The aim of this study was to assess whether body mass index (BMI) affects clinical outcomes in rheumatoid arthritis (RA) patients starting a second line biological drug after failure of a first TNF-α blocker.

From a longitudinal cohort, we analyzed 292 RA patients (66 obese, 109 overweight, and 117 normal-weight) treated with a first ever anti-TNF-α drug. Patients discontinuing the therapy were followed-up if began a second biological drug. Drug survival, by Kaplan-Meier life analysis, and 12 months disease remission based on the 28-joint Disease Activity Score (DAS28) were assessed for either course of biologics. The baseline predictors of clinical outcomes were assessed by Cox regression analysis.

Survival of the first anti-TNF-α drug was lower in obese (39.4%) than in normal-weight (49.1%) patients, but the difference was not statistically significant. Obese patients had the highest hazard to discontinue the first anti-TNF-α drug (HR 1.64, 1.02–2.62 95% IC, P=0.04), and the lowest percentage of DAS28-based disease remission at 12 months (P=0.04). In 97 (37 normal-weight, 36 overweight, 24 obese) patients who started a second non-anti-TNF-α biological drug, persistence on therapy was significantly lower in obese (43.5%) than in normal-weight (80%, P=0.04) group, and again obesity significantly predicted drug discontinuation (HR 2.9, 1.08–8.45 95% IC, P=0.04). Significantly, less obese patients attained a disease remission (12%, P=0.004) at 12 months.

Our study provides evidence that obese RA patients poorly respond to second line non-anti-TNF-α drugs after failure of a first TNF-α inhibitor.