Surgeon General's Workshop on Deep Vein Thrombosis

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SLIDE 1:

Major Risk Factors for Venous Thrombosis

Mary Cushman, MD
Department of Medicine
Division of Hematology-Oncology
The University of Vermont

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SLIDE 2:

Risk factors for VTE
Modifiable Risk Factors
- Obesity
Non-Modifiable Risk Factors
- Genetic
Interventions
- Personal level
- Health System level

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SLIDE 3:

Graphic showing VTE Risk factors:

Older Age
Obesity / Overweight
Personal History of Prior Venous Thrombosis
Family Member with Venous Thrombosis
Surgery
Hospitalization for Surgery or Medical Condition
Cancer
Trauma / Injury, especially of the legs
Immobility (longer than 4 days)
Varicose Veins
Pregnancy
Contraceptive Medications
Postmenopausal Hormone Medications, including estrogen modulators
Long Air Travel
Genetic (inherited) Factors Affecting Clotting Balance

These RFs all add together to enhance risk and it is most common that more than one of these is present in individuals affected by thrombosis

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SLIDE 4: Obesity and VTE

BMI > 30 associated with 2 to 2.5-fold increased risk
- Risk higher with BMI >40

Abdollahi Thromb Haemost 2003;89:493. Tsai M Arch Intern Med 2002;162:1182.

- Reasons are unclear - ? physical factors with body size, coagulation factor changes
Obesity risk adds to impact of other risk factors
- Oral contraceptives: 2-3 10-fold with obesity
- HRT: 2-3 6-fold with obesity

Abdollahi Thromb Haemost 2003;89:493. Cushman JAMA 2004;292:1573.

Why do we care so much?

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SLIDE 5: Obesity Trends* Among U.S. Adults BRFSS, 1991, 1996, 2004 (*BMI ?30, or about 30 lbs overweight for 5’4” person)

1991 map of the U.S. showing Obesity Trends Among U.S. Adults
1996 map of the U.S. showing Obesity Trends Among U.S. Adults
2004 map of the U.S. showing Obesity Trends Among U.S. Adults

The association of obesity with thrombosis is especially important currently in the United States because obesity is increasing dramatically. Between 1991 and 2004 rates of obesity have more than doubled, with estimates as high as 30% in some areas of the United States. To illustrate the impact of this obesity epidemic on expected rates of thrombosis in the United States we used data from the United States Census and the Centers for Disease Control and Prevention to estimate the rates of thrombosis attributed to obesity from 1990 to 2000. We estimate that in 1990 there were 18,500 cases of venous thrombosis among obese people aged 45-64 years (based on the number of people in that age range, a prevalence of obesity of 10% at that time, and the expected rate of thrombosis with obesity compared to normal weight). However, in 2000, we estimate that with a 25% rate of obesity, there were 62,000 cases of thrombosis among obese persons aged 45-64. If the prevalence of obesity had stayed at 10% in 2000, only 24,000 cases of thrombosis would have been expected in obese persons in 2000. Thus, in 2000, there were 38,000 excess thrombosis cases among people aged 45-64 solely due to the rise in obesity.

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SLIDE 6: Obesity Impact

Obesity in the US, age 45-64

1990 46.3M people 10% obese
2000 62 M people 25% obese

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SLIDE 7: Obesity Impact

Obesity in the US, age 45-64

1990 46.3M people 10% obese
- 18,500 cases among obese
2000 62 M people 25% obese
- 62,000 cases among obese

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SLIDE 8: Obesity Impact

If only 10% were obese in 2000 we would have 24,000 cases in this age group

1990 46.3M people 10% obese
- 18,500 cases among obese
2000 62 M people 25% obese
- 62,000 cases among obese

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SLIDE 9: Air Travel and Thrombosis

Precise incidence unclear

Risk higher with

prolonged trips
oral contraceptives
genetic predisposition

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SLIDE 10: Genetic VTE Risk Factors

Factor V Leiden mutation / Activated protein C resistance
Prothrombin 20210A mutation
Protein C deficiency
Protein S Deficiency
Antithrombin deficiency
Elevated factor VIII*

* elevated factor VIII tends to be found in families and is partly related to blood type. The precise genetic disorder causing this is not known.

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SLIDE 11: World Distribution of FVL

Map of the world showing world distribution of FVL

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SLIDE 12: VTE Risk Factor Model

Graphic showing the VTE Risk Factor Model

Venous events often occur when multiple risk factors, including genetic and environmental, are present at the same time.

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SLIDE 13: How Can We Intervene?

Personal Level
- Public education, awareness of family history
- Weight loss
Health System Level
- National
  - Promote education
  - Promote thinning of America
- Hospitals
  - Implement prevention methods in high risk situations

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