A Comparison of Low-Dose Heparin with Low-Molecular Weight Heparin as Prophylaxis against Venous Thromboembolism after Major Trauma

Background

Patients who have had major trauma are at very high risk for venous thromboembolism if they do not receive thromboprophylaxis. We compared low-dose heparin and a low-molecular weight heparin with regard to efficacy and safety in a randomized clinical trial in patients with trauma.

Methods

Consecutive adult patients admitted to a trauma center who had Injury Severity Scores of at least 9 and no intracranial bleeding were randomly assigned to heparin (5000 units) or enoxaprin (30 mg), each given subcutaneously every 12 hours in a double-blind manner, beginning within 36 hours after the injury. The primary outcome was deep vein thrombosis (DVT) as assessed by contrast venography performed on or before day 14 after randomization.

Results

Among 344 randomized patients, 136 who received low-dose heparin and 129 who received enoxaparin had venograms adequate for analysis. Sixty patients given heparin (44%) and 40 patients given enoxaparin (31%) had DVT (p = 0.014). The rates of proximal-vein thrombosis were 15% and 6%, respectively (p = 0.012). The reductions in risk with enoxaparin as compared to heparin were 30% (95% confidence interval, 4%–50%) for all DVT and 58% (95% confidence interval, 12%–87%) for proximal-vein thrombosis. Only six patients (1.7%) had major bleeding (one in the heparin group and five in the enoxaparin group, p = 0.12).

Conclusions

Low-molecular weight heparin was more effective than low-dose heparin in preventing venous thromboembolism after major trauma. Both interventions were safe.