Background: The primary objective of this post hoc analysis was to evaluate clinical outcomes of tadalafil in patients with pulmonary arterial hypertension (PAH) associated with connective tissue disease (CTD-PAH) compared with patients with idiopathic/heritable PAH (I/H-PAH) for primary and key secondary efficacy endpoints, and safety. This analysis included adult patients with CTD-PAH or I/H-PAH who participated in the PHIRST and PHIRST-2 studies.
Methods: Patients were randomized 1:1:1:1:1 to tadalafil (2.5, 10, 20, or 40mg) or placebo in the PHIRST study and the majority of these patients were subsequently assigned 40mg in PHIRST-2. Patients taking 20mg in PHIRST without demonstrating clinical worsening continued on 20mg in PHIRST-2. Outcomes analyzed included 6MWD, WHO-FC, and incidence and time to first occurrence of clinical worsening. Safety was assessed through evaluation of adverse events (AEs), clinical laboratory data, electrocardiograms, and physical examinations.
Results: Increased 6MWD in PHIRST was maintained in both CTD-PAH and I/H-PAH subgroups for 52weeks. Patients with CTD-PAH tended to be older, were more likely female, had lower exercise capacity, were more likely to have clinical worsening, and experienced AEs more frequently than patients with I/H-PAH.
Conclusion: The effect of tadalafil treatment in patients enrolled in both PHIRST studies was detectable for both I/H-PAH and CTD-PAH subgroups. In general, subgroup differences were modest. Patients with CTD-PAH may perform less well than patients with I/H-PAH in safety and efficacy measures in all treatment groups, which is similar to other studies demonstrating a worse prognosis for patients with CTD-PAH.
Keywords: Associated PAH; Heritable; Idiopathic; PHIRST; PHIRST-2.
Copyright © 2017. Published by Elsevier B.V.