Association Between Copayment and Adherence to Medications for Pulmonary Arterial Hypertension

Abstract

BACKGROUND: Pharmacologic treatment for pulmonary arterial hypertension (PAH) improves exercise capacity, functional class, and hemodynamic indexes. However, monthly prescription costs often exceed $4000. We examined associations between (1) medication copayment and (2) annual household income with adherence to pulmonary vasodilator therapy among individuals with PAH. METHODS AND RESULTS: We used administrative claims data from an insured population in the United States to identify individuals diagnosed with PAH between 2015 and 2020. All individuals had ≥1 medication claim for endothelin receptor antagonists, phosphodiesterase type-5 inhibitors, prostanoids or prostacyclin receptor agonists, or the soluble guanylate cyclase stimu-lator riociguat. We defined copayments as low, medium, or high, as determined by their distributions for each medication class. Annual household income was categorized as <0.001) and combination therapy with endothelin receptor antagonist and phosphodiesterase type-5 inhibitor (OR, 0.61 [95% CI, 0.38– 0.97]; P=0.03). CONCLUSIONS: We identified associations between copayment and adherence to prostanoids and combination therapy among individuals with PAH. Copayment may be a structural barrier to medication adherence and merits inclusion in studies examin-ing access to pharmacotherapy among individuals with PAH.