To evaluate the efficacy, radiographic changes, and safety of abatacept and methotrexate therapy through 2 years in a long-term extension of a previously published 1-year study.
Patients who received placebo during year 1 were switched to abatacept. Patients taking abatacept continued to take it. Efficacy and safety were assessed through 2 years.
Of 539 patients enrolled in the initial 1-year study, 488 completed 1 year of the long-term extension (2% discontinued for lack of efficacy). At 2 years, patients taking abatacept had maintained their responses on the American College of Rheumatology (ACR) improvement criteria and the Disease Activity Score in 28 joints (DAS28; using the C-reactive protein [CRP] level), as well as their physical function (according to the Health Assessment Questionnaire [HAQ] disability index [DI]) and health-related quality of life (HRQOL; assessed with the Short Form 36 [SF-36] health survey), that were observed at the end of the double-blind period (year 1 versus year 2 values were 81.9% versus 80.3% for ACR 20% improvement, 25.4% versus 30.9% for a DAS28 [CRP] of <2.6, 71.8% versus 66.8% for the HAQ DI, and 9.7 versus 10.6 and 7.3 versus 7.2, respectively, for the mean change in the physical and mental components summary scores of the SF-36). In the abatacept group, post hoc analysis demonstrated further inhibition of radiographic progression during year 2 (57% reduction in mean change of total score in year 2 versus year 1; P<0.0001), and minimal radiographic progression was observed (mean change in total score from baseline was 1.1 and 1.6 at year 1 and 2, respectively). Rates of adverse events (AEs) and severe AEs were consistent throughout the cumulative period.
The improvements in signs and symptoms, physical function, and HRQOL observed after 1 year of abatacept treatment were maintained through 2 years of treatment. This durability was accompanied by a safety profile consistent with that in the double-blind portion of the study. Radiographic progression was further inhibited in year 2 compared with year 1, suggesting an increasing effect of abatacept on the inhibition of structural damage in year 2.