Hematoma evacuation modifies the relationship between early changes in neutrophil-to-lymphocyte ratio and mortality after intracerebral hemorrhage.

Abstract

Neutrophil-to-lymphocyte ratio (NLR) is a prognostic indicator in intracerebral hemorrhage (ICH) thought to reflect systemic inflammation driving secondary brain injury. Recent evidence suggests that surgical hematoma evacuation improves long-term outcomes, presumably by reducing secondary brain injury triggered by hematoma-induced inflammation. We hypothesized that stereotactic intracerebral hemorrhage underwater blood aspiration (SCUBA), a minimally invasive hematoma evacuation technique, alters the association between early rise in NLR and outcomes in ICH patients. We conducted a retrospective matched cohort study of 514 ICH patients: 264 underwent SCUBA and 250 were matched controls. Serial white blood cell (WBC) counts with differential were obtained from admission through hospital day 7. We analyzed relationships between the change in NLR from admission to hospital day 2 (delta NLR (ΔNLR)) and in-hospital mortality (primary outcome) using multivariable logistic regression, adjusting for ICH severity and infection status. Baseline characteristics, admission WBC count, and admission NLR were well-balanced without significant differences between groups. Hospital mortality was significantly lower in SCUBA patients (7.2% vs 22.8%, P<0.001). ΔNLR was independently associated with mortality (adjusted OR (aOR) 1.068 per unit increase, P=0.033). However, there was a significant interaction between SCUBA and ΔNLR (aOR 0.884, P=0.019). Predicted mortality probability remained low across NLR ranges in SCUBA patients while increasing sharply in the matched cohort. Our findings suggest that SCUBA modifies the association between ΔNLR and mortality, such that NLR was not a predictor of outcome after hematoma evacuation. Further work is needed to determine whether hematoma evacuation alters systemic inflammatory pathways that drive secondary brain injury after ICH.