Table of Contents

## How do you calculate population attributable risk percentage?

Calculating the population attributable risk percent allows you to determine what percent of an outcome could possibly be prevented if a risk factor were to be removed from the population. To calculate the attributable risk, one simply subtracts the risk for the non-exposed group from the risk for the exposed group.

**What is the formula for attributable risk?**

Attributable risk (AR) is the risk difference between exposed and unexposed groups. In equation form (Table 1) it is Risk(exposed)−Risk(unexposed)=[A/(A+B)]−[C/(C+D)]. It is the quantity of disease that one could hope to avoid by removal of the risk factor in question.

**What is population attributable risk in epidemiology?**

Population Attributable Risk (PAR) is the porportion of the incidence of a disease in the population (exposed and nonexposed) that is due to exposure. PAR is the difference between the risk in the total population and that in unexposed subjects.

### What is population attributable risk fraction?

Definition: The population attributable fraction is the proportional reduction in population disease or mortality would occur if exposure to a risk factor were reduced to an alternative ideal exposure scenario.

**What is attributable risk example?**

Often, attributable risk is given as a percentage (called the attributable risk percent or AR%). For example, lung cancer has many causes, including smoking cigarettes and exposure to indoor radon. One study showed that the AR% for cigarette smoking and lung cancer was 85%.

**How do you calculate population risk difference?**

The risk difference is calculated by subtracting the cumulative incidence in the unexposed group (or least exposed group) from the cumulative incidence in the group with the exposure.

## How do you calculate attributable proportion?

It is calculated by taking the risk difference, dividing it by the incidence in the exposed group, and then multiplying it by 100 to convert it into a percentage.

**How is attributable fraction calculated?**

The attributable fraction is calculated as the sum of the category-specific differences between observed and expected, divided by the sum of the observed numbers. There are 162 deaths in this example, but if there were no excess risk associated with overweight, there would be 150 deaths.

**Can PAF be negative?**

While in general PAF can be negative, here we assume that the risk factor has been coded so that P(Y = 1) > P(Ya = 0 = 1), which is usually implied if a = 0 indicates absence of the risk factor.