In SERAPHIN, a long-term, randomised, controlled trial (NCT00660179) in pulmonary arterial hypertension (PAH), macitentan significantly reduced the risk of morbidity/mortality and PAH-related death/hospitalisation. We evaluated disease progression and the effect of macitentan in treatment-nave incident and prevalent cohorts.

Patients allocated to placebo, or macitentan 3 mg or 10 mg were classified by time from diagnosis to enrolment as incident (<= 6 months; n=110) or prevalent (>6 months; n=157). The risk of morbidity/mortality and PAH-related death/hospitalisation was determined using Cox regression.

The risk of morbidity/mortality (Kaplan-Meier estimates at month 12: 54.4% versus 26.7%; p=0.006) and PAH-related death/hospitalisation (Kaplan-Meier estimates at month 12: 47.3% versus 19.9%; p=0.006) were significantly higher for incident versus prevalent patients receiving placebo, respectively. There was no significant difference in the risk of all-cause death between incident and prevalent cohorts (p=0.587). Macitentan 10 mg significantly reduced the risk of morbidity/mortality and PAH-related death/hospitalisation versus placebo in incident and prevalent cohorts.

Incident patients had a higher risk for PAH progression compared with prevalent patients but not a higher risk of death. Macitentan delayed disease progression in both incident and prevalent PAH patients.