Basics of methodologic analysis of therapeutic trials. Part I: Validity of the results.

One of the most compelling questions a cardiologist (and, for that matter, any clinician) has to face involves choosing the optimal management strategy for their patients. One of the best sources of information about therapy is the randomized controlled trial, which, despite several significant shortcomings, is considered to be the gold standard in studies about therapeutics and prevention. The methodological quality of therapeutic trials is highly variable and--as already discussed in previous articles--in order to be useful they have to be critically appraised in terms of the validity of their results, their importance, and their applicability to the individual patient. In this article, we will introduce guidelines for the critical appraisal of evidence in therapy, discussing the issue of validity. In future articles we will present a critical appraisal of the importance and applicability of randomized clinical trial results.