Background/Purpose: Abatacept is an effective biologic agent indicated for the treatment of RA.¹ Recent studies have indicated that obesity and being overweight could reduce the effect of conventional DMARDs and of anti-TNF treatment in patients with RA. However, there are limited data on the effect of weight on the treatment response for abatacept.^2,3 The aim of this study was to evaluate whether BMI is a modifier for the effect of abatacept measured by DAS28 (CRP) over the first 6 months of treatment in patients with RA.

Methods: Patients with RA from Radboud UMC and the Maartenskliniek were consecutively included if they were treated for ≥5 months with abatacept. Length and weight to calculate BMI had been assessed before treatment start. DAS28 (CRP) was prospectively assessed at baseline and 6 months. Concomitant treatment and treatment history were assessed at treatment start, and closest values for RF and anti-cyclic citrullinated peptide (anti-CCP) positivity obtained before baseline were used. BMI was classified as normal (BMI ≤25 kg/m²) or overweight (BMI >25 kg/m²). The relationship between BMI and response according to DAS28 (CRP) was analyzed using multivariate linear regression to control for confounding baseline covariates.

Results: A total of 113 patients were included in this analysis: 81% were female, mean (SD) age was 59 (13) years and median (P25–P75) disease duration was 13 (9–20) years. All patients had previously used other biologics, including anti-TNF. Conventional DMARDs were used as concomitant therapy in 58% of patients, most often MTX (32%); 69% of patients used IV abatacept. There were some baseline differences (p<0.10) between normal weight (39%) and overweight (61%) patients. Overweight patients were on average older (mean [SD] 60 [13] vs 56 [14] years), the proportion of males was higher (26 vs 7%), RF (75 vs 57%) and anti-CCP (77 vs 61%) positivity occurred more often, and SC abatacept was more frequently used (38 vs 21%), while they used more (median [P25–P75]) previous biologics (4 [3–4] vs 3 [2–4]). The mean (SD) baseline DAS28 (CRP) was 4.2 (1.0) in normal weight and 4.2 (1.2) in overweight patients (p=0.81). The mean (SD) change from baseline in DAS28 (CRP) over 6 months was –0.51 (1.4) in normal weight and –0.70 (1.8) in overweight patients (p=0.55). The difference of –0.19 in change of DAS28 (CRP) was reduced to –0.10 (p=0.71) after correcting for age, sex and baseline DAS28 (CRP), and further attenuated to –0.026 (p=0.92) if also corrected for anti-CCP positivity and number of previous biologic agents. Remission percentages (DAS28 <2.6) at 6 months were 23% in normal weight patients and 26% in overweight patients with an odds ratio (95% CI) of 1.2 (0.5, 2.9), which became 1.1 (0.4, 2.8) after correction for the same confounders.

Conclusion: In patients with RA, BMI was not a modifier of the effect of abatacept on DAS28 (CRP) at 6 months after treatment start. After controlling for confounders, the reduction in DAS28 (CRP) was the same for normal weight (BMI ≤25 kg/m²) and overweight (BMI >25 kg/m²) patients.

1.    Maxwell L, et al. Cochrane Database Syst Rev 2009;7:CD007277.

2.    Gremese E, et al. Arthritis Care Res 2013;65:94–100.

3.     Sandberg M, et al. Ann Rheum Dis 2014;73:2029–33.