Attributable fraction among the exposed explained

In epidemiology, attributable fraction among the exposed (AF_e) is the proportion of incidents in the exposed group that are attributable to the risk factor. The term attributable risk percent among the exposed is used if the fraction is expressed as a percentage.^[1] It is calculated as

AF _{e} = (I _{e} - I _{u)/I} _{e} = (RR - 1 ) / RR , where I _{e} is the incidence in the exposed group, I _{u} is the incidence in the unexposed group, and RR is the relative risk.^[2] It is used when an exposure increases the risk, as opposed to reducing it, in which case its symmetrical notion is preventable fraction among the unexposed.

Synonyms

Multiple synonyms of AF_e are in use: attributable fraction,^[3] relative attributable risk, attributable proportion among the exposed, and attributable risk among the exposed.^[4]

Similarly, attributable risk percent (ARP) is used as a synonym for the attributable risk percent among the exposed.

In climatology, fraction of attributable risk (FAR) is used to denote a proportion of adverse event risk attributable to the human influence on climate or other forcing factor.^[5]

See also

• Population Impact Measures
• Attributable fraction for the population

Notes and References

1. Book: Dictionary of Epidemiology - Oxford Reference. A Dictionary of Epidemiology . en. 10.1093/acref/9780199976720.001.0001. 2018-05-09. 2014. 9780199976720. Oxford University Press. Porta . Miquel .
2. Cole P, MacMahon B. November 1971. Attributable risk percent in case-control studies. Br J Prev Soc Med. 25. 4. 242–4. 10.1136/jech.25.4.242. 478665. 5160433.
3. Book: J., Rothman, Kenneth. Epidemiology : an introduction. 2012. Oxford University Press. 9780199754557. 2nd. New York, NY. 66. 750986180.
4. Book: P., Armitage. Statistical methods in medical research. 2002. Blackwell Scientific Publications. Berry, G. (Geoffrey), Matthews, J. N. S.. 9780470773666. 4th. Oxford. 683. 646751070.
5. Book: Climate science for serving society : research, modeling and prediction priorities. 2013. Springer. 9789400766921. Asrar, Ghassem . Hurrell, James W.. Dordrecht. 315. Attribution of Weather and Climate-Related Events. 851370783. Peter A. Stott . etal .