Prognostic value of lactate‐albumin ratio measured on day 2 of intensive care unit admission: A retrospective cohort study

Abstract Introduction Lactate and albumin are well‐established prognostic markers in critically ill patients. Lactate‐to‐albumin ratio (LAR) may improve risk stratification. This study aimed to evaluate the prognostic significance of LAR measured at intensive care unit (ICU) admission, on Day 2 (D2), and the change between these time points (ΔLAR) for predicting ICU mortality. Methods A retrospective cohort study was conducted between 1 January 2022 and 30 June 2024. Patients with ICU stays ≤24 h or deaths within the first 24 h were excluded. The primary outcome was ICU mortality; the secondary outcome was 90‐day mortality. Results 1669 patients fulfilled the inclusion criteria. ICU non‐survivors ( n = 133; 8.0%) were older, more likely to be male and had higher incidences of chronic kidney disease. They had higher APACHE IV scores, increased lactate concentrations, reduced albumin levels, and elevated LAR values. In logistic regression analysis, D2 LAR (OR 1.608, p < 0.001), APACHE IV score (OR 1.031, p < 0.001), diabetes mellitus (OR 0.546, p = 0.015), hyperlipidemia (OR 0.525, p = 0.006), and congestive heart failure (OR 0.372, p = 0.032) were independently associated with ICU mortality. D2 LAR demonstrated strong discriminative ability (AUROC 0.814) comparably to APACHE IV score (0.804) and predicted risk of death (0.825). In Cox regression, D2 LAR showed an association with 90‐day mortality, but bootstrap resampling demonstrated model instability ( p = 0.088). D2 LAR is a robust predictor of ICU mortality, but its utility for long‐term (90‐day) prognostication is limited and unconfirmed upon internal validation. Conclusion D2 LAR is a robust predictor of ICU mortality in critically ill patients with emergency admissions and ICU stays exceeding 24 h.