Assessing hepatitis B virus serologies when transitioning patients from intravenous immune globulin therapy to rituximab for the treatment of autoimmune neuromuscular diseases

Introduction/AimsIntravenous immune globulin (IVIG) has been used as early treatment for autoimmune neuromuscular diseases, but due to cost and frequency, may be switched to rituximab. Rituximab and other B‐cell‐depleting medications require screening of hepatitis B virus (HBV) serologies given the risk of HBV reactivation (HBVr). We aimed to describe the incidence and characteristics of passively transferred antiviral serologies from IVIG and how to differentiate between passive antibody transfer and resolved HBV infection.MethodsThis was a single‐center descriptive study of neurology patients prescribed rituximab and IVIG. Retrospective medical record reviews were performed and patient‐specific variables were collected.ResultsTwelve patients had reactive anti‐HBc results after starting IVIG, but only 9 were confirmed to have reactive anti‐HBc from passive transfer. Whether reactive anti‐HBc in the remaining three patients was from passive IVIG transfer could not be confirmed. Five patients with reactive anti‐HBc results during rituximab screening did not have pre‐IVIG anti‐HBc results for comparison and were started on antiviral prophylaxis. Reactive anti‐HBc serologies changed to nonreactive after IVIG discontinuation 44–321 days after the last IVIG infusion.DiscussionThis study confirms IVIG can passively transfer anti‐HBc serologies in a neurologic cohort. Ideally, HBV serologies would be checked before starting IVIG to help later determine if passive transfer occurred. With the increasing use of B‐cell‐depleting medications for neuromuscular conditions, it is important for providers to be knowledgeable on the interpretation of HBV serologies for patients on IVIG and to ensure implementation of an HBVr prophylaxis management strategy for patients when appropriate.