Body mass index and response to tocilizumab in rheumatoid arthritis: a real life study

Several studies have suggested that obesity could have a negative effect on response to anti-tumor necrosis factor α (anti-TNFα) in rheumatoid arthritis (RA). Little is known about the impact of body mass index (BMI) on other biologic agents. We aimed to evaluate the effect of BMI on response to tocilizumab (TCZ) in RA. RA patients treated with TCZ were included in this multicenter retrospective study. BMI was calculated at the initiation of treatment. After 6 months of treatment, change from baseline in DAS28, pain on a visual analog scale, erythrocyte sedimentation rate and C-reactive protein level, and tender and swollen joints were analyzed. The primary endpoint was decrease in DAS28 ≥ 1.2. Secondary outcomes were good response and remission by EULAR criteria. At baseline, among 115 RA patients included, the median (interquartile range) BMI was 25.4 (22.0-28.8) kg/m(2). The number of patients with normal weight, overweight, and obesity was 53 (46 %), 37 (32 %), and 25 (22 %), respectively. Baseline characteristics did not differ between the three subgroups of BMI. The median BMI did not differ between responders and non-responders for DAS28 decrease ≥1.2 (25.7 [22.1-29.9] vs 24.9 [22.0-27.1], P = 0.38), EULAR good response (25.9 [22.8-30.0] vs 25.4 [22.0-28.4], P = 0.61), and remission (25.1 [22.5-28.6] vs 25.4 [22.0-28.9], P = 0.76). BMI did not affect the response to TCZ in RA. If confirmed, these results could be helpful for the selection of a biologic agent in obese RA patients.