Metformin is associated with lower hospitalizations, mortality and severe coronavirus infection among elderly medicare minority patients in 8 states in USA.

Background And Aims: Metformin has antiviral and anti-inflammatory effects and several cohort studies have shown that metformin lower mortality in the COVID population in a majority white population. There is no data documenting the effect of metformin taken as an outpatient on COVID-19 related hospitalizations. Our aim was to evaluate if metformin decreases hospitalization and severe COVID-19 among minority Medicare patients who acquired the SARS-CoV2 virus.

Methods: We conducted a retrospective cohort study including elderly minority Medicare COVID-19 patients across eight states. We collected data from the inpatient and outpatient electronic health records, demographic data, as well as clinical and echocardiographic data. We classified those using metformin as those patients who had a pharmacy claim for metformin and non-metformin users as those who were diabetics and did not use metformin as well as non-diabetic patients. Our primary outcome was hospitalization. Our secondary outcomes were mortality and acute respiratory distress syndrome (ARDS).

Results: We identified 1139 COVID-19 positive patients of whom 392 were metformin users. Metformin users had a higher comorbidity score than non-metformin users (p < 0.01). The adjusted relative hazard (RH) of those hospitalized for metformin users was 0.71; 95% CI 0.52-0.86. The RH of death for metformin users was 0.34; 95% CI 0.19-0.59. The RH of ARDS for metformin users was 0.32; 95% CI 0.22-0.45. Metformin users on 1000 mg daily had lower mortality, but similar hospitalization and ARDS rates when compared to those on 500-850 mg of metformin daily.

Conclusions: Metformin is associated with lower hospitalization, mortality and ARDS among a minority COVID-19 population. Future randomized trials should confirm this finding and evaluate for a causative effect of the drug preventing disease.