What is attributable fraction in epidemiology?
In epidemiology, attributable fraction for the population (AFp) is the proportion of incidents in the population that are attributable to the risk factor. The term attributable risk percent for the population is used if the fraction is expressed as a percentage.
What is a attributable risk in medical terms?
Listen to pronunciation. (uh-TRIH-byoo-tuh-bul …) Proportion of a disease in exposed individuals that can be attributed to an exposure. In the context of genetic studies, the “exposure” is the frequency of a specific genetic variant.
What is the difference between attributable risk and attributable fraction?
Attributable Risk(AR) (sometimes called Attributable Proportion or Attributable Fraction) is a measure of the prevalence of a condition or disease. Given a group of people exposed to a risk, it’s the fraction who develop a disease or condition.
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.
What does attributable risk tell you?
Attributable risk helps you determine how much of an outcome may be attributable to a particular risk factor (i.e. an estimate of the excess risk) in a population exposed to that factor.
What is attributable disease burden?
The attributable burden is the share of the burden of disease that can be estimated to occur due to exposure to a particular risk factor.
How do you interpret attributable proportions?
Attributable Proportion Among the Exposed 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 do you calculate population attributable risk fraction?
PAR is usually expressed as a percentage. The PAR% is calculated by dividing the population attributable risk (PAR) by the incidence in the total population and then multiplying the product by 100 to obtain a percentage.
What is an example of attributable risk?
This means 17.31% of incidence of cardiovascular disease in the population is attributable to smoking. In other words, if smoking were eliminated in the population then we would expect to see a 17.31% reduction in cases of cardiovascular disease.
Which is the best index for burden of disease?
Probably the most well-known assessment of disease burden is the Global Burden of Disease (GBD) Study carried out by the World Health Organisation. GBD researchers first devised the concept of DALYs.
How is disease burden measured?
The sum of mortality and morbidity is referred to as the ‘burden of disease’ and can be measured by a metric called ‘Disability Adjusted Life Years’ (DALYs).
What does population attributable risk measure?
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.
How is attributable risk used in epidemiology?
Attributable Risk (AR) The term attributable risk is used below to refer to the excess incidence of disease in those exposed to a given (causal) factor, and AR% is the percentage of the incidence of a disease in the exposed that would be eliminated if exposure were eliminated; it is sometimes expressed as a proportion.
Is attributable risk the same as risk difference?
Attributable risk (AR) or risk difference is the difference between the incidence rates in exposed and non-exposed groups. In a cohort study, AR is calculated as the difference in cumulative incidences (risk difference) or incidence densities (rate difference).
What is a Level 3 cause of death?
Level 3 includes specific causes such as tuberculosis, stroke, and road injuries.
What is attributable fraction for the population?
Attributable fraction for the population combines both the relative risk of an incident with respect to the factor, as well as the prevalence of the factor in the population. Values of AF p close to 1 indicate that both the relative risk is high, and that the risk factor is prevalent.
What is an attributable fraction of risk?
attributable fraction. The percentage of instances of an illness that can be accounted for by a particular risk factor. For example, people exposed to asbestos have a certain risk of developing lung cancer, and if they also smoke tobacco, they are also at risk from that factor.
What are the two types of attributable fractions?
Rothman explains that there are two major classes of attributable fractions. (Rothman, Greenland et al. 2008) Excess fractions measure the number of excess cases of disease due to a specific exposure of interest. Etiologic fractions measure the number of cases of disease due to a specific exposure of interest.
How do you calculate sequential attributable fraction?
By removing exposures in turn, it is possible to calculate a sequential attributable fraction by subtracting the adjusted attributable fraction with only the first exposure removed from the adjusted attributable fraction with both the first and second exposures removed.