Long-term treatment of deep venous thrombosis with a low molecular weight heparin (tinzaparin): a prospective randomized trial.

OBJECTIVES Evaluation of the effectiveness and safety of the low molecular weight heparin (LMWH) tinzaparin versus unfractionated heparin (UFH) followed by acenocoumarol in proximal deep venous thrombosis (DVT). DESIGN Prospective, randomized clinical trial. MATERIAL AND METHODS Consecutive patients (n=108) with acute leg DVT, confirmed by duplex, were randomized to either tinzaparin alone or UFH and acenocoumarol for 6 months. Patients were evaluated ultrasonographically at entry, 1, 3, 6 and 12 months. Thrombus regression, reflux distribution and the incidence of complications were studied. A cost-analysis, comparing the two treatments, was performed. RESULTS The overall incidence of major events (mortality, DVT recurrence, pulmonary embolism, major bleeding, heparin-induced thrombocytopenia) was significantly different (p=0.035) in favor of tinzaparin (7 versus 17 events). The ultrasonographic clot volume score (an index of recanalization) decreased significantly in both treatment groups. However, tinzaparin produced significantly more extended overall recanalization from 3 months onwards (p<0.02). Thrombus regression was equivalent or in favor of tinzaparin in the different DVT subgroups and venous segments, but the statistical significance varied. Reflux showed non-significant differences overall or in subgroups. A cost-analysis resulted in favor of LMWH. CONCLUSIONS A fixed daily dose of tinzaparin for 6 months was at least as effective and safe as UFH and acenocoumarol. Regarding major events and recanalization, there was a significant benefit in favor of tinzaparin. Long-term DVT treatment with tinzaparin could represent an alternative to conventional treatment.