Real-world effectiveness of abatacept for rheumatoid arthritis treatment in European and Canadian populations: a 6-month interim analysis of the 2-year, observational, prospective ACTION study

Background: Discontinuation of rheumatoid arthritis (RA) treatment for lack or loss of initial response, tolerability issues, or development of antibodies against the therapeutic agent remains a challenge in clinical practice. Here we present a 6-month interim analysis of a 2-year prospective observational trial in Europe and Canada aiming to assess the real-world effectiveness, safety, and tolerability of intravenous abatacept for the treatment of moderate-to-severe RA. Methods: ACTION (AbataCepT In rOutiNe clinical practice) is a prospective, observational study assessing effectiveness, safety, and tolerability of abatacept in patients with RA enrolled in Europe and Canada between May 2008 and January 2011. The patient population was divided into two groups: biologic naive ('first-line') patients and patients who had previously failed treatment with at least one biologic agent ('second-line'). Retention rates were calculated using Kaplan-Meier curve estimates. Effectiveness was measured using European League Against Rheumatism (EULAR) response criteria, the 28-item Disease Activity Score, the Clinical Disease Activity Index (CDAI), and physical function, as assessed by the Health Assessment Questionnaire-Disability Index (HAQ-DI). Serious adverse events (SAEs) were reported for all enrolled patients. Results: Of 1138 consecutively enrolled patients, 1114 and 1079 patients were evaluable for retention and effectiveness, respectively. Overall, retention rates were 88.6% (95% confidence interval [CI]: 86.4, 90.4); 67.4% of patients achieved good/moderate EULAR response; 32.8% had a CDAI Low Disease Activity State (LDAS); and 44.7% a HAQ-DI response. Retention rates among first-and second-line patients were 93.0% (95% CI: 85.9, 96.6) and 88.1% (95% CI: 85.7, 90.0), respectively. The percentage of patients achieving CDAI LDAS was 40.0% (95% CI: 26.4, 53.6) for first- and 32.2% (95% CI: 28.4, 36.0) for second-line patients and the proportion achieving a HAQ-DI response was 60.3% (95% CI: 47.8, 72.9) versus 43.1% (95% CI: 39.0, 47.2), respectively. The incidence of SAEs was 4.7%. Conclusions: Evidence from this 6-month interim analysis suggests that abatacept offers an effective and well-tolerated treatment option for patients with RA, including those who have previously failed anti-tumor necrosis factor treatment. In addition, higher retention rates and effectiveness outcomes were observed when abatacept treatment was initiated earlier in the course of the disease.