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

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 I2 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, I2 = 0%] conferred better neurological outcomes while elevated CSF protein [RR: 1.25 95% CI: 1.07-1.46, p = 0.006, n = 7, I2 = 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.