title: Use of prestudy heparin did not influence the efficacy and safety of rivaroxaban in patients treated for symptomatic venous thromboem-bolism in the EINSTEIN DVT and EINSTEIN PE studies.
abstract: OBJECTIVE
  In the EINSTEIN DVT and EINSTEIN PE studies, the majority of patients received heparins to bridge the period during venous thromboembolism (VTE) diagnosis confirmation and the start of the study. In contrast to vitamin K antagonists (VKAs), rivaroxaban may not require initial heparin treatment.
  
  
  METHODS
  To evaluate the effect of prestudy heparin on the efficacy and safety of rivaroxaban relative to enoxaparin/VKA, the 3-month incidence of recurrent VTE, and the 14-day incidence of major and nonmajor clinically relevant bleeding were compared in patients who did and did not receive prestudy heparin.
  
  
  RESULTS
  Of the 8,281 patients randomized, 6,937 (83.8%) received prestudy heparin (mean ± SD duration = rivaroxaban: 1.04 [± 0.74] days; enoxaparin 1.03 [± 0.42] days), and 1,344 (16.2%) did not. In patients who did not receive prestudy heparin, the incidences of recurrent VTE were similar in rivaroxaban (15 of 649, 2.3%) and enoxaparin/VKA (13 of 695, 1.9%) patients (adjusted hazard ratio [HR] = 1.11; 95% confidence interval [CI] = 0.52 to 2.37). The incidences of recurrent VTE were also similar in rivaroxaban (54 of 3,501, 1.5%) and enoxaparin/VKA (69 of 3,436, 2.0%) patients who did receive prestudy heparin (adjusted HR = 0.74; 95% CI = 0.52 to 1.06; pinteraction  = 0.32). The incidences of major or nonmajor clinically relevant bleeding with rivaroxaban were not significantly different from those with enoxaparin/VKA, either with (105 of 3,485, 3.0% vs. 104 of 3,428, 3.0%; adjusted HR = 0.98; 95% CI = 0.75 to 1.29) or without (24 of 645, 3.7% vs. 30 of 688, 4.4%; adjusted HR = 0.81; 95% CI = 0.46 to 1.40; pinteraction  = 0.68) prestudy heparin.
  
  
  CONCLUSIONS
  Although the majority of patients in the EINSTEIN studies received prestudy heparin, there were no notable differences in treatment effect of rivaroxaban versus enoxaparin/VKA in those who did and did not receive it.
authors: The Department of Cardiothoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors: Paolo
authors: P
authors: Prandoni
authors: Martin H
authors: MH
authors: Prins
authors: Alexander T
authors: AT
authors: Cohen
authors: Katharina
authors: K
authors: Müller
authors: Ákos F
authors: ÁF
authors: Pap
authors: Miriam C
authors: MC
authors: Tewes
authors: Anthonie W A
authors: AW
authors: Lensing
mesh_terms: D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D017984:Enoxaparin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006493:Heparin / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009025:Morpholines / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D000069552:Rivaroxaban; D012449:Safety; D013876:Thiophenes / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D054556:Venous Thromboembolism / Q000188:drug therapy*; D014812:Vitamin K / Q000037:antagonists & inhibitors
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D009025:Morpholines; D013876:Thiophenes; D014812:Vitamin K; D006493:Heparin; D000069552:Rivaroxaban