Preoperative Prognostic Nutritional Index Is a Predictive Factor for Postoperative Delirium in Elderly Patients with Femoral Neck Fracture

This study aimed to investigate the potential risk factors of postoperative delirium (POD) in elderly patients (≥65 years old) undergoing femoral neck fracture (FNF) surgery, and explore whether preoperative prognostic nutritional index (PNI) could predict the occurrence of POD. A total of 260 cases with FNF were included in this study at The Affiliated Jinling Hospital of Nanjing University from May 2018 and May 2024. The baseline characteristics were recorded. The receiver operating characteristic (ROC) curve analysis was developed to evaluate the diagnostic ability of preoperative PNI for POD. LASSO regression and multivariate logistic regression analyses were used to identify the risk factors for POD. Eighty-one of the 260 cases with FNF suffered POD with an incidence of 31.2%. Patients with POD showed lower Mini-Mental State Examination (MMSE) score (P=0.011), lymphocyte count (P=0.002), albumin level (P=0.011), and PNI level (P<0.001) than those in non-POD group. ROC curve analysis indicated that PNI was a good predictor for POD with an area under the curve (AUC) value of 0.708 (95% CI: 0.648-0.762, P<0.001); the sensitivity and specificity were 79.01 and 60.89, respectively. LASSO regression analysis identified eleven key variables including gender, age, body mass index, diabetes mellitus, surgery duration, anesthesia duration, fracture position, neutrophil, lymphocyte, PNI, and MMSE score. Multivariate logistic regression analysis showed that MMSE score < 27, BMI > 23.9 kg/m2, and PNI < 45.45 were independent risk factors of POD. In conclusion, preoperative PNI is a significant predictor for POD in elderly patients after FNF surgery.