What are the criteria for deep vein thrombosis (DVT) prophylaxis?

Criteria for DVT Prophylaxis

DVT prophylaxis should be provided to hospitalized medical patients who are acutely ill with reduced mobility and have additional risk factors such as active malignancy, prior VTE, age >60 years, or acute infection, using pharmacologic anticoagulation (LMWH, UFH, or fondaparinux) unless contraindicated by active bleeding or high bleeding risk. 1, 2

Risk Stratification Framework

The decision to initiate DVT prophylaxis requires assessment of both patient-specific and procedure-related risk factors:

High-Risk Medical Patients Requiring Prophylaxis

• Acutely ill hospitalized patients with congestive heart failure, severe respiratory disease, or acute infectious/inflammatory conditions who are immobilized 1
• Active malignancy patients, particularly those hospitalized with neutropenia and presumed infection 2
• Prior history of VTE 2, 3
• Age ≥60 years with additional risk factors 3, 4
• Multiple concurrent risk factors including obesity, restricted mobility, smoking, estrogen therapy, or known thrombophilic disorders 1, 4

Low-Risk Patients NOT Requiring Prophylaxis

• Minor surgery in patients <40 years without additional risk factors 1
• Fully ambulatory medical patients without acute illness 1
• Low-risk transurethral procedures where early ambulation alone is sufficient 1

Critical caveat: The American College of Physicians explicitly opposes universal prophylaxis regardless of risk, as the evidence does not support routine prophylaxis in all medical patients and emphasizes the tradeoff between benefits and harms 1. Performance measures promoting blanket prophylaxis may encourage inappropriate use in low-risk patients where risks exceed benefits 1.

Pharmacologic Prophylaxis Options

First-Line Agents (Equivalent Efficacy)

LMWH (enoxaparin): 40 mg subcutaneously once daily 1, 2

• Renal adjustment: Reduce to 30 mg once daily if creatinine clearance <30 mL/min 2, 3
• Obesity adjustment: Consider 40 mg every 12 hours for patients >150 kg 2

Unfractionated heparin (UFH): 5,000 units subcutaneously three times daily 1, 2

• Alternative dosing: 5,000 units twice daily (less effective but acceptable) 1
• Morbidly obese patients: Consider 7,500 units three times daily 5

Fondaparinux: 2.5 mg subcutaneously once daily 1, 2, 6

• Renal adjustment: Reduce to 1.5 mg once daily if creatinine clearance 30-50 mL/min 2
• Particularly useful in patients with history of heparin-induced thrombocytopenia 3

Agent Selection Considerations

The choice between LMWH, UFH, and fondaparinux should be based on convenience of dosing frequency, renal function, and cost, as clinical efficacy is equivalent 1. LMWH costs approximately $35/day versus $10/day for UFH 1. Heparin-induced thrombocytopenia occurs less frequently with LMWH (1/1900) compared to UFH (7/1900), though this difference did not reach statistical significance 1.

Timing and Duration

Initiation Timing

• Surgical patients: Administer initial dose no earlier than 6-8 hours after surgery once hemostasis is established 6. Earlier administration significantly increases major bleeding risk 6.
• Medical patients: Begin prophylaxis at admission for high-risk patients 1

Duration of Prophylaxis

• Standard medical patients: Continue throughout hospitalization until full mobility is restored, typically 6-21 days 1
• Standard surgical patients: 7-10 days postoperatively 2, 3
• Extended prophylaxis (4 weeks total): Strongly recommended for major abdominal/pelvic surgery, hip fracture surgery, cancer surgery, and patients with restricted mobility or obesity 2, 3
• Hip fracture surgery: Up to 32 days total (perioperative plus extended prophylaxis) 6

Mechanical Prophylaxis

When to Use Mechanical Methods

Intermittent pneumatic compression (IPC) devices or graduated compression stockings (GCS) should be used when: 1, 2, 4

• Active bleeding is present
• High risk for major bleeding exists
• Pharmacologic prophylaxis is contraindicated
• As adjunctive therapy in very high-risk patients

Important Limitation

The American College of Physicians strongly recommends AGAINST graduated compression stockings as standalone prophylaxis, as they were not effective in preventing VTE or reducing mortality and resulted in clinically important lower-extremity skin damage 1. IPC may be reasonable in high bleeding-risk patients, though it has not been sufficiently evaluated in medical patients 1.

Absolute Contraindications to Pharmacologic Prophylaxis

• Active bleeding 2, 3
• Severe thrombocytopenia (platelet count <50,000/μL) 2
• Active intracranial bleeding in CNS malignancy patients 2
• Recent neurosurgery 2

Critical warning: Epidural or spinal hematomas may occur with anticoagulation and neuraxial procedures, potentially causing permanent paralysis 2, 6. The optimal timing between fondaparinux administration and neuraxial procedures is not known; monitor patients frequently for neurologic impairment 6.

Special Population Considerations

Cancer Patients

• Hospitalized cancer patients with acute illness require prophylaxis 2
• Ambulatory cancer patients: Consider prophylaxis for locally advanced/metastatic pancreatic cancer on chemotherapy, Khorana score ≥2 on systemic therapy, or myeloma patients on immunomodulatory drugs with steroids 2
• Do NOT use routine prophylaxis for lung cancer patients or those with indwelling central venous catheters 2

Surgical Risk Categories

Moderate risk (minor surgery with risk factors, or age 40-60 without risk factors): Consider pharmacologic prophylaxis 1

High risk (age >60, or age 40-60 with additional risk factors): Pharmacologic prophylaxis recommended 1

Highest risk (multiple risk factors including age >40, cancer, prior VTE): Pharmacologic prophylaxis plus possible mechanical adjunct 1