True about confounding factor:
It is itself a risk factor for the disease Ref- Park 20/e p68; 19/e p67 Epidemiological studies search for the causes of diseases, based on associations with various risk factors that are measured in the study. In addition to the exposures that the study is investigating, there may be other factors that are associated with the exposure and are also risk factors for the disease. If the prevalence of these other factors differs between groups being compared, they will disto the observed association between the disease and exposure under study. Such variables may paially or completely account for any apparent association between an exposure variable and disease. These distoing factors are called confounding factors or variables. Thus a Confounding factor is defined as one which is associated with both the exposure and the disease and is distributed unequally in study and control groups. It is itself a risk.factor.for the disease. A hypothetical example would be a study of coffee drinking and lung cancer. If coffee drinkers were also more likely to be cigarette smokers, and the study measured coffee drinking but not smoking, the results may seem to show that coffee drinking increases the risk of lung cancer, which may not be true. However, if a confounding factor (in this example, smoking) is recognized, adjustments can be made in the study design or data analysis so that the factor does not confound the study results. Confounding can be neutralized by matching. Matching is defined as the process by which we select control in such a way that they are similar to cases With regard to confounding factors
It is found equally between study and the control groups
It is itself a risk factor for the disease
Confounding can be eliminated by selecting a small group
It is associated with either the exposure or the disease