Development and application of a generic methodology to assess the quality of clinical guidelines

BACKGROUND: Despite clinical guidelines penetrating every aspect of clinical practice and health policy, doubts persist over their ability to improve patient care. We have designed and tested a generic critical appraisal instrument, that assesses whether developers have minimized the biases inherent in creating guidelines, and addressed the requirements for effective implementation. DESIGN: Thirty-seven items describing suggested predictors of guideline quality were grouped into three dimensions covering the rigour of development, clarity of presentation (including the context and content) and implementation issues. The ease of use, reliability and validity of the instrument was tested on a national sample of guidelines for the management of asthma, breast cancer, depression and coronary heart disease, with 120 appraisers. A numerical score was derived to allow comparison of guidelines within and between diseases. RESULTS: The instrument has acceptable reliability (Cronbach's alpha coefficient, 0.68-0.84; intra-class correlation coefficient, (0.82-0.90)). The results provided some evidence of validity (Pearson's correlation coefficient between appraisers' dimension scores and their global assessment was 0.49 for dimension one, 0.63 for dimension two and 0.40 for dimension three). The instrument could differentiate between national and local guidelines and was easy to apply. There was variation in the performance of guidelines with most not achieving a majority of criteria in each dimension. CONCLUSIONS: Use of this instrument should encourage developers to create guidelines that reflect relevant research evidence more accurately. Potential users or groups adapting guidelines for local use could apply the instrument to help decide which one to follow. The National Health Service Executive is using the instrument to assist in deciding which guidelines to recommend to the UK National Health Service. This methodology forms the basis of a common approach to assessing guideline quality in Europe.