Effect of postoperative delirium after cardiovascular surgery on 5-year mortality

INTRODUCTION: Postoperative delirium is a common complication after cardiovascular surgery. A meta-analysis revealed that postoperative delirium was associated with cognitive decline and dementia, which may affect long-term mortality. However, few studies have reported the association between postoperative delirium after cardiovascular surgery and long-term postoperative mortality. Therefore, we investigated the effect of postoperative delirium on 5-year survival rates of patients who underwent cardiovascular surgery. METHODS: We retrospectively reviewed the records of patients who underwent cardiovascular surgery with cardiopulmonary bypass from January 2016 to December 2019. Postoperative delirium was defined as an Intensive Care Delirium Screening score ≥ 3, which might include subclinical delirium. Cox proportional hazards modeling was performed to assess the association between postoperative delirium and mortality. Postoperative mortality in patients with and without delirium was assessed using the Kaplan–Meier method and compared using the log-rank test. RESULTS: Postoperative delirium was observed in 562 (31.9%) of 1731 patients. There were more elderly patients, more emergent surgery procedures, longer operative time, and larger transfusion volume in the postoperative delirium group. Cox regression analyses showed that delirium (hazard ratio (HR), 1.501; 95% confidence interval (CI), 1.053–2.140; p = 0.025) and emergent surgery (HR, 3.380; 95% CI, 2.231–5.122; p < 0.001) are significantly associated with 5-year mortality. Among patients who underwent elective surgery, postoperative delirium (HR, 1.987; 95% CI, 1.135–3.481; p = 0.016) is significantly associated with 5-year mortality. Kaplan–Meier survival analysis revealed that patients with postoperative delirium had significantly higher 5-year mortality. CONCLUSIONS: Patients with postoperative delirium after cardiovascular surgery have significantly higher 5-year mortality.