Number needed to treat

Abstract

The Number Needed To Treat (NNT) is a measure used in epidemiology to convey the effectiveness of an intervention. It is the average number of patients who need to be treated to prevent one bad outcome. It is the reverse of the Absolute Risk Reduction. The lower the NNT, the more effective the intervention. In this article we discuss the concept and limitations of this measure.

Keywords

• Number needed to treat
• odd's ratio
• randomized clinical trials
• relative risk reduction