title: Perspective on the optimal endpoints for pulmonary arterial hypertension trials.
abstract: OBJECTIVE
  Traditional endpoints in trials of therapies for pulmonary arterial hypertension (PAH), including 6-min walk distance, are associated with significant limitations. Time to clinical worsening (TTCW) may represent an alternative, and although it is being considered as a primary endpoint in future trials, it will ultimately require refinement before it can be broadly applied.
  
  
  RESULTS
  Discussions with regulators about TTCW are ongoing, and there are several potential strategies that could be applied to enhance its robustness. For example, reliability and reproducibility could be increased if each individual component of TTCW were carefully defined. The optimal definition of TTCW may need to be varied in order to meet the differing needs of factors that include PAH cause, functional class, and age. The establishment of an independent and blinded committee who adjudicate problematic events (e.g. PAH-related hospitalization) in PAH trials using TTCW would further increase reliability, reducing intersite and interinvestigator variability.
  
  
  CONCLUSIONS
  As the field continues to develop, overall trial design may warrant attention; to make results more clinically relevant, goal-orientated therapy strategies may be considered, in addition to traditional randomized controlled trial designs.
authors.affiliation: University of California, San Diego School of Medicine, La Jolla, California 92037, USA. ljrubin@ucsd.edu
authors.forename: Lewis
authors.initials: L
authors.lastname: Rubin
authors.forename: Gérald
authors.initials: G
authors.lastname: Simonneau
mesh_terms: D018450:Disease Progression; D023381:Endpoint Determination; D017079:Exercise Tolerance; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy*; D015203:Reproducibility of Results; D013997:Time Factors; D016896:Treatment Outcome