Similar to drug and device markets, a critical part of the success of novel diagnostics is educating providers on clinical and therapeutic utility. However, unlike pharmaceutical drugs, the ordering of a diagnostic test does not necessarily imply a change in provider behavior or a change in treatment strategy. It’s a bit like whether a tree falling in the forest makes any noise.
Medicine is as much art as science, and many physicians continue to rely disproportionately on intuition, traditional forms of diagnosis, and the standard practices of the medical community—all of which are reinforced by practice cultures which vary by setting, geography, training, and so on.
With the exception of diseases and conditions in which clinical practice guidelines (CPGs) strongly promote the use of a particular diagnostic, not only are physicians under no obligation to order a test, but they are under no obligation to take action based on a test result.
For a diagnostic to have “value”—clinical or economic—the results of the test must in some way lead to a change in provider behavior in the form of an altered or augmented treatment approach, the ordering of additional tests, or referral to additional services.
This may be less of a problem for companion diagnostics, where the bundling of tests and treatments explicitly links test results and provider behavior, as in the case of, for example, the companion diagnostic HER2/neu in treatment of breast cancer. HER2/neu helps identify patients who will benefit from the oncology drug trastuzumab (Herceptin®), and oncology guidelines have explicitly recognized this. But other molecular diagnostics are only effective if provider behavior changes in response to test results. Again, the existence of an ordered test does not necessarily compel caregivers to deviate from the status quo.
The path toward moving genomic diagnostics from the laboratory into clinical practice is heavily dependent on the generation of reliable evidence of clinical utility. A diagnostic test has clinical utility if its use leads to clinician decision making resulting in improved patient outcomes. With sufficient evidence, clinicians in leadership roles are more likely to promote the use of novel diagnostics, and such promotion is a critical first step toward incorporating biomarkers into clinical protocols and CPGs.
-John E. Schneider, PhD & Cara M. Scheibling
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 M. R. Trusheim et al., “Uncertain Prognosis for High-Quality Diagnostics: Clinical Challenges, Economic Barriers and Needed Reforms,” Pharmacogenomics 14, no. 3 (2013).
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