Abstract

This article is second translation of a GRADE series published in the BMJ to create a highly structured, transparent, and informative system for rating quality of evidence for developing recommendations. The process to develop a guideline, we should formulate a clear question with specification of all outcomes of importance to patients. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) offers four levels of evidence quality: high, moderate, low, and very low for these patient-important outcomes. Randomized trials begin as high quality evidence and observational studies as low quality evidence. Although randomized trials begin as high quality evidence, quality may be downgraded as a result of study limitations (risk of bias), inconsistency (variability in results), indirectness, imprecision (wide confidence intervals), or publication bias. While the quality of evidence derived from observational studies starts at ‘low’ but may be upgraded based on a very large magnitude of effect, a dose-response gradient, and if all plausible biases would reduce an apparent treatment effect.