Anticoagulation period in idiopathic venous thromboembolism. How long is enough?
OBJECTIVE
The period of anticoagulation of a first episode of idiopathic venous thromboembolism has been 6 months. It is unclear if such patients would benefit from longer treatment, as there appears to be an increased risk of recurrence after anticoagulation is stopped.


METHODS
In a randomized prospective study of 64 patients admitted to King Hussein Medical city, Amman, Jordan, who developed a first episode of venous thromboembolism, 32 patients were given warfarin for 24-months, while 32 patients stopped anticoagulation after completion of 6-months of therapy. Our goal was to determine the effects of extended anticoagulation on rates of recurrence of symptomatic venous thromboembolism and bleeding. The patients were followed for 12-months after stopping anticoagulation.


RESULTS
After 24-months, 7 of the 32 patients (21%) who had standard anticoagulation for 6-months had a recurrent episode of thromboembolism compared to one of the 32 patients who received anticoagulation for 24 months (3%). Extended warfarin therapy for 24-months has resulted in an absolute risk reduction of 0.1% (p<0.05). This translates into 8 patients having to be treated for 24-months to avoid one recurrence without increasing the risk of major bleeding. Two patients in each group (6%) had major nonfatal bleeding, all 4 bleeding episodes occurring within the first 3-months of anticoagulation. After 36-months of follow up, the recurrence rate of extended warfarin therapy was only 3 patients (9%), which is a 43% relative reduction in recurrence of thromboembolism compared to standard therapy for 6-months.


CONCLUSIONS
Patients with first episodes of idiopathic venous thromboembolism have an increased risk of recurrent venous thromboembolism and should be treated with oral anticoagulants for longer than 6-months, probably 24-months.
Farraj
Rami S
RS
Department of Internal Medicine, King Hussein Medical Center, Amman 11180, Jordan. rfarraj@go.com.jo
D000284:Administration, Oral; D000328:Adult; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000188:drug therapy*; D012307:Risk Factors; D055502:Secondary Prevention; D020246:Venous Thrombosis / Q000188:drug therapy*; D014859:Warfarin / Q000008:administration & dosage* / Q000009:adverse effects
D000925:Anticoagulants; D014859:Warfarin