Development of clinical guidelines: methodological and practical issues.

The key elements for developing a clinical guideline are (a) guidelines are developed by multidisciplinary groups, (b) they are based on a systematic review of the scientific evidence, and (c) recommendations are explicitly linked to the supporting evidence and graded according to the strength of that evidence. Besides reporting the statistical strength of the randomised controlled trial results, it is necessary to consider the strength of the evidence, the methodological quality of the studies and the external validity by applying a "considered judgement" to the whole amount of the data. The Scottish Intercollegiate Guidelines Network (SIGN) process for developing guidelines is based on 4 steps: (a) methodological evaluation, (b) synthesis of evidence, (c) considered judgement and (d) grading system. The judgement on grading of recommendations is made on the basis of an (objective) assessment of the study design and quality, and a (perhaps more subjective) judgement of the consistency, clinical relevance and external validity of the evidence. The SPREAD group decided to adopt this methodology starting from the 3rd edition (2003); however, it was agreed to integrate the principles of the SIGN [4] with the statistical considerations on alpha and beta error size suggested by the Centre for Evidence-Based Medicine methodology [6], to give a more comprehensive evaluation of the available evidence. By being the product of a multidisciplinary approach, being explicit and providing information on the way agreement has been reached or on the reasons of disagreement, the SPREAD guidelines seem to fulfil the needs for shared guidelines, and to avoid the concerns related to pitfalls in the transparency of the process and in the reaching of a consensus.