Body mass index and response to infliximab in rheumatoid arthritis.

Objectives: Excess adipose tissue in obese individuals may have immunomodulating properties and pharmacokinetics consequences. Previous studies have suggested that obesity could negatively affect the response to anti-TNF-α agents, notably infliximab (IFX). We aimed to determine whether body mass index (BMI) is involved in the response to IFX in rheumatoid arthritis (RA).

Methods: We retrospectively examined data for 76 RA patients receiving IFX. BMI was calculated before treatment, and change from baseline in DAS28, pain on a visual analog scale, erythrocyte sedimentation rate, C-reactive protein level, tender and swollen joint count was analysed at 6 months after treatment. The primary outcome was decrease in DAS28 ≥1.2. Secondary outcomes were good response and remission according to EULAR.

Results: At baseline, the median [interquartile range] BMI was 26.6 [22.6-30.6] kg/m2. The number of patients with normal weight, overweight and obesity was 25, 29 and 22. In multivariable analyses, IFX treated patients with lower BMI showed a more frequent DAS28 decrease ≥1.2 (25.5 [22.3-28.3] vs. 28.0 [23.2-32.5], p=0.02, odds ratio [OR] 0.88 [95% confidence interval 0.79-0.98]), EULAR good response (25.3 [21.9-27.5] vs. 27.5 [24.3-31.2], p=0.03, OR 0.87 [0.76-0.99]) and EULAR remission, although not significant (25.3 [21.9-26.4] vs. 27.5 [23.2-30.9], p=0.14, OR 0.88 [0.75-1.04]).

Conclusions: Obesity may negatively influence the response to IFX in RA. These data could help physicians to choose biologic agents for obese RA patients.