Treatment of Venous Thromboembolism

Question 1

DVT/PE diagnosis

Answer 1

Patients with a low pretest probability (Wells model) who are younger than 65 and have a negative D-dimer can have DVT/PE ruled out of their differential diagnosis.
Other patients should proceed to duplex ultrasonography (DVT) or CT (PE) to confirm diagnosis.

Question 2

Bridging therapy strategy

Answer 2

Injectable anticoagulant (UFH, LMWH, or fondaparinux) initiated with warfarin and overlapped for at least 5 days and until the INR is greater than 2.0. Then discontinue injectable anticoagulant and continue warfarin for the appropriate duration

Question 3

UFH Dosing for VTE

Answer 3

IV -Weight adjusted with an initial bolus of 80 units/kg, followed by an initial infusion of 18 units/kg/hr. Subsequent doses should be adjusted to maintain the institution’s goal aPTT
SC - UFH 333 units/kg, followed by 250 units/kg given q12hr with or without aPTT monitoring

Question 4

Enoxaparin VTE dosing

Answer 4

1 mg/kg q12hr or 1.5 mg/kg q24hr (avoid in patients with current or history of malignancy, weight > 120 kg, DVT with iliac vein involvement, or antiphospholipid syndrome)

Question 5

Dalteparin VTE dosing

Answer 5

100 units/kg q12hr or 200 units/kg q24hr

Question 6

Fondaparinux VTE dosing

Answer 6

Weight < 50 kg – Give 5 mg q24hr
Weight 50–100 kg – Give 7.5 mg q24hr
Weight > 100 kg – Give 10 mg q24hr
CrCl < 30 mL/min/1.73 m2 – Contraindicated

Question 7

Dabigatran VTE dosing

Answer 7

150 mg twice daily after 5–10 days of injectable anticoagulation

Question 8

Dabigatran VTE avoid use

Answer 8

CrCl ≤ 30 mL/min/1.73 m2
CrCl 30–50 mL/min and concomitant use of P-gp inhibitors

Question 9

Edoxaban VTE Dosing

Answer 9

60 mg once daily after 5–10 days of injectable anticoagulation

Question 10

Edoxaban VTE dose adjustment

Answer 10

30 mg once daily after 5–10 days of injectable anticoagulation
CrCl 15–50 mL/min/1.73 m2 (avoid if less than 15)
Potent P-gp inhibitor (verapamil, dronedarone, or quinidine)
Weight ≤ 60 kg

Question 11

Rivaroxaban VTE dosing

Answer 11

15 mg twice daily with food for 21 days, followed by 20 mg daily with food. After 6 mo, dose can be reduced to 10 mg daily (± food); avoid if CrCL ≤ 15

Question 12

Apixaban VTE dosing

Answer 12

10 mg twice daily for 7 days, followed by 5 mg twice daily. After 6 months, dose can be reduced to 2.5 mg twice daily; Avoid if SCr > 2.5 mg/dL

Question 13

Apixaban VTE dose adjustment

Answer 13

50% dose reduction if receiving 5 or 10 mg twice daily with strong CYP3A4 and P-gp inhibitors (avoid if on 2.5 mg dose)

Question 14

Duration of Anticoagulation Therapy in Patients with VTE

Answer 14

At least 3 months, Indefinite after 2nd VTE

Question 15

Treatment of Cancer-Associated VTE

Answer 15

LMWH is preferred as monotherapy for 3–6 months
Direct Xa inhibitors can be used (avoid in GI cancers)