Deep vein thrombosis risk factors

Editor(s)-In-Chief: The APEX Trial Investigators, C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2] Kashish Goel, M.D.; Assistant Editor(s)-In-Chief: Justine Cadet; Rim Halaby, M.D. [3]

Deep Vein Thrombosis Microchapters
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Patient Information
Overview
Classification
Pathophysiology
Causes
Differentiating Deep vein thrombosis from other Diseases
Epidemiology and Demographics
Risk Factors
Triggers
Screening
Natural History, Complications and Prognosis
Diagnosis
Diagnostic Approach
Assessment of Clinical Probability and Risk Scores
Assessment of Probability of Subsequent VTE and Risk Scores
History and Symptoms
Physical Examination
Laboratory Findings
Ultrasound
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Upper extremity DVT
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Overview

Venous thromboembolism (VTE) consists of deep vein thrombosis (DVT), pulmonary embolism (PE), or both. In these chapters on VTE, the word risk factors refers to those epidemiologic and genetic variables that expose someone to a higher risk of developing venous thrombosis. The word triggers refer to those factors in the patients immediate history or environment that may have lead to the occurrence of the venous thrombosis. The risk factors for VTE are a constellation of predisposing conditions which stem from the three principles of Virchow's triad: stasis of the blood flow, damage to the vascular endothelial cells, and hypercoagulability. The risk factors for VTE can be classified as temporary, modifiable and non-modifiable. It is suggested that venous thrombosis also shares risk factors with arterial thrombosis, such as obesity, hypertension, smoking, and diabetes mellitus.

Risk Factors

Shown below is a list of predisposing factors to VTE. The risk factors are classified as strong, moderate and weak depending on how strongly they predispose for a VTE.

Strong risk factors	Moderate risk factors	Weak risk factors
❑ Bone fracture (hip or leg) ❑ Hip replacement surgery ❑ Knee replacement surgery ❑ Major general surgery ❑ Significant trauma ❑ Spinal cord injury	❑ Athroscopic knee surgery ❑ Central venous lines ❑ Chemotherapy ❑ Chronic heart failure ❑ Respiratory failure ❑ Hormone replacement therapy ❑ Cancer ❑ Oral contraceptive pills ❑ Stroke ❑ Pregnancy ❑ Postpartum ❑ Prior history of VTE ❑ Thrombophilia	❑ Bed rest for more than 3 days ❑ Prolonged car or air travel ❑ Advanced age ❑ Laparoscopic surgery ❑ Prepartum ❑ Obesity ❑ Varicose veins

The risk factors of VTE can be further classified into modifiable, non-modifiable and temporary.

Modifiable Risk Factors

Modifiable risk factors are reversible based upon lifestyle/behavior modification.

• Obesity: Obesity is defined as a body-mass index (BMI) above 30 kg/m2.

• Smoking: Smoking significantly increases the risk of DVT, particularly in women who are taking oral contraceptive pills as well as among obese people.

• Use of oral contraceptives

• Prolonged travel: Travel by air increases the risk to the same extent as travel by bus, train or car, suggesting that the increased risk of air travel is due primarily to prolonged immobility.

• Hyperhomocysteinemia: Hyperhomocysteinemia can be reduced with vitamin B supplementation.

Non-Modifiable Risk Factors

• Advanced age
• Heart failure
• Thrombophilia or hypercoagulable state
  • Factor V Leiden
  • Prothrombin G20210A mutation
  • Protein C deficiency
  • Protein S deficiency
  • Antithrombin deficiency
  • Activated protein C resistance
  • Antithrombin III deficiency
  • Factor VIII mutation
  • Antiphospholipid syndrome
  • Heparin induced thrombocytopenia
  • Nephrotic syndrome
  • Paroxysmal nocturnal hemoglobinuria
• Polycythemia vera

Temporary Risk Factors

• Injury to a deep vein from surgery, a fracture, or other trauma, especially a paralytic spinal cord injury
• Prolonged immobilization that causes stasis in the deep veins which may occur after surgery, with prolonged bedrest, or prolonged seating during travel
• Pregnancy and the peri-partum period
• Active cancer
• Central venous catheter