Ardeparin, a low-molecular-weight heparin, has recently been labeled by the U.S. Food and Drug Administration for prophylaxis against venous thromboembolism in patients undergoing elective total knee replacement. It has not, however, been evaluated in a randomized controlled trial of patients being treated for established acute deep venous thrombosis (DVT). Goldhaber and associates compared the efficacy of ardeparin and unfractionated heparin in 80 patients with acute symptomatic DVT of the legs that was documented by ultrasound examination.

Patients were randomized to receive one of the following regimens: subcutaneous low-molecular-weight heparin (ardeparin) twice daily during a two-day hospitalization, or a 5,000- to 7,500-unit bolus of unfractionated heparin followed by a continuous intravenous infusion administered for five days or more in the hospital to achieve a target partial thromboplastin time of 1.5 to 2.5 times the upper limit of control. All patients were discharged home with vascular compression stockings and scheduled to return for two-and six-week office visits. The principal efficacy end point was the change on the six-week ultrasound scan compared with baseline. A total of 75 patients underwent follow-up ultrasonography.

No deaths or recurrent DVT occurred in either group. One case of symptomatic, hemodynamically stable pulmonary embolism was diagnosed by high-probability lung scan in a patient assigned to the heparin-treated group. One patient in each group had a major bleeding complication.

Thirty-one of the patients treated with ardeparin improved (79 percent), compared with 21 of the patients treated with unfractionated heparin (58 percent). Hospital costs were greater in the unfractionated heparin group, which averaged 5.7 days of hospitalization compared with the ardeparin group, which averaged 2.2 days of hospitalization. The mean hospital charges were $6,500 and $2,815, respectively. On a satisfaction scale of 1 to 5, with 1 being excellent and 5 being poor, both groups reported an average score of 1.3 for the care they received. Two weeks after treatment, members of both groups were achieving the same level of activity.

Results of this study indicated that, in terms of thrombus resolution, efficacy was greater with ardeparin than with unfractionated heparin. Safety and patient satisfaction were similar. The principal difference between the two management strategies was the dramatic decrease in hospital costs among the patients in the ardeparin group.

The authors conclude that the beneficial effects of ardeparin for orthopedic surgical prophylaxis might be extended to treatment of established acute DVT. In a dosage more than 2.5 times greater than that used for prophylaxis, ardeparin was demonstrated to be more effective and as safe as un-fractionated heparin. The use of ardeparin permitted early hospital discharge, resulting in significant savings. The authors note that their study numbers are small, and these results will need to be validated by a larger trial.