Methodological appraisal of guidelines. The AGREE instrument

The increasingly important role of clinical practice guidelines as a support tool for clinical decision-making is shown by a growing number of publications in the literature. In fact, it is almost impossible to open a medical journal without coming across one or more guidelines on various subjects. Guidelines serve several objectives: 1) improvement in health care (increasing good and decreasing bad practices); 2) greater availability of and access to medical knowledge; and 3) promotion of cost-effective strategies. The recommended methodology for guideline design and development requires that the recommendations should be evidence-based, i.e., based on selected and critically appraised data, with the final inclusion of evidence that is valid, important and applicable, based on explicit pre-defined criteria. The methodological quality of guidelines varies substantially, raising credibility issues, with subsequent lack of results (in terms of changing medical practice). This has given rise to a series of recent publications on methodological rules for the design and writing of guidelines. This paper presents the first international instrument that can be used as a quality assurance tool for evidence-based clinical guidelines: the Appraisal of Guidelines Research and Evaluation (AGREE) instrument.