The importance of test accuracy in economic evaluations of companion diagnostics

Background: Economic evaluations of companion diagnostics often fail to include the impact that tests have on the overall economic value of test–drug combinations. Methods: To illustrate the importance of test accuracy on the cost–effectiveness of companion diagnostics by means of examples. Data were extracted from the literature. Results: The accuracy of a test and in particularly its specificity, is often more influential on the overall cost–effectiveness results than the price of the test. Specificity becomes more crucial when prevalence of the biomarker is low. Multiple, simultaneous testing faces specific challenges regarding its overall specificity. Conclusion: This article opens a discussion on some fundamental points linked to economic evaluations of test–therapy combinations