Risk Factors and a Nomogram Model Establishment for Postoperative Delirium in Elderly Patients Undergoing Arthroplasty Surgery: A Single-Center Retrospective Study

Abstract

Objective. To explore the related risk factors of postoperative delirium (POD) after hip or knee arthroplasty in elderly orthopedic patients and the predictive value of related risk factors. Material and Methods. In total, 309 patients (≥60 years) who received knee and hip arthroplasty between January 2017 and May 2020 were consecutively selected into the POD and nonpostoperative delirium (NPOD) groups. Group bias was eliminated through propensity score matching. Univariate and multivariable logistic analysis was used to determine the risk factors for POD. The nomogram was made by R. Results. 58 patients were included in each group after propensity score matching; multivariable analysis demonstrated that LDH ( $\text{OR}=4.364$ , $P=0.017$ ), CHE ( $\text{OR}=4.640$ , $P=0.004$ ), Cystatin C ( $\text{OR}=5.283$ , $P=0.006$ ), arrhythmia ( $\text{OR}=5.253$ , $P=0.002$ ), and operation duration ( $\text{OR}=1.017$ , $P=0.050$ ) were independent risk factors of POD. LDH, CHE, Cystatin C, and arrhythmia were used to construct a nomogram to predict the POD. The nomogram was well calibrated and had moderate discriminative ability ( $\text{AUC}=0.821$ , 95% CI: 0.760~0.883). Decision curve analysis demonstrated that the nomogram was clinically useful. Conclusions. Our study revealed that arrhythmia, operation duration, the increase of lactate dehydrogenase and Cystatin C, and the decrease of cholinesterase were reliable factors for predicting postoperative delirium after elderly hip and knee arthroplasty. Meanwhile, the nomogram we developed can assist the clinician to filtrate potential patients with postoperative delirium.