Browse the glossary:
NNH, NNTH
The number needed to harm is an estimate of how many people need to receive a treatment before one person would experience a bad outcome.
For example, if a study found that for every 100 participants allocated to a drug, there was one additional death over a period of one year compared to every 100 people allocated to a placebo, the number needed to harm would be 100 for one year.
adverse effects · number needed to treat
If you feel that this definition hasn't helped you to understand the term, click on our monkey to let us know.