A retrospective survival analysis of relapse rate in pediatric and adult autoimmune encephalitis
Jennifer Yang1, Emilie Liu1, Linda Nguyen2, Anastasie Dunn-Pirio1, Jennifer Graves1
1University of California, San Diego, 2University of Texas Southwestern
Objective:
To investigate relapse rate in pediatric and adult autoimmune encephalitis (AE)
Background:
Prior observational studies for AE have mostly focused on outcomes following acute immunotherapies. Varying relapse rates are reported among the different autoantibodies with limited evidence on long-term immunotherapy use after acute treatment and its associated clinical outcomes.
Design/Methods:

We conducted a retrospective study of consecutive patients meeting clinical criteria for AE evaluated at UC San Diego and Rady Children’s Hospital from January 2007 to November 2021. Survival analysis and cox multivariable regression models were employed to evaluate relapse risk using rituximab exposure as a time-dependent variable.

Results:

A total of 35 pediatric (29 seropositive, 6 seronegative) and 75 adult (57 seropositive, 18 seronegative) patients were included in the study. The most common antibody subtype in both cohorts was anti-NMDA receptor (NMDAR). Relapses occurred in 31% of pediatric seropositive, 50% of pediatric seronegative, 38% of adult seropositive, and 27% of adult seronegative cases. Times to first relapse (TTFR) were 10.3 ± 7.4 months (pediatric seropositive), 6.9 ± 4.3 months (pediatric seronegative), 15.4 ± 29.3 months (adult seropositive), and 7.8 ± 6.5 months (adult seronegative). Combining pediatric and adult data, and adjusting for age and sex, rituximab use was associated with 74% lower hazard to relapse (HR 0.26, 95% CI 0.09 – 0.75, p= 0.01) for TTFR and the adjusted HR for rituximab use for recurring relapses was 0.36 (95% CI 0.15 – 0.87, p=0.03). The effect of rituximab was stronger for non-NMDA encephalitis than anti-NMDAR encephalitis (HR 0.39, 95% CI 0.16 – 0.96 vs HR 0.49, 95% CI 0.11 – 2.30).

Conclusions:
Relapses occur in approximately one-third of pediatric and adult patients with AE, although less frequent in anti-NMDARE. Our data demonstrate a substantial benefit of rituximab use for reducing relapse rate as acute or chronic immunotherapy.
10.1212/WNL.0000000000202847