The Induction Period First Cohort (IP1C) arms (30/10 mg/kg and 10 mg/kg) were placebo-controlled arms that were used for the primary endpoint and its analysis. The Induction Period Second Cohort arms (IP2C 30/10 mg/kg and 10 mg/kg) were not placebo-controlled, their sole purpose being to provide sufficient numbers of participants for the maintenance phase. The first cohort (IP1C) was randomized to receive placebo or 1 of 3 doses of abatacept. Following completion of the IP1C randomization, a second cohort (IP2C) was randomized to receive 1 of 2 doses of abatacept. After all participants in the IP1C completed or discontinued, the data was locked and the formal analysis for the Induction Period primary endpoint was performed. Summary tables for the second cohort (IP2C) and the Maintenance and Open-label phases were generated from a second, subsequent data lock.
