What is Attributable Risk?
Attributable Risk (AR), also known as Risk Difference, measures the excess risk of disease or outcome that can be attributed to a specific exposure. It represents the absolute difference in incidence rates between exposed and non-exposed groups.
Formula
The formula for Attributable Risk is:
$$\text{AR} = I_{e} - I_{u}$$
Where:
- Iโ = Incidence rate in the exposed group
- Iแตค = Incidence rate in the non-exposed (unexposed) group
How to Use This Calculator
- Enter the Incidence Rate in Exposed Group (Iโ) - the proportion of exposed individuals who develop the outcome
- Enter the Incidence Rate in Non-Exposed Group (Iแตค) - the proportion of non-exposed individuals who develop the outcome
- Click Calculate to get the Attributable Risk
The result shows the excess risk attributable to the exposure.
Example Calculation
Given:
- Incidence Rate in Exposed Group = 0.05 (5%)
- Incidence Rate in Non-Exposed Group = 0.0133 (1.33%)
Calculation:
$$\text{AR} = 0.05 - 0.0133 = 0.0367$$
Result: The attributable risk is 0.0367 or 3.67%, meaning that 3.67% of the disease incidence in the exposed group can be attributed to the exposure.
Interpretation
- Positive AR: Indicates the exposure increases risk (harmful exposure)
- Negative AR: Indicates the exposure decreases risk (protective exposure)
- AR = 0: Indicates no association between exposure and outcome
Attributable Risk is particularly useful in public health for:
- Estimating the disease burden attributable to a specific risk factor
- Prioritizing interventions
- Assessing the potential impact of removing an exposure
Applications
- Epidemiological studies: Assessing environmental or behavioral risk factors
- Occupational health: Evaluating workplace exposures
- Public health policy: Determining intervention priorities
- Clinical research: Understanding treatment effects in absolute terms