The estimation of physiologic ability and surgical stress (E-PASS) is a predictive postoperative complication scoring system. Recently, its relevance to postoperative delirium has also been shown. The E-PASS system comprises the preoperative risk score (PRS), surgical stress score (SSS), and comprehensive risk score (CRS), the latter of which is determined by the PRS and SSS. This study was carried out to determine the risk factors and predictive factors of postoperative delirium in oral cancer surgery. In total, 164 patients who underwent treatment for oral cancer between 2001 and 2017 were studied retrospectively. Postoperative delirium developed in 14 of the 164 patients (8.5%). Benzodiazepine administration, diabetes mellitus, blood loss at surgery, operation time (>7 hours), tracheotomy, continuous-suction drain, postoperative serum albumin, PRS, SSS, and CRS significantly correlated with the incidence of postoperative delirium on univariate analysis. No significant differences were found in flap reconstruction. Multivariate analysis showed that benzodiazepine administration (odds ratio: 11.7, 95% confidence interval: 2.62− 62.5) and CRS (odds ratio: 11.5, 95% confidence interval: 1.89 − 96.2) were independent risk factors for increasing the incidence of delirium. Significant differences were found in benzodiazepine administration (odds ratio: 7.00, 95% confidence interval: 1.9 − 25.9) and PRS (odds ratio: 3.92, 95% confidence interval: 1.1 − 14.6) among the preoperative predictors. It was suggested that the E-PASS system can be used to evaluate factors predicting the preoperative and postoperative risks of the development of delirium in patients with oral cancer.
