riskfactor

A risk factor is a characteristic, condition, or exposure that is associated with an increased probability of a disease or other adverse health outcome. It is not a guarantee of that outcome, and many people with a risk factor never develop the condition. Risk factors can be biological, behavioral, environmental, or social, and they may be modifiable or non-modifiable.

Common examples include age and family history (non-modifiable factors) and smoking, poor diet, physical inactivity, high blood pressure, and obesity (modifiable factors) in relation to cardiovascular disease. Other risk factors cover exposure to carcinogens, excessive sun exposure, or chronic stress, which can influence cancer and other illnesses. Socioeconomic status and access to care also act as risk factors for a range of conditions.

Risk factors are identified and studied through epidemiologic research. Measures such as relative risk, hazard ratio, and odds ratio quantify the strength of associations between a factor and an outcome. Population-attributable risk estimates the portion of disease that could be avoided if the factor were eliminated. Risk prediction models combine multiple factors to estimate an individual’s absolute risk over a given time frame.

Implications and limitations: recognizing risk factors informs screening, prevention, and counseling, and helps allocate public health resources. However, association does not imply causation, and residual confounding or measurement error can bias results. Risk factors describe population-level associations and may not perfectly predict risk for an individual.

The term is used beyond health to describe factors that influence financial, safety, or project risk in other fields as well.