Association of Prescription Co-payment With Adherence to Glucagon-Like Peptide-1 Receptor Agonist and Sodium-Glucose Cotransporter-2 Inhibitor Therapies in Patients With Heart Failure and Diabetes

IMPORTANCE Type 2 diabetes (T2D) and heart failure (HF) prevalence are rising in the US. Although glucagon-like peptide-1 receptor agonists (GLP1-RA) and sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve outcomes for these conditions, high out-of-pocket costs may be associated with reduced medication adherence. OBJECTIVE To compare 1-year adherence to GLP1-RA and SGLT2i therapies by prescription co-payment level in individuals with T2D and/or HF. DESIGN, SETTING, AND PARTICIPANTS This retrospective cohort study used deidentified data from Optum Insight's Clinformatics Data Mart Database of enrollees with commercial and Medicare health insurance plans. Individuals aged 18 years or older with T2D and/or HF who had a prescription claim for a GLP1-RA or SLGT2i from January 1, 2014, to September 30, 2020, were included. EXPOSURES Prescription co-payment, categorized as low (<$10), medium ($10 to<$50), and high (similar to$50). MAIN OUTCOMES AND MEASURES The primary outcome was medication adherence, defined as a proportion of days covered (PDC) of 80% or greater at 1 year. Logistic regression models were used to examine the association between co-payment and adherence, adjusting for patient demographics, medical comorbidities, and socioeconomic factors. RESULTS A total of 94 610 individuals (mean [SD] age, 61.8 [11.4] years; 51 226 [54.1%] male) were prescribed GLP1-RA or SGLT2i therapy. Overall, 39 149 individuals had a claim for a GLP1-RA, of whom 25 557 (65.3%) had a PDC of 80% or greater at 1 year. In fully adjusted models, individuals with a medium (adjusted odds ratio [AOR], 0.62; 95% CI, 0.58-0.67) or high (AOR, 0.47; 95% CI, 0.44-0.51) co-payment were less likely to have a PDC of 80% or greater with a GLP1-RA compared with those with a low co-payment. Overall, 51 072 individuals had a claim for an SGLT2i, of whom 37 339 (73.1%) had a PDC of 80% or greater at 1 year. Individuals with a medium (AOR, 0.67; 95% CI, 0.63-0.72) or high (AOR, 0.68; 95% CI, 0.63-0.72) co-payment were less likely to have a PDC of 80% or greater with an SGLT2i compared with those with a low co-payment. CONCLUSIONS AND RELEVANCE In this cohort study of individuals with T2D and/or HF, 1-year adherence to GLP1-RA or SGLT2i therapies was highest among individuals with a low co-payment. Improving adherence to guideline-based therapies may require interventions that reduce out-ofpocket prescription costs.