Two major clinical trials have compared
tinzaparin to UH in the initial treatment of VTE. All patients subsequently
received oral anticoagulation and were followed closely for three months
for recurrent VTE, bleeding and death. The first trial, done in North
America, randomized patients with acute proximal DVT to either UH given
intravenously with APTT monitoring and dose adjustment or to tinzaparin
at 175 IU/kg given subcutaneously once daily without monitoring or dose
adjustment. The study was performed in a double-blind fashion. Baseline
characteristics of the patients illustrate the contribution of the major
risk factors of surgery, trauma, cancer and immobilization to the causation
of DVT.