NNT

Medical abbreviation · Medical Research

NNT stands for Number needed to treat, a medical research abbreviation.

Average number of patients who must receive a treatment over a stated period for one additional patient to benefit compared with the control, calculated as 1 divided by the absolute risk reduction. Smaller numbers indicate more effective treatments; an NNT of 1 would mean every treated patient benefits.

Example: Over five years, the NNT to prevent one heart attack with the statin was 50.

Usage notes

Introduced by Laupacis, Sackett and Roberts in 1988 to make trial results easier to apply at the bedside. An NNT is meaningful only with its comparator, outcome and time frame stated. Because it depends on baseline risk, the same drug has a lower NNT in high-risk patients than in low-risk ones.

Related abbreviations

More medical research abbreviations

• MeSH – Medical Subject Headings
• MHRA – Medicines and Healthcare products Regulatory Agency
• NCT – National Clinical Trial (number)
• NICE – National Institute for Health and Care Excellence
• NME – New molecular entity
• NNH – Number needed to harm
• NPV – Negative predictive value
• NS – Not significant (statistically)
• ODD – Orphan drug designation
• OHRP – Office for Human Research Protections
• OR – Odds ratio
• PBO – Placebo

See all 94 medical research abbreviations →

Edited by the AbbreviationList.com team. Spotted an error or a missing meaning? Contact us.

This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.