Medication Nonadherence in Patients with Pulmonary Arterial Hypertension: The Pulmonary Hypertension Association Registry (PHAR)

<b>Rationale:</b> Pulmonary arterial hypertension (PAH) is associated with significant morbidity and mortality. The extent of medication nonadherence in PAH is uncertain and may be linked to adverse outcomes. There has been a lack of multicenter, registry-based studies assessing medication nonadherence and patient-centered outcomes in PAH. <b>Objectives:</b> To determine the prevalence of self-reported nonadherence in Pulmonary Hypertension Association Registry (PHAR) participants with PAH or chronic thromboembolic pulmonary hypertension and the relationship of nonadherence with several patient-centered outcomes (mortality, hospitalization rates, emergency department visits, and health-related quality of life). <b>Methods:</b> Self-reported PAH medication nonadherence was captured at PHAR enrollment and during follow-up visits. Predictors of nonadherence were modeled using generalized estimating equations assuming a binary distribution. Outcomes associated with nonadherence were modeled using generalized estimating equations with a Poisson distribution. <b>Results:</b> A total of 1,543 patients were included, of whom 1,092 (70.8%) were female and 1,340 (86.8%) had PAH. The overall rate of any self-reported nonadherence was 6.1% (95% confidence interval [CI], 5.3-6.9). Predictors of nonadherence included self-reported male sex at birth (odds ratio [OR], 1.4; 95% CI, 1.0-1.9; <i>P</i> = 0.02), poverty (OR, 1.6; 95% CI, 1.2-2.3; <i>P</i> = 0.01), not being married or partnered (OR, 1.5; 95% CI, 1.1-1.9; <i>P</i> = 0.01), having Medicaid or no health insurance (OR, 2.1; 95% CI, 1.5-2.9; <i>P</i> < 0.001), and having completed high school but not having a college degree (OR, 1.7; 95% CI, 1.1-2.9; <i>P</i> < 0.001). PHAR participants who reported any nonadherence had 50.0% more emergency department visits (<i>P</i> < 0.001), 13.3% more hospital admissions (<i>P</i> = 0.03), and 61.9% more days hospitalized (<i>P</i> = 0.01). No relationship was observed between nonadherence and the type or number of PAH therapies or all-cause mortality. Participants reporting nonadherence had worse mean Short Form-12 scores (<i>P</i> < 0.001) and worse emPHasis-10 scores (<i>P</i> = 0.02). <b>Conclusions:</b> The rate of self-reported nonadherence in PHAR registrants was low but was associated with male sex and several social determinants of health. Although the complexity or type of PAH regimen did not appear to influence nonadherence, nonadherence was associated with numerous adverse patient-centered outcomes, including greater healthcare use and worse health-related quality of life. Because of limitations in the structure of the gathered data, relationships between exposure and outcomes were not temporally definitive; these observations warrant additional prospective studies.