Attributable Risk (AR)

Attributable risk, also known as risk difference or excess risk, is a concept in medical statistics and epidemiology that measures the contribution of a specific risk factor to the occurrence of a given outcome or disease in a population. It is used to understand the public health impact of eliminating a risk factor and to prioritize healthcare interventions.

• Attributable Risk (AR): It is the difference in the rate of a condition between an exposed population and an unexposed population.
• AR = Incidence in Exposed Group (Ie) - Incidence in Unexposed Group (Iu).
• 
  

Calculation

• The formula for Attributable Risk (AR) is

  AR=Ie−Iu

  where:

  • Ie is the incidence of the disease in the exposed group.
  • Iu is the incidence in the unexposed group.
  
  

• A positive AR indicates that the exposure is associated with an increased risk of the disease.
• A negative AR suggests that the exposure might be protective against the disease.

Attributable Risk Percent

• This is another related measure, calculated as $$AR\mathrm{\%}=\frac{AR}{I{R}_E}\times 100$$
• $$\mathrm{<br>}$$
• $$AR\% = \frac{AR}{IR_E} \times 100$$represents the proportion of the disease in the exposed group that can be attributed to the exposure.

• ARP provides a direct...