Association between preoperative cognitive impairment and perioperative neurocognitive disorders within 30 days after surgery in elderly patients: a secondary exploratory retrospective analysis

Background: Preoperative cognitive impairment (PCI) is a recognized risk factor for postoperative cognitive dysfunction, but its association with the broader syndrome of perioperative neurocognitive disorders (PND) within 30 days after surgery requires further investigation. This study aimed to evaluate the association between preoperative cognitive performance, assessed by the Montreal Cognitive Assessment (MoCA), and the risk of PND in elderly patients. Methods: This secondary exploratory retrospective analysis based on a completed prospective randomized controlled trial (RCT) cohort included 236 patients aged ≥65 years undergoing non-cardiac surgery under general anesthesia. Preoperative cognitive performance was evaluated using the MoCA, with a score <26 defining PCI. PND was defined as either postoperative delirium (assessed daily with CAM-ICU) or delayed neurocognitive recovery (assessed by MoCA at 7 and 30 days postoperatively). Logistic regression models were used to analyze the association between PCI (as a binary and continuous variable) and PND, adjusting for confounders including age, education, frailty, and surgical factors. Results: The overall incidence of PND was 40.7%. Patients with PCI (n = 81) had a significantly higher incidence of PND compared to those without PCI (74.1% vs. 23.2%, p < 0.001). In unadjusted analysis, PCI was associated with a 9.44-fold increased odds of PND (OR = 9.44, 95% CI: 5.07-17.58). After multivariable adjustment, PCI remained independently associated with PND (adjusted OR = 6.95, 95% CI: 2.71∼17.79). When analyzed as a continuous variable, each 1-point increase in the MoCA score was associated with a 32% reduction in the odds of PND (adjusted OR = 0.68, 95% CI: 0.58∼0.80). Subgroup analyses showed no statistically significant interaction was observed with age, education, or frailty. Conclusion: Preoperative cognitive impairment, assessed by the MoCA, is an independent risk factor for PND within 30 days after surgery in elderly patients. Preoperative MoCA screening may help identify high-risk patients for targeted interventions.