Abatacept is second to rituximab at risk of HBsAg reverse seroconversion in patients with rheumatic disease.

Background Hepatitis B surface antigen (HBsAg) reverse seroconversion (RS) can happen in patients with rheumatoid arthritis (RA) with resolved hepatitis B (RHB) undergoing biological disease-modifying antirheumatic drugs (bDMARDs). But the incidence and risk factors need to be delineated. Methods From 2003 to 2019, 1937 patients with RA with available HBsAg and antibody to hepatitis B virus (HBV) core antigen data were retrospectively reviewed, and 489 patients with RHB undergoing bDMARDs treatment were identified. Factors associated with HBsAg RS were analysed. Results During 67 828 person-months of follow-up, 27 (5.5%) patients developed HBsAg RS after bDMARD treatment. As compared with those without HBsAg RS, patients with HBsAg RS were older, had lower frequency of antibody to HBsAg (anti-HBs), and lower baseline anti-HBs levels. In multivariate analysis, rituximab, abatacept and baseline negative for anti-HBs were the independent risk factors for HBsAg RS (adjusted HR: 87.76, 95% CI: 11.50 to 669.73, p Conclusions Not only rituximab, but also abatacept has a high risk of HBV reactivation in patient with RA with RHB. Anti-HBs positivity cannot confer HBV reactivation-free status if the anti-HBs levels are not high enough for patients with RHB on rituximab and abatacept treatment.