Preoperative lactate-to-albumin ratio and risk of postoperative delirium after cardiac surgery in older adults: a retrospective cohort study

BACKGROUND: The association between the lactate-to-albumin ratio (LAR) and postoperative delirium (POD) in older adults undergoing cardiac surgery remains uncertain. This study aimed to explore the association between preoperative LAR and POD in this population. METHODS: Participants were selected from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Preoperative lactate and albumin values obtained within 7 days before surgery were used to calculate LAR. The primary endpoint was POD within 7 days after surgery. Cox proportional hazards models, restricted cubic splines, sensitivity analysis, and Kaplan-Meier analysis were used to assess the association between LAR and POD. RESULTS: A total of 2,021 patients were included, and 271 (13.41%) developed POD. In the main adjusted model, higher LAR was associated with a higher hazard of POD (HR 1.649, 95% CI 1.367-1.990, p < 0.001). Compared with the low LAR group, the medium and high LAR groups had higher hazards of POD (HR 1.561, 95% CI 1.157-2.106; HR 2.403, 95% CI 1.754-3.293, respectively). This association persisted in sensitivity analysis. Restricted cubic spline analysis suggested a linear relationship between higher LAR and increased POD risk. CONCLUSIONS: The study findings indicate that elevated preoperative LAR is associated with increased POD risk in older adults undergoing cardiac surgery. LAR may be a simple and practical marker for preoperative risk stratification.