A Novel Nomogram Developed Based on Preoperative Immune Inflammation-Related Indicators for the Prediction of Postoperative Delirium Risk in Elderly Hip Fracture Cases: A Single-Center Retrospective Cohort Study.

Objective: Postoperative delirium (POD) commonly occurs in elderly individuals following hip fracture surgery, with unclear pathophysiological mechanism. Inflammation is a known factor affecting the onset of delirium. The current work aimed to examine the associations of preoperative immune inflammation-related indicators with POD occurrence in elderly cases following hip fracture surgery. Methods: The current retrospective cohort study included 437 elderly cases administered hip fracture surgery from January 2018 to December 2023. The clinicodemographic data and laboratory findings of all cases were retrospectively analyzed. Immune inflammation-related indicators were assessed, eg, MLR, NLR and PLR, as well as SII and SIRI. The bootstrap method was employed to assign cases at 7:3 to the training (48 and 258 cases in the POD and no-POD groups, respectively) and internal validation (13 and 118 cases in the POD and no-POD groups, respectively) cohorts. Next, LASSO, univariable and multivariable logistic regression analyses were applied to determine risk factors in the training cohort, based on which a nomogram model was built. The obtained nomogram was examined for accuracy by calibration plot analysis. Finally, the nomogram's clinical value was assessed by decision curve analysis (DCA), followed by internal validation based on the training cohort. Results: Of all 437 cases, 61 developed POD, indicating a POD incidence of 13.96%. LASSO regression and multivariable analyses revealed preoperative SIRI independently predicted POD in the training cohort. The developed nomogram had an area under the curve (AUC) of 0.991 (95% CI 0.983~0.998) in the training cohort versus 0.986 (95% CI 0.966~1.000) in the validation cohort. Calibration curve analysis revealed nomogram-predicted and actual probabilities were in line. DCA demonstrated the novel nomogram could confer net benefits for POD prediction in elderly cases administered hip fracture surgery. Conclusion: The immune inflammation-related indicators SIRI could predict POD in elderly cases following hip fracture surgery.