Population attributable risk

Population Attributable Risk
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Synonyms	Attributable Risk Percent in the Population
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Population Attributable Risk (PAR) is a measure used in epidemiology to quantify the proportion of disease incidence in a population that can be attributed to a specific risk factor. It provides insight into the public health impact of eliminating a risk factor from the population.

Definition

Population Attributable Risk is defined as the difference in the rate of a disease between the exposed population and the total population. It is expressed as a percentage and indicates the proportion of the disease that could be prevented if the risk factor were eliminated.

Formula

The formula for calculating PAR is:

PAR = (P_e * (RR - 1)) / (1 + P_e * (RR - 1))

Where:

• P_e is the proportion of the population that is exposed to the risk factor.
• RR is the relative risk of the disease associated with the risk factor.

Interpretation

PAR provides a measure of the public health impact of a risk factor. A higher PAR indicates a greater potential for reducing disease incidence by eliminating the risk factor. It is important to note that PAR assumes a causal relationship between the risk factor and the disease.

Applications

PAR is used in public health to prioritize interventions and allocate resources. It helps identify which risk factors have the greatest impact on disease burden and where preventive measures could be most effective.

Limitations

While PAR is a useful measure, it has limitations:

• It assumes a causal relationship between the risk factor and the disease.
• It does not account for confounding factors that may influence the association.
• It is dependent on the accuracy of the relative risk and the proportion of the population exposed.

Examples

Consider a population where 30% of individuals smoke, and the relative risk of developing lung cancer for smokers is 10. The PAR for smoking in relation to lung cancer can be calculated as follows:

PAR = (0.3 * (10 - 1)) / (1 + 0.3 * (10 - 1)) = 0.73 or 73%

This means that 73% of lung cancer cases in the population can be attributed to smoking.

See Also

• Relative Risk
• Risk Factor
• Epidemiology
• Public Health

External Links

• [Link to relevant public health resources]