[Consensus development in evidence-based guidelines: from myths to rational strategies].

Guidelines are meant to be decision aids with precise procedural recommendations that are based upon the best knowledge available and thus should contribute to improving healthcare delivery. The achievement of this goal necessitates both a systematic and methodically sound approach in guideline development. Essential elements include the search for and the selection and evaluation of empirical evidence for existing knowledge. In addition, personal experience and subjective judgements will always be part of guideline recommendations, especially when the applicability of the evidence is appraised and health benefits and risks of different management options for the disease or condition are considered. To achieve high-quality results in this process, formal consensus techniques should be employed and potential users and affected patients should be involved. Typical of this technique is the structured interaction that provides the framework in which contributions of individual participants are documented, made transparent and brought together. Quality and acceptance of results are determined by the preparation and practical implementation of these procedures, in which individual- and group-psychological influencing factors play an important role. Along with the methods of evidence synthesis, structured consensus building methodology represents a cornerstone of guideline development.