To evaluate the trends in the incidence of venous thromboembolism, to determine the risk
factors for venous thromboembolism in patients with medical and surgical illness, and to
evaluate the efficacy of the anticoagulant therapy in reducing venous thromboembolism.
Venous thromboembolism (VTE) occurs frequently among patients hospitalized for major surgery
or hospitalized for a medical illness primarily due to prolonged duration of immobilization.
However, many patients undergo major surgery without any occurrence of VTE. Standard
prophylactic therapy after surgery is heparin, which reduces the risk of VTE. However,
heparin is associated with bleeding complications. Thus, it would be desirable to identify
patients at high risk for VTE who might benefit the most from heparin therapy. An important
focus of the study is to look at genetic factors which might play an important role in VTE
The study is a population based, retrospective case and case-control investigation of the
genetic and environmental determinants of venous thromboembolism in the Rochester Minnesota
Olmsted County population. The first five years of the study had three specific aims. The
first specific aim was to update the 1966-1995 inception cohort to include Olmsted County
residents with VTE during the five year period, 1996-2000. The second aim was to extend the
analysis of risk factors for VTE by identifying two Olmsted County residents (controls)
without VTE matched by age and gender to each definite or probable case within the 1996-2000
cohort, and to obtain plasma and genomic DNA from all cases and controls and perform a
case-control study. The third specific aim was to evaluate the efficacy of anticoagulant
therapy to prevent VTE recurrence.
The study was extended through March, 2009 to investigate trends in the incidence of venous
thromboembolism, new risk factors including lipid-lowering, beta-blocker, and ACE-inhibitor
therapies, and introduction of low molecular weight heparin (LMWH) therapy.