The Lactate/Albumin Ratio Predicts Mortality in Critically Ill Patients with Acute Kidney Injury: An Observational Multicenter Study on the eICU Database

Objective: The serum lactate/albumin ratio (LAR) can be used to independently predict mortality due to sepsis. However, whether the LAR predicts the outcomes of critically ill patients with acute kidney injury (AKI) remains unclear. This study was performed to assess the prognostic value of the LAR in critically ill AKI patients. Methods: This retrospective observational study enrolled AKI patients, and all data were collected through the eICU Collaborative Research Database. Outcomes included in-hospital and intensive care unit (ICU) death. Multivariate Cox regression analysis was used to determine independent risk factors. Forest plots and smoothing curves were generated. A series of subgroup analyses were performed to further validate the robustness of the findings. Results: A total of 4666 eligible patients were enrolled. We divided the participants into four groups according to the LAR: quartile (Q)1 (LAR < 0.46, n = 1167), Q2 (0.46 <= LAR < 0.79, n = 1162), Q3 (0.79 <= LAR < 1.49, n = 1170), and Q4 (LAR >= 1.49, n = 1167). The LAR, when analyzed as a continuous variable, was associated with hospital and ICU mortality (adjusted hazard ratio [HR] 1.22, 95% confidence interval [CI] 1.18-1.26, P < 0.0001 for both). The risk of in-hospital and ICU mortality increased with increasing LAR Q relative to Q1. The smoothing curves revealed a continuous linear association after adjusting for all covariates. By the Kaplan-Meier analysis, patients in the higher LAR group showed significantly shorter survival time. By the receiver operating characteristic analysis, LAR was efficient in predicting in-hospital mortality (area under the curve [AUC]: 0.717) and ICU mortality (AUC: 0.733). A positive and consistent effect of the LAR was seen in all subgroups analyses after adjusting for all covariates. Conclusion: A high LAR is an independent risk factor for in-hospital and ICU mortality in critically ill patients with AKI. Further prospective studies are needed to validate these result.