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

Preoperative anxiety and depression may be associated with adverse postoperative neurocognitive outcomes, but their relationships with postoperative delirium (POD) and delayed neurocognitive recovery (DNR) remain uncertain in older adults undergoing off-pump coronary artery bypass grafting (OPCABG). We examined these associations and explored whether the observed data were consistent with a potential intermediary pathway through POD. This prospective cohort enrolled patients aged 60 years or older undergoing elective OPCABG from January to December 2024. Anxiety and depression were assessed one day before surgery using the Hospital Anxiety and Depression Scale. Cognitive function was evaluated with the Montreal Cognitive Assessment-Basic before surgery and on postoperative day 28. POD was assessed twice daily on postoperative days 1–7 using validated delirium instruments after assessment of arousal with the Richmond Agitation-Sedation Scale. DNR was defined as a decline of at least 4 points from baseline. Multivariable logistic regression evaluated associations with POD and DNR; DNR models were fitted without and with adjustment for POD. Exploratory counterfactual mediation analyses used 5000 bootstrap resamples and reported effects on the probability-difference scale. Among 168 participants, DNR occurred in 71 (42.26%) and POD in 61 (36.31%); 58 (34.52%) had preoperative anxiety and 45 (26.79%) had preoperative depression. Anxiety and depression were associated with higher odds of POD (odds ratio [OR] 3.87, 95% confidence interval [CI] 1.97–7.58; and OR 2.94, 95% CI 1.35–6.37, respectively). In DNR models excluding POD, the corresponding ORs were 3.71 (95% CI 1.74–7.92) and 4.41 (95% CI 1.96–9.91). After adjustment for POD, the estimates were attenuated to 2.41 (95% CI 1.06–5.48) and 2.53 (95% CI 1.05–6.08), respectively. Exploratory analyses estimated proportions mediated of 27.88% for anxiety and 27.45% for depression. Preoperative anxiety and depression were associated with POD and DNR after OPCABG. The mediation pattern was compatible with a potential partial intermediary pathway through POD, but the observational design and untestable assumptions preclude causal conclusions. Larger multicenter and interventional studies are required. Chinese Clinical Trial Registry, ChiCTR2300079246. Registered on 28 December 2023.