Clinical Features and Outcomes in Adult Patients with Autoimmune Encephalitis Requiring Intensive Care: A Retrospective Cohort Study

Abstract Background This study aims to explore the predictors of poor outcomes by analyzing the clinical characteristics and prognosis of adult patients with severe forms of autoimmune encephalitis (AE) requiring intensive care unit (ICU) admission. Methods A retrospective analysis was conducted on 134 adult patients diagnosed with definite or possible AE and admitted to the neurology ICU between January 2015 and December 2023. Neurological outcomes at 6 and 12 months were assessed using the modified Rankin scale (mRS). The study further analyzed the relationship between their clinical characteristics, auxiliary examinations, and prognosis. Results A total of 134 adult patients with AE requiring ICU admission were included. The 6- and 12-month survival rates were 91.8% and 91.5%, respectively. At 6 months, 72.4% (97 of 134) of patients had favorable outcomes (mRS score ≤ 2), whereas 27.6% (37 of 134) had poor outcomes (mRS score ≥ 3). Compared with the favorable group, patients in the poor outcome group were older (42.92 vs. 30.71 years, p = 0.002), had a higher incidence of tumors (24.3% vs. 4.1%, p < 0.001), and were more likely to require mechanical ventilation (67.6% vs. 26.8%, p < 0.001). They also had lower Glasgow Coma Scale scores on ICU admission ( p = 0.006), higher Acute Physiology and Chronic Health Evaluation II scores ( p = 0.006), elevated cerebrospinal fluid glucose ( p = 0.004) and protein levels ( p = 0.029), higher autoantibody seronegativity (32.4% vs. 13.4%, p = 0.011), lower glucocorticoid use ( p = 0.038), and longer ICU stays ( p = 0.031). Multivariate logistic regression identified age ( p = 0.001), presence of tumor ( p = 0.03), mechanical ventilation ( p = 0.025), antibody negativity ( p = 0.042), and ICU length of stay ( p = 0.000) as independent predictors of poor prognosis. Conclusions These factors may help identify high-risk patients with AE early, enabling timely and targeted interventions to improve outcomes.