Comparative effectiveness of endothelin receptor antagonists on mortality in patients with pulmonary arterial hypertension in a US Medicare population: a retrospective database analysis

Limited evidence is available on outcomes associated with currently available medications from the endothelin receptor antagonist drug class (bosentan, ambrisentan, and macitentan) in elderly patients with pulmonary arterial hypertension. We evaluated mortality in predominantly elderly patients with pulmonary arterial hypertension in the US taking endothelin receptor antagonists. A retrospective administrative claims study was conducted using the Centers for Medicare and Medicaid Services national Medicare database. Patients with pulmonary arterial hypertension were identified using diagnostic codes. Cohort inclusion required age ≥18 years; ≥1 claim for macitentan, ambrisentan, or bosentan between 1 January 2014 and 31 December 2015 (index date and index endothelin receptor antagonist defined by first such claim); continuous enrollment for ≥12 months before and after the index date; and ≥80% of days covered for the index endothelin receptor antagonist. Follow-up was from index date until the earliest of Medicare disenrollment, death, or 31 December 2016. Multivariable Cox proportional hazards regression models were used to estimate mortality hazard ratios with 95% confidence intervals for macitentan vs. ambrisentan or bosentan, adjusting for potential confounders. The study cohort included 1628 patients on index macitentan, 2852 on ambrisentan, and 1972 on bosentan. Overall, 69% of patients were aged ≥65 years and most were females (76%). Macitentan was associated with an 18% lower risk for mortality than ambrisentan (hazard ratio: 0.82, 95% confidence interval: 0.72–0.93; P = 0.0026) and a 39% lower risk than bosentan (hazard ratio: 0.61, 95% confidence interval: 0.53–0.71; P < 0.0001). Variables that independently increased the risk of mortality included higher comorbidity index, increasing age, and inpatient hospitalizations at baseline.