Importance — Postoperative delirium in older adults undergoing hip fracture surgery is associated with significant morbidity and increased health care costs, yet little is known of potential modifiable factors that may help limit the risks.
Objective — To use population-wide individual-level data on the duration of hip fracture surgery to determine if prolonged surgical times and type of anesthesia are associated with an increased risk of postoperative delirium.
Design, Setting, and Participants — This retrospective population-based cohort study analyzed patients aged 65 and older receiving hip fracture surgery between April 1, 2009, and March 30, 2017, at 80 hospitals in Ontario, Canada. Generalized estimated equations with logistic regression analysis were used to determine the relationship between procedure duration, type of anesthesia and the occurrence of postoperative delirium. Restricted cubic splines were also generated to visualize this relationship. Data analysis was conducted from July to October 2018, revision in January 2019.
Exposure — Surgery duration, measured as the total time in the operating room.
Main Outcomes and Measures — A diagnosis of postoperative delirium during hospitalization.
Results — Among 68 131 patients with surgically managed hip fracture (median [interquartile range] age 84 [78-89] years; 72% women) identified, 7150 patients experienced postoperative delirium. In total, 26 853 patients (39.4%) received general anesthesia. Receiving general anesthesia was associated with a slightly higher rate of postoperative delirium compared with not receiving general anesthesia (2943 [11.0%] vs 4207 [10.2%]; P=.001). The risk for delirium increased with increased surgical duration – every 30-minute increase in the duration of surgery was associated with a 6% increase in the risk for delirium (adjusted odds ratio, 1.06; 95% CI, 1.03-1.08; P<.001). This risk was also increased by a general anesthetic (adjusted odds ratio, 1.07, 95% CI 1.01-1.13, P=.02).
Conclusions and Relevance — Among older adults undergoing hip fracture surgery, both an increased duration of surgery and a general anesthetic were associated with an increased risk for postoperative delirium.
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