Metformin may lower mortality in Obese Patients with Influenza

As influenza vaccination or weight loss among obesity does not provide similar influenza outcomes compared to non-obesity, repurposing of existing medications to address this clinical disparity is an urgent priority. A preclinical study demonstrated that metformin can improve or restore T cell function and could serve as a potential treatment for influenza among patients with obesity. Therefore, Dr S. Scott Sutton and his team conducted a study to evaluate the potential drug repurposing of metformin for the management of influenza among patients with obesity.

In this drug-disease cohort study, the researchers used the VA Informatics and Computing Infrastructure (VINCI), a database of the U.S. Department of Veterans Affairs, to obtain individual-level information on demographics, administrative claims, and pharmacy dispensation. They included 3551patients with a laboratory-confirmed influenza diagnosis with fever, cough, influenza, or acute upper respiratory infection in an outpatient setting. Among 3551 patients 461 patients were in the non-diabetic cohort, 1597 patients were in the diabetic / metformin cohort, and 493 patients were in the diabetic no metformin cohort.

The major outcome assessed was death after diagnosis of influenza. They formed a cohort using diabetes status and metformin exposure before a positive influenza diagnosis. They used the cox proportional hazards model adjusting for baseline covariates to estimate hazard ratios for mortality. They further conducted a sub-analysis utilizing propensity score matching. A greedy nearest neighbour algorithm was utilized to match 1 to 1 non-metformin diabetic controls and non-diabetic controls to diabetic patients receiving metformin.

Key findings of the study:

• Compared to non-diabetic patients, the researchers found that diabetic patients with metformin had a lower rate of death (aHR 0.78).
• They observed no statistical difference between the non-diabetic patients and the diabetic patients without metformin (aHR 1.046).
• They noted that the propensity score-matched cohort's results were consistent with the primary analysis.

The authors concluded, "Obesity is an independent risk factor for increased morbidity and mortality in response to influenza infection. Therefore, we aimed to evaluate metformin utilization for the management of influenza utilizing a large, national claims and electronic health record database. Our results demonstrated a decreased mortality rate for patients with obesity diagnosed with influenza and treated with metformin. Further research on metformin is warranted for the treatment of influenza."

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DOI: https://doi.org/10.3390/pathogens11020270