Attributable risk

Attributable risk is a measure of the amount of risk that is due to a particular factor or exposure. It is calculated by subtracting the risk of a control group from the risk of an experimental group and quantifying the difference. Attributable risk is expressed as a proportion or a percentage. For example, if the experimental group has a 10% risk of a certain health outcome, and the control group has a 5% risk of the same health outcome, the attributable risk is 5%. *Attributable risk can be used to determine the impact of a particular risk factor on a certain health outcome.* It is an important tool in epidemiologic studies and can be used to help inform public health policy decisions.

Example of Attributable risk

Attributable risk can be used to quantify the impact of a particular risk factor on a certain health outcome. For example, if there is an association between smoking and lung cancer, the attributable risk of smoking on lung cancer can be calculated. If the risk of lung cancer among smokers is 20%, and the risk of lung cancer among non-smokers is 10%, then the attributable risk of smoking is 10%. This means that 10% of the risk of lung cancer is due to smoking. *Attributable risk can be used to determine the impact of a particular risk factor on a certain health outcome, and is an important tool in epidemiologic studies and public health policy decisions.*

Formula of Attributable risk

Attributable Risk (AR) is defined mathematically as the the difference between the observed risk (OR) in the exposed group and the expected risk (ER) in the unexposed group. It is represented as:

AR = OR - ER

Using the example from above, the Attributable Risk is calculated as follows:

AR = 10% - 5% = 5%

Therefore, the attributable risk for this example is 5%, meaning that the difference between the two groups is 5%, and that this difference can be attributed to the risk factor.

When to use Attributable risk

Attributable risk is most useful when there are two groups for comparison, such as an experimental group and a control group. This is often seen in epidemiologic studies where researchers compare the risk of a certain health outcome in people who have been exposed to a certain risk factor, with the risk of the same health outcome in people who have not been exposed to the same risk factor.

Types of Attributable risk

There are two types of attributable risk, relative risk and absolute risk.

Relative risk is the ratio of the risk of an event occurring in the exposed group to the risk of the same event occurring in the unexposed group. It is expressed as a proportion and can range from 0 to infinity.

Absolute risk is the difference between the risk of an event occurring in the exposed group and the risk of the same event occurring in the unexposed group. It is expressed as a percentage and can range from negative infinity to positive infinity.

Steps of Attributable risk

1. Calculate the Risk in the Exposed Group: Calculate the risk of developing a specific health outcome in the exposed group. 2. Calculate the Risk in the Unexposed Group: Calculate the risk of developing the same health outcome in the unexposed group. 3. Subtract the Risk in the Unexposed Group from the Risk in the Exposed Group: Subtract the risk of developing the same health outcome in the unexposed group from the risk of developing the same health outcome in the exposed group. 4. Calculate the Attributable Risk: The result of the subtraction is the attributable risk and is expressed as a proportion or percentage.

Attributable risk is an important tool in epidemiologic studies as it helps to quantify the effect of a particular risk factor on a health outcome. This information can then be used to inform public health policy decisions.

Advantages of Attributable risk

• Attributable risk can be used to quantify the burden of disease attributable to a certain risk factor, which can help inform public health policy decisions.
• It can also be used to compare the risk of different factors, making it useful for identifying which factors are most important for reducing the risk of a certain health outcome.
• Additionally, calculating attributable risk can help to identify individuals who are at greater risk of a health outcome due to a particular risk factor, which can help to better target public health interventions.
• Finally, calculating attributable risk can help to identify potential areas of research to better understand the impact of a certain risk factor on a health outcome.

In conclusion, attributable risk is an important measure used in epidemiologic studies to quantify the amount of risk due to a particular factor or exposure. It can be used to compare the risk of different factors, identify individuals who are at greater risk of a health outcome due to a particular risk factor, and better inform public health policy decisions.

Limitations of Attributable risk

• Attributable risk is limited by the accuracy of the data used to calculate it. For example, if the data used to calculate risk is incomplete or inaccurate, the attributable risk will also be inaccurate.
• Additionally, it may be difficult to accurately measure the effect of a particular risk factor on the health outcome if there are other factors that may be influencing the outcome.
• Finally, attributable risk can only be used to measure relative risk, not absolute risk. This means that it can be used to determine the relative risk of a particular health outcome among different groups, but it cannot be used to determine the absolute risk of a particular health outcome.

In summary, attributable risk is an important tool for measuring the impact of a particular risk factor on a certain health outcome. However, its efficacy is limited by the accuracy of the data used to calculate it and the potential for other factors to influence the results. Additionally, it can only be used to measure relative risk, not absolute risk.

Other approaches related to Attributable risk

There are several other approaches related to Attributable risk that are used to measure the impact of various factors on health outcomes. These include:

• Odds ratio, which is the ratio of the odds of an outcome in an exposed group to the odds of an outcome in an unexposed group;
• Attributable fraction, which is the proportion of the incidence of a particular outcome in an exposed group that is attributable to the exposure; and
• Population attributable risk, which is the proportion of the total risk of a particular outcome that is attributable to a particular exposure. All of these measures are useful for understanding the impact of risk factors on health outcomes and determining the most effective interventions to reduce the risk of a particular outcome.

In summary, Attributable risk is a measure of the amount of risk that is due to a particular factor or exposure. It is an important tool in epidemiologic studies and is used to measure the impact of various factors on health outcomes. Relative risk, odds ratio, attributable fraction, and population attributable risk are all related approaches that are also used to measure the impact of various factors on health outcomes.

Attributable risk — recommended articles

Standardized regression coefficients — Residual standard deviation — Autocorrelation — Hierarchical regression analysis — Measurement uncertainty — Statistical significance — Asymmetrical distribution — Index of diversity — Analysis of covariance

References

• Cole, P., & MacMahon, B. (1971). Attributable risk percent in case-control studies. British journal of preventive & social medicine, 25(4), 242.
• Claus, E. B., Schildkraut, J. M., Thompson, W. D., & Risch, N. J. (1996). The genetic attributable risk of breast and ovarian cancer. Cancer: Interdisciplinary International Journal of the American Cancer Society, 77(11), 2318-2324.
• Li, Z., Page, A., Martin, G., & Taylor, R. (2011). [Attributable risk of psychiatric and socio-economic factors for suicide from individual-level, population-based studies: a systematic review]. Social science & medicine, 72(4), 608-616.