title: Efficacy and bleeding complications among patients randomized to enoxaparin or unfractionated heparin for antithrombin therapy in non-ST-Segment elevation acute coronary syndromes: a systematic overview.
abstract: BACKGROUND
  Antithrombin therapy has become a guidelines-recommended standard of care in the treatment of acute coronary syndromes (ACS), but recent trials comparing use of enoxaparin and unfractionated heparin in ACS have yielded less robust efficacy and safety results than have earlier trials of these antithrombin therapies.
  
  
  OBJECTIVE
  To systematically evaluate the end points of all-cause death and nonfatal myocardial infarction (MI), transfusion, and major bleeding observed in the 6 randomized controlled trials comparing enoxaparin and unfractionated heparin in treatment of ACS.
  
  
  METHODS
  The primary data sets for ESSENCE, A to Z, and SYNERGY were available at the Duke Clinical Research Institute. Baseline characteristics and event frequencies for TIMI 11B, ACUTE II, and INTERACT were provided by the principal investigator of each study.
  
  
  METHODS
  All 6 randomized controlled trials comparing enoxaparin and unfractionated heparin in non-ST-segment elevation ACS were selected for analysis.
  
  
  METHODS
  Efficacy and safety end points were extracted from the overall trial populations and the subpopulation receiving no antithrombin therapy prior to randomization.
  
  
  RESULTS
  Systematic evaluation of the outcomes for 21 946 patients was performed using a random-effects empirical Bayes model. No significant difference was found in death at 30 days for enoxaparin vs unfractionated heparin (3.0% vs 3.0%; odds ratio [OR], 1.00; 95% confidence interval [CI], 0.85-1.17). A statistically significant reduction in the combined end point of death or nonfatal MI at 30 days was observed for enoxaparin vs unfractionated heparin in the overall trial populations (10.1% vs 11.0%; OR, 0.91; 95% CI, 0.83-0.99; number needed to treat, 107). A statistically significant reduction in the combined end point of death or MI at 30 days was also observed for enoxaparin in the populations receiving no prerandomization antithrombin therapy (8.0% vs 9.4%; OR, 0.81; 95% CI, 0.70-0.94; number needed to treat, 72). No significant difference was found in blood transfusion (OR, 1.01; 95% CI, 0.89-1.14) or major bleeding (OR, 1.04; 95% CI, 0.83-1.30) at 7 days after randomization in the overall safety population or in the population of patients receiving no prerandomization antithrombin therapy.
  
  
  CONCLUSIONS
  In a systematic overview of approximately 22 000 patients across the spectrum of ACS, enoxaparin is more effective than unfractionated heparin in preventing the combined end point of death or MI.
authors.affiliation: Duke Clinical Research Institute, Durham, NC 27715, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Petersen
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Mahaffey
authors.forename: Vic
authors.initials: V
authors.lastname: Hasselblad
authors.forename: Elliott M
authors.initials: EM
authors.lastname: Antman
authors.forename: Marc
authors.initials: M
authors.lastname: Cohen
authors.forename: Shaun G
authors.initials: SG
authors.lastname: Goodman
authors.forename: Anatoly
authors.initials: A
authors.lastname: Langer
authors.forename: Michael A
authors.initials: MA
authors.lastname: Blazing
authors.forename: Anne
authors.initials: A
authors.lastname: Le-Moigne-Amrani
authors.forename: James A
authors.initials: JA
authors.lastname: de Lemos
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Nessel
authors.forename: Robert A
authors.initials: RA
authors.lastname: Harrington
authors.forename: James J
authors.initials: JJ
authors.lastname: Ferguson
authors.forename: Eugene
authors.initials: E
authors.lastname: Braunwald
authors.forename: Robert M
authors.initials: RM
authors.lastname: Califf
mesh_terms: D000787:Angina Pectoris / Q000188:drug therapy* / Q000401:mortality; D000789:Angina, Unstable / Q000188:drug therapy; D002423:Cause of Death; D017984:Enoxaparin / Q000009:adverse effects / Q000627:therapeutic use*; D005343:Fibrinolytic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D006470:Hemorrhage / Q000453:epidemiology; D006493:Heparin / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D009203:Myocardial Infarction / Q000188:drug therapy; D016032:Randomized Controlled Trials as Topic
chemical_list: D017984:Enoxaparin; D005343:Fibrinolytic Agents; D006493:Heparin