Preoperative frontal lobe and global cognitive function as predictors of postoperative delirium after cardiovascular...

Postoperative delirium (POD) is a serious complication after cardiovascular surgery, and preoperative cognitive impairment is a well-established risk factor. However, the specific cognitive domains relevant to POD prediction remain unclear. This study investigated whether preoperative frontal lobe function, assessed by the Frontal Assessment Battery (FAB), predicts POD in patients undergoing cardiovascular surgery and explored the potential mediating role of frontal executive function in the relationship between global cognitive function and POD. We retrospectively studied 105 patients (mean age 69 ± 12 years) undergoing cardiovascular surgery. Preoperative global cognitive and frontal lobe functions were assessed using the Mini-Mental State Examination (MMSE) and the FAB, respectively. POD was diagnosed using the Confusion Assessment Method for the Intensive Care Unit. POD occurred in 16 patients (15.2%). In univariate analysis, both lower FAB (odds ratio [OR], 0.75; 95% confidence interval [CI] 0.60-0.92) and MMSE (OR, 0.78; 95% CI 0.63-0.97) predicted POD with similar effect sizes. After adjusting for age (≥ 65 years) and sex, FAB remained a significant predictor (adjusted OR, 0.79; 95% CI 0.62-0.99), whereas MMSE showed a similar magnitude of association that did not reach statistical significance (adjusted OR, 0.82; 95% CI 0.65-1.02). Exploratory mediation analysis suggested that FAB may partially mediate the MMSE-POD association (indirect effect: p = 0.029; proportion mediated, 55%), although these findings require cautious interpretation given the limited sample size. Both FAB and MMSE predict POD with comparable effect sizes. Frontal executive function may contribute to the cognitive pathway underlying POD risk, and prospective studies with larger samples are needed to validate these findings.