of the prostate-specific antigen (PSA) test for prostate cancer from diagnosis to screening, described below, is a prime example of this scenario. Once adopted in such a fashion, it may be difficult or impossible to adequately assess the risks, benefits, and value of a screening test. Postmarket surveillance of diagnostic tests is minimal, and once insurers provide coverage for something, coverage is rarely withdrawn unless the item is removed from the market because of safety concerns (reviewed by IOM, 2001).
Ultimately, the value of a test to society also depends on its cost-effectiveness and economic impact. Although these factors have not generally been considered in coverage and adoption decisions for health care in the United States, interest in such assessments is increasing as the cost of medical care continues to rise. Few economic evaluations of diagnostics have been undertaken thus far, perhaps because of their relatively low cost compared with many drugs and other medical interventions (Rogowski, in press). However, the newer class of pharmacogenomics-based molecular diagnostics that will enable personalized medicine may come under closer scrutiny because of their potentially significant budget impact due to high drug costs and the high cost of adverse drug reactions. Nonetheless, economic evidence for this class of diagnostics is presently still quite limited (Rogowski, 2007).
This chapter provides an overview of the challenges and needs of technology assessment and adoption, with the goal of identifying possible ways to facilitate data collection and analysis to monitor and improve the value of biomarker tests. Examples described below, as well as in Chapter 3, illustrate the complexity of this topic. Problematic cases include instances in which markers approved for one purpose were widely diffused and adopted for another purpose without sufficient evidence; instances in which the use of markers for vital treatment guidance is based on small, poor-quality studies likely to be less than definitive; and many instances in which evidence for the value of markers to improve patient outcomes is flawed or insufficient.
As a result of the limited scope of FDA oversight of laboratory tests, biomarker tests often are applied in clinical settings with little assessment of their clinical utility for specific medical situations (Reid et al., 1995; Feinstein, 2002; Weinstein et al., 2005). This does not seem to hinder widespread clinical adoption, however.