Incidence and risk factors of postoperative delirium in elderly patients undergoing urological surgery: A multi-institutional prospective study

Objectives To investigate the incidence and risk factors of postoperative delirium among patients aged >= 65 years undergoing elective urological surgery. Methods From April 2015 through December 2016, 1023 consecutive patients aged >= 65 years who received transurethral, laparoscopic (with or without robot assistance) or open surgery in eight institutions were enrolled in this prospective observational study. Their preoperative cognitive status was assessed with the Hasegawa Dementia Scale-Revised score. The treating physician or nurse assessed delirium using the Intensive Care Delirium Screening Checklist. Multivariate logistic regression analysis was used to determine predictive factors for postoperative delirium. Results We analyzed 946 patients whose median age was 74 years (range 65-95 years). Postoperative delirium was observed in 32 patients (3.4%). Multivariate analysis showed that a history of cerebrovascular disease (odds ratio 5.24, 95% confidence interval 2.05-13.40), low Hasegawa Dementia Scale-Revised score <20 points (odds ratio 3.50, 95% confidence interval 1.36-9.02), low serum albumin level <3.5 g/dL (odds ratio 3.12, 95% confidence interval 1.25-7.83) and long surgery duration >4 h (odds ratio 4.94, 95% confidence interval 2.20-11.10) were independent risk factors for the development of postoperative delirium. Conclusions The preoperative medical history, cognitive status, low serum albumin level and operative duration were associated with the development of postoperative delirium, although the incidence was just 3.4% in elective urological surgery. The present results suggest that the Hasegawa Dementia Scale-Revised is a useful tool for assessment of the risk for delirium.