Preoperative risk factors for delirium in hip-fracture surgery under regional anesthesia: A nationwide population-based study

Background Delirium is common, but is frequently undetected by clinicians, despite the fact that it can be life-threatening. The objective of this study was to identify the incidence of delirium and the preoperative factors associated with postoperative delirium in elderly patients who underwent hip fracture surgery under regional anesthesia. Methods We retrospectively reviewed records of all patients ≥65 years who underwent hip fracture surgery under regional anesthesia, covered by the Korean National Health Insurance, between January 1, 2009 and December 31, 2015. A univariate and stepwise logistic regression model with the occurrence of delirium as the dependent variable was used to identify perioperative factors for this sample of patients. Results Among the 70696 patients who underwent hip fracture surgery, 58972 patients were who received regional anesthesia during surgery were included in our study. Delirium was detected in 8680 (14.7%) patients. Performing stepwise logistic regression, preoperative variables including female gender, included age ≥85 years, hospital type (medical center), ICU and ventilator care, neurodegenerative disorders, uncomplicated diabetes mellitus, peptic ulcer disease, psychoses, and depression (OR=1.49[1.42-1.58], 4.7[4.15-5.37], 13.3[7.57-23.8], 1.52[1.43-1.60], 1.19[1.01-1.40], 1.20[1.14-1.27], 1.09[1.04-1.14], 0.87[0.96-0.00], 2.23[1.48-3.37], and 1.38[1.32-1.46], respectively) were identified to be associated with delirium. Conclusion Delirium could occur in approximately 15% of elderly hip fracture surgery cases in which regional anesthesia is used. Multiple preoperative risk factors were found to be associated with delirium.