Preventive fraction

Preventive fraction (PF), also called preventable fraction, is a calculation that can be derived from relative risk or odds ratio.

It may be used when an exposure seems to reduce the risk (in opposition to attributable risk percent), and gives the percentage of cases that can be prevented if a population is exposed to an intervention, compared to an unexposed population.

It can be calculated as ( 1 &minus; relative risk ) or as ( 1 &minus; odds ratio ).