PREPIC.

Methods	Study design: Multicentre study; randomised control open trial using a 2x2 factorial design. Country: France. Intention‐to‐treat analysis.
Participants	Number: 400 participants. Age: 73 +/‐ 11. Sex: 64% were male. Inclusion criteria: Age >18 with documented proximal DVT or PE, and considered high risk for pulmonary embolism. Exclusion criteria: previous filter; contraindication or failure of anticoagulation; curative anticoagulation > 48 hours duration; indication for thrombolysis; short life expectancy; allergy to iodine; hereditary thrombophilia; severe renal or hepatic failure; pregnancy; likely non‐compliance.
Interventions	(Permanent) caval filter vs no filter LMWH vs unfractionated heparin
Outcomes	Primary outcomes. Pulmonary embolism. Mortality. Deep venous thrombosis. Secondary outcomes. Bleeding. Post‐thrombotic syndrome. Filter‐related complications. Outcomes assessed at 12 days, two years, eight years.
Notes	Study had low power. Jadad score 3/5
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Randomisation was based on a centralised computer system.
Allocation concealment?	Unclear risk	Not described.
Blinding? Mortality	High risk	Open study design.
Blinding? Pulmonary embolism	High risk	Open study design.
Incomplete outcome data addressed? Mortality	Low risk	Negligible losses to follow up (only 4 of 400 participants). No missing outcome data. Causes of death reported. Mortality reported at 12 days, two years and eight years.
Incomplete outcome data addressed? Pulmonary embolism	Low risk	No missing outcome data. Pulmonary embolism reported at12 days, two years and eight years.
Free of selective reporting?	Low risk	Primary and secondary outcomes were reported.

DVT: deep vein thrombosis 
 LMWH: low molecular weight heparin 
 PE: pulmonary embolism