Development of a Risk Score to Predict Postoperative Delirium in Patients With Hip Fracture

BACKGROUND: Post-hip fracture surgery delirium (PHFD) is a significant clinical problem in older patients, but an adequate, simple risk prediction model for use in the preoperative period has not been developed. METHODS: The 2016 American College of Surgeons National Surgical Quality Improvement Program Hip Fracture Procedure Targeted Participant Use Data File was used to obtain a cohort of patients >= 60 years of age who underwent hip fracture surgery (n = 8871; randomly assigned to derivation [70%] or validation [30%] cohorts). A parsimonious prediction model for PHFD was developed in the derivation cohort using stepwise multivariable logistic regression with further removal of variables by evaluating changes in the area under the receiver operator characteristic curve (AUC). A risk score was developed from the final multivariable model. RESULTS: Of 6210 patients in the derivation cohort, PHFD occurred in 1816 (29.2%). Of 32 candidate variables, 9 were included in the final model: (1) preoperative delirium (adjusted odds ratio [aOR], 8.32 [95% confidence interval {CI}, 6.78-10.21], 8 risk score points); (2) preoperative dementia (aOR, 2.38 [95% CI, 2.05-2.76], 3 points); (3) age (reference, 60-69 years of age) (age 70-79: aOR, 1.60 [95% CI, 1.20-2.12], 2 points; age 80-89: aOR, 2.09 [95% CI, 1.59-2.74], 2 points; and age >= 90: aOR, 2.43 [95% CI, 1.82-3.23], 3 points); (4) medical comanagement (aOR, 1.43 [95% CI, 1.13-1.81], 1 point); (5) American Society of Anesthesiologists (ASA) physical status III-V (aOR, 1.40 [95% CI, 1.14-1.73], 1 point); (6) functional dependence (aOR, 1.37 [95% CI, 1.17-1.61], 1 point); (7) smoking (aOR, 1.36 [95% CI, 1.07-1.72], 1 point); (8) systemic inflammatory response syndrome/sepsis/septic shock (aOR, 1.34 [95% CI, 1.09-1.65], 1 point); and (9) preoperative use of mobility aid (aOR, 1.32 [95% CI, 1.14-1.52], 1 point), resulting in a risk score ranging from 0 to 20 points. The AUCs of the logistic regression and risk score models were 0.77 (95% CI, 0.76-0.78) and 0.77 (95% CI, 0.76-0.78), respectively, with similar results in the validation cohort. CONCLUSIONS: A risk score based on 9 preoperative risk factors can predict PHFD in older adult patients with fairly good accuracy.