Traditionally, patients with deep vein thrombosis (DVT) or pulmonary embolism (PE) are treated with oral anticoagulants for at least 6 months following initial treatment with heparin. However, the optimum duration for anticoagulation has not been determined. This UK study looked at more than 700 patients to assess whether it was advantageous to use anticoagulants for patients with DVT or PE for 6 months rather than 3 months.
Adult patients with either DVT or PE (or both) were randomized into 1 of 2 groups to receive either 3 (n = 369) or 6 months (n = 380) of anticoagulation with warfarin following heparin treatment for 5 days. The target international normalized ratio (INR) was 2.0 to 3.5. Patients with risk factors for recurrence (eg, prolonged or continuous immobility, predisposing hematologic disorders, pregnancy, recurrent DVT or PE, neoplasia) or those requiring thrombolyisis or embolectomy were excluded from the trial. Patients were monitored for up to 12 months.
The researchers found that fatal and non-fatal DVT or PE occurred during or after treatment for 31 (8%) patients in the 3-month group, compared with 29 (8%) patients treated for 6 months (P = .80; 95% confidence interval, -3.1 to 4.7). Two people in the 3-month group died from DVT or PE during treatment, and 3 people in the 6-month group died. Failed resolution, extension, or recurrence affected 6 patients in the 3-month group, compared with 10 in the 6-month group.
After treatment, 23 non-fatal recurrences occurred in those treated for 3 months, compared with 16 in those treated for 6 months. There were no fatal hemorrhages during treatment, but there were 8 major hemorrhages in the 6-month group and none in the 3-month group. Control was similar in both groups.
Bottom line
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There seems to be little or no advantage to increasing the duration of anticoagulation from 3 to 6 months in those with DVT or PE, and no risk factors for recurrence are known. There is an increased risk of hemorrhage associated with the longer duration of treatment with warfarin.
Footnotes
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Source: Campbell IA, Bentley DP, Prescott RJ, Routledge PA, Shetty HG, Williamson IJ. Anticoagulation for three versus six months in patients with deep vein thrombosis or pulmonary embolism, or both: randomised trial. BMJ 2007;0(2007):bmj.39098.583356.55v1(8 February).
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