A75-01 Metformin Is Associated With Reduced 30-Day Readmissions in Diabetic Individuals Hospitalized for an Acute Exacerbation of COPD: A Propensity Score Matched Analysis

Rationale

Individuals hospitalized for acute exacerbations of chronic obstructive pulmonary disease (AE-COPD) have a high rate of 30-day readmissions. Around half of these readmissions are due to pulmonary issues, while the other half are due to other causes like cardiovascular events and infections. The reasons behind these readmissions are unknown, but inflammatory and metabolic changes due to AE-COPD and corticosteroids for AE-COPD treatment may contribute. Metformin has beneficial effects on inflammation and metabolism beyond glycemic control, and has been proposed as a therapy for individuals with COPD. We hypothesized that diabetic patients on metformin would have a lower risk of 30-day readmission than those on other diabetes medications.

Methods

Data were obtained from the inpatient and outpatient medical records of 10 hospitals in a single health care system in Minnesota for this retrospective, propensity score matched analysis. Data extraction utilized the Common Longitudinal ICU Data Format (CLIF). We identified AE-COPD admissions in individuals with diabetes between 2011 and 2024 using a previously validated ICD-10 algorithm. Individuals taking metformin at the time of hospitalization versus those on other diabetes medications were propensity score matched 1:1 on demographics, comorbidities, and illness severity. In our primary analysis, we tested associations between metformin use and 30-day readmission using a Fine-Gray competing risks model (which accounts for death as a competing event for readmission). We also tested associations in subgroups stratified by sex, age, heart failure, and ICU stay during index admission.

Results

We identified 11,818 AE-COPD admissions among diabetic individuals on diabetes medications; 3,672 were on metformin and 8,146 were on other diabetes medications. Propensity score matching was successful in 3,585 (97.6%) individuals on metformin. Thirty-day readmissions occurred in 13% of individuals on metformin and 16% on other diabetes medications. Diabetic individuals on metformin had a lower risk of 30-day readmission (HR 0.81, 95% CI 0.71 to 0.92). Results were consistent across all subgroups (Figure). Results were also consistent when excluding admissions within the first 72 hours of discharge (HR 0.80, 95% CI 0.70 to 0.93) and when extending the readmission window out to 90-days (HR 0.85, 95% CI 0.77 to 0.94).

Conclusions

In a propensity score matched analysis, metformin is associated with a reduced risk of 30-day readmissions. These data provide further observational evidence of beneficial effects of metformin in individuals with COPD and these effects should be tested in a randomized clinical trial.

This abstract is funded by: None