c Timing of randomization relative to the start of treatment and length of treatment varied across studies: Pinede et al223 and Campbell et al222 randomized at diagnosis; and Agnelli et al,223 Eischer et al,227 and Couturaud et al60 randomized after the initial 3 mo (Agnelli et al224 ) or 6 mo (Eischer et al227 Couturaud et al60 ) of treatment to stop or continued treatment. The longer duration of treatment was 6 mo in Agnelli et al224 (provoked PE) and Pinede et al,223 , 12 mo in Agnelli et al224,225 (unprovoked DVT; unprovoked PE), 24 mo in Couturaud et al,60 and 30 mo in Eischer et al.227 Generally, study design was strong. No study stopped early for bene t; 3 stopped early because of slow recruitment (Campbell et al,222 Pinede et al,223 Eischer et al227 ) and 1 because of lack of bene t (Agnelli et al224 ). In 1 study (Campbell et al222 ), 20% of VTE outcomes were not objectively con rmed. Patients and caregivers were blinded in Couturaud et al,60 but none of the other studies was. Adjudicators of outcomes were blinded in all but 1 study (Campbell et al222 ). All studies used effective randomization concealment, intention-to-treat analysis, and a low unexplained dropout frequency. d Study populations varied across studies: Pinede et al223 enrolled provoked and unprovoked proximal DVT and PE; Campbell et al,222 enrolled provoked and unprovoked isolated distal DVT, proximal DVT, and PE; Agnelli et al224 had separate randomizations for provoked PE (3 vs 6 mo) and unprovoked (3 vs 12 mo); Agnelli et al225 enrolled unprovoked proximal DVT; Eischer et al227 enrolled unprovoked isolated DVT, proximal DVT, and PE with high levels of factor VIII; and Couturaud et al60 enrolled unprovoked PE. 