Which measure estimates the amount of disease in the population that would be prevented if exposure were eliminated?

• A. Relative risk
• B. Population Attributable Risk
• C. Population Attributable Fraction
• D. Attributable risk

Answer: (B)

This measure captures the actual amount of disease in the population that could be avoided by removing the exposure. It looks at the difference between what happens in the entire population and what would happen if everyone were unexposed, giving the number of cases (per unit population) that are attributable to the exposure.

Concretely, it’s the difference between the incidence in the total population and the incidence among the unexposed. If removing the exposure would bring the population’s incidence down to the level of the unexposed, the reduction in cases equals this measure. That’s why it’s described as the amount of disease that would be prevented overall, not a rate or proportion.

This is distinct from the attributable risk among the exposed, which only tells you how much extra risk the exposed group bears compared to the unexposed. It’s also different from the population attributable fraction, which expresses that preventable burden as a proportion of the total disease in the population rather than as an absolute amount. For questions about how many cases could be prevented by eliminating exposure, this absolute, population-wide measure is the right one.

Therefore, the correct concept is Population Attributable Risk.