Diuretic adherence in patients with pre-capillary pulmonary hypertension: insights from the PHARE study.

Background: Supportive treatments, such as diuretics, play a critical role in managing pulmonary hypertension (PH). While low adherence to oral PH therapies worsens outcomes, the impact of diuretic adherence is less clear. This study aimed to determine diuretic adherence in patients managed for pre-capillary PH. Methods: This prospective, single-centre study, conducted from January 2022 to January 2024, evaluated medication adherence using the medication possession ratio (MPR) and a self-administered questionnaire (Girerd score). Factors contributing to low adherence and their potential association with serious clinical events were analysed. Results: Among the 220 patients included, 39% demonstrated low adherence to diuretics based on the MPR. According to the Girerd score, 28% of patients reported high adherence, 62% reported minor adherence issues and 10% reported low adherence to diuretics. Factors associated with low adherence measured by the MPR included younger age (<40 versus ≥40 years: OR 4.65 (95% CI 1.83-11.84); p<0.001), active employment (OR 3.05 (95% CI 1.41-6.58); p<0.01) and a high level of general information about PH (OR 2.43 (95% CI 1.14-5.17); p=0.02). Low adherence to diuretics was significantly associated with a higher risk of serious clinical events, including unplanned hospitalisations, disease progression and intensification of oral PH therapies (OR 1.86 (95% CI 1.03-3.39); p=0.04) in univariate analysis. Conclusion: These findings suggest that low adherence to diuretics is frequent in PH and could be associated with worse outcomes. Future studies should assess whether detection of PH patients at risk of low adherence and subsequent targeted educational interventions may improve clinical outcomes.