Abstract / Summary
ABSTRACT Objective: To evaluate the predictive value of the preoperative Prognostic Nutritional Index (PNI) for multidimensional postoperative outcomes in elderly patients undergoing major abdominal surgery. Methods: This single-center retrospective cohort study included 761 patients aged ≥65 years from 2015 to 2025. Patients were stratified into low-PNI (<40) and high-PNI (≥40) groups. The primary outcome was postoperative delirium within 7 days. Secondary outcomes included 90-day mortality, Clavien–Dindo classification, postoperative hospital stay, and functional recovery milestones (time to first ambulation, oral intake, and defecation). Multivariable regression models (logistic, Cox proportional hazards, and competing risk Fine-Gray models) were employed, adjusting for age, ASA grade, surgical factors, and comorbidities. PNI was further stratified into four categories (<35, 35–40, 40–45, and >45) for dose–response trend analysis. Results: Compared to the low-PNI group, the high-PNI group had a significantly lower risk of postoperative delirium (adjusted odds ratio [aOR] =0.21, 95% confidence interval [CI]:0.13–0.35, P < 0.001), 90-day mortality (adjusted hazard ratio [aHR] = 0.22, 95% CI: 0.10–0.48, P < 0.001), and severe complications (OR = 0.18, 95% CI: 0.12–0.27, P < 0.001). In the competing risk analysis, high PNI was independently associated with faster achievement of all functional recovery milestones (all subdistribution hazard ratios [SHR] >1, P < 0.001). The dose–response analysis confirmed a significant gradient effect: Each increment in PNI category was associated with progressively lower risks of adverse events and faster recovery. Conclusion: Preoperative PNI is a robust, independent predictor of multiple postoperative outcomes in elderly abdominal surgery patients. As a simple and cost-effective tool, PNI is well suited for preoperative risk stratification and guiding personalized perioperative management.