Prognostic value of lactic dehydrogenase-to-albumin ratio in critically ill patients with acute respiratory distress syndrome: a retrospective cohort study.

Background: Lactic dehydrogenase (LDH)-to-albumin ratio (LAR) was an independent risk factor for mortality in the patients with acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19), while the relationship among LAR and short-term, long-term, in-hospital mortalities of ARDS remains unclear. The current study aims to investigate the association between LAR and significant prognosis in patients with ARDS. Methods: We conducted a retrospective cohort study and analyzed patients with ARDS on the Medical Information Mart for Intensive Care IV (MIMIC-IV) version 2.0 database. In the current study, 30-day mortality was defined as the primary outcome; 90-day mortality and in-hospital mortality were defined as secondary outcomes. Multivariate regression analysis, Kaplan-Meier curve analysis and subgroup analysis were performed to research the association between LAR and prognosis in patients with ARDS. Results: A total of 358 critically ill patients with ARDS were enrolled in the current study. The mean age of the participants was 62.6±16.0 and the median of LAR was 14.3. According to the Kaplan-Meier curve analysis, the higher LAR group had a higher 30-day, 90-day and in-hospital mortalities. We also analyzed the 30-day mortality to receiver operating characteristic (ROC) curves by comparing the value between LAR and LAR + simplified acute physiology score II (SAPS II). The area under the curve (AUC) of the LAR group was 0.694 [95% confidence interval (CI): 0.634-0.754, P<0.001], and 0.661 for the LAR + SAPS II (95% CI: 0.599-0.722, P<0.001). For 30-day mortality, after adjusting for covariates, hazard ratios (HRs) (95% CIs) for tertile 2 (LAR 8.7-30.9) and tertile 3 (LAR >30.9) were 2.00 (1.37, 2.92) and 2.50 (1.50, 4.15), respectively. Similar results were also observed for 90-day mortality and in-hospital mortality. Conclusions: Elevated LAR levels are associated with increased 30- and 90-day mortalities, as well as in-hospital mortality in patients with ARDS, which means LAR levels may predict the mortalities of ARDS patients.