To compare the efficacy and safety of different oral prednisone tapering (OPT) course in anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis.

There is no international guideline regarding the OPT following IVMP in NMDAR encephalitis.

The CHASE study is a multicenter, prospective, observational cohort study, which continuously enrolled patients diagnosed with autoimmune encephalitis between October 2011 to March 2023. Patients treated with oral prednisone, including three groups : oral prednisone tapering course for ≤3 months (Group ≤3 mo), 3-6 months (Group 3-6 mo), >6 months (Group＞6 mo). A propensity score matching was performed to control for major confounding factors.

Among 666 screened patients, 171 (median [IQR] age was 27 [21.0-36.5] years, 55.0% were female) met selection criteria. After propensity score matching, no differences were observed in the proportion of responders and the degree of mRS change at different time points among the three groups (P＞0.05). Weight gain was more frequent in the Group >6 months than in Group ≤3 months (80.0% [95% CI 61.6% to 98.4%] vs. 33.3% [95% CI 14.1% to 52.6%], P_corr < 0.05). There were no significant differences for the proportion of relapse-free patients within 2 years, the proportion of patients who fully recovered from onset within 2 years, the time to total recovery within 2 years, the impact of residual symptoms on activities of daily living, and adverse events.

The findings from this study indicate that extending oral prednisone treatment for adult NMDAR encephalitis beyond 3 months may not significantly improve outcomes but could increase the risk of adverse events, particularly weight gain. We recommend evaluating the possibility of shortening the duration of oral prednisone after a thorough patient assessment.