Body mass index as a driver of selection of biologic therapy in rheumatoid arthritis. Results from the US-CLARA study

Purpose: Body mass index (BMI) demonstrated to influence the clinical response to different drugs in rheumatoid arthritis (RA). The aim of this study was to investigate the role of BMI in the achievement of remission in active RA patients starting the treatment with abatacept. Methods: Data regarding 130 RA patients enrolled in the UltraSound-CLinical ARthritis Activity (US-CLARA) study were retrospectively analyzed. Patients were assessed at baseline (when starting abatacept treatment) and at 3- and 6-months. An extensive clinimetric evaluation, including a new ultrasound (US)/clinical composite disease activity index, termed US-CLARA, was performed at every timepoints. Outcome of interest of the study was the impact of BMI on the achievement of the Disease Activity Score 28-joints erythrocyte sedimentation rate (DAS28-ESR) or the ACR/EULAR Boolean remission criteria at 6 month. Results: At 6-month 26 out of 130 patients were defined as responders to abatacept. Comparing the baseline characteristics of responders to non-responders, US-CLARA showed a statistically significant difference between the two groups. The logistic regression analysis showed that the two indipendent variables, predictive of treatment response (keeping the DAS28-ESR and/or Boolean remission criteria as dependent variable), were the self-tender joint count assessment (p=0.0412) and the ultrasound score (p=0.0211). No other baseline variable, notably BMI, was associated to 6-month abatacept response. Conclusions: BMI does not influence the abatacept response in RA patients with active disease. During abatacept treatment, the clinical response can be achieved despite a condition of overweight or obesity.