PREPIC, 1998 | caval filter (n=200) vs. no filter (n=200) 2x2 factorial design also comparing LMWH vs unfractionated heparin | patients with documented proximal DVT or PE, and considered high risk for pulmonary
embolism | open Parallel groups Sample size: 200/200 Primary endpoint: none FU duration: 12 days and 2 years |