Association of preoperative prognostic nutritional index with postoperative delirium after gastric cancer surgery

Background Postoperative delirium (POD) is a common complication following gastric cancer (GC) surgery, leading to increased morbidity, prolonged hospitalization, and higher healthcare costs. Although other clinical and inflammatory markers have shown promise, the prognostic nutritional index (PNI)—a marker reflecting both immune and nutritional status—has rarely been evaluated for its ability to predict POD among GC patients. This study aimed to determine whether preoperative PNI could serve as an independent predictor of POD in GC cases undergoing gastrectomy. Methods In our retrospective observational study, we analyzed relevant data from 354 GC patients after gastrectomy between January 2023 and December 2024. Receiver operating characteristic (ROC) analysis was used to ascertain the predictive value of PNI for POD. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors for POD. Results Of 354 GC patients, 103 (29.1%) developed POD after gastrectomy. Compared to patients without POD, those who developed POD had significantly higher proportions of older age (60 years), longer hospital stay time (≥19 days), lower platelet counts (≥206*10 9 /L), ASA III, lower lymphocyte counts (≤1.45*10 9 /L), low albumin levels (41.1 g/L), and low PNI (≤48.4). ROC analysis indicated that preoperative PNI predicted POD with an AUC of 0.780 at a cut-off value of 48.4, a sensitivity of 82.52%, a specificity of 65.34%, and a Youden index of 0.4786. Univariate logistic regression analysis revealed that age ≥60 years, hospital stay time ≥19 days, platelet count ≥206*10 9 /L, ASA III, lymphocyte count ≤1.45*10 9 /L, albumin 41.1 g/L, and preoperative PNI ≤ 48.4 were associated with the risk of POD. Multivariate logistic regression analysis confirmed that age ≥60 years, ASA III, and preoperative PNI ≤ 48.4 (OR = 3.952, 95% CI: 1.742–8.964, p = 0.001) were independent risk factors of POD. Conclusion Preoperative PNI is an independent and clinically useful predictor of POD in GC patients. Regular PNI screening may help identify at-risk individuals among GC patients.