Methods of formal consensus in classification/diagnostic criteria and guideline development

Guidelines or diagnostic criteria in clinical practice assist physicians in their clinical decision-making and improve health outcomes for patients. Diagnostic and classification criteria should be based on evidence from rigorously conducted controlled studies. Formal group consensus methods have been developed to organize subjective judgments and to synthesize them with the available evidence. This review discusses 4 types of formal consensus methods used in the health field and their applications in rheumatology: the Delphi method, Nominal Group Technique, RAND/UCLA Appropriateness Method, and National Institutes of Health consensus development conference.