EBM notebook A graphic framework for teaching critical appraisal of randomised controlled trials

However, > 20 published users’ guides currently exist, and our experience shows that residents and clinicians attempting to pursue a practice that uses evidence-based medicine have 1 of 2 problems: either they try to memorise, without much success, all the questions from several of these guides, or they rely completely on small pocket cards that contain the pertinent questions and then find themselves lost if they misplace or forget those cards. Other groups have developed more general criteria. For example, the Newcastle Critical Appraisal Worksheet is a 3 × 10 grid that can be applied to any type of study, but it requires some basic knowledge of epidemiological terms and concepts. Over time, we’ve put together a flow diagram of RCTs and the points at which bias can creep in; this flow diagram serves as a memory aid and can act as a framework on which to “hang” whatever critical appraisal guide the user is most comfortable with. We have often found that the process of drawing this flow diagram for the particular study being appraised shows the sources of bias and allows the reader to track the patients and points at which patients are lost, even before referring to a set of critical appraisal questions. We offer this framework as a pedagogical aid when teaching clinicians and residents. Figure 1 shows the flow of an RCT and can be drawn as the starting point for a critical appraisal exercise. Each of the 5 numbered steps in the RCT flow diagram can act as the focal point for a discussion of methods.