Metformin use was associated with decreased mortality rates among older patients with diabetes hospitalized with community-acquired pneumonia (CAP). These study results were published in Clinical Infectious Diseases.
Between October 2001 and September 2012, researchers conducted a retrospective study to assess the association between metformin use prior to hospitalization for community-acquired pneumonia among older patients (≤65 years old) with diabetes. The primary outcomes were all-cause mortality within 30 and 90 days after admission. Eligible patients were those who were diagnosed with diabetes and reported at least 3 outpatient clinic visits within the past year. All patients received least 1 dose of antimicrobial therapy within 48 hours of admission. Outcomes were compared between patients who did vs did not report receipt of at least 1 prescription for metformin within 90 days of admission. Propensity score and nearest-number matching were used to balance measured confounders between the cohorts, with scores derived via logistic regression.
After propensity-score matching, the metformin and control cohorts each comprised 6899 patients. The mean (SD) patient age was 75.1 (6.6) years, 98.7% were men, and approximately 83% were Black.
In the matched analysis, the rate of all-cause 30-day mortality was significantly lower among patients in the metformin vs control cohorts (9.6% vs 13.9%; relative risk [RR], 0.86; 95% CI, 0.78-0.95; P <.003). Similar results were noted for the rate of all-cause 90-day mortality between the cohorts (15.8% vs 23.0%; RR, 0.85; 95% CI, 0.79-0.92; P <.001).
Further analysis was performed using Cox proportional hazards models. Results showed a significant association between prior metformin use and decreased 90-day all-cause mortality risk (hazard ratio [HR], 0.85; 95% CI, 0.80-0.91). This association also was observed among patients with diabetes-related complications (HR, 0.76; 95% CI, 0.66-0.87), those with a history of chronic obstructive pulmonary disease (HR, 0.85; 95% CI, 0.77-0.93), and those who used insulin (HR, 0.76; 95% CI, 0.66-0.87).
Limitations include the lack of microbiologic and vaccination data, as well as the predominance of men in the study population.
“Prospective, well-designed studies are needed to further examine the association of metformin, and other potentially protective medications, in populations that are at high risk of respiratory infections,” the researchers concluded.
Disclosure: One author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Mohammed T, Bowe M, Plant A, Perez M, Alvarez CA, Mortensen EM. Metformin use is associated with lower mortality in veterans with diabetes hospitalized with pneumonia. Clin Infect Dis. Published online December 28, 2022. doi:10.1093/cid/ciac900.