Association of delayed enteral nutrition with hospital-acquired pneumonia and 30-day mortality following craniotomy for severe traumatic brain injury: a retrospective cohort study

Background Hospital-acquired pneumonia (HAP) is a serious complication after craniotomy for severe traumatic brain injury (TBI), but evidence on modifiable factors, especially delayed enteral nutrition, remains limited. Objective To evaluate factors associated with HAP after severe TBI surgery, focusing on enteral nutrition timing and the association between HAP and 30-day mortality. Methods This retrospective cohort study included 600 adult patients undergoing craniotomy for severe TBI who survived >48 h. HAP was diagnosed according to CDC/NHSN criteria. Multivariable logistic regression identified factors associated with HAP, and a fully adjusted model assessed the HAP–mortality association. Model performance was assessed by the AUC and Hosmer–Lemeshow test. Sensitivity analyses included forced inclusion of tracheostomy and comparison of the primary model (pre-HAP ventilation duration) with the total ventilation model. A 48-h landmark analysis was also performed. The primary outcome was postoperative HAP; secondary outcomes were ICU stay and 30-day mortality. Results Postoperative HAP incidence was 11.5%. After adjustment, delayed enteral nutrition (≥48 h) was independently associated with HAP (OR = 4.46, 95% CI: 2.52–8.19, p < 0.001). Other associated factors included age, admission GCS, mechanical ventilation duration, and serum albumin. The model showed good discrimination (AUC = 0.795) and calibration (Hosmer–Lemeshow p = 0.829). In the time-dependent Cox model, HAP was associated with higher 30-day mortality (HR = 4.31, 95% CI: 1.52–12.25, p = 0.006). The primary model and total ventilation model yielded nearly identical results. In the landmark analysis, mechanical ventilation at 48 h was associated with subsequent HAP (OR = 2.19, 95% CI: 1.02–5.30, p = 0.06). Forced inclusion of tracheostomy did not materially alter core results. Conclusion In severe TBI patients undergoing craniotomy, delayed enteral nutrition was independently associated with increased HAP risk, and HAP was associated with higher 30-day mortality. These findings highlight the potential importance of early enteral nutrition, but causal inference is limited by the observational design; prospective studies are needed.