Depression is associated with delirium after cardiac surgery—a population-based cohort study

OBJECTIVES: Depression is common in patients with cardiac disease, and preoperative depression is associated with worse outcomes after cardiac surgery. Depression is also correlated with postoperative delirium (POD) after major surgery. However, the association between preoperative depression and POD after cardiac surgery is sparsely studied. The aim of this study was to investigate depression as a predictor for POD in cardiac surgery patients. METHODS: This population-based cohort study included 1133 cardiac surgery patients in Stockholm 2013–2016. Depression was defined by the Patient Health Questionnaire-9, and POD was evaluated by assessing medical records for symptoms of POD according to Diagnostic and Statistical Manual of Mental Disorders criteria. The association between depression and POD was determined through multivariable logistic regression analysis. RESULTS: A total of 162 (14%) individuals reported depressive symptoms preoperatively. The incidence of POD was 26% and highest among elderly patients. Among patients with depression, 34% developed POD. In the group of non-depressed patients, 24% developed POD. The overall adjusted odds of delirium were 2.19 times higher in individuals with depressive symptoms compared to controls (95% confidence interval 1.43–3.34). The onset of delirium was most common on Days 0–2 after surgery. CONCLUSIONS: This unique population-based study in patients undergoing cardiac surgery shows that preoperative depression is associated with POD in a large proportion of treated patients. The findings support the need for improved preoperative screening for depression, especially in younger patients, and enhanced clinical surveillance in the early postoperative period for all patients.