GRADE guidelines: a new series of articles in the Journal of Clinical Epidemiology.

The "Grades of Recommendation, Assessment, Development, and Evaluation" (GRADE) approach provides guidance for rating quality of evidence and grading strength of recommendations in health care. It has important implications for those summarizing evidence for systematic reviews, health technology assessment, and clinical practice guidelines. GRADE provides a systematic and transparent framework for clarifying questions, determining the outcomes of interest, summarizing the evidence that addresses a question, and moving from the evidence to a recommendation or decision. Wide dissemination and use of the GRADE approach, with endorsement from more than 50 organizations worldwide, many highly influential (http://www.gradeworkinggroup.org/), attests to the importance of this work. This article introduces a 20-part series providing guidance for the use of GRADE methodology that will appear in the Journal of Clinical Epidemiology.