Prospective trial of low-molecular-weight heparin versus unfractionated heparin in moderately injured patients

The safety and efficacy of low-molecular-weight heparin (LMWH) was compared with those of conventional unfractionated heparin (UH) in preventing deep venous thrombosis (DVT) in trauma patients with moderate injuries in a prospective double-blind, randomized trial at a level I trauma center. After informed consent, trauma patients meeting inclusion criteria (age > 45 or requiring > 2 days' bedrest) received LMWH or UH twice daily in a double-blind, randomized trial. Patients were excluded if they had severe brain injuries or bleeding injuries not accessible to hemostatic control (eg, severe visceral contusions). Clinical examination and weekly venous duplex ultrasound evaluations were performed to identify DVT. One hundred four patients were randomized, 53 to receive UH and 51 to receive LMWH; 32 UH and 34 LMWH patients completed the study (mean injury severity score [ISS] = 1.2). There were no significant differences between groups with regard to age, sex, ISS, mechanism of injury, or doses of drug given. Outcome measures such as length of stay in the surgical intensive care unit and hospital days were similar. There were two patients with DVT in the UH group, none in the LMWH group (p = 0.493 by Fisher's exact test). This was not a statistically significant difference. There were five major bleeding complications in each group. The incidence of DVT in injured patients receiving prophylaxis appears to be quite low if individuals such as those with severe head injury or visceral contusions are excluded. LMWH is not clearly beneficial when compared with UH in this moderate-risk trauma population.