Table 1.

Components and Definitions of the Primary Endpoint

Component	Definition
Death (all-cause)	Certificate of death
Hospitalization for worsening PAH	Adjudicated and defined as any hospitalization for worsening PAH, lung or heart/lung transplant, atrial septostomy; participants who initiated parenteral prostanoid therapy were included in this group
Disease progression	Adjudicated and defined as a (decrease of > 15% from baseline in 6MWD combined with WHO FC III or IV symptoms) at 2 consecutive visits separated by ≥14 days
Unsatisfactory long-term clinical response	Adjudicated and requiring participation in the study for ≥6 months; defined as sustained WHO FC III symptoms AND any decrease from baseline in 6MWD at 2 consecutive visits separated by ≥14 days

From New England Journal of Medicine. Galiè N, Barberà JA, Frost AE, Ghofrani HA, Hoeper MM, McLaughlin VV, Peacock AJ, Simonneau G, Vachiery JL, Grünig E, Oudiz RJ, Vonk-Noordegraaf A, White RJ, Blair C, Gillies H, Miller KL, Harris JH, Langley J, Rubin LJ; AMBITION Investigators. Initial use of ambrisentan plus tadalafil in pulmonary arterial hypertension. Volume 373, Pages 834–844. Copyright© (2015) Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society

6MWD 6-min walk distance, FC Functional class, PAH Pulmonary arterial hypertension, WHO World Health Organization