Preoperative and operative predictors of delirium after cardiac surgery in elderly patients

Delirium is a common complication in elderly patients after cardiac surgery and is associated with adverse outcomes including prolonged hospital stay and increased mortality. Therefore, prevention or early detection of delirium is indicated. Our objective was to identify preoperative and operative characteristics that could predict delirium after cardiac surgery in elderly patients. We conducted a prospective cohort study in which we analysed 201 patients of 70 years and older who underwent cardiac surgery, for developing a delirium. Patients were assessed daily using the Confusion Assessment Method-Intensive Care Unit. Sixty-three patients (31%) developed a delirium after cardiac surgery. The Mini-Mental State Examination (MMSE) score prior to surgery was lower in the delirious patients when compared with the non-delirious patients (27 vs. 28, P = 0.026), creatinine level was higher (98 vs. 88 mu mol/l, P = 0.003) and extracorporeal circulation (ECC) time was longer (145 vs. 113 min, P < 0.001). Mortality during the first 30 days after surgery in patients with delirium was significantly higher than that in the non-delirious patients (14 vs. 0%, P < 0.001). Low MMSE score and high creatinine level prior to surgery as well as increased ECC time are important independent predictors of delirium. In addition, delirium is an important predictor of 30-day mortality. Patients with a substantial risk for delirium should be candidates for interventions to reduce postoperative delirium and to potentially improve overall surgical outcomes.