Show Me the Evidence: Using Number Needed to Treat

Abstract
This article reviews one of the basic tools of evidence-based medicine, the calculation and interpretation of Number Needed to Treat (NNT) and Number Needed to Harm (NNH). Especially appealing is the simplicity of extracting this information from journal articles that report binary outcomes, such as medication response or emergence of adverse events. On-line resources and calculators can help the...