Background: The pleiotropic effect of metformin prevents lung injury in animal models. However, metformin has a controversial effect on survival outcomes in patients with acute respiratory distress syndrome (ARDS). This study aimed to investigate the effect of metformin therapy before ARDS diagnosis on mortality in ARDS patients with diabetes mellitus (DM).
Methods: Medical records from the national database, stored and provided by the National Health Insurance Service (NHIS) in South Korea were used. All adult diabetic patients admitted to a hospital for ARDS treatment from January 1, 2013 to December 31, 2017 were included in this study. Metformin users were defined as those prescribed continuous oral metformin for ≥30 days before ARDS diagnosis. All other patients were included in the control group.
Results: Of the 6,500 patients selected for the study; 2,876 patients were prior metformin users. After propensity score matching (PSM), a total of 5,752 patients (2,876 patients in each group) were included in the analysis. The hazard of 30-day mortality in metformin users was not significantly different compared to the control group [hazard ratio (HR), 1.05; 95% confidence interval (CI), 0.97-1.14; P=0.154]. The survival time by the log-rank test was not significantly different between metformin users and controls (median time, 39.0 vs. 42.0 days, respectively; P=0.735).
Conclusions: This population-based cohort study showed no significant association between prior metformin therapy and 30-day mortality in ARDS patients with DM. Moreover, prior metformin therapy was not associated with increase in overall survival times in ARDS patients with DM.
Keywords: Critical care; adult; diabetes mellitus (DM); intensive care units (ICUs); metformin; respiratory distress syndrome.