# Population Attributable Risk (PAR)

**DOI:**https://doi.org/10.1007/978-1-4020-5614-7_2685

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## Synonyms

Attributable risk proportion

## Definition

Population attributable risk (*PAR*) is the proportion of the incidence of a disease in the population (exposed and unexposed) that is due to exposure. It is the incidence of a disease in the population that would be eliminated if exposure were eliminated.

The PAR is calculated by subtracting the incidence in the unexposed from the incidence in the total population (exposed and unexposed).

PAR is usually expressed as a percentage. The *PAR*% is calculated by dividing the population attributable risk (PAR) by the incidence in the total population and then multiplying the product by 100 to obtain a percentage.

PAR measures the potential impact of control measures in a population, and is relevant to decisions in public health.

In order to calculate PAR, the prevalence of exposure in the study population must be known or estimated (PAR = AR × prevalence of exposure to risk factor in the population).