Interpreting and using clinical trials

In 1754, aboard HMS Salisbury, James Lind conducted a simple, controlled clinical trial. He took 12 patients with "pale and bloated skin, listlessness, an aversion to exercise, swollen gums, halitosis, ecchymotic mucous membranes, and limb edema" and allocated them to receive treatment with one of six different therapies. Since the patients receiving two of his six chosen interventions had such a dramatic recovery, he felt ethically obligated to end his trial and administer these treatments to all the remaining sailors. Today we fully recognize the impact that the controlled clinical trial can have on the development of new interventions. Unfortunately, very few of these interventions are likely to have as dramatic an impact on outcomes as lemons and oranges did on scurvy. Because the interventions we study tend to have relatively small treatment effects, and because the design and reporting of published RCTs has consistently been documented to be less than perfect, there is a real need for us to develop critical appraisal skills. This article is by no means the only approach to critical appraisal, but hopefully it serves as an adequate starting point for the journey.