Systemic sclerosis-associated pulmonary hypertension: why disease-specific composite endpoints are needed

Table 1 Domains and measurement tools for the assessment of pulmonary arterial hypertension in systemic sclerosis

Domain	Measurement tools	Specific points to consider in application to PAH-SSc^a
Lung vascular	Right heart catheter, echocardiography	Other forms of PAH are prevalent in SSc, including type II (cardiac disease) and type III (lung fibrosis) and confound assessment, especially by echocardiography
Exercise testing	6MWD, oxygen saturation at exercise	Musculoskeletal involvement and deconditioning have a major impact on exercise capacity in SSc in addition to PAH
Cardiac function	Right heart catheter, echocardiography	Cardiac abnormalities (diagnosed and undiagnosed) are prevalent in SSc, including high frequency of diastolic dysfunction
Dyspnea	Dyspnea VAS	There are multiple non-PAH causes for dyspnoea in SSc (lung fibrosis, deconditioning, anaemia, cardiac disease)
Discontinuation of treatment	Adverse events, serious adverse events	Concomitant medication for SSc or co-morbidity may impact on adverse events
Quality of life	SF-36, HAQ DI	Extra-pulmonary involvement has a major impact on health status and function in SSc
Global state by physician	Survival	SSc-PAH currently has a substantially worse mortality than iPAH

^aDomains identified through the EPOSS initiative may be integrated into the TTCW composite end-point and whether these may be different for idiopathic pulmonary arterial hypertension and pulmonary arterial hypertension associated with systemic sclerosis (PAH-SSc). 6MWD, 6-minute walking distance; HAQ DI = Health Assessment Questionnaire Disability Index; iPAH, idiopathic pulmonary arterial hypertension; PAH, pulmonary arterial hypertension; SF-36, Short Form 36 score; SSc, systemic sclerosis; VAS, visual analog scale.

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