Research published in Respiratory Medicine on January 12, 2026, explored adherence to pulmonary arterial hypertension-specific therapies across different therapeutic classes, identified factors associated with non-adherence and evaluated its impact on clinical outcomes.
Adherence was measured by proportion of days covered (PDC) during the treatment period, defined as 60 days after first therapy until treatment discontinuation/censor. Non-adherence was defined as proportion of days covered <80%.
Among the 7.496 patients studied between January 2017 and June 2022, treatment distribution at initiation was:
- 56.6% phosphodiesterase type 5 inhibitors (PDE5i)
- 25.9% endothelin receptor antagonists (ERA)
- 6.6% injectable prostacyclin pathway agents (PPA)
- 4.7% inhaled prostacyclin pathway agents
- 3.3% oral prostacyclin pathway agents
- 2.9% soluble guanylate cyclase (sGC) stimulatorss.
Overall adherence was strong across treatment categories (mean proportion of days covered >90%), though non-adherence rates were notably higher for phosphodiesterase type 5 inhibitors (17.0%) and inhaled prostacyclin pathway agents (15.3%). The factors linked to non-adherence differed depending on the drug class.
Crucially, non-adherence was associated with significantly poorer clinical outcomes: patients in the phosphodiesterase type 5 inhibitors group who were non-adherent faced more than double the mortality risk (HR 2.33 [95% CI 1.79-3.03]; p<0.001), while those in the endothelin receptor antagonists group experienced a more than five-fold increase in mortality risk.
The authors conclude that non-adherence to pulmonary arterial hypertension therapy is associated with poor clinical outcomes. Strategies to improve adherence are crucial to optimizing patient outcomes.
Citation
De Marco T, Paoli CJ, Germack HD, Croteau NS, Simeone JC, Tang F, Doad G, Panjabi S, Farber H. Exploring the relationship between adherence and outcomes in pulmonary arterial hypertension: A retrospective cohort study in the United States. Respir Med. 2026 Jan 12:108649. doi: 10.1016/j.rmed.2026.108649. Epub ahead of print. PMID: 41534720.
Abstract is available at this link on PubMed