Thromboembolic prophylaxis in orthopaedic trauma patients: a comparison between a fixed dose and an individually adjusted dose of a low molecular weight heparin (nadroparin calcium)

Abstract

In a prospective, randomized multicentre trial the safety and efficacy of two regimens of a low molecular weight heparin (nadroparin calcium) were compared for the prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE) in orthopaedic trauma patients. Two hundred and eighty-three patients with a spinal fracture, a pelvic fracture, or a lower limb injury were randomized to receive either a fixed dose (7500 anti-Xa IC units = 3075 anti-Xa IU) or a variable dose depending on body weight and time since operation (100 to 150 anti-Xa IC units/kg approximately equal to 40 to 60 anti-Xa IU/kg). The patients continued the prophylactic regimen for 6 weeks, but were withdrawn from the study medication in the presence of a major complication or if they were completely cured from their injury. To assess the rate of DVT, a B-mode ultrasound scan of both legs was performed. Positive results were confirmed by phlebography. If signs or symptoms of PE were present, a ventilation-perfusion scan was performed. Both prophylactic regimens were equally safe. In each group, five patients developed major haemorrhagic complications. In each group, one case of reversible thrombocytopenia was seen. DVT was confirmed by phlebography in one patient given the fixed dose and in four patients given the variable dose. PE was confirmed by ventilation-perfusion scans in one patient with the fixed dose and in two patients with the variable dose. An intention-to-treat analysis was performed on the overall randomized population, with the assumption that all patients who were lost to follow-up had DVT. A therapeutic efficacy analysis was performed on those patients, who completed the course of the prophylactic regimen and in whom B-mode ultrasound scanning was performed 10 days and also 6 weeks after injury. These two modes of analysis showed no significant differences in the incidence of DVT or PE between both prophylactic regimens. In conclusion, both regimens were equally safe following a spinal fracture, a pelvic fracture or a lower limb injury. The risk of DVT and PE was similar with both regimens.