Methods and Limitations of Assessing New Noninvasive Tests

Abstract

The introduction and dissemination of new technology provide the potential for enhancing and expanding our understanding of disease processes (eg, atherosclerosis, myocardial dysfunction) and extending our treatment options while providing a tool for monitoring therapeutic responses.1,2 However, the growth of cardiac imaging has profound cost implications that will be exacerbated if newer technology is widely disseminated and used freely3 without appropriate validation. Hence, technology validation has become an important consideration in today’s healthcare reality.3 Our goal is to provide a critical review of the methods and challenges inherent to the validation of existing or emerging noninvasive imaging technologies. Historically, imaging has been considered in the context of anatomic end points. A shift from anatomy-based to outcomes-based assessments of testing has been accepted. More recently, a further shift occurred from imaging for risk identification to imaging for identification of patients’ optimal therapeutic management, ie, identifying a therapeutic approach associated with optimal survival or improved well being after a given test result for a patient. This review focuses on diagnostic approaches; the second part focuses on test validation using risk and benefit end points. In the context of assessing cardiac imaging, several factors must be considered. First, the assessment of a new modality is not a simple determination of sensitivity and specificity. Rather, it is a stepwise, multifactorial process incorporating diagnostic, prognostic, therapeutic, resource use, cost-effectiveness, and other end points that considers the perspectives of patients, payers, ordering physicians, and the healthcare system.4 A series of questions drive this process: Does the modality work? For which end point? In which patient? At what cost? How does it compare with other modalities? Can it be used to improve clinical outcomes? Importantly, the end product of this assessment process must remain practical. Although “scientific” differences may be found between tests, …