Evidence-appraisal glossary
Attributable risk
Attributable risk is the extra risk of an outcome in an exposed group that can be ascribed to the exposure, calculated as the risk in the exposed minus the risk in the unexposed. It is the harm-side counterpart of absolute risk reduction and, unlike relative risk, is expressed in absolute terms.
Also called: risk difference, excess risk, attributable risk in the exposed.
Also called the risk difference or excess risk, attributable risk tells you how much of an exposed group's risk sits above the background level, which is what matters for judging the real impact of a harmful exposure. It is often turned into an attributable risk percent, the share of the exposed group's risk that the exposure accounts for. The number only equals the risk the exposure actually causes if the association is genuinely causal and free of confounding; a large relative risk on a tiny baseline can still mean a small attributable risk.
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This is a plain-language methodology definition for reading research. It is general education, not medical advice.