Risk factors of elderly patients with postoperative delirium following major abdominal surgery for cancer.

Purpose: Postoperative delirium (POD) is a common complication in elderly patients after major abdominal surgery for cancer. Although POD is related with a poor outcome, there have not been many reports about POD after abdominal surgery in Korea. The aims of study were to analyze the characteristics and surgical outcomes of elderly patients with POD and to identify the risk factors of POD. Methods: From November 2016 to January 2019, we prospectively enrolled 63 patients who were aged ≥75 years and underwent major abdominal surgery for cancer. POD was daily assessed for up to 10 days postoperatively with the Confusion Assessment Method and a validated chart review. Results: POD occurred in eight patients (12.7%). Univariate analysis showed that the occurrence of POD was related to sodium <135 mEq/L (P=0.037), combined resection (P=0.023), longer surgery/anesthesia time (P=0.023 and P=0.037, respectively), increased blood loss (P=0.004), postoperative admission to intensive care unit (ICU) (P=0.023), and duration of Foley catheter (P=0.011), however, multivariate analysis identified no significant risk factors of POD. There was no difference in postoperative outcomes such as hospital stay, mortality, reoperation, and morbidity between patients with POD and without POD. Conclusion: Elderly patients with hyponatremia, combined resection, longer operation/anesthesia time and admission to ICU had tendencies to develop POD after major abdominal surgery. Surgeons should pay more attention to prevent POD, and a large-scale prospective study is needed to identify the risk factors of POD.