DVT Risk Factors
Deep vein thrombosis risk factors can be systematically categorized into patient-related, disease-related, and treatment-related factors, with age >60 years, previous VTE, active malignancy, surgery, immobility, and acute infection representing the most clinically significant independent risk factors. 1, 2
Patient-Related Risk Factors
Demographic and Constitutional Factors
- Age: Risk increases sharply after age 45, with age >60 years conferring significantly elevated risk 1, 2. Before age 40, the risk is approximately 1 in 10,000 persons per year, increasing to 1 in 100 persons per year after age 75 2
- Male sex in older age groups 2
- Obesity (BMI >25-30 kg/m²) 1, 3, 4
- Smoking 5, 2
Medical History
- Previous VTE: The single strongest predictor, conferring a 6-fold increased risk 1, 3, 6, 7. Recurrence risk is approximately 20% within 5 years and 30% within 10 years 2
- Known thrombophilia: Including Factor V Leiden, prothrombin G20210A mutation, antithrombin III, protein C, or protein S deficiency 5, 1, 2
- Family history of VTE 4
Cardiovascular and Metabolic Conditions
- Heart failure (chronic or acute) 3, 4, 7
- Acute myocardial infarction 4
- Hypertension 8
- Diabetes mellitus 8
Hematologic Factors
- Prechemotherapy thrombocytosis and leukocytosis 3
- Anemia (hemoglobin <10 g/dL) 3
- Elevated D-dimer levels 6, 8
- Elevated hematocrit 8
- Elevated triglycerides 8
Disease-Related Risk Factors
Malignancy
Active cancer represents one of the most potent risk factors, with cancer patients undergoing surgery having twice the risk of postoperative VTE and more than three times the risk of fatal PE compared to patients without cancer 9. Specific high-risk cancers include brain tumors, pancreatic cancer, and hematologic malignancies 9, 3.
Cancer-related factors include:
- Active malignancy with or without chemotherapy 1, 3, 6
- Type, location, and stage of cancer 10
- Anticancer treatment including chemotherapy, hormonal therapy, angiogenesis inhibitors, thalidomide, and lenalidomide 1, 10
Acute Medical Conditions
- Acute infection/sepsis: Identified as a significant risk factor not adequately considered in many existing risk assessment models 3, 6, 4
- Inflammatory bowel disease 4
- Acute respiratory failure 4
- Ischemic stroke 4
Neurologic Disease
Treatment-Related Risk Factors
Surgical and Procedural
- Surgery: Confers a 21.7-fold increased risk, with the highest risk in the first 3 months post-operatively 7. For urologic surgery specifically, radical prostatectomy carries an estimated 32% DVT risk without prophylaxis 5
- Major trauma: 12.7-fold increased risk 7
- Operative time (prolonged procedures) 5
- Central venous catheter or pacemaker: 5.6-fold increased risk 1, 3, 7
Immobilization
- Hospital or nursing home confinement: 8-fold increased risk 7
- Prolonged immobilization or bed rest 1, 3, 2, 4
- Critical illness requiring ICU/CCU stay 6, 4
- Mechanical ventilation 10, 11
- Plaster cast application 4, 7
Medications and Hormones
- Estrogen use: Including oral contraceptives and hormone replacement therapy 1, 2
- Tamoxifen and raloxifene 2
- Erythropoiesis-stimulating agents (ESAs) 3
- Vasoactive agents 11
Pregnancy-Related
Additional Risk Factors
Venous Disease
- Superficial vein thrombosis: 4.3-fold increased risk 7
- Varicose veins: Risk diminishes with age but significant in younger patients 7, 12
- Chronic venous insufficiency 12
Other Factors
- Long-distance travel (>4-6 hours) 1
- Recent trauma 1
- Indwelling central venous catheters 9, 3
- Poor performance status 3
- Prolonged ICU stay 11
Important Clinical Considerations
The cumulative effect of multiple risk factors is critical—patients rarely present with a single isolated risk factor 3, 2. Risk stratification should account for the interaction between patient-specific predisposing factors and procedure-related risks 5.
Approximately 50% of first-time VTE cases are apparently unprovoked, highlighting the multifactorial nature and the presence of unidentified or subclinical risk factors 2.
For hospitalized medical patients, the combination of age >60 years, acute infection, immobility, acute paresis, active malignancy, critical illness, and known thrombophilia represents the core risk assessment framework 6.