Different Intensities of Oral Anticoagulant Therapy in the Treatment of Proximal-Vein Thrombosis

TLDR

Long‑term warfarin therapy effectively prevents recurrent venous thromboembolism in proximal‑vein thrombosis patients but carries a significant hemorrhage risk. The study aimed to determine whether reducing anticoagulant intensity could lower hemorrhage risk without compromising efficacy. Ninety‑six patients were randomized to receive either less intense therapy (mean prothrombin time 26.9 s) or more intense therapy (mean Simplastin 19.4 s). The less intense group had a markedly lower hemorrhage rate (4 % vs 22 %) with only minor bleeding, while recurrent venous thromboembolism remained low (2 %) in both groups. N Engl J Med 1982; 307:1676–81.

Abstract

We have previously reported that long-term therapy with warfarin is effective for preventing recurrent venous thromboembolism in patients with proximal-vein thrombosis but that there is an appreciable risk of hemorrhage. To determine whether that risk could be reduced without a loss of effectiveness, we randomly allocated 96 patients with proximal-vein thrombosis to a group receiving less intense anticoagulant therapy, with a mean prothrombin time of 26.9 seconds using the Manchester comparative reagent (corresponding Simplastin time, 15 seconds), or a group given more intense therapy, with a mean Simplastin time of 19.4 seconds (corresponding prothrombin time 41 seconds with the Manchester comparative reagent) (P<0.001). Two of 47 patients (4 per cent) in the less intensely treated group had hemorrhagic complications, as compared with 11 of 49 patients (22 per cent) in the more intensely anticoagulated group (P = 0.015 by the two-tailed test). This difference was due to minor bleeding episodes. The frequency of recurrent venous thromboembolism was low in both groups (2 per cent). Our findings indicate that less intense anticoagulant therapy is associated with a low frequency of recurrent venous thromboembolism (2 per cent) and a reduced risk of hemorrhage. (N Engl J Med. 1982; 307:1676–81.)