Practice Variation in Treatment of NMDAR- IgG Encephalitis Across International Centers from the Clinical Outcomes in Autoimmune Encephalitis Study (COAST)

ObjectiveTo 1) examine the baseline characteristics of patients with NMDAR-IgG encephalitis (NMDAR-IgG AE) and 2) understand practice variation in the treatment of NMDAR-IgG AE across international centers contributing to the Clinical Outcomes in Autoimmune Encephalitis Study (COAST). BackgroundNMDAR-IgG AE is treated with acute immunosuppressive therapy (IST). Second-line therapies like rituximab and cyclophosphamide are used in refractory cases. However, the optimal treatment regimen and duration of treatment is not established. Design/MethodsDescriptive statistics summarized baseline cohort characteristics. Outcome measures were modified rankin scale (mRS) and clinical assessment scale for autoimmune encephalitis (CASE). Computations were performed in R, version 4.1.1. ResultsIn this international, multicenter study we included 126 NMDAR-IgG AE patients. The median age at onset was 27 (21, 33) and 98 (77.8 %) were female. Presenting symptoms included psychiatric dysfunction (108 (85.7%)), seizures (81 (64.3%)), and movement disorders (67 (53.2%)). Median baseline mRS was 4 (3,5), and median baseline total CASE score was 9 (6,16). Teratoma was identified in 39/112 (34.8%) patients. CSF showed leukocytosis in 77/118 (65.2%) patients. Median length of stay in the hospital was 39 (17,61) days, and 69/116 (59.5%) patients had an ICU admission for a median of 25 (12,53) days. Median time to first-line IST (IVMP, IVIG, PLEX) was 3 (2,7) weeks after symptom onset. Patients received varied second-line therapies including rituximab (76 (60.3%)), corticosteroids (30 (23.8%)), IV/oral cyclophosphamide (17 (13.5%)), mycophenolate mofetil (8, (6.3%)), azathioprine (6, (4.8%)), tocilizumab (5, (4.0%)), bortezomib (5, (4.0%)), methotrexate (1, (0.8%)) and IVIG (1 (0.8%). At the last follow up visit, patients had a median mRS of 1 (0,2) and median total CASE score of 1 (0,3). ConclusionsMulticenter international data demonstrates substantial practice variation across centers, especially regarding the type and duration of second-line therapies. Further studies are underway to determine optimal treatment regimens.