Incidence and Predictors of Postoperative Delirium in Patients Undergoing Elective Hip and Knee Arthroplasty : A Prospective Observational Study

Background/Objectives: Postoperative delirium has not been well explored in patients undergoing elective hip and knee arthroplasty. This study assessed the incidence of delirium in these patients in the postanesthetic care unit (PACU) and throughout their hospital admission. Predictors of postoperative delirium and impact of delirium on length of stay were also analyzed. Methods: This prospective observational study recruited patients (n = 978) with normal cognitive function presenting for elective primary hip or knee arthroplasty at a single tertiary academic center. Delirium was assessed using the Nursing Delirium Scoring Scale (NuDESC) in the PACU, and twice daily after that on postoperative days 1, 2 and 3, or until discharge, whichever came first. Results: In total, 26 (2.7%) patients developed delirium postoperatively. Unadjusted logistic regression analyses revealed that age; history of cardiovascular, central nervous system, hematologic, endocrinologic, psychiatric disease; postoperative opioid use; and ASA level were associated with an increased risk of delirium, with odds ratios (95% confidence interval) of 1.7 (1.35 to 2.11), 3.6 (1.09 to 12.25), 3.5 (1.53 to 8.03), 2.7 (1.09 to 6.45), 2.3 (1.04 to 4.97), 4.7 (2.10 to 10.70), 0.4 (0.17 to 0.89), and 2.37 (1.05 to 5.33), respectively. A Mann–Whitney U test showed no difference in PACU or hospital length of stay between patients who did and did not have delirium in the PACU (within the first hour). Conclusions: Age, ASA > 3, a history of cardiovascular disease, central nervous system disease, hematologic disease, endocrinologic disease, psychiatric disease and postoperative opioid use are individually associated with postoperative delirium. A future study with an even larger sample size is needed to further evaluate these factors in an adjusted analysis.