Abstract: Objective To investigate the risk factors of postoperative delirium in the elderly patients undergoing hip replacement and the relationship between hemoglobin (Hb) concentration and postoperative delirium. Methods The patients aged ≥65 years who underwent hip replacement in Hongqi Hospital Affiliated to Mudanjiang Medical College from June 2019 to January 2023 were enrolled in this study, and the clinical data were collected from the electronic medical record system. Postoperative delirium was assessed by Confusion Assessment Method Intensive Care Unit (CAM-ICU). Multivariate Logistic regression was used to analyze the influencing factors of postoperative delirium. Logistic regression models with different influencing factors were established, and receiver operating characteristic (ROC) curves were drawn to analyze the sensitivity of the models. Results A total of 86 patients were enrolled in the study, including 21 patients with postoperative delirium (24.4%). There were significant differences in age, postoperative Hb concentration, perioperative Hb concentration, combined with brain or lung disease, disease type and the rate of Hb concentration decline between delirium group and non-delirium group (P<0.05 or P<0.01). Multivariate Logistic regression analysis showed that age, combined with brain or lung disease, Hb concentration after surgery and Hb concentration during perioperative period were independent influencing factors for postoperative delirium in the elderly patients undergoing hip replacement. ROC curve analysis of different models showed that the combination of postoperative Hb concentration, perioperative Hb concentration change, age and combined with brain or lung disease to predict postoperative delirium in the elderly patients undergoing hip replacement had the largest area under the curve. Conclusions In the perioperative period of elderly patients undergoing hip replacement, correcting low Hb concentration after surgery and avoiding great change of Hb concentration during perioperative period are important to reduce the occurrence of postoperative delirium.

Key words: hip replacement, postoperative delirium, hemoglobin, aged