OBJECTIVE: Assess whether baseline anticyclic citrullinated peptide antibodies (anti-CCP) status is associated with treatment response in patients with rheumatoid arthritis (RA) initiating abatacept (ABA) or a tumor necrosis factor-alpha inhibitor (TNFi).

METHODS: Using the Corrona RA registry, patients were identified who initiated ABA or a TNFi (June 2004-January 2015), had a followup visit 6 months (+/- 3 mos) after initiation, and anti-CCP measured at or prior to initiation. Primary outcome was mean change in Clinical Disease Activity Index (CDAI) from initiation to 6 months. Treatment response was evaluated based on a typical patient profile (female, aged 57 yrs, body mass index of 30 kg/m(2), baseline CDAI of 20, 1 prior biologic, and no comorbidities other than RA). Secondary outcomes included remission and low disease activity.

RESULTS: There were 566 ABA initiators [anti-CCP+ ( > /= 20 units/ml): n = 362; anti-CCP- ( < 20 units/ml): n = 204] and 1715 TNFi initiators (anti-CCP+: n = 1113; anti-CCP-: n = 602). Differences between treatment groups included baseline disease duration, CDAI, and prior biologic use. At 6 months, anti-CCP+ ABA initiators were associated with significantly greater CDAI response versus anti-CCP- ABA initiators; no significant difference was observed for TNFi initiators. When considering a typical RA patient profile, CDAI response was greater in anti-CCP+ versus anti-CCP- ABA initiators; anti-CCP+ versus anti-CCP- TNFi initiators were similar. Secondary outcome responses were also greater in anti-CCP+ versus anti-CCP- ABA initiators; TNFi initiators did not differ by anti-CCP status.

CONCLUSION: In a US-based clinical practice setting, anti-CCP status was associated with a differential treatment response to ABA, but not TNFi.