BACKGROUND: Abatacept (ABA, available in intravenous [IV] and subcutaneous [SC] formulations) is a biologic disease-modifying anti-rheumatic drug (BDM) indicated for rheumatoid arthritis (RA) treatment. ABA may be prescribed to inadequate responders of non-biologic disease-modifying anti-rheumatic drugs (DMARD) or other BDM therapies.
OBJECTIVES: To characterize RA patients initiating ABA (IV or SC), other BDMs, or DMARDs with respect to baseline demographic, clinical, and healthcare utilization characteristics as part of a postmarketing safety evaluation of ABA.
METHODS: US commercial health plan members≥18 years of age who initiated ABA IV or SC, other BDMs, or DMARDs were identified from December 2005–April 2015. Initiators were required to have ≥6months continuous health plan enrollment prior to drug initiation (baseline period), a baseline claim for RA (ICD-9 diagnosis code 714.xx), and no baseline administration of the same drug. Descriptive comparisons of baseline characteristics of ABA IV and SC, BDM, and DMARD initiators were made.
RESULTS: 981 ABA IV, 287 ABA SC, 17,183 BDM,and 62,881 DMARD initiators were identified. ABAIV and SC initiators were more likely to be female (ABA IV: 83%, ABA SC: 85%, BDM: 73%, DMARD:76%) and have prior BDM use (ABA IV: 47%, ABASC: 47%, BDMs: 19%, DMARDs: 9%). ABA IV initiators were more likely to have corticosteroid use (ABAIV: 75%, ABA SC: 69%, BDM: 64%, DMARD: 66%)and≥3 creactive protein test claims (ABA IV: 17%,ABA SC: 13%, BDM: 11%, DMARD, 6%). Amonginitiators with prior BDM use, ABA IV initiators were more likely to receive infliximab (ABA IV: 51%, ABASC: 4%, BDM: 19%, DMARD: 28%). ABA SC initia-tors were more likely to receive etanercept (ABA IV:23%, ABA SC: 48%, BDM: 47%, DMARD 42%), certolizumab (ABA IV: 3%, ABA SC: 11%, BDM:2%, DMARD: 2%) and golimumab (ABA IV: 2%,ABA SC: 8%, BDM: 3%, DMARD: 2%).
CONCLUSIONS: ABA IV and SC, BDM, and DMARDinitiators differ in clinically important aspects. These findings highlight the need for careful evaluation of potential comparator groups to appropriately address confounding in ABA safety assessments.
