Objective: Postoperative delirium is one of the most common complications of critically ill patients in the SICU. However, the negative impact of postoperative delirium on long-term outcomes is still unclear. In this study, we aimed to identify the influence of postoperative delirium on long-term morbidity, mortality, cognitive function and quality of life of patients admitted to the SICU after non-cardiac surgery.

Methods: This was a prospective cohort study. A total of 205 consecutive patients who were admitted to SICU after noncardiac surgery were enrolled. Delirium was diagnosed by Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) during the first postoperative week. Long-term morbidity, mortality, cognitive function, quality of life, depression and anxiety were evaluated at a follow-up period of more than two years.

Results: One hundred and eighty-four patients completed the long-term follow-up study. After a mean follow-up period of 27.9±3.1 months, 121 patients were alive, and 98 (81.0%) of them completed the follow-up assessment of cognitive function and quality of life. The overall incidence of postoperative delirium was 46.7%. Multiple Logistics Regression analyses showed that increasing age (odds ratio [OR], 1.93; 95% confidence interval [CI], 1.11-3.35), preoperative stroke (OR, 3.40; 95% CI, 1.11-10.41) and high Acute Physiology and Chronic Health Evaluation (APACHE) II score on SICU admission (OR, 1.53; 95% CI, 1.33-1.76) were independent predictors of postoperative delirium. The cumulative survival rate at the end of follow-up period were 78.6% in patients without delirium and 51.2% in patients with delirium, respectively (P<0.001). Cox Regression Analysis showed that occurrence of postoperative delirium (Hazard Ratio [HR], 2.11; 95% CI, 1.16~3.83), advanced malignant tumor stage (HR, 4.8; 95% CI, 2.57-8.93), and occurrence of postoperative pulmonary complications (HR, 5.70; 95% CI 2.94-11.04) were independent predictors of long-term postoperative death. The occurrence of postoperative delirium was associated with significantly deteriorated long-term cognitive function and quality of life.

Conclusions: In critically ill patients who were admitted to the SICU after noncardiac surgery, the occurrence of postoperative delirium was an independent predictor of long-term postoperative death. Patients with postoperative delirium had significantly deteriorated long-term cognitive function and quality of life.

Key Words: postoperative delirium; cognitive function; quality of life; mortality; noncardiac surgery; critical illness