To examine changes in activity participation following abatacept treatment for rheumatoid arthritis (RA), and which factors contributed to such changes.
Data were analyzed from the Abatacept in Inadequate responders to Methotrexate (AIM) and Abatacept Trial in Treatment of Anti-TNF INadequate responders (ATTAIN) clinical trials of abatacept in patients with RA. Activity participation was evaluated by the validated Activity Participation Questionnaire (APaQ), along with measures of clinical response and health-related quality of life. Changes in the APaQ during the two study periods were compared between treatment groups. Multiple regression analyses were performed to investigate the determinants of change in activity participation. The relationship between clinical efficacy measures (including low disease activity state [LDAS], Disease Activity Score 28-defined remission, and European League Against Rheumatism [EULAR] responses) and changes in activity participation were investigated.
Statistically significant, substantive improvements in activity participation were observed over the entire study period in patients treated with abatacept. Abatacept-treated patients showed improvements from baseline of 8.4 and 7.3 days in activity participation, compared with 4.5 and 1.4 days in the placebo group (P < 0.005 vs. placebo in both trials), at the end of AIM and ATTAIN, respectively. The Short Form-36 physical and mental component scores, patient global assessment, and the Health Assessment Questionnaire-Disability Index score were found to be the strongest determinants of changes in activity participation. Patients who achieved LDAS, disease remission and good EULAR responses experienced greater improvements in activity participation measures.
Abatacept treatment substantively and significantly improved patients' ability to participate in their usual activities. The gain in activity was closely related to improvements in clinical status, physical function and quality of life.