Because conventional warfarin thera...

Because conventional warfarin therapy (a target International Normalized Ratio [INR] of 20 to 30) has been shown to virtually eliminate the risk of returning venous thromboembolism, interest has make knowned in attempting low-intensity anticoagulation. The latter technique still may be effective in preventing family clots but may decrease the risk of serious bleeding that sometimes meet the eyes with standard warfarin administration. Kearon and colleagues designed a trial of low-intensity versus conventional-intensity anticoagulation in patients with a history of shrewd venous thrombosis or pulmonary embolism.

The investigators veiled 1,455 consecutive patients with unprovok venous thromboembolism and registered 738 patients in the inquiry The most common causes for exclusion were declined compliance an additional indication for warfarin use beyond prophylaxis of intermittent blood clots (e.g., atrial fibrillation), or a life expectancy of les than sum of two units years. All patients had complet at least three month of standard, full-dose anticoagulation therapy before subject of attention entry. Patients were randomized to continuation of conventional-intensity anticoagulation or low-intensity warfarin use (target INR of 15 to 19) and were followed for a mean duration of 24 years. A total of 142 patients withdrew from the thought Randomization equalized the prevalence in the pair treatment groups of most risk factors for returning clotting (i.e., advanced age, inherited hypercoagulability [eg factor V Leiden], duration of previous full-dose anticoagulation) if it were not that unexpectedly left significantly more patients with a history of more than the same clot in the low-intensity dispose (13 patients) than in the conventional-intensity clump (two patients).

returning venous thromboembolism was significantly more everyday in patients taking low-intensity warfarin (16 episodes) than in those taking standard anticoagulation (six episodes). Fatal pulmonary embolism occurr in individual low-intensity patient and two conventional-intensity patients. The incidence of major bleeding was not significantly different between patients taking low-intensity treatment (nine episodes) and patients taking full-dose warfarin (eight episodes).No fatal or intracranial bleeding episodes occurr in either treatment group

The authors judge that low-intensity warfarin anticoagulation is not as effective as conventional-intensity anticoagulation in preventing renewed venous thromboembolism and does not improve the rate of major bleeding complications.

Kearon C et al. Comparison of low-intensity warfarin therapy with conventional-intensity warfarin therapy for long-term prevention of intermittent venous thromboembolism. N Engl J M August 14 2003;349:631-9

EDITOR'S NOTE: This research is best considered in design with another recently published trial (1) of low-intensity anticoagulation that showed favorable conclusions. This other trial compared low-intensity warfarin with placebo and showed that the risk of returning blood clots was cut on two thirds without any significant increase in bleeding. The reader also will want to consider a number of factors in the first subject of attention that may have skewed the findings. Despite randomization, the same half of the initially cloaked patients were enrolled, almost 20 percent failed to entire the assigned treatment, and there were more patients in the low-intensity treatment collection with a history of more than undivided clot.--B.Z.

REFERENCE

(1) Ridker PM Goldhaber SZ Danielson E Rosenberg Y Eby C Deitcher SR et al. Long-term low-intensity warfarin therapy for the prevention of renewed venous thromboembolism. N Engl J M 2003; 348:1425-34

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