Attributable Risk

Definition: Assuming a factor is the cause of a disease, attributable risk is the amount of risk that is due to that factor. In other words, it is the amount of risk reduced if the factor is removed. Another way to say this is attributable risk is the difference in risk between exposed and unexposed people.

Example: In this example, non-smokers are expected to develop lung cancer at a rate of 10 cases of lung cancer per 100,000 people per year. Among smokers, the rate of lung cancer is 100 cases of lung cancer per 100,000 people per year. This is an excess risk or attributable risk of 90 per 100,000 per year.

Risk of developing lung cancer

  • for non-smokers: 0.0001
  • for current smokers: 0.001

Attributable Risk =

0.001 - 0.0001 = 0.0009