Risk factors for delirium in the elderly after coronary artery bypass graft surgery

OBJECTIVE: To investigate the risk factors for delirium in the elderly during the post-operative period of coronary artery bypass graft surgery (CABG). METHODS: A total of 220 inpatients submitted to CABG were evaluated prior to and after surgery. In order to investigate the possible risk factors, data were collected from pre- intra- and post-operative periods. INSTRUMENTS: The patients were assessed using the Mini-mental State Examination and to the Geriatric Depression Scale. The diagnosis of delirium was determined according to DSM-IV criteria. RESULTS: Delirium was detected in 74 (33.6%) patients. Increasing age, blood urea level, cardio-thoracic index, hypertension, smoking habits, blood replacement during bypass, atrial fibrillation (AF), pneumonia and blood balance in the post-operative period were the risk factors for delirium selected by the logistic regression analysis. No specific factor associated with the CABG (perfusion pressure, number of grafts) was correlated with an increased risk for delirium post-operatively. The length of stay was twice as long in the delirious group (p<0.001). CONCLUSIONS: Delirium in the elderly after CABG is a multifactorial disorder. Nine factors taken together can identify patients at great risk for delirium. No specific factor associated with bypass procedure could be identified as a risk factor for delirium. The control of the risk factors should bring a decrease in delirium morbidity and mortality.