Chapter 10: deciding whether to complement a systematic review of medical tests with decision modeling

Abstract

Limited by what is reported in the literature, most systematic reviews of medical tests focus on "test accuracy" (or better, test performance), rather than on the impact of testing on patient outcomes. The link between testing, test results and patient outcomes is typically complex: even when testing has high accuracy, there is no guarantee that physicians will act according to test results, that patients will follow their orders, or that the intervention will yield a beneficial endpoint. Therefore, test performance is typically not sufficient for assessing the usefulness of medical tests. Modeling (in the form of decision or economic analysis) is a natural framework for linking test performance data to clinical outcomes. We propose that (some) modeling should be considered to facilitate the interpretation of summary test performance measures by connecting testing and patient outcomes. We discuss a simple algorithm for helping systematic reviewers think through this possibility, and illustrate it by means of an example.

Figure 1.

Simplified analytic framework. AD: Alzheimer’s disease; AChE-I: acetylcholinesterase inhibitors (the treatment available at the time of the evidence report). The framework assumes no major adverse effects from the treatment.

Figure 2.

Management options for mild cognitive impairment. * When applicable. As per the evidence report, the then-available treatment options (achetylcholinesterase inhibitors) do not have important adverse effects. However, in other cases, harms can be induced both by the treatment and the test (e.g., if the test is invasive). The evidence report also modeled hypothetical treatments with various effectiveness and safety profiles to gain insight on how sensitive their conclusions were to treatment characteristics. Note that at the time the evidence report was performed, other testing options for Alzheimer’s were not in consideration. AD: Alzheimer’s disease; MCI: mild cognitive impairment; PET: positron emission tomography.