Hospital-Course Infectious Complications Associated with In-Hospital Mortality in a Neurological Intensive Care Cohort: A Six-Year Retrospective Study

Background/Objectives: Infectious complications are frequent in neurological intensive care unit (ICU) patients and may contribute to in-hospital mortality. However, their independent association with in-hospital mortality in full neurological ICU cohorts remains insufficiently defined. This study evaluated documented hospital-course infectious complications as factors associated with in-hospital mortality in a six-year neurological ICU cohort. Methods: We performed a retrospective, single-center cohort study including all available neurological ICU admission episodes recorded between 1 January 2020 and 31 December 2025. The primary outcome was in-hospital mortality. Infectious variables included pneumonia, COVID-related pneumonia, urinary tract infection, pressure sore or pressure sore-related infection, sepsis-related coding, and any infectious complication. Multivariable logistic regression was used to assess independent associations with mortality. The primary model included individual infectious complications without Glasgow Coma Scale (GCS), while a GCS-adjusted model was used as a sensitivity analysis. Incremental model analysis, model validation/calibration, and COVID-related sensitivity analyses were also performed. Results: The cohort included 5509 neurological ICU admission episodes; 999 ended in in-hospital death, corresponding to a mortality rate of 18.1%. Any infectious complication was documented in 1911 episodes (34.7%). Pneumonia was the most frequent infectious complication (22.2%) and remained independently associated with mortality in the primary model (adjusted OR 6.82, 95% CI 5.70–8.18; p < 0.001) and in the GCS-adjusted model (adjusted OR 5.25, 95% CI 4.05–6.80; p < 0.001). Sepsis-related coding, interpreted as a documentation-based marker of severe systemic infectious deterioration rather than formally adjudicated sepsis, showed the strongest adjusted association with death (adjusted OR 12.40, 95% CI 6.53–23.54; p < 0.001). Urinary tract infection and pressure sore-related infection were associated with mortality in unadjusted analyses but not after adjustment. Conclusions: Pneumonia and sepsis-related coding were robustly and independently associated with in-hospital mortality. Infectious complications added mortality-related information beyond baseline clinical variables and should be integrated into neurological ICU risk assessment and infection-surveillance strategies.