Risk factors for delirium after coronary artery bypass grafting in elderly patients

Postoperative delirium (POD) is a common complication of major surgery and is associated with fortified morbidity, mortality, and long-term cognitive dysfunction. This study sought to evaluate the incidence and risk factors of delirium in elderly (aged ≥65 years) patients who underwent coronary artery bypass grafting (CABG).

We performed a retrospective cohort analysis. The clinical data of 1,426 elderly patients who underwent CABG at our hospital from October 2018 to October 2020 were collected and analyzed. Delirium was defined as any positive Confusion Assessment Method for Intensive Care Unit examination following surgery during the intensive care unit (ICU) stay. Risk factors for POD were authenticated via univariate and multivariate logistic regression analyses. The intraoperative and postoperative factors were evaluated using a propensity score-matched regression analysis based on preoperative factors.

A total of 39.3% (560 of 1,426) of elderly patients who underwent CABG were diagnosed with delirium. Based on the multivariate analysis, age [odds ratio (OR) 1.013], long-term alcohol consumption (OR 2.026), diabetes (OR 1.51), stroke (OR 1.41), and extracardiac arteriopathy (OR 1.61) were found to be independent predictors of post-cardiac surgery delirium. Conversely, high-density lipoprotein cholesterol levels (HDL-C) ≥1.0 mmol/L (OR 0.71) was found to be a protective factor. Among the intraoperative and postoperative factors evaluated, only a prolonged ICU stay (≥48 h; OR 1.62) was identified as a risk factor for developing delirium in the propensity-score matched analysis, after adjusting for potential confounding variables and selection bias. In contrast to the earlier analysis, the multivariate logistic regression further revealed that peri-procedural myocardial infarction and postoperative arterial oxygen partial pressures were not significantly associated with POD.

The incidence of POD in elderly patients undergoing CABG was high. Factors such as older age, long-term alcohol consumption, diabetes, stroke, and extracardiac arteriopathy were independent risk factors for POD in these patients. In relation to the intraoperative and postoperative factors, after adjusting for preoperative confounding factors, only a prolonged ICU stay was identified as a risk factor for POD. Additionally, high levels of HDL-C may be beneficial in reducing the incidence of delirium.