Scientific evidence underlying the American College of Gastroenterology's clinical practice guidelines

Clinical practice guidelines contain recommendations for physicians to determine the most appropriate care for patients. These guidelines systematically combine scientific evidence and clinical judgment, culminating in recommendations intended to optimize patient care. The recommendations in CPGs are supported by evidence which varies in quality. We aim to survey the clinical practice guidelines created by the American College of Gastroenterology, report the level of evidence supporting their recommendations, and identify areas where evidence can be improved with additional research. We extracted 1328 recommendations from 39 clinical practice guidelines published by the American College of Gastroenterology. Several of the clinical practice guidelines used the differing classifications of evidence for their recommendations. To standardize our results, we devised a uniform system for evidence. A total of 39 clinical practice guidelines were surveyed in our study. Together they account for 1328 recommendations. 693 (52.2%) of the recommendations were based on low evidence, indicating poor evidence or expert opinion. Among individual guidelines, 13/39 (33.3%) had no recommendations based on high evidence. Very few recommendations made by the American College of Gastroenterology are supported by high levels of evidence. More than half of all recommendations made by the American College of Gastroenterology are based on low-quality evidence or expert opinion.