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.

BACKGROUND:

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 incidence.

DESIGN NARRATIVE:

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.

No eligibility criteria

Using the data resouces of the Rochester Epidemiology Project, we will update the 1966-1995 inception cohort to include Olmsted County, Minnesota residents with with a first-lifetime deep vein thrombosis (DVT) or pulmonary embolism (PE) during the five year period, 1996-2000. All subjects will be followed forward in time through their linked medical records in the community (retrospective cohort study), until death or the most recent clinical contact. For each subject, all inpatient and outpatient medical records of any local health care provider will be searched for vital status at last clinical contact. For deceased patients, all death certificates will be reviewed regardless of the patient location at death.

We also identified two Olmsted County residents (controls) without VTE matched by age and gender to each definite or probable case within the 1996-2000 cohort to perform a case-control study.