Study designs of evaluations included in the review
Randomised dose-ranging studies, open randomised studies, randomised single and double-blinded studies. Trials were included if they were randomised, open or controlled with dextran, UFH (alone or with dihydroergotamine), warfarin or placebo.
Specific interventions included in the review
LMWH versus dextran, UFH (alone or with dihydroergotamine), warfarin or placebo. The LMWH studied were: logiparin, Kabi 2165, CY216, enoxaparin, embolex, sandoparin, lovenox, clivarine, heparin NM, and dihydergot.
Participants included in the review
Patients who underwent general surgery and deep vein thrombosis (DVT) prophylaxis with LMWH, UFH or warfarin.
Outcomes assessed in the review
The outcomes assessed were DVT, pulmonary embolism (PE), and safety effects. DVT was diagnosed by phlebography, whilst PE was diagnosed by pulmonary angiography, ventilation or perfusion lung scan, or at autopsy. Safety effects were assessed by major or minor bleeding.
How were decisions on the relevance of primary studies made?
The trials were assessed independently by two physicians, and any disagreements were resolved by discussion.