Risk Factors

3 Key excerpts on "Risk Factors"

• 

  eBook - PDF

  Epidemiology

  Study Design and Data Analysis, Third Edition

  • Mark Woodward(Author)
  • 2013(Publication Date)
  • Chapman and Hall/CRC

    (Publisher)

  CHAPTER 3 Assessing Risk Factors 3.1 Risk and relative risk In epidemiology, we are often interested in evaluating the chance that an individual who possesses a certain attribute also has a specific disease. The most basic epidemi-ological measure is the probability of an individual becoming newly diseased given that the individual has the particular attribute under consideration. This is called the risk of disease; as defined in Section 1.1, the attribute considered is called the risk factor . Hence, risk measures the probability of disease incidence. Although risk is a useful summary of the relationship between risk factor and disease, it is not sufficient by itself for assessing the importance of the risk factor to disease outcome. For instance, we may find that 30% of a sample of women who use a particular type of contraceptive pill develop breast cancer, so the risk of breast cancer is 0.3 for pill users. This would seem impressive evidence implicating the pill, unless it transpired that a similar percentage of nonpill users have also developed breast cancer. As in most procedures in epidemiology, a comparison group is required; the simplest one to take here is the group without the risk factor. This leads to the definition of the relative risk (or risk ratio ) as the ratio of the risk of disease for those with the risk factor to the risk of disease for those without the risk factor. If the relative risk is above 1, the factor under investigation increases risk; if less than 1, it reduces risk. A factor with a relative risk less than 1 is sometimes referred to as a protective factor . In most cases, we shall use the general term ‘risk factor’ without specifying the direction of its effect. Sometimes (somewhat unnecessarily) risk is called absolute risk , to distinguish it from relative risk.

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  Cardiovascular Diseases

  Genetic Susceptibility, Environmental Factors and their Interaction

  • Nikolaos Papageorgiou(Author)
  • 2016(Publication Date)
  • Academic Press

    (Publisher)

  [1] use Risk Factors in this way to quantify an individual’s likelihood of developing disease within a given time period, such as the 5 or 10 years following the point of prediction. For the purposes of disease prediction, using such risk calculators, a risk factor need not play a causal role but must reliably associate with differences in disease risk.

  Figure 8.1  Relationships of Risk Factors with disease. A risk factor that has an observed association with disease risk may directly contribute to the causation of the disease endpoint (A). Alternatively, differences in the risk factor may merely reflect the presence of disease since the risk factor is influenced by the disease process itself, leading to a phenomenon known as “reverse causation” (B). Finally, a third variable related both to the risk factor and the disease may be the true causal mediator. This third variable is termed a confounder, and failure to recognize its presence may result in a causal role being erroneously ascribed to the initial risk factor (C).

  An observed association of a risk factor with disease risk may suggest etiological mechanisms underlying disease, and in this case a causal relationship is necessary to infer a role for the risk factor in disease pathogenesis. Closely related to this is the value of Risk Factors for indicating biological pathways that might be modulated either pharmacologically or through other interventions to prevent and treat disease. In order to act as a therapeutic or preventive target a risk factor must play a causal role in disease development.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Advances in Environmental Control Technology: Health and Toxicology

  • Paul Cheremisinoff(Author)
  • 1997(Publication Date)
  • Gulf Professional Publishing

    (Publisher)

  In less-developed countries, the lack of information on actual environmental Risk Factors is widespread. This refers also to persons with elevated risk levels such as radiologists and nuclear physicists. Usually the estimation of Risk Factors is limited to the measurements of exposure on ionizing radiation only. But according to the founder of ecotoxicology—Rene Truhaut, expert of WHO, FAO, EC, etc.—the ability of keeping homeostasis in an organism, including the risk of cancer incidence, is influenced by a synergistic Environmental Risk Factors on Cancer and Their Primary Prevention 31 effect of physical, chemical, biological, and other factors that directly or indirectly cause neoplastic diseases. Thus, at the same working exposure the risk can be dif-ferent depending on total exposure to all carcinogens, co-carcinogens, immunosup-pressors, and promoters of carcinogenesis out of work. That refers not only to the content of harmful ingredients in food (potentially pathogenic), but also the content of protective ingredients in the diet of a particular person as well as individual bio-logical susceptibility, which is defined genetically. These rules imply both the necessity of the development of interdisciplinary studies combined with the devel-opment of multifactorial risk analyses based on estimation of personal exposure. There are differences both in total exposure to complex environmental carcinogens as well as individual biological susceptibility. Thus, there is a trend to combine the assessment of the exposure on external factors with the biological monitoring of many different physiological, biochemical, biophysical, and other parameters char-acterized by an individual reaction. To minimize the risk of the occurrence of irreversible morphophysiological changes, it is necessary to develop interdisciplinary studies in larger and larger teams and combine them with the promotion of the methods of early detection of Risk Factors of cancer incidence.

  Sign up to read

  Learn more about book