The potential risks and benefits of a screening or diagnostic testing strategy extend beyond the immediate impact and accuracy of the test itself. The result of testing will determine the available next steps and options for follow-up and management, and therefore will affect various patient-important outcomes in addition to potential resource utilization and equity considerations. These downstream consequences, and the certainty of evidence in these consequences, need to be considered when formulating recommendations surrounding testing. In a July 2019 paper published as part 22 of the Journal of Clinical Epidemiology’s GRADE guidelines series, Schünemann and colleagues provide suggestions for assessing certainty of evidence and determining recommendations for diagnostic tests and strategies.
While a collection of randomized controlled trial evidence examining the downstream consequences of various testing strategies is ideal in this scenario, such data are sparse. In lieu of this, guideline authors should develop a framework that includes each possible testing and follow-up treatment scenario, starting with the test in question and ending with patient-important outcomes.
H.J. Schunemann et al. / Journal of Clinical Epidemiology 111 (2019) 69e82
This will allow the panel to visually link all relevant existing data together and develop clinical questions that are answerable with the evidence at hand. Data on the accuracy of a given test will help inform the expected number of false negatives and positives, which would then lead to potentially important downstream consequences - such as anxiety or a missed diagnosis - in addition to the effects of treating a diagnosed condition. The estimates of these beneficial and harmful potential outcomes should ideally come from a systematic review of evidence which can then be assessed for certainty.
Schünemann HJ, Mustafa RA, Brozek J, Santesso N, Bossuyt PM, Steingart KR, Leeflang M, Lange S, Trenti T, Langendam M, Scholten R. GRADE guidelines: 22. The GRADE approach for tests and strategies—from test accuracy to patient-important outcomes and recommendations. Journal of clinical epidemiology. 2019 Jul 1;111:69-82.