Attributable fraction among the exposed
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In epidemiology, attributable fraction among the exposed (AFe) 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 , where is the incidence in the exposed group, is the incidence in the unexposed group, and 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.