Medication adherence and clinical outcome in patients with pulmonary arterial hypertension or distal chronic thromboembolic pulmonary hypertension.

Abstract

Introduction: In pulmonary arterial hypertension (PAH) and distal chronic thromboembolic pulmonary hypertension (CTEPH), the consistent use of disease-specific therapies is crucial. We aimed to investigate medication adherence to oral disease-specific medication and the impact on clinical outcome among patients with PAH or CTEPH to identify potential patient-related reasons for treatment incompliance.

Study design and methods: This prospective study focused on medication adherence using a multimeasure approach, including specialty pharmacy order data to calculate medication possession ratio (MPR) and self-reporting via questionnaire among patients with PAH or CTEPH. Adherence rates of ≥80% were considered adherent. Simplified four-strata risk categories according to the 2022 European Respiratory Society/European Society of Cardiology pulmonary hypertension (PH) guidelines were determined.

Results: We included 93 patients (66% women, 75% PAH, 25% CTEPH, 57±17 years), all on PH-targeted oral medication between 2013 and 2023. Overall, a number of 73 patients (78%) were classified as adherent. The mean MPR was 98±19% and the mean value of questionnaire responses was 89±10%. At the end of the observation period, adherent patients improved their risk category, while non-adherent patients did not. Factors associated with adherence were older age (OR=1.03, 95% CI=1.01 to 1.07) and being classified in a higher risk category (OR=2.13; 95% CI=1.11 to 4.64). Patients with adverse drug reactions were 75% more likely to be non-adherent to medication (OR=0.25; 95% CI=0.08 to 0.77).

Conclusion: In this collective, mean MPR and self-reported adherence were overall high, with 78% of patients classified as adherent. Adherent patients improved clinical outcomes contrary to non-adherent patients. Insufficient adherence and potential contributing factors should be regularly considered, especially in patients without improvement after starting disease-specific therapy.