Number Needed to Treat (NNT)

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concepts

Number needed to treat (NNT) is a clinical epidemiology measure describing how many patients must receive a given treatment, on average, to prevent one additional adverse outcome (such as a disease diagnosis or death) compared with not treating them. It is calculated as the inverse of the absolute risk reduction between a treated and untreated (or placebo) group. A lower NNT indicates a more efficient, more targeted therapy, and NNT is commonly used to judge whether a preventive intervention is practical to deploy across a population versus only in a biomarker-defined higher-risk subgroup.

Source papers

  • Plasma signals of lung tumor promotion for molecular cancer prevention Tej Pandya, Maria Zagorulya, Michelle M. Leung, et al., William Hill, Clare E. Weeden, Charles Swanton · 2026 doi:10.1016/j.cell.2026.05.005