The effect of body mass index on clinical response to abatacept as a first-line biologic for rheumatoid arthritis: 6-month results from the 2-year, observational, prospective ACTION study

Objective: To assess the impact of baseline body mass index (BMI) on the efficacy and retention of intravenous abatacept at 6 months in biologic-naive patients with rheumatoid arthritis (RA). Methods: This was a 6-month analysis of a 2-year, non-interventional, international, prospective study. Baseline characteristics, clinical response and retention rates were compared by BMI subgroup: under-weight/normal, overweight and obese (< 25, 25 to < 30 and = 30 kg/m(2), respectively). Results: BMI was reported in 643/672 (96%) patients: 264 (41%) were underweight/normal, 224 (35%) overweight and 155 (24%) obese. At baseline, the obese group had more active disease (mean [95% confidence intervals] 28-joint Disease Activity Score [C-reactive protein; derived] 4.6 [4.5, 4.7], 4.8 [4.7, 5.0] and 5.1 [4.9, 5.2] for underweight/normal, overweight and obese groups, respectively), a higher prevalence of metabolic disorders, a greater proportion of women and a lower proportion of patients with rheumatoid factor positivity. There were no significant differences in the percentages of patients achieving a good/moderate European League Against Rheumatism response by BMI group (80.7, 86.1 and 77.0% for underweight/normal, overweight and obese groups, respectively; P = 0.178). Overall retention rates at 6 months did not differ across groups (89, 92 and 89% for underweight/normal, overweight and obese groups, respectively; log-rank P = 0.382). After adjustment for baseline characteristics, BMI was not significantly associated with risk of discontinuation (reference BMI < 25 kg/m(2); hazard ratio [95% confidence intervals] 0.46 [0.22, 0.99] and 0.69 [0.34, 1.41] for overweight and obese patients, respectively). Conclusion: BMI does not impact abatacept clinical response or retention in biologic-naive patients with RA. (C) 2017 The Authors. Published by Elsevier Masson SAS on behalf of Societe francaise de rhumatologie. This is an open access article under the CC BY license.