Risk factor

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Risk factor

A risk factor is a variable associated with an increased risk

Risk

Risk is a concept that denotes the precise probability of specific eventualities. Technically, the notion of risk is independent from the notion of value and, as such, eventualities may have both beneficial and adverse consequences....
of disease

Disease

A disease or medical condition is an abnormal condition of an organism that impairs bodily functions, associated with specific symptoms and Medical signs....
or infection

Infection

An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host resources to multiply ....
. Risk factors are correlational

Correlation

In probability theory and statistics, correlation indicates the strength and direction of a linear relationship between two random variables....
and not necessarily causal

Causality

Causality denotes a necessary relationship between one event and another event which is the direct consequence of the first.While this informal understanding suffices in everyday use, the Philosophy analysis of how best to characterize causality extends over millennia....
, because correlation does not imply causation. For example, being young cannot be said to cause measles

Measles

Measles is a infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus. Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses....
, but young people are more at risk as they are less likely to have developed immunity

Immunity

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Encyclopedia

A risk factor is a variable associated with an increased risk

Risk

Disease

A disease or medical condition is an abnormal condition of an organism that impairs bodily functions, associated with specific symptoms and Medical signs....
or infection

Infection

Correlation

In probability theory and statistics, correlation indicates the strength and direction of a linear relationship between two random variables....
and not necessarily causal

Causality

Measles

Immunity

Immunity may refer to:* Immunity , resistance of an organism to infection, disease, or other unwanted biological invasion* Immunity , exclusion from legal obligations, such as liabilities and punishments...
during a previous epidemic.

Risk factors are evaluated by comparing the risk of those exposed to the potential risk factor to those not exposed. Let's say that 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, suggesting that eating chicken was the cause of the illness. Note, however, that this is not proof. Statistical

Statistics

Statistics is a Mathematics pertaining to the collection, analysis, interpretation or explanation, and presentation of data. It also provides tools for prediction and forecasting based on data....
methods would be used in a less clear cut case to decide what level of risk the risk factor would have to present to be able to say the risk factor is linked to the disease (for example in a study

British Doctors Study

The British doctors study is the generally accepted name of a prospective cohort study which has been running from 1951 to 2001, and in 1956 provided convincing statistical proof that tobacco smoking increased the risk of lung cancer....
of the link between smoking and lung cancer). Even then, no amount of statistical analysis could prove that the risk factor causes the disease; this could only be proven using direct methods such as a medical explanation of the disease's roots.

The earliest use of risk factor analysis dates back to Avicenna

Avicenna

, known as Abu Ali Sina Balkhi or Ibn Sina and commonly known in English by his Latinized name Avicenna , was a Persian people polymath and the foremost Islamic medicine and Early Islamic philosophy of his time....
's The Canon of Medicine
The Canon of Medicine

The Canon of Medicine is a 14-volume Islamic medicine written by a Science in medieval Islam and physician Avicenna and completed in 1025....
(1020s), though the term "risk factor" was first coined by heart researcher Dr. Thomas R. Dawber in a landmark scientific paper in 1961, where he attributed heart disease

Heart disease

Heart disease is an umbrella term for a variety for different diseases affecting the heart. As of 2007, it is the leading cause of death in the United States, England, Canada and Wales, killing one person every 34 seconds in the United States alone....
to specific conditions (blood pressure

Blood pressure

Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through artery and capillary, and toward the heart through veins....
, cholesterol

Cholesterol

Cholesterol is a lipidic, waxy alcohol found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and membrane fluidity....
, smoking

Tobacco smoking

Tobacco smoking is the inhalation of smoke from burned dried or cured leaves of the tobacco plant, most often in the form of a cigarette. People may smoke casually for pleasure, habitually to satisfy an addiction to the nicotine present in tobacco and to the act of smoking, or in response to social pressure....
).

Risk factor

See also