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Variable associated with an increased risk of disease or infection From Wikipedia, the free encyclopedia
In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection.[1]: 38
![]() | This article needs attention from an expert in medicine. The specific problem is: defining, "determinant," a complicated, poorly harmonized concept in medicine. Some sources use the term loosely while others use it as a technical term.. (July 2019) |
Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often used as a synonym. The main difference lies in the realm of practice: medicine (clinical practice) versus public health. As an example from clinical practice, low ingestion of dietary sources of vitamin C is a known risk factor for developing scurvy. Specific to public health policy, a determinant is a health risk that is general, abstract, related to inequalities, and difficult for an individual to control.[2][3][4] For example, poverty is known to be a determinant of an individual's standard of health.
Risk factors may be used to identify high-risk people.
Risk factors or determinants are correlational and not necessarily causal, because correlation does not prove causation. For example, being young cannot be said to cause measles, but young people have a higher rate of measles because they are less likely to have developed immunity during a previous epidemic. Statistical methods are frequently used to assess the strength of an association and to provide causal evidence, for example in the study of the link between smoking and lung cancer. Statistical analysis along with the biological sciences can establish that risk factors are causal. Some prefer the term risk factor to mean causal determinants of increased rates of disease, and for unproven links to be called possible risks, associations, etc.[citation needed]
When done thoughtfully and based on research, identification of risk factors can be a strategy for medical screening.[5]
Mainly taken from risk factors for breast cancer, risk factors can be described in terms of, for example:
At a wedding, 74 people ate the chicken and 22 of them were ill, while of the 35 people who had the fish or vegetarian meal only 2 were ill. Did the chicken make the people ill?
So the chicken eaters' risk = 22/74 = 0.297
And non-chicken eaters' risk = 2/35 = 0.057.
Those who ate the chicken had a risk over five times as high as those who did not, that is, a relative risk of more than five. This suggests that eating chicken was the cause of the illness, but this is not proof.
This example of a risk factor is described in terms of the relative risk it confers, which is evaluated by comparing the risk of those exposed to the potential risk factor to those not exposed.
The probability of an outcome usually depends on an interplay between multiple associated variables. When performing epidemiological studies to evaluate one or more determinants for a specific outcome, the other determinants may act as confounding factors, and need to be controlled for, e.g. by stratification. The potentially confounding determinants varies with what outcome is studied, but the following general confounders are common to most epidemiological associations, and are the determinants most commonly controlled for in epidemiological studies:[citation needed]
Other less commonly adjusted for possible confounders include:
A risk marker is a variable that is quantitatively associated with a disease or other outcome, but direct alteration of the risk marker does not necessarily alter the risk of the outcome. For example, driving-while-intoxicated (DWI) history is a risk marker for pilots as epidemiologic studies indicate that pilots with a DWI history are significantly more likely than their counterparts without a DWI history to be involved in aviation crashes.[13]
The term "risk factor" was coined by former Framingham Heart Study director, William B. Kannel in a 1961 article in Annals of Internal Medicine.[14]