The NNT is the number of patients who need to be treated in order to prevent one additional bad outcome. So, the number of patients that need to be treated for one person to benefit when compared with a control in a clinical trial. When reading literature on prescription drugs and other interventions, this number has to often be calculated by hand – although many times it’s the most telling part of the intervention being studied or suggested.

A group of Emergency Medicine physicians have created a fantastic website that focuses on the NNT (Number Needed to Treat). The layout of the website is impressive, and it’s extremely easy to use.  Above is a screen clipping from the website of a popular cardiac intervention broken down with the NNT method.  These calculations are defined in greater detail on the website with source literature cited.  While we often times remember how many are helped – we often times forget that even though negative outcomes are small – they need to be taken into account, as these calculations show.

Continue on for a video explaining the NNT

TheNNT website

A thanks to Gary Schwitzer for pointing out this great resource, the author of the venerable blog,