Risk factor

In medicine, a risk factor is understood to be an increased probability of acquiring a certain disease if certain physiological or anatomical characteristics, genetic predispositions or environmental constellations are present. The characteristics themselves are referred to, for example, as disposition (to a disease), the environmental influences as exposure; the increase in probability is expressed as a mathematical factor.

The concept of risk factor is presented in epidemiologically precise terms by means of descriptive statistics. The characteristics of two groups are compared with the frequency of a particular disease. This resulting factor (expressed as an odds ratio or relative risk) indicates how many times more often a disease occurs with a certain characteristic or constellation compared to a control group. A risk factor greater than 1 means an increased risk compared to the control group, a risk factor between 0 and 1 means a reduced risk.

The statistically determined risk factor is no proof of an actual, causal relationship between characteristic and disease, since it represents a purely descriptive measure of an observed frequency. In this respect, the determination of risk factors is only able to provide indications of a possible cause of a disease (aetiology). However, it does not prove or explain it. The causal relationship is often known in the case of diseases that carry an increased risk of developing a second disease. This is also referred to as an underlying disease and the risk of a secondary disease (secondary condition). A well-studied example is the increased risk of developing renal insufficiency with diabetes mellitus.

Risk constellations that are frequently studied and taken up in the media are, for example, excessive alcohol consumption, obesity, diet, lack of exercise and tobacco smoking, which are associated with other changing risk factors for specific diseases. Linguistically, the term risk factor is used incorrectly here. Often an unproven or unprovable causal relationship between a single factor and a disease is assumed and this is presented (unscientifically) as a risk factor. Frequently, the characteristic itself is also incorrectly described as a risk factor and not the frequency, for example in formulations such as "smoking is a risk factor for bronchial carcinoma". The correct statement would be that smokers have a risk factor of 7.8 for the occurrence of bronchial carcinoma.

Some risk factors - such as chronic anger, which is an even stronger predictor of heart disease than, say, high blood pressure - have been scientifically proven, but play little role in social discourse.

See also

• Protection factor
• Health determinant