What is a provoked Deep Vein Thrombosis (DVT)?

What is a Provoked DVT?

A provoked deep vein thrombosis (DVT) is one that occurs in association with an identifiable environmental risk factor, which can be either transient or persistent, as opposed to an unprovoked DVT which occurs without such factors. 1

Types of Provoked DVT

According to the International Society on Thrombosis and Haemostasis (ISTH), provoked DVT can be classified into two main categories:

1. DVT Provoked by Transient Risk Factors

These are risk factors that resolve after they have triggered the DVT. They can be further subdivided into:

Major Transient Risk Factors (within 3 months before diagnosis)

• Surgery with general anesthesia lasting >30 minutes
• Hospitalization with bed confinement (only bathroom privileges) for ≥3 days
• Cesarean section

Minor Transient Risk Factors (within 2 months before diagnosis)

• Surgery with general anesthesia <30 minutes
• Hospital admission <3 days with acute illness
• Estrogen therapy
• Pregnancy or puerperium
• Out-of-hospital bed confinement ≥3 days
• Leg injury with reduced mobility for ≥3 days 1

2. DVT Provoked by Persistent Risk Factors

These are ongoing risk factors that continue to increase thrombosis risk:

• Active cancer (untreated, non-curative treatment, evidence of recurrence, or ongoing treatment)
• Non-malignant conditions associated with at least 2-fold risk of recurrent VTE (e.g., inflammatory bowel disease) 1

Clinical Significance

The distinction between provoked and unprovoked DVT is crucial for:

1. Determining recurrence risk: Patients with DVT provoked by transient risk factors have approximately half the risk of recurrent VTE after stopping anticoagulation compared to those with unprovoked DVT 1

2. Treatment duration decisions:

   • DVT provoked by major transient risk factors carries a very low risk of recurrence after stopping therapy
   • DVT provoked by persistent risk factors (especially progressive ones like metastatic cancer) has a high recurrence risk
   • Unprovoked DVT has an intermediate recurrence risk 1

3. Anticoagulation management: Approximately 90% of patients enrolled in the AMPLIFY study had unprovoked DVT or PE, while the remaining 10% with provoked DVT/PE required additional ongoing risk factors to be included 2

Patient Characteristics

Research shows important differences between patients with transient risk (TR) factors versus continuous risk (CR) factors:

• Patients with TR factors tend to be younger (60.4 vs 65.9 years)
• TR DVT is more commonly provoked by surgery (70.9% vs 55.4%)
• CR DVT is more likely associated with immobilization (21.5% vs 12.6%)
• TR DVT more commonly affects calf veins (36.2% vs 26.2%)
• CR DVT has higher rates of recurrent VTE (14.0% vs 6.8%) and mortality (23.5% vs 7.1%) 3

Clinical Approach

When evaluating a patient with DVT:

1. Determine if the DVT is provoked or unprovoked
2. If provoked, identify whether the risk factor is transient or persistent
3. For transient factors, assess whether they are major or minor
4. Confirm resolution of transient risk factors before stopping anticoagulation 1

Important Considerations

• Non-environmental risk factors (hereditary thrombophilias, male sex, older age) do not qualify a DVT as provoked but may influence recurrence risk 1
• Some conditions may be difficult to categorize as purely transient or persistent (e.g., stroke with incomplete recovery, inflammatory bowel disease with fluctuating activity)
• Patients may have both transient and persistent risk factors, complicating risk assessment 1

Remember that the categorization of DVT as provoked or unprovoked has significant implications for treatment duration and recurrence risk assessment, making it a critical distinction in clinical practice.