Number needed to treat (NNT)

Ann Emerg Med. 1999 Apr;33(4):433-6. doi: 10.1016/s0196-0644(99)70308-2.


Because decisions regarding therapy are so common in clinical practice, the application of number needed to treat (NNT) is one of the most important evidence-based medicine skills to be acquired. NNT provides a clinically useful "yardstick" of the effort required to have a beneficial outcome or prevent a bad outcome with a therapy. A brief overview of the concept, derivation, and application of NNT is presented.

MeSH terms

  • Clinical Trials as Topic / statistics & numerical data*
  • Emergency Medical Services / statistics & numerical data*
  • Evidence-Based Medicine / statistics & numerical data*
  • Humans
  • Outcome and Process Assessment, Health Care*
  • Risk Assessment
  • Treatment Outcome