Measures of Executive Function and Depression Identify Patients at Risk for Postoperative Delirium

BACKGROUND: Postoperative delirium is associated with increased morbidity and mortality. Preexisting cognitive impairment and depression have been frequently cited as important risk factors for this complication. This prospective cohort study was designed to determine whether individuals who perform poorly on preoperative cognitive tests and/or exhibited depressive symptoms would be at high risk for the development of postoperative delirium. METHODS: One hundred nondemented patients, aged 50 yr and older, scheduled to undergo major, elective noncardiac surgery completed a preoperative test battery that included measures of global cognition, executive function, and symptoms of depression. Known preoperative risk factors for delirium were collected and examined with the results of the preoperative test battery to determine the independent predictors of delirium. RESULTS: The overall incidence of delirium was 16% and was associated with increased hospital duration of stay (P < 0.05) and an increased incidence of postoperative complications (P < 0.01). Delirious subjects did not differ from their nondelirious cohorts with regard to their preoperative global cognitive function, preexisting medical comorbidities, age, anesthetic management, or history of alcohol use. Preoperative executive scores (P < 0.001) and depression (P < 0.001), as measured by the Trail Making B test and Geriatric Depression Scale-Short Form, respectively, were found to be independent predictors of postoperative delirium. CONCLUSIONS: Low preoperative executive scores and depressive symptoms independently predict postoperative delirium in older individuals. A rapid, simple test combination including tests of executive function and depression could improve physicians' ability to recognize patients who might benefit from a perioperative intervention strategy to prevent postoperative delirium.