Number needed to treat

Definition: 

The number of patients who need to be treated with a new treatment rather than the standard (control) treatment iin order for one additional patient to benefit. It is calculated as the inverse of the absolute risk reduction.

Definition: 

The number of pep[le who must participate in the treatment to save one life is the number needed to treat (NNT). This number can be easily derived from the absolute risk reduction. The number of people who needed to be treated to save one life is 111, because 9 in 1,000 deaths (which is about 1 in 111) are prevented by the drug.