Background: Pulmonary hypertension (PH) is a chronic condition necessitating lifelong medication, where adherence to prescribed therapy is critical. Previous studies indicate an average 50% adherence rate among patients with chronic disease, and higher adherence in pulmonary arterial hypertension has been linked with reduced hospitalisations.

Aims: To evaluate adherence levels in PH patients in a national centre and identify factors influencing results.

Methods: 130 PH patients on therapy for over a year were surveyed using the Medication Adherence Report Scale (MARS-5) and two qualitative questions. Data collection was conducted via email or phone.

Results: Of the 53 respondents, the distribution of clinical subtypes was: 20.8% idiopathic PAH, 24.5% associated with congenital heart disease, 41.5% associated with connective tissue disease and 13.2% chronic thromboembolic pulmonary hypertension. Mean age was 54.3 (+/- 19) years, 75.5% were female. The proportion of patients with high adherence (MARS-5 score of 25) was 56.6%. Average MARS-5 scores varied with type of treatment: 23.62 for monotherapy, 24.08 for dual therapy, and 24.75 for triple therapy. Non-adherence reasons included forgetfulness, illness, holidays, and medication-related issues (frequency and side effects). Adherence aids reported were phone reminders, pill organisers, and carer support.

Discussion: The relatively high adherence rate possibly reflects unique features of our PH service such as nurse-led follow ups. However, limitations include small sample size and potential self-reporting bias. The findings underscore the need for targeted interventions to improve medication adherence among PH patients, which could improve long-term outcomes.