The Evidence Hierarchy

  • Mical PaulEmail author


GRADE provides a strategy for appraising the quality of the evidence, expanding risk of bias assessment of individual studies to an appraisal of the quality of the evidence for specific interventions, considering the totality of evidence, its relevance to the clinical scenario, its importance to patients, and its plausibility. Diagnostic tests can be assessed in randomized controlled trials (RCTs) that compared patients undergoing evaluation using an index test vs. patients evaluated with a control or standard test examining clinical outcomes, preferably outcomes that are important to patients. Similarly, they can be tested in comparative observational studies. However, most tests are evaluated only in diagnostic test accuracy (DTA) studies that report on test performance. High-quality evidence for diagnostic tests can typically be obtained only from well-conducted interventional RCTs examining patient-relevant outcomes. DTA studies provide only indirect evidence, thus usually cannot achieve high-quality evidence ranking. Significant heterogeneity is common to DTA meta-analyses, thus further lowering their quality of evidence. The GRADE strategy for quality appraisal in DTA systematic reviews is presented and discussed.


Diagnostic test accuracy QUADAS GRADE Evidence-based medicine Bias Patient-relevant outcomes 


Conflicts of Interests





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© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Rambam Heath Care Campus and The Ruth and Bruce Rappaport Faculty of MedicineTechnion—Israel Institute of TechnologyHaifaIsrael

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