Early systemic immune-inflammation index is associated with mortality and functional outcome in brainstem hemorrhage.

BACKGROUND: Brainstem hemorrhage is a severe subtype of spontaneous intracerebral hemorrhage, characterized by high mortality and disability rates, and is closely associated with systemic inflammatory responses. The systemic immune-inflammation index (SII), as a comprehensive inflammatory marker, reflects the balance between immunity and inflammation. However, its dynamic changes and clinical significance in patients with brainstem hemorrhage remain unclear. OBJECTIVE: This study aimed to investigate the early dynamic changes in SII in patients with brainstem hemorrhage and to evaluate its association with 30-day mortality and 90-day functional outcomes, thereby providing a potential biomarker for clinical risk assessment. METHODS: We retrospectively enrolled 140 patients with brainstem hemorrhage admitted to the Department of Neurosurgery. SII was calculated from complete blood counts on days 1, 3, and 7 after admission. Patients were divided into high and low SII groups based on the median SII on day 1. Demographic data, medical history, admission GCS score, and blood pressure were collected. Outcomes included 30-day mortality, 90-day modified Rankin Scale (mRS) score, and complications. Linear mixed-effects models were used to analyze SII trajectories, multivariable logistic regression to identify independent predictors, and ROC curve analysis to evaluate predictive performance. RESULTS: SII was significantly elevated on day 1, peaked on day 3, and declined by day 7. The linear mixed-effects model revealed a significant group-by-time interaction (p < 0.001), indicating a more intense and slower-resolving inflammatory response in the high-SII group. The high-SII group had significantly higher rates of 90-day poor functional outcome (p < 0.001) and 30-day mortality (p = 0.004). Multivariable logistic regression identified Day 3 SII as an independent predictor of both 90-day poor outcome (p = 0.011) and 30-day mortality (p < 0.001). ROC analysis showed that Day 3 SII predicted 30-day mortality with an AUC of 0.878, and the combined model achieved an AUC of 0.920. CONCLUSION: In patients with brainstem hemorrhage, SII is markedly elevated in the early phase, showing a dynamic pattern of rapid rise on day 1, peak on day 3, and gradual decline by day 7. High SII is closely associated with increased mortality and poor functional outcomes, suggesting that SII can serve as an early prognostic biomarker and guide clinical risk stratification and treatment decisions.