Defining ranges for certainty ratings of diagnostic accuracy: a GRADE concept paper

OBJECTIVE: The objective of the study was to clarify how the Grading of Recommendations Assessment, Development and Evaluation (GRADE) concept of certainty of evidence applies to certainty ratings of test accuracy. STUDY DESIGN AND SETTING: After initial brainstorming with GRADE Working Group members, we iteratively refined and clarified the approaches for defining ranges when assessing the certainty of evidence for test accuracy within a systematic review, health technology assessment, or guideline. RESULTS: Ranges can be defined both for single test accuracy and for comparative accuracy of multiple tests. For systematic reviews and health technology assessments, approaches for defining ranges include some that do not require value judgments regarding downstream health outcomes. Key challenges arise in the context of a guideline that requires ranges for sensitivity and specificity that are set considering possible effects on all critical outcomes. We illustrate possible approaches and provide an example from a systematic review of a direct comparison between two test strategies. CONCLUSIONS: This GRADE concept paper provides a framework for assessing, presenting, and making decisions based on the certainty of evidence for test accuracy. More empirical research is needed to support future GRADE guidance on how to best operationalize the candidate approaches.