Ferrara 2006.

Methods	Open, randomised, controlled clinical trial
Participants	Number: 192 participants Group 1: 68 participants, involved a single collecting vein. 24 participants had undergone orthopaedic surgery, 22 abdominal surgery and 22 urological surgery. The thrombus was present in a single collecting vein in 48 of these participants and in a single muscular vein in 20. This group was subdivided into 2 subgroups of 34 participants (called 1A and 1B); in the 1A subgroup, the treatment was continued for 12 weeks, and in the 1B subgroup, it was continued for 6 weeks. Group 2: 124 participants involved > 1 collecting vein. 35 participants had undergone orthopaedic surgery, 45 abdominal surgery and 44 urological surgery. 89 of these participants with distal DVT in > 1 vessel presented with thrombotic lesions in 2 vessels and 35 participants had thrombotic lesions in 3 vessels. This group was divided into 2 subgroups of 62 participants (called 2A and 2B); in the 2A subgroup, treatment was continued for 12 weeks, and in the 2B subgroup, it was continued for 6 weeks. Age (range; years): 44–71, group 1; 48–72, group 2 Gender (M/F): 23/45, group 1; 41/83, group 2
Interventions	VKAs for 12 weeks vs VKAs for 6 weeks. All participants were treated with nadroparin calcium at daily doses of 200 IU anti‐Xa per kg bodyweight, given in 2 doses. Contemporarily, sodium warfarin was administered, and nadroparin was stopped until prothrombin activity had stabilised at about 30–40% with an INR of 2–3. Heparin treatment was stopped in all participants after 5 or 6 days.
Outcomes	Extension of calf DVT to proximal veins, symptomatic PE and major bleeding
Notes	People with cancer, inherited coagulopathies (factor V Leiden, G20120 mutation in prothrombin, hyperhomocystinaemia, dysplasminogenaemia, deficits in vitamin C or protein S, dysfibrinogenaemia), hyperviscosity syndromes or antiphospholipid antibodies, or absolute or relative contraindications for heparin or anticoagulant treatment were excluded. Funding/support: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information about the sequence generation process.
Allocation concealment (selection bias)	Unclear risk	Insufficient information about the allocation concealment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open‐label study.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	No blinding of outcome assessment but the review authors judged that the outcome measurement was unlikely to be influenced by lack of blinding.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing data.
Selective reporting (reporting bias)	Low risk	The published report included all expected outcomes.
Other bias	Low risk	The study appeared free of other sources of bias.