Challenge of communicating uncertainty in systematic reviews when applying GRADE ratings

One of the most widely used tools for assessing and communicating scienti c uncertainty is Grading of Recommendations Assessment, Development, and Evaluation (GRADE), a system for rating the quality of evidence and grading strength of recommendations in healthcare. More than 100 organisations around the world—WHO included1— are using GRADE or have endorsed it.
In GRADE, a quantitative assessment of uncertainty is qualitatively communicated, so that a result obtained as a CI relative to a threshold is expressed as a nding in which assessors have low, moderate or high certainty, or certainty described with other such quali ers. What these correspond to in quantitative terms, and how decision-makers interpret them, is our issue here. We con ne our attention to GRADE’s decision rules for systematic reviews, and do not comment on the problem of multiple outcomes in guideline recommendations.