Study designs of evaluations included in the review
All of the included studies were randomised controlled trials (RCTs).
Specific interventions included in the review
The included studies needed to evaluate subcutaneous LMWHs versus standard intravenous unfractionated heparin. The LMWHs assessed were enoxaparin, dalteparin and nadroparin (the doses were listed in the paper).
Participants included in the review
Patients with DVT, as diagnosed by phlebography or ultrasound, were eligible. Studies of patients with symptoms of pulmonary embolism or thrombosis of veins in the arms were excluded. In five of the included trials all patients had proximal DVT, while in the remaining four this group represented 57 to 79% of the participants. The dose was always related to patient weight and varied from 175 to 240 UI/kg per day, administered as one or two doses. LMWH was given for 5 to 10 days.
Outcomes assessed in the review
Efficacy was examined in terms of survival and resolution of DVT. The adverse events assessed included thrombocytopenia, major and minor bleeding, and recurrence of DVT. Both early and late adverse events were examined. Early events were defined as occurring during heparin treatment or up to 48 hours after the cessation of heparin treatment.
How were decisions on the relevance of primary studies made?
The authors do not state how the papers were selected for the review, or how many of the reviewers performed the selection.