BACKGROUND: Postoperative delirium (POD) is a prevalent complication, particularly in elderly patients with hip fractures (HFs). It significantly affects recovery, length of hospital stay, healthcare costs, and long-term outcomes. Existing studies have investigated risk factors for POD, but most are limited by single-factor analyses or small sample sizes. This study systematically determines independent risk factors using large-scale data and machine learning techniques and develops a validated nomogram model to support early prediction and management of POD. AIM: To investigate POD incidence in elderly patients with HF and the independent risk factors, according to which a nomogram prediction model was developed and validated. METHODS: This retrospective study included elderly patients with HF who were surgically treated in Dongying People's Hospital from April 2018 to April 2022. The endpoint event includes POD. They were categorized into the modeling and validation cohorts in a 7:3 ratio by randomization. Both cohorts were further classified into the delirium and normal (non-delirium) groups according to the presence or absence of the endpoint event. The incidence of POD was calculated, and logistic multivariate analysis was conducted to determine the independent risk factors. The calibration curve and the Hosmer-Lemeshow test as well as the net benefit threshold probability interval by the decision curve were utilized to statistically validate the accuracy of the nomogram prediction model, developed according to each factor's influence intensity. RESULTS: This study included 532 elderly patients with HF, with an overall POD incidence of 14.85%. The comparison of baseline data with perioperative indicators revealed statistical differences in age ( CONCLUSION: This study reveals cognitive impairment history, American Society of Anesthesiologists grade of >
2, RBC transfusion of ≥ 2 units, postoperative intensive care unit care, and preoperative hemoglobin level as independent risk factors for POD in elderly patients with HF. The developed nomogram model demonstrates excellent accuracy and stability in predicting the risk of POD, which is recommended to be applied in clinical practice to optimize postoperative management and reduce delirium incidence.