Association between increased Systemic Immune-Inflammation Index and postoperative delirium in older intertrochanteric fracture patients

Abstract

Abstract Background and Purpose Systemic immune-inflammation index (SII), a novel inflammation index derived from counts of circulating platelets, neutrophils and lymphocytes, has been studied in developing incident acute cancer and ischemic stroke (AIS). However, the clinical value of SII in postoperative delirium patients had not been further investigated. The purpose of our research was to study the incidence and preoperative risk factors for postoperative delirium (POD) and verify whether SII could serve as a potential marker for POD in older intertrochanteric fracture patients. Finally, we create a novel nomogram for predicting POD patients with older intertrochanteric fracture. Methods We enrolled elderly patients with intertrochanteric fracture who underwent proximal femoral nail anti-rotation(PFNA)between February 2021 to April 2023. Uni variate and multivariate logistic analyses were performed to confirm the risk factors and then construct a nomogram model. The calibration curve and clinical decision curve analysis (DCA) were used to assess the model’s fitting performance. The performance of the nomogram was evaluated for discrimination, calibration, and clinical utility. Results 293 patients were eligible for inclusion in the study, 25.6% (75/293) of patients had POD. The POD patients had higher SII levels than the non-POD group. SII is the stronger correlator for POD in older intertrochanteric fracture patients, of which the optimal cut-off value was 752.6×109. Multivariate analysis revealed that the age, diabetes, total albumin,SII > 752.6×109 and CRP > 20.25mg/L were independent risk factors for POD patients. Incorporating these 5 factors, the model achieved a concordance index of 0.745 (95% CI, 0.683–0.808) and had a well-fitted calibration curve and good clinical application value. Conclusion The SII was a simple and valuable biomarker for POD, and the new nomogram model based on it can accurately forecast the occurrence of POD. They can be utilized in clinical practice to identify those at high risk of POD in older intertrochanteric fracture patients.