THROMBOEMBOLISM: LOW MOLECULAR WEIGHT HEPARIN PRODUCES BOTH FEWER RECURRENCES AND FEWER BLEEDS THAN UNFRACTIONATED HEPARIN
Clinical Bottom Line:
LMWH's are more effective and safer than UFH in the treatment of pts with DVT. |
Question: In a patient with DVT, is LMWH as effective as UFH in preventing recurrent DVT?
Search Terms: venous thromboembolism, low molecular weight heparin in MEDLINE
The Study:
- systematic review of 16 RCTs that evaluated LMWH and UFH
- pts included were those with their first DVT confirmed with venogram or PE confirmed by high probability V/Q scan or angio
- duration of LMWH varied from 5-14 days
- oral anticoagulation usually started on day 3, with target INR of 2-3
- outcomes: either symptomatic recurrent VTE or extension of DVT, death or major bleeding
- studies evaluated for quality, and analysis performed on Level 1 (good RCTs) and Level 2 (not quite as good RCTs) studies separately and then in combination
- not all 16 trials included in analysis of each outcome (inclusion depended on quality with which they determined that outcome)
The Evidence from Level 1 trials:
| Outcome | Time | ARR | NNT |
| recurrent VTE | from day 1-15 | 0.024 | 42 |
|---|
| recurrent VTE | from day 15-90 | 0.037 | 29 |
|---|
| major bleeding | from days 1-90 | 0.037 |
29 |
|---|
| overall mortality | from days 1-90 | 0.026 | 38 |
|---|
Comments:
- studies used different preparations of LMWH
- strangley, the difference in mortality was due to reduced mortality in cancer pts after being switched to warfarin (days 15-90)! - no difference in mortality in cancer pts from days 1-15 and no difference in mortality in non-cancer pts from days 1-90
- see also systematic reviews in BMJ 1994;309:299-304 and Arch Intern Med 1995;155:601-7.
Expiry Date: November 1998
Reference:
- Siragusa S et al. Low-molecular-weight heparins and unfractionated heparin in the treatment of patients with acute venous thromboembolism: results of a meta-analysis. Am J Med 1996;100:269-77.
