Warfarin should be started simultaneously at a usual daily dose of 5 mg for the first two days, with subsequent doses adjusted to achieve a goal international normalized ratio (INR) of 2.0 to 3.0. Parenteral agents should be given for a minimum of five days and until the INR has been >2.0 for at least 24 hours.3
The new factor-Xa inhibitor rivaroxaban and the direct thrombin inhibitor dabigatran are promising oral alternatives to warfarin.9-11 However, neither drug is currently FDA-approved for the treatment of VTE, nor are they recommended by current guidelines (given limited data for DVT treatment and concerns of bleeding risk).3,12,13 See Table 2 (above) for comparisons of common anticoagulants.3,14-17
Duration of anticoagulation. Anticoagulant treatment of acute DVT should continue for at least three months, as shorter durations are associated with higher recurrence rates. Longer treatment may be indicated depending on the patient’s risk of recurrence.3
The ACCP guidelines estimate risk of recurrence using primary, secondary, and additional factors (see Table 3, p. 19) and recommend the following durations:
- First episode provoked: three months (proximal or distal, provoked by surgery or a nonsurgical transient risk factor);
- First episode unprovoked distal: three months (see “Considerations for isolated distal DVT,” below);
- First episode unprovoked proximal: Indefinite if low to moderate bleeding risk, three months if high bleeding risk;
- Recurrent unprovoked: Indefinite if low to moderate bleeding risk, three months if high bleeding risk; and
- With active cancer: Indefinite with LMWH due to higher risk of recurrence.3,18
These treatment duration guidelines might need to be individualized based on other factors including patient preference, ability to obtain accurate INR monitoring (for those on warfarin), treatment cost, and comorbidities.3
Considerations for isolated distal DVT. Patients with an initial episode of distal DVT, without significant symptoms or risk factors for extension (e.g. positive D-dimer, extensive clot near proximal veins, absence of a reversible provoking factor, active cancer, inpatient status, or previous VTE) might not need anticoagulation.
The DVT can be followed with serial ultrasounds for the first two weeks; anticoagulation is recommended only if the thrombus extends during that time period. The development of significant symptoms or risk factors of extension might indicate the need for anticoagulation.3
Considerations for upper-extremity DVT (UEDVT). Anticoagulation for an UEDVT is generally consistent with the above guidelines for lower-extremity DVT, with a few caveats. If an UEDVT is associated with a central venous catheter (CVC), the CVC should be removed if possible; there are no recommendations to determine whether CVC removal should be preceded by a period of anticoagulation.
A catheter-associated UEDVT requires a minimum of three months of anticoagulation; if the CVC remains in place beyond three months, anticoagulation should be continued until the catheter is removed. Unprovoked UEDVT has a lower risk of recurrence than lower-extremity DVT and three months of anticoagulation, rather than indefinite therapy, is recommended.3
Non-pharmacologic therapies, such as knee-high graduated compression stockings with pressure of 30 mmHg to 40 mmHg at the ankle, can help reduce the morbidity of post-thrombotic syndrome (PTS) when combined with anticoagulation. Symptomatic patients who use compression stockings as soon as feasible and for a minimum of two years can reduce their incidence of PTS by 50%.3,19,20
Thigh-length stockings are not more effective than knee-high, and while multilayer compression bandages might relieve symptoms during the first-week post-DVT, they do not reduce the one-year incidence of PTS.21,22 Early mobilization is not associated with an increased risk of PE, extension of DVT, or death; patients should ambulate as soon as physically able.23,24