Introduction to Venous Thromboembolism
This section introduces venous thromboembolic disorders, their incidence, prevalence, classification and risk factors
In this section:
Introduction
Formation of a blood clot – a thrombus – within a vein is known as venous thrombosis. Venous thrombosis can occur in any vein, but the most common manifestation is DVT, which occurs predominantly in the large veins in the leg.1,2 A DVT may form without a known reason, but the risk is higher (for example):
- If a leg has been immobilized for a long period, such as after a surgical operation or even after long-distance air travel
- If a patient has a medical condition such as cancer
- During pregnancy
Deep vein thrombosis
If part or all of a DVT or other thrombus breaks away from the blood vessel wall and travels through the venous blood system, it is known as an embolus.2
- An embolus that is carried in the direction of blood flow towards the lungs can block one of the arteries in the lung. This is known as a PE
- Patients with DVT are at risk of PE, which can potentially be life-threatening
Pulmonary embolism
Collectively, DVT and PE are known as VTE.
Incidence and prevalence of VTE
VTE is a major healthcare problem worldwide
- In 2007, over 500,000 deaths in the EU were associated with an estimated 1.1 million venous thromboembolic events – approximately one-third of these events manifested as PE3
- In the US, DVT and PE together affect an estimated 350,000–600,000 people each year, leading to an estimated 100,000–300,000 deaths4,5
VTE is a major cause of death. European data for 20073
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Although the annual incidence of VTE is estimated at approximately 1 in 1000 of the population,6,7 certain groups are at considerably higher risk. For example, routine screening of patients in clinical trials showed the DVT frequency without prophylaxis to be:
Classification and risk factors
Approximately half of diagnosed venous thromboembolic events are classed as provoked (caused by a known risk factor or factors), the other half are unprovoked (idiopathic), meaning that the cause is not known7,8,10
- Known risk factors for VTE are either reversible (temporary) or not (intrinsic)
- A patient may initially be diagnosed with unprovoked VTE, but this may be because the provoking risk factor, often cancer, has not yet been identified
- Multiple risk factors generally have a cumulative impact on the risk of VTE
Among the reversible risk factors, surgery – especially major orthopaedic surgery involving the lower limbs and major surgery for cancer – acute medical illness, often involving immobilization, and pregnancy are major risk factors for VTE.
References
- Mackman N. Triggers, targets and treatments for thrombosis. Nature 2008;451:914–918. Mackman N. Triggers, targets and treatments for thrombosis. Nature 2008;451:914–918. Return to content
- Turpie AGG, Esmon C. Venous and arterial thrombosis – pathogenesis and the rationale for anticoagulation. Thromb Haemost 2011;105:586–596. Return to content
- Cohen AT, Agnelli G, Anderson FA et al. Venous thromboembolism (VTE) in Europe. The number of VTE events and associated morbidity and mortality. Thromb Haemost 2007;98:756–764. Cohen AT, Agnelli G, Anderson FA et al. Venous thromboembolism (VTE) in Europe. The number of VTE events and associated morbidity and mortality. Thromb Haemost 2007;98:756–764. Return to content
- US Department of Health and Human Services. The Surgeon General's call to action to prevent deep vein thrombosis and pulmonary embolism: Section I: deep vein thrombosis and pulmonary embolism as major public health problems. 2008. Available at: http://www.ncbi.nlm.nih.gov/books/NBK44181/ [accessed 22 August 2018]. US Department of Health and Human Services. The Surgeon General's call to action to prevent deep vein thrombosis and pulmonary embolism: Section I: deep vein thrombosis and pulmonary embolism as major public health problems. 2008. Available at: http://www.ncbi.nlm.nih.gov/books/NBK44181/ [accessed 22 August 2018]. Return to content
- Heit JA, Cohen AT, Anderson FA, VTE Impact Assessment Group. Estimated annual number of incident and recurrent, non-fatal and fatal venous thromboembolism (VTE) events in the US. Blood (ASH Annual Meeting Abstracts) 2005;106. Abstract 910. Return to content
- Silverstein MD, Heit JA, Mohr DN et al. Trends in the incidence of deep vein thrombosis and pulmonary embolism: a 25-year population-based study. Arch Intern Med 1998;158:585–593. Silverstein MD, Heit JA, Mohr DN et al. Trends in the incidence of deep vein thrombosis and pulmonary embolism: a 25-year population-based study. Arch Intern Med 1998;158:585–593. Return to content
- Martinez C, Cohen A, Bamber L, Rietbrock S. Epidemiology of first and recurrent venous thromboembolism: a population-based cohort study in patients without active cancer. Thromb Haemost 2014;112:255–263. Return to content
- Geerts WH, Bergqvist D, Pineo GF et al. Prevention of venous thromboembolism: American College of Chest Physicians evidence-based clinical practice guidelines (8th edition). Chest 2008;133:381S–453S. Geerts WH, Bergqvist D, Pineo GF et al. Prevention of venous thromboembolism: American College of Chest Physicians evidence-based clinical practice guidelines (8th edition). Chest 2008;133:381S–453S. Return to content
- Cohen AT, Tapson VF, Bergmann JF et al. Venous thromboembolism risk and prophylaxis in the acute hospital care setting (ENDORSE study): a multinational cross-sectional study. Lancet 2008;371:387–394. Return to content
- Turpie AGG, Chin BSP, Lip GYH. Venous thromboembolism: pathophysiology, clinical features, and prevention. Br Med J 2002;325:887–890. Turpie AGG, Chin BSP, Lip GYH. Venous thromboembolism: pathophysiology, clinical features, and prevention. Br Med J 2002;325:887–890. Return to content
See Also
Peripheral Artery Disease: causes and consequences
See Also
Coronary Artery Disease: causes and consequences
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