An Evidence-Based Medicine Approach to Studies of Diagnostic Tests: Assessing the Validity of Virtual Colonoscopy

This is the second in the series of articles on the application of evidence-based medicine (EBM) approaches to evaluating therapy, natural history, and diagnostic tests that are of interest to gastroenterologists and hepatologists. The article provides an EBM framework to critically assess articles that evaluate diagnostic tests: When are diagnostic tests necessary? What study design was used to appraise the comparison between the test being considered and the acceptable comparator? Did all study patients, including those in whom the diagnosis was in doubt, undergo the gold standard test? Was the frequency of indeterminate results reported? Are the data reported as likelihood ratios? This article addresses the choice of best approach to management of a 53-year-old woman who is referred for colorectal cancer surveillance. She had a 1-cm diameter adenoma snared from the colon about 3 years previously and she seeks advice on the possibility of undergoing virtual colonoscopy" and avoiding colonoscopy because of discomfort during the prior examination. The article appraises recent literature and applies the results to the patient and practice setting to determine the optimal approach for the individual patient."