Relative risk
- Slovak term: Slovenský termín
- As it relates to illness, it is a measure of association where the risk of an illness (attack rate) is compared between a group of exposed subjects and a group of unexposed subjects (WHO 2007).
- The relative risk is the ratio of the risk of occurrence of a disease among exposed people to that among the unexposed (Bonita et al. 2006).
Explanation
Example
The risk ratio is used in assessing the likelihood that an association represents a causal relationship. For example, the risk ratio of lung cancer in long-term heavy smokers compared with non-smokers is approximately 20. This is very high and indicates that this relationship is not likely to be a chance finding. Of course, smaller risk ratios can also indicate a causal relationship, but care must be taken to eliminate other possible explanations (Bonita et al. 2006).
The ratio of the risk of disease or death among an exposed population to the risk among an unexposed population. A value of 1 indicates an increased risk, provided the association is not subject to systematic or andom error. For example, a relative risk of 2.0 in a study of cancer risk in a population exposed to a drinking water contraminant indicates tht the risk of cancer is doubled among those exposed to the contaminant compard to those not exposed (Symons et al. 2000).
References
- Bonita, R., Beaglehold, R., Kjellstrom, T. 2006. Basic Epidemiology, Second Edition. World Health Organization.
- Symons, J. M., Bradley, L. C. Jr. and Cleveland, T. C. 2000. The Drinking Water Dictionary. American Water Works Association
- WHO (2007) Foodborne disease outbreaks: Guidelines for investigation and controal
