Body mass index and response to infliximab in rheumatoid arthritis

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).

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.

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]).

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