Certainty may remain the best term for GRADE evidence ratings despite conceptual limitations: a commentary

The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach initially described its ratings as confidence in an effect estimate. Current applications retain this focus while specifying the inference of interest, such as whether the true effect lies above or below a decision-relevant threshold. The terminology later changed from "quality of evidence" to "certainty of evidence."

GRADE reports four ordered levels-high, moderate, low, and very low-of support for an outcome- and inference-specific conclusion. Ordinary English may give certainty an all-or-none state, but technical attributes permit gradation. We compare certainty, quality, confidence, strength, and trustworthiness through their strengths and limitations. None resolves the tension without adding another concern.

In the absence of a superior alternative, certainty may remain the most practical term because it is established in guidance, teaching, software, and practice. It should be defined as an ordered judgment about support for a specified inference, not as proof.