Early delirium after cardiac surgery: an analysis of incidence and risk factors in elderly (≥65 years) and very elderly (≥80 years) patients

INTRODUCTION: Postoperative delirium is a common complication of cardiac surgery associated with increased mortality, morbidity, and long-term cognitive dysfunction. The aim of this study was to identify incidence and risk factors of delirium in elderly (≥65 years) and very elderly (≥80 years) patients undergoing major cardiac surgery. MATERIALS AND METHODS: We performed a retrospective cohort analysis of prospectively collected data from a register of the cardiac surgery department of a tertiary referral university hospital between 2014 and 2016. Analysis was performed in two groups, ≥65 years and ≥80 years. RESULTS: We analyzed 1,797 patients ≥65 years, including 230 (7.24%) patients ≥80 years. Delirium was diagnosed in 21.4% (384/1,797) of patients above 65 years, and in 33.5% (77/230) of octogenarians. Early mortality did not differ between patients with and without delirium. Intensive care unit (ICU) stay (p<0.001), hospital stay (p<0.001), and intubation time (p=0.002) were significantly longer in patients undergoing cardiac surgery ≥65 years with delirium. According to multivariable analysis, <65 years, age (odds ratio [OR] 1.036, p=0.002), low ejection fraction (OR 1.634, p=0.035), diabetes (1.346, p=0.019), and extracardiac arteriopathy (OR 1.564, p=0.007) were found to be independent predictors of post-cardiac surgery delirium. Postoperative risk factors for developing delirium ≥65 years were atrial fibrillation (1.563, p=0.001), postoperative pneumonia (OR 1.896, p=0.022), elevated postoperative creatinine (OR 1.384, p=0.004), and prolonged hospitalization (OR 1.019, p=0.009). CONCLUSION: Patients above 65 years of age with postoperative delirium have poorer outcome and are more likely to have prolonged hospitalization and ICU stay, and longer intubation times, but 30-day mortality is not increased. In our study, eight independent risk factors for development of post-cardiac surgery delirium were age, low ejection fraction, diabetes, extracardiac arteriopathy, postoperative atrial fibrillation, pneumonia, elevated creatinine, and prolonged hospitalization time.