Interpreting Number Needed to Treat

Kevin Shea, MD; Jayson Murray, MA; and Peter Shores, MPH

What is the number needed to treat (NNT)? How does it relate to orthopaedic practice and, ultimately, orthopaedic patient outcomes?

Quite simply, the NNT tells how many patients would need to be treated to prevent one adverse outcome for a particular intervention. A perfect NNT would be 1; this would mean that for every person treated, there would be a reduction of one adverse outcome.

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