An evidence-based approach to clinical practice guidelines: diagnosis and treatment of irritable bowel syndrome1

The Institute of Medicine defines clinical practice guidelines as “systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances.”1 In other words, clinical practice guidelines may offer clear recommendations about the utility of diagnostic tests and the efficacy of different treatments for specific disorders. Guidelines have been promoted as tools that enhance the quality of medical care by reducing practice variations, minimizing spending on unnecessary diagnostic tests, and preventing the use of ineffective treatments.2 During the past decade, the number of published guidelines has increased exponentially. The Agency of Health Care Research and Quality established a National Guidelines Clearinghouse website, which lists hundreds of guidelines. Although it is in vogue to state that a guideline is evidence-based, most guidelines are developed from the consensus opinion of experts. An evidence-based guideline usually consists of multiple systematic reviews about the diagnosis and treatment of a disorder. These systematic reviews should meet rigorous criteria for the critical appraisal of clinical research on which the guidelines for diagnosis and treatment are based. Nevertheless, expert opinion is still important in evidence-based guidelines because these experts are called on to render an opinion when there simply are no data. Experts also provide guidance about the implementation of evidence-based recommendations!