Treatment patterns and factors associated with adherence in pulmonary arterial hypertension

Objective: Improving understanding of actual pulmonary hypertension (PH) treatment adherence patterns is crucial to properly treating these patients. We aimed to primarily assess adherence to treatments used for pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) specific therapies, identify potential factors related to it and secondly describe its treatment patterns.

Methods: A 6-month observational cross-sectional study in a tertiary care hospital was conducted. Patients with PH-targeted therapy who picked it up in the ambulatory hospital pharmacy and who had been on treatment with the same drug for at least 1 year were included. Adherence was assessed as: 1) Proportion of days covered (PDC); and 2) Simplified Medication Adherence Questionnaire (SMAQ). PDC ≥80% was considered adherent. Statistical analyses were performed to evaluate the study outcomes. Logistic regressions were estimated to identify the association between baseline characteristics and factors associated with adherence. P < 0.05 indicated statistical significance.

Results: A total of 63 patients with 127 different treatments were included, 71.4% were females with a mean age (SD) of 59 (15) years. PAH was the most common diagnosis (74.6%). Double therapy was used in 39.7% of patients, being the combination of Macitentan + Tadalafil and Ambrisentan + Tadalafil the most prescribed. Endothelin receptor antagonists were the most used treatment (40.2%). Adherence according to PDC was 93.7%, showing no great differences depending on the targeted drug used, and according to SMAQ 61.9%. The agreement degree of both methods was slight (65.1%; Kappa 0.12). Only female sex (OR: 0.23, 95% CI: 0.06-0.90; p = 0.035) was associated with worse adherence in the SMAQ method but not in the PDC. Adverse events were reported by a 55.6% of participants and the perception of effective treatment was high (95.2%).

Conclusions: Adherence to PH therapy differs depending on the assessment method; PDC showed greater adherence rate than SMAQ. According to SMAQ, female sex may have a negative impact on adherence in this cohort, but PDC revealed no factors influencing it. No notable differences in adherence between treatment types were found and generally patients felt the treatments were effective in controlling their disease.