Defining appropriate outcome measures in pulmonary arterial hypertension related to systemic sclerosis: A Delphi consensus study with cluster analysis

Objective. Outcome measures for pulmonary arterial hypertension associated with systemic sclerosis (PAH-SSc) are only partially validated. The aim of the present study was to establish an expert consensus regarding which outcome measures are most appropriate for clinical trials in PAH-SSc. Methods. Sixty-nine PAH-SSc experts (rheumatologists, cardiologists, pulmonologists) rated a list of disease domains and measurement tools in an Internet-based 3-stage Delphi consensus study. In stages 2 and 3, the medians of domains and measurement tools and frequency distributions of ratings, along with requests for re-ratings, were distributed to respondents to provide feedback. A final score of items was identified by means of cluster analysis. Results. The experts judged the following domains and tools as most appropriate for randomized controlled trials in PAH-SSc: lung vascular/pulmonary arterial pressure and cardiac function both measured by right heart catheterization and echo cardiography, exercise testing measured by 6-minute walking test and oxygen saturation at exercise, severity of dyspnea measured on a visual analog scale, discontinuation of treatment measured by (serious) adverse events, quality of life/activities of daily living measured by the Short Form 36 and Health Assessment Questionnaire disability index, and global state assessed by physician measured by survival. Conclusion. Among experts in PAH-SSc, a core set of outcome measures has been defined for clinical trials by Delphi consensus methods. Although these outcome measures are recommended by this expert group to be used as an interim tool, it will be necessary to formally validate the present measures, as well as potential research measures, in further studies.