Remission using different composite disease indices in MTX-IR RA patients treated with abatacept or infliximab, +MTX

Background Levels of acute-phase reactants, which correlate with clinical disease activity in RA,1 are differentially weighted in the calculation of disease activity indices such as DAS28/SDAI. Acute-phase reactants and disease activity measures may be affected differently by biologics with different mechanisms of action.2 Objectives To evaluate remission using the ACR/EULAR index-based definition of remission3 vs DAS28-defined remission in biologic-naïve MTX-IR RA patients (pts) from AIM4 and ATTEST5 trials, and assess the contribution of core components. Methods In AIM, pts were randomized to abatacept (ABA; ∼10 mg/kg every 4 wks) or PBO, plus MTX.4 In ATTEST, pts were randomized to ABA (∼10 mg/kg every 4 wks), IFX (3 mg/kg every 8 wks), or PBO (every 4 wks), plus MTX.5 Post-hoc analyses evaluated remission according to DAS28(CRP) and SDAI at 6 mths; missing data were imputed by LOCF. Results Baseline demographics and disease characteristics were similar between groups in each trial.4,5 All pts achieving DAS28 remission at 6 mths were either in SDAI remission or SDAI LDAS. At 6 mths, for pts achieving SDAI remission, core components were generally similar and≤1. Conclusions In ATTEST, remission rates at 6 mths were similar for abatacept and IFX independent of the composite measure. When using SDAI remission criteria to assess remission, core components of abatacept-treated pts were consistent in AIM and ATTEST and similar to that of IFX-treated pts and ≤1, suggesting no residual disease activity in contrast with DAS28 remission criteria. This confirms that SDAI is a more accurate composite index than DAS28-CRP in assessing true remission. (Table Presented).