P.027 Autoimmune encephalitis: modifiable and non-modifiable predictors of relapse

Abstract

Background: Approximately 25% of encephalitis cases in North America are autoimmune (AIE). For most forms of AIE, it is unclear which patients have the highest relapse risk and whether standard treatments reduce this risk. Our objective was to determine the overall risk of relapse and whether chronic immunosuppressive therapy modifies that risk. Methods: We performed a chart review consisting of all patients with AIE presenting to the Calgary Neuro-Immunology Clinic and Tom Baker Cancer Centre between 2015 and 2020. Predictors of relapse were determined with use of t-test. Results: Outcome data was assessable in 39 patients, 17/39 (44%) patients relapsed, and most relapses (76%) occurred within 3 years. Patients not on any immunosuppression at the time of relapse had a greater increase in CASE score, a proxy for presentation severity, at relapse compared to those on immunosuppression (p=0.0035). Conclusions: The risk of relapse in AIE is high (44%). Immunosuppression at the time of relapse, which may occur up to 3 years after initial presentation, lessens the relapse severity, although it remains unclear if it can reliably prevent relapses. Our data enforces the importance of long-term follow up and that ongoing immunosuppression may be helpful, particularly in the first 3 years after initial presentation.