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number needed to harm

— The number of people who would need to be treated over a specific period of time before one bad outcome of the treatment will occur



Full explanation:

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.

See also:

adverse effects  ·  number needed to treat

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