Association of Postoperative Stress Hyperglycemia Ratio with Suspected Infection, Culture Positivity, Sepsis, and Septic Shock in 1408 Patients After Cranial Neurosurgery

Background/Objectives: The early postoperative stress hyperglycemia ratio (SHR) may capture acute glycemic stress relative to chronic glycemia, but its association with infection-related events after cranial neurosurgery remains uncertain. We evaluated these associations in critically ill patients after cranial neurosurgical procedures. Methods: We retrospectively analyzed 1408 adults in MIMIC-IV after eligible cranial neurosurgical procedures. SHR was calculated from the first serum glucose measurement 6–24 h after surgery and estimated average glucose was derived from HbA1c. Primary outcomes were electronic health record (EHR)-defined suspected infection, culture-positive infection from any qualifying specimen, Sepsis-3-defined sepsis, and an EHR-based septic shock proxy. The secondary outcome was 90-day mortality. Results: In fully adjusted models, each 0.1-unit increase in SHR was associated with suspected infection (OR 1.08, 95% CI 1.04–1.12), culture-positive infection (OR 1.05, 95% CI 1.01–1.09), Sepsis-3-defined sepsis (OR 1.07, 95% CI 1.03–1.11), and septic shock (OR 1.10, 95% CI 1.05–1.15). In nested analyses, each 1-SD increase in SHR was associated with 90-day mortality (OR 1.59, 95% CI 1.29–1.96). Associations persisted in 24-h lag analyses. Adding SHR yielded small, non-significant AUC increases but improved reclassification for Sepsis-3-defined sepsis and septic shock. Conclusions: Higher early postoperative SHR was associated with EHR-derived, all-source infection-related and sepsis-related events and 90-day mortality in a heterogeneous postoperative neurocritical care cohort. These findings do not establish that SHR predicts postoperative neurosurgical infection; prospective external validation is required before clinical use.