Ito H, Tsuji S, Nakayama M, et al. - In patients with rheumatoid arthritis (RA), experts aspired to explore if abatacept (ABA) causes more adverse events (AE) than conventional synthetic disease-modifying antirheumatic drugs (csDMARD) after orthopedic surgery. For this retrospective multicenter nested case–control study, individuals receiving ABA (ABA group) were matched individually with those receiving csDMARD and/or steroids (control group). A total of 3,358 cases have been collected. Two thousand six hundred fifty-one patients were chosen for matching after inclusion and exclusion, and 194 patients in 97 pairs were selected for subsequent comparative analyses between the ABA and control groups. Adding ABA to the treatment does not seem to increase the incidence rates of postoperative AE in patients with RA undergoing orthopedic surgery compared with csDMARD and/or steroids without ABA. Large cohort studies should be undertaken to provide evidence for ABA's perioperative safety profile.