Background/Purpose: The efficacy and safety of subcutaneous (SC) abatacept in the management of rheumatoid arthritis (RA) has been demonstrated in numerous controlled clinical trials. However, real-world data of SC abatacept in routine care are scarce. The aim of this interim analysis is to compare the effectiveness and safety of SC abatacept used as first line or second biologic agent in Canadian patients enrolled thus far in Abatacept Best Care (ABC).

Methods: ABC is a prospective, multicenter, randomized study aimed at comparing a T2T approach vs. standard of care in real-life management of patients with RA starting SC abatacept as first line or second line biologic agent, and describing the adherence of physicians to the recommended T2T treatment guidelines while collecting data on the real-life use of SC abatacept. General linear models were used to assess the impact of prior biologic use on treatment effectiveness.

Results: 276 patients (74.3% females) were included with a mean (SD) age of 59.7 (11.7) years and duration since RA diagnosis of 7.5 (8.9) years; of these 214 (77.5%) and 189 (68.5%) had available follow-up data at 6 and 12 months, respectively. Prior biologic use was reported for 39.5% while 60.5% were biologic-naive. Overall, baseline disease parameters were comparable with the exception of time since RA diagnosis (9.0 vs. 6.4 years; P<0.001) which was significantly higher in biologic experienced patients and TJC28 (10.5 vs. 9.1; P=0.062) which was numerically higher.

After 6 months of treatment, both patient groups experienced significant improvements in all disease parameters which were maintained or further enhanced by 12 months. However, upon adjusting for baseline disease activity, improvements in CDAI (P=0.020), physician global (P=0.011), TJC28 (P=0.031), SJC28 (P=0.009), and HAQ (P=0.037) at 6 months were significantly higher in biologic-naive patients (Table 1). Similar results were obtained at 12 months.

A total of 533 AEs were reported for 162 (58.7%) patients, 67.0% of biologic-experienced patients and 53.3% of biologic-naïve patients (256.1 vs. 211.2 events/100 PY). The most common AEs were upper respiratory infections (biologic-experienced vs. biologic-naive: 4.6% vs. 9.0%; 5.2 vs. 14.6 events/100 PY) and bronchitis (7.3% vs. 7.8%; 8.4 vs. 10.2 events/100 PY). Serious AEs and serious infections were reported for 26 (9.4%) patients (10.1% vs. 9.0%; 16.8 vs. 13.2 events per 100/PY) and 5 (1.8%) patients (0.9% vs. 2.4%; 0 vs. 1.5 events/100 PY), respectively. 

Conclusion: The results of the current analysis suggest that SC abatacept has similar safety in biologic-naïve and -experienced patients with more improvement in outcome measures in the former.

Acknowledgments: The authors would like to thank Dr. Kristina Sladojevic and Dr. Eleonora Muratti for their contributions in the study.