Postoperative delirium may partially mediate the association between preoperative psychological symptoms and delayed neurocognitive recovery in older adults undergoing off-pump coronary artery bypass grafting: a prospective cohort study

Background Preoperative anxiety and depression are common in older surgical patients and may increase vulnerability to adverse postoperative neurocognitive outcomes. However, their associations with postoperative delirium and delayed neurocognitive recovery, as well as the potential mediating role of postoperative delirium, remain unclear in older adults undergoing off-pump coronary artery bypass grafting. Methods In this single-center prospective cohort study, we consecutively enrolled patients aged 60 years or older who underwent elective off-pump coronary artery bypass grafting between January 2024 and December 2024. Preoperative anxiety and depression were assessed one day before surgery using the Hospital Anxiety and Depression Scale. Cognitive function was assessed using the Montreal Cognitive Assessment-Basic before surgery and on postoperative day 28. Postoperative delirium was assessed twice daily on postoperative days 1–7 using the Confusion Assessment Method for the Intensive Care Unit in the intensive care unit and the 3-Minute Diagnostic Interview for CAM-defined Delirium in the general ward. Delayed neurocognitive recovery was defined as a decline of at least 4 points in the postoperative day-28 Montreal Cognitive Assessment-Basic score from baseline. Multivariable logistic regression and bootstrap mediation analyses were performed. Results A total of 168 patients were included in the final analysis. Delayed neurocognitive recovery occurred in 71 patients (42.26%), and postoperative delirium occurred in 61 patients (36.31%). The prevalences of preoperative anxiety and depression were 34.52% and 26.79%, respectively. After adjustment for potential confounders, preoperative anxiety was associated with higher odds of delayed neurocognitive recovery (odds ratio 2.41, 95% confidence interval 1.06–5.48; P = 0.037) and postoperative delirium, and preoperative depression was also associated with higher odds of delayed neurocognitive recovery (odds ratio 2.53, 95% confidence interval 1.05–6.08; P = 0.038) and postoperative delirium. Mediation analysis showed that postoperative delirium partially mediated the associations of preoperative anxiety and depression with delayed neurocognitive recovery, accounting for 27.88% and 27.45% of the total effects, respectively. Conclusions In older adults undergoing off-pump coronary artery bypass grafting, preoperative anxiety and depression were associated with increased risks of postoperative delirium and delayed neurocognitive recovery. Postoperative delirium partially mediated these associations, suggesting that preoperative psychological symptoms and delirium prevention may both be important targets in perioperative brain health management. Trial registration Chinese Clinical Trial Registry, ChiCTR2300079246. Registered on 28 December 2023.