Independent Predictors of the Duration and Overall Burden of Postoperative Delirium After Cardiac Surgery in Adults: An Observational Cohort Study

Abstract

Objective: Postoperative delirium (POD) is a common complication after cardiac surgery and is associated with increased patient morbidity and mortality. The objective of this study was to identify risk factors for long duration and overall burden of POD after cardiac surgery.

Design: One-year, single-center, retrospective, observational cohort study.

Setting: University hospital.

Participants: Adult patients undergoing cardiac surgery with cardiopulmonary bypass in 2013.

Interventions: None.

Measurements and main results: Patients were screened for POD using the Intensive Care Delirium Screening Checklist. The primary outcome measure was the incidence of POD. Secondary outcome measures were the duration of POD and the area under the curve determined using the Intensive Care Delirium Screening Checklist score over time. Independent predictors of POD were estimated in multivariable logistic regression models. Hospital length of stay, medications, and outcome data also were analyzed. Among the 656 patients included in the cohort, 618 were analyzed. The overall incidence of POD was 39%. Older patient age (odds ratio [95% confidence interval]) 1.06 [1.04-1.09] for an increase of 1 year, p < 0.001); low preoperative serum albumin (1.08 [1.03-1.13] for a decrease of 1 g/L, p < 0.001); a history of atrial fibrillation (2.30 [1.30-4.09], p = 0.004); perioperative stroke (6.27 [1.54-43.64], p = 0.008); ascending aortic replacement surgery (2.99 [1.50-6.05], p = 0.002); longer duration of procedure (1.37 [1.16-1.63] for an increase of 1 hour, p < 0.001); and increased postoperative C-reactive protein concentration (2.16 [1.49-3.16] for a 2-fold increase, p < 0.001) were associated with higher odds of POD. Among patients affected by POD, older age, perioperative stroke, longer procedure time, and increased postoperative C-reactive protein were consistently predictive of longer duration of POD and greater area under the curve.

Conclusions: Known risk factors for the development of POD after cardiac surgery also are predictive of prolonged duration and high overall burden of POD.

Keywords: cardiac surgery; duration; postoperative delirium; risk factors.