Distribution of Risk Factors for Venous Thromboembolism in Blood Donors
Condition: Venous Thromboembolism; Risk Factor, Cardiovascular; Blood Type
MeSH terms: Thromboembolism; Venous Thromboembolism
Study type: Observational

Summary: 
      Venous thromboembolism occurs with an incidence of about 1 per 1000 per year in adults . The
      main consequences are death, recurrence, post-thrombotic syndrome and major bleeding due to
      anticoagulation. Mortality rates are lower among patients with idiopathic venous thrombosis
      and higher among those in whom thrombosis occurs in the presence of cancer.

      The risk increases with the age for unclear reasons. There are also differences in the
      incidence according to ethnicity; however, data in subjects of European ancestry are scarce.

      Several studies have documented an association between thrombosis and ABO group.
      Specifically, non-O blood groups have a higher risk of myocardial infarction, angina,
      peripheral vascular disease, cerebral ischemia and venous thromboembolism than O. While there
      are numerous studies carried out in patients who have already shown thromboembolic events,
      data on the incidence of risk factors in the healthy population are completely inadequate.

      Understanding the risk factors for venous thrombosis is necessary to maximize the prevention
      of this disease in individuals and groups of high-risk patients . For this purpose a
      self-administered questionnaire will be used. Data obtained by blood donors on exposure to
      risk factors will be used to set up a clinical score to validate in future studies to carry
      out in patients with VTE.
    

Detailed description: 
      Venous thromboembolism, defined by deep vein thrombosis (DVT) and / or pulmonary embolism
      (PE), occurs with an incidence of about 1 per 1000 per year in adult populations. Rates are
      slightly higher in men than women. About two-thirds of the episodes are manifested as DVT and
      one third as PE with or without DVT. The main consequences of venous thrombosis are death,
      recurrence, post-thrombotic syndrome and major bleeding due to anticoagulation. Thrombosis is
      also associated with impaired quality of life, especially when developing posttrombotic
      syndrome. The mortality rate within one month from an episode is about 6% in patients with
      DVT and 10% in those with PE. The mortality rate for PE was estimated to be around 30% in the
      studies that included the PE diagnosis of autopsy, pointing out that many PEs are not
      clinically recognized before death. Mortality rates are lower among patients with idiopathic
      venous thrombosis and higher among those in whom thrombosis occurs in the presence of cancer.

      Venous thrombosis is a most frequent disease in elderly patients with a low rate of about 1
      per 10,000 per year before the fourth decade of life, which increases rapidly after the age
      of 45 and approaches 5-6 per 1000 per year at the age of 80 years. In a study, the rate of
      events over a period of 8 years and in individuals over 85 years of age was 13 times greater
      than that of individuals between 45 and 55 years, with an absolute rate of 7 per 1000 per
      year and a greater mortality in older people. It is likely that thrombosis is less diagnosed
      in some debilitated elderly patients so that these estimates are probably underestimated. The
      reasons for an increased risk of thrombosis with age are not clear, but may include the
      increasing presence of other thrombotic diseases, increased coagulation potential, or some
      combination of these.

      There are also differences in the incidence of venous thrombosis diagnosed among lower-rate
      ethnic groups in the United States, Asians, Pacific Islanders, and Hispanics than Whites and
      with some studies showing an approximate rate of 25% higher in Afro-Americans. There is
      little information on the epidemiology of thrombosis in Europe.

      Several studies have documented an association between thrombosis and ABO group.
      Specifically, non-O blood groups have a higher risk of myocardial infarction, angina,
      peripheral vascular disease, cerebral ischemia and venous thromboembolism (VTE) than O,
      probably because factor VIII, factor von Willebrand is lower in group 0 patients. While there
      are numerous studies conducted on patients who have already shown thromboembolic events, data
      on the incidence of risk factors in the healthy population are completely inadequate.

      Understanding the risk factors for venous thrombosis is necessary to maximize the prevention
      of this disease in individuals and groups of high-risk patients . For this purpose blood
      donors will be requested to fill in a self-administered questionnaire. Healthy blood donors
      will be requested to give personal and family information regarding previous use of current
      of anticoagulant drugs, surgery, contraceptive use, pregnancy, previous blood transfusion.
      The presence of one or more risk factors will be used to set up a clinical score to validate
      in future studies on patients with previous VTE.
    

Intervention name(s): no intervention
Intervention type(s): Behavioral
Intervention description(s): no intervention
Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Blood donors consecutively observed