# Relative, Attributable, and Population Attributable Risks

Explain the difference between relative risk, attributable risk, and population attributable risk.
Provide an example (not from the textbook) of how each type of risk is used in epidemiology. How
would you propose using population attributable risk to advocate for a health policy or
intervention relative to your health interest?

Relative, Attributable, and Population Attributable Risks

Relative Risk

Relative risk a ratio which is used to show the probability of an outcome in an exposed and
unexposed group in a disease. Moreover, it shows the strength, relationship and the association
between a condition or its factors and the outcomes of the same in a group of individuals who have
been exposed to a condition and another that has not been exposed. Its application is in cohort
studies, randomized trials, cross-sectional, and experimental studies to bring out the relationship
and associations (Noordzij, Van Diepen, Caskey, & Jager, 2017) . Moreover, it can be estimated from
two by two contingency table. An example of its application is the randomized clinical trials using a
medicament and a placebo to find out its efficacy in the treatment of a condition.

Attributable Risk

The attributable risk is calculated from prospective data and is related to the relative risk but
is the difference between the incidence rate in exposed and unexposed groups in a set of data to
show the prevalence of a condition. Furthermore, it is given as a percentage to the relationship
between a risk factor and the outcome of the disease. It also denotes the number of exposure cases
reported when the risk factor is eliminated in an ailment (Sjolander, 2016) . An example of its
application is that hypothetically, smoking causes 85% of the lung cancers cases seen, and hence, the
attributable risk represented as a percentage is 85%. It denotes that when smoking as a risk factor to
lung cancer is eliminated, there would be the eradication of 85% of the total lung cancer cases
recorded.

Population Attributable Risk

Population attributable risk is a proportion of the incidence of the disease in the exposed
and unexposed populations, which is brought about by exposure to the condition and is expressed
as a percentage. In addition, it denotes the portion of the population that would be eliminated if the
condition was eliminated in a given demographic (Zapata-Diomedi, Barendregt, & Veerman, 2016) . It
is calculated by subtracting the incidence rate in the exposed from that of the unexposed and then
dividing the results by the incidence rate in the total population and hence expressed as a
percentage. Furthermore, it is applied in public health with an example being how effective the
prevention measures of suicides have been effective in the prevention of actual suicides carried out
in the community.

RISK TERMINOLOGY IN EPIDEMIOLOGY 2

References

Noordzij, M., Van Diepen, M., Caskey, F. C., & Jager, K. J. (2017). Relative risk versus absolute risk:
One cannot be interpreted without the other. Nephrology Dialysis Transplantation,
32(supp_2), ii13-ii18.
Sjolander, A. (2016). A cautionary note on the use of attributable fractions in cohort studies.
Statistical Methods in Medical Research, 25(6), 2434-2443.
Zapata-Diomedi, B., Barendregt, J. J., & Veerman, J. L. (2016). Population attributable fraction:
names, types and issues with incorrect interpretation of relative risks. British Journal of
Sports Medicine, 52(4), 212-213.