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Number Needed to Treat

The number needed to treat (NNT) is defined as the number of patients that would need to be treated to prevent an adverse outcome in one additional patient compared with control treatment over a specified time period. The term was first introduced in 1988 by Andreas Laupacis, David Sackett, and Robin Roberts as the number needed to be treated but has been shortened to number needed to treat or its abbreviation NNT.

In medicine and other clinical practices, the well-performed randomized clinical trial is often considered the gold standard for judging the effectiveness of therapeutic interventions. The outcome measures from such studies are reported in many ways that involve both group and individual patient outcomes. An example of the former might be the mean reduction in ...

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