Recent technological developments have created a new generation of laboratory diagnostics, which promise to provide better ways of detecting diseases and monitoring response to treatment. These tests create the possibility of earlier and more accurate diagnosis, and of shifting health care from hospitals to the community—making it more effective, efficient, and accessible. But two recent reports—one of which is published this week—highlight the relatively low importance given by clinicians and policy makers to evaluating laboratory diagnostic tests.1 2 In an accompanying analysis, Melzer and colleagues outline the problems caused by this, specifically relating to the evaluation of genetic tests, and propose ways of overcoming them.3

So how should we evaluate tests? First, we must be clear about the purpose of the test—whether it is meant to diagnose, monitor, guide prognosis or treatment, or predict risk. Then the context in which it is used needs to be specified—for example, the disorder or disease, its prevalence in a particular population, and the care pathway that the test …