Lower Adherence with GLP1RA, SGLT2i Therapies Linked to Higher Prescription Copayments

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Insurance coverage alone does not guarantee adherence with newer evidence-based cardiovascular therapies by patients with type 2 diabetes (T2D) and/or heart failure (HF), suggest findings from a new study published in JAMA Network Open.

In the retrospective cohort study of over 94 000 commercially insured US adults with T2D and/or HF, researchers found that persons with higher prescription copayments were significantly less likely to achieve 1-year adherence to glucagon-like peptide-1 receptor agonists (GLP1-RA) and sodium-glucose cotransporter 2 inhibitors (SGLT2i) medications.

“The findings suggest that improving adherence to guideline-based therapies for the prevention of adverse cardiovascular outcomes warrants policy-level interventions to reduce prescription copayment,” wrote first author Utibe R. Essien, MD, MPH, assistant professor of medicine at the University of California, and colleagues.

The prevalence of T2D and HF in the US is rising, and while GLP1-RAs and SGLT2is have demonstrated reduction in morbidity and mortality among these patient populations, previous research has shown that high out-of-pocket costs “represent a significant barrier to medication initiation,” wrote investigators.

“Yet, less is known about how cost sharing by patients, specifically through prescription co-payment, influences long-term adherence to these medications,” added Essien and coauthors. To find out more, they compared 1-year adherence to GLP1-RA and SGLT2i therapies by prescription copayment level in persons with T2D and or/ HF.

Researchers used data from Optum Insight’s deidentified Clinformatics Data Mart Database of persons enrolled with commercial and Medicare health insurance plans. A total of 94 610 adults (mean age, 61.8 years, 54.1% men) with T2D and/or HF with a prescription claim for a GLP1-RA or SLGT2i from January 1, 2014, to September 30, 2020, were included in the study.

Prescription copayment was categorized as low (<$10), medium ($10 to <$50), and high (≥$50). The primary outcome was medication adherence, defined for the purpose of the study as a proportion of days covered (PDC) of ≥80% at 1 year. Investigators used logistic regression models to analyze the association between insurance copayment and adherence, and adjusted for patient demographics, medical comorbidities, and socioeconomic factors.

FINDINGS

GLP1-RA adherence. The final cohort included 39 149 participants who had a pharmacy claim for a GLP1-RA medication, of whom 25 557 (65.3%) achieved 12-month adherence.

In fully adjusted models, participants 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) copayment were less likely to achieve 12-month adherence to GLP1-RA therapies compared with those with a low copayment, according to the results.

SGLT2i adherence. The final cohort also included 51 072 persons with a claim for an SGLT2i medication, of whom 37 339 (73.1%) achieved 12-month adherence. Researchers found that participants with a medium (aOR 0.67, 95% CI 0.63-0.72) or high (aOR 0.68, 95% CI 0.63-0.72) copayment were less likely to achieve 12-month adherence compared with those with a low copayment.

“Lowering high out-of-pocket prescription costs may be key to improving adherence to guideline-recommended therapies and advancing overall quality of care in T2D and HF management,” wrote study authors.

Researchers noted that while they did not include persons without health insurance or those with public insurance, the results demonstrated “even among those with health insurance, the variability of co-payment was associated with reduced medication adherence, which may be even more pronounced among those who are underinsured or uninsured.”

Reference: Essien UR, Singh B, Swabe G, et al. 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. JAMA Netw Open. 2023;6:e2316290.