational data are not consistent. We compared their effectiveness over 1 year in a prospective cohort. Analyses were performed on subjects' first episode of TNFi use in the Rheumatic Diseases Portuguese Register, Reuma.pt. The primary outcome was the proportion of patients with European League Against Rheumatism good response sustained at two consecutive observations separated by 3 months during the first year of TNFi use. Comparisons were performed using conventional adjusted logistic regression, as well as matching subjects across the three agents using a propensity score. In addition, baseline predictors of treatment response to TNFi were identified. The study cohort included 617 RA patients, 250 starting etanercept, 206 infliximab and 161 adalimumab. Good response was achieved by 59.6% for adalimumab, 59.2% for etanercept and 51.9% for infliximab (P = 0.21). The modelled probability of good response did not significantly differ across agents (etanercept vs adalimumab OR = 0.97, 95% CI 0.55, 1.71; etanercept vs infliximab OR = 1.25, 95% CI 0.74, 2.12; infliximab vs adalimumab OR = 0.80, 95% CI 0.47, 1.36). Matched propensity score analyses also showed no significant treatment response differences. Greater educational attainment was a predictor of better response, while smoking, presence of ACPA, glucocorticoid use and worse physician assessment of disease activity at baseline each predicted a reduced likelihood of treatment response. Over 1 year, we found no difference in effectiveness between adalimumab, etanercept and infliximab.