Association between lactate-to-albumin ratio and 30-day all-cause mortality in patients with acute pancreatitis-associated acute kidney injury

In recent years, the lactate-to-albumin ratio (LAR) has emerged as a novel prognostic marker in various critical illnesses, including sepsis, heart failure, and acute respiratory failure. However, its predictive value in patients with acute pancreatitis (AP)-particularly those who develop acute pancreatitis-associated acute kidney injury (AP-AKI)-has not been fully evaluated. Given the high short-term all-cause mortality observed in AP-AKI patients, this study aims to examine the association between admission LAR levels and 30-day all-cause mortality in this population, with the goal of providing new evidence for clinical risk stratification and early intervention. We performed a retrospective cohort study of 877 critically ill patients with AP-AKI using the MIMIC-IV/III database, and used the eICU-CRD database and a cohort of AP-AKI patients admitted to the Department of Critical Care Medicine, First Affiliated Hospital of Fujian Medical University (FAHFMU) for external validation. Patients were stratified into four groups according to LAR quartiles. Confounding was assessed via linear or logistic regression with stepwise covariate removal, and univariable and multivariable Cox models were used to identify predictors of mortality. ROC analysis (AUC) evaluated LAR and other markers, establishing an optimal cut-off for Kaplan-Meier survival curves (log-rank test). Restricted cubic spline (RCS) functions were used to explore the potential nonlinear relationship between LAR and 30-day mortality. Subgroup analyses were conducted across age, sex, comorbidities, and treatment categories. The study found that higher LAR levels were significantly associated with increased 30-day mortality in AP-AKI patients. After adjusting for potential confounders, LAR remained an independent predictor of mortality (HR 1.172, 95% CI 1.054-1.303, P < 0.05). ROC analysis showed an AUC of 0.695 for LAR, surpassing that of lactate alone (0.683) or albumin (0.589), and comparable to the SOFA score (0.684). Compared with the low LAR group, the high LAR group had a significantly higher mortality rate (P < 0.001), and a nonlinear association between LAR and 30-day mortality was observed. LAR is an independent predictor of 30-day all-cause mortality in AP-AKI. Given its simplicity and accessibility yet modest discrimination, LAR may serve as a useful adjunct for early risk assessment, particularly when combined with established scores or used serially.