Clinical and Laboratory Predictors of Poor Neurological Outcomes Following Infectious Encephalitis: Systematic Review and Meta‐Analysis

ABSTRACT Background and Objectives Infectious encephalitis is a serious global health problem linked to high rates of mortality and morbidity. However, clinical and laboratory factors that impact neurological outcomes following infectious encephalitis remain poorly understood. Accordingly, we undertook a systematic review and meta‐analysis of clinical and laboratory factors influencing neurological outcomes following infectious encephalitis. Methods We searched MEDLINE and EMBASE from inception to 25th September 2023 for observational studies that reported on neurological outcomes at discharge or at ≥ 6 months. We assessed the prognostic value of a priori selected clinical and laboratory‐based features by estimating pooled risk ratios (RRs) through a random‐effects meta‐analysis. The I 2 statistic was used to assess heterogeneity. This study is registered with PROSPERO (CRD42023485045). Results There were several key findings. First, immunocompromised status, status epilepticus, and Glasgow coma scale of < 8 during initial admission were significantly associated with poor neurological outcomes both at discharge and ≥ 6 months after infectious encephalitis onset. Second, CSF leucocytosis [RR: 0.83 95% CI: 0.69–0.98, p  = 0.03, n  = 5, I 2  = 0%] conferred better neurological outcomes while elevated CSF protein [RR: 1.25 95% CI: 1.07–1.46, p  = 0.006, n  = 7, I 2  = 0%] was linked to worse neurological outcomes at discharge. Third, there was no significant association between adjunct steroid therapy and neurological outcomes at discharge and ≥ 6 months. Discussion This is the first systematic review and meta‐analysis to investigate prognostic factors linked to neurological outcomes following infectious encephalitis. The results highlight the prognostic value of a range of easily accessible clinical and laboratory parameters.