Risk Factors for Deep Vein Thrombosis
Classification and Risk Factors
- DVT risk factors are categorized into provoked and unprovoked based on their association with recurrence risk and duration of anticoagulation needed, with the classification directly impacting treatment duration and patient outcomes 1, 2
- Unprovoked DVT occurs without any identifiable environmental risk factors and carries an intermediate recurrence risk (>5% annually), while provoked DVT occurs in the presence of specific triggers that can be transient or persistent 2, 3
- The single most important variable influencing recurrent VTE risk after stopping anticoagulation is whether an environmental provoking factor was present 2, 3
- Provoked DVT with major transient factors has a <1% annual recurrence risk 4
- Unprovoked DVT has a >5% annual recurrence risk 4
- Persistent risk factors confer the highest recurrence risk 5, 4
Major Transient Risk Factors
- Surgery with general anesthesia >30 minutes increases DVT risk 1, 6, 7
- Hospital bed confinement ≥3 days with acute illness increases DVT risk 1, 6, 7
- Cesarean section increases DVT risk 1, 6, 7
Minor Transient Risk Factors
- Surgery with general anesthesia <30 minutes increases DVT risk 1, 6
- Hospital admission <3 days with acute illness increases DVT risk 1, 6
- Estrogen therapy increases DVT risk 1, 6, 7
- Pregnancy or puerperium increases DVT risk 1, 6, 7
Persistent Risk Factors
- Active cancer is the most important persistent risk factor for DVT 1, 6, 7
- Inflammatory bowel disease increases DVT risk by ≥2-fold 1, 6, 7
- Chronic inflammatory conditions and autoimmune diseases increase DVT risk 8