A global ranking approach to end points in trials of mechanical circulatory support devices

Background: Although previous studies of mechanical circulatory support devices (MCSDs) have used all-cause mortality as a primary end point, trends in device technology and implementation will increasingly necessitate the use of composite end points for MCSD studies. The ideal composite end point for studies of MCSDs is uncertain. Methods and Results: We reviewed the advantages and disadvantages of traditional composite end points in MCSD studies from both a clinical and statistical perspective. Although composite end points may increase statistical power, they also introduce potential problems in interpretation of data, and in some situations may interpret a given clinical course in ways very different than it would be viewed by patients or providers. A global ranking end point, which ranks various aspects of the clinical course based on a prespecified hierarchical ranking system, may provide many of the advantages of composite end points while avoiding many of the pitfalls. One version of such an end point for use in MCSD studies is proposed. Conclusions: Use of a global ranking end point for incorporating various components of the clinical course into a single end point retains much of the benefit of composite end points while avoiding many of the limitations associated with the use of composites. Adoption of such end points may facilitate the development of MCSD therapy.