Prognostic utility of the NEOS score in pediatric antibody-negative encephalitis: A cohort study.

BACKGROUND: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis and antibody-negative autoimmune encephalitis (AE) are important contributors to pediatric neurological morbidities; however, long-term outcomes and prognostic scores in these entities remain poorly defined, particularly in resource-limited areas. OBJECTIVE: To evaluate the predictive value of prognosis of the anti-NMDAR Encephalitis One-Year Functional Status (NEOS) score in children with antibody-negative and anti-NMDAR AE in Vietnam. METHODS: We performed a retrospective and prospective cohort study of children with AE, evaluated at Children's Hospital 2 (CH2), Vietnam between January 2019 and June 2022, with follow-up completed in August 2023. Outcomes were evaluated at discharge and at final follow-up by the modified Rankin Scale (mRS). The NEOS score, estimated at initial hospitalization, was used to predict poor outcomes (mRS ≥ 2). RESULTS: This study included 82 pediatric patients with AE (<16 years old, 40 with anti-NMDAR encephalitis and 42 with antibody-negative AE), with median ages of 6.7 years (IQR: 4.2-12.2) and 7.4 years (IQR: 4.6-9.6), respectively. NEOS scores and complete outcome data were available for 78 patients (39 per group). At final follow-up, 79.5% of anti-NMDAR patients and 75.0% of antibody-negative AE patients achieved good functional outcomes (mRS 0-1), showing no significant between-group difference (p = 0.634). In antibody-negative AE, the NEOS score demonstrated predictive value for poor outcomes (mRS ≥ 2) with an AUC of 0.785 (p = 0.010), achieving 90% specificity and 55.6% sensitivity at a cut-off > 2, while showing no predictive ability in anti-NMDAR encephalitis (AUC = 0.520, p = 0.862). Both patient groups showed significant functional improvement, with median mRS scores decreasing from 2.0 (IQR: 1-4) at discharge to 0.0 (IQR: 0-1) at follow-up (p < 0.001). Follow-up assessments were conducted at a median of 19.5 months (IQR: 13.9-26.1) for anti-NMDAR patients and 23.7 months (IQR: 18.5-28.2) for antibody-negative AE patients. CONCLUSIONS: Our results suggest that the NEOS score could be a useful prognostic tool for identifying poor outcomes in children with antibody-negative AE, but may lack discriminatory value in anti-NMDAR cases. Further multicenter prospective studies are needed to validate these findings and optimize prognostic tools for pediatric autoimmune encephalitis.