Minimally Clinically Important Difference of the Clinical Assessment Scale in Autoimmune Encephalitis.

The Clinical Assessment Scale in Autoimmune Encephalitis (CASE) tracks disease severity in autoimmune encephalitis (AE), but no threshold for significant change exists. We aimed to determine the minimally clinically important difference (MCID) for CASE. Using our AE cohort, receiver operating characteristic analyses were anchored to ≥ 1-point improvement in mRS over 3-month intervals. Among 222 AE patients (65 NMDAR, 49 LGI1, and 108 seronegative AE), a 30% CASE reduction showed good discriminatory performance for mRS improvement in the first 6 months, particularly in NMDAR and seronegative subgroups. A 30% CASE reduction may standardize AE response definitions.