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2-11 THE DURATION OF ORAL ANTICOAGULANT
THERAPY AFTER A SECOND EPISODE OF VENOUS THROMBOEMBOLISM
Prophylactic oral anticoagulation continued for an
indefinite period after a second episode of venous
thromboembolism was associated with a much lower rate of
recurrence than treatment for 6 months.
There was a trend toward a higher risk of major
hemorrhage when anticoagulation was continued
indefinitely. NEJM February 6, 1997; 336:393-98. 2-11 THE DURATION OF ORAL
ANTICOAGULANT THERAPY AFTER A SECOND EPISODE OF VENOUS
THROMBOEMBOLISM
Recent trials have demonstrated that if the duration of
anticoagulation after a first episode of thromboembolism
is extended to 3 to 6 months, instead of 4 to 6 weeks,
the rate of recurrence can be reduced, especially among
patients with permanent risk factors such as venous
insufficiency and "idiopathic" thromboembolism.
The study asks - what is the optimum duration of oral
anticoagulation after a second episode? Conclusion:
Indefinite therapy
STUDY
- Multicenter trial
compared 1) 6 months of anticoagulation with 2)
indefinite duration (4 years in this study).
- Randomized over 200
patients, all with a second episode of venous
thromboembolism (deep vein thrombosis of the
lower extremity or iliac veins, or pulmonary
embolism).
- Targeted INR = 2.0 to
2.8.
- Both groups were
instructed to use compression stockings.
RESULTS
- At 4 years there were
26 recurrences: 23 (21%) in the 6 month group; 3
(3%) in the indefinite duration group ( No
recurrence occurred during anticoagulant therapy.
All occurred after patients had discontinued
therapy 1 to 10 months prior.)
- There were 13 major
hemorrhages: 3 (3%) in the 6 month group; 10 (9%)
in the indefinite-duration group (in 5 of these
the targeted INR was exceeded [3.7 to 6.7] ).
DISCUSSION
- The risk of recurrent
thromboembolism was significantly reduced when
the oral anticoagulant was continued
indefinitely.
- The target INR of 2.0
to 2.8 proved effective.
- The results indicated
that if 100 patients were treated indefinitely,
instead of for 6 months, 0.4 episodes of
recurrent thromboembolism would be averted each
month at a cost of 0.2 episodes of major
hemorrhage per month.
CONCLUSION
Prophylactic oral anticoagulation continued for an
indefinite period after a second episode of venous
thromboembolism was associated with a much lower rate of
recurrence than treatment for 6 months.
There was a trend toward a higher risk of major
hemorrhage when anticoagulation was continued
indefinitely.
NEJM February 6,
1997; 336:393-98. Original investigation from the
Duration of Anticoagulation Trial Study Group (DURAC).
First author from Karolinska Hospital, Stockholm, Sweden
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