Absolute risk reduction

An absolute comparison of risks: it tells you how much lower the modified risk is than the starting risk in absolute terms.

For example, in a randomized trial, women take drug × or a placebo. After 10 years:

Here are two ways to express this absolute risk reduction:

  • Drug × lowers the 10-year risk of breast cancer death by 0.1 percentage points.
  • For every 1,000 women who take drug × for 10 years (instead of a placebo), there will be 1 less breast cancer death.