title: Causality analysis of the relationship between bleeding and lethality in Acute Coronary Syndromes.
abstract: BACKGROUND
  Hemorrhagic events in Acute Coronary Syndromes (ACS) have been independently associated with death in international multicenter registries. However, that association has not been tested in Brazil and the true causal relationship between bleeding and death has not been completely shown.
  
  
  OBJECTIVE
  To test the following hypotheses: (1) major bleeding is an independent predictor of in-hospital death in ACS; (2) the relationship between those two endpoints is causal.
  
  
  METHODS
  This study included patients meeting predefined criteria of unstable angina, non-ST-segment elevation myocardial infarction or ST-segment elevation myocardial infarction. Major bleeding during hospitalization was defined according to the Bleeding Academic Research Consortium (types 3 or 5). Logistic regression and analysis of the sequence of events were used to assess the association between bleeding and death.
  
  
  RESULTS
  Of the 455 patients studied, 29 experienced major bleeding (6.4%; 95% CI = 4.3-9.0%). They had in-hospital mortality of 21%, as compared with 5.6% of those not experiencing bleeding (RR = 4.0; 95% CI = 1.8-9.1; P = 0.001). After adjusting for the propensity score, major bleeding remained as a predictor of in-hospital death (OR = 3.34; 95% CI = 1.2-9.5; P = 0.02). Of the 29 patients who experienced bleeding, six died. However, the detailed analysis of the sequence of events showed causal relationship only in one case.
  
  
  CONCLUSIONS
  (1) Major bleeding is an independent predictor of in-hospital death in ACS; (2) the role of bleeding as a risk marker overcomes that as a risk factor for death. This conclusion should be seen as a hypothesis generator to be confirmed by larger-sample studies.
authors.affiliation: Escola Bahiana de Medicina, Salvador, BA, Brasil. lccorreia@cardiol.br
authors.forename: Luis Cláudio Lemos
authors.initials: LC
authors.lastname: Correia
authors.forename: Michael
authors.initials: M
authors.lastname: Sabino
authors.forename: Mariana
authors.initials: M
authors.lastname: Brito
authors.forename: Guilherme
authors.initials: G
authors.lastname: Garcia
authors.forename: Mateus
authors.initials: M
authors.lastname: Viana
authors.forename: J Péricles
authors.initials: JP
authors.lastname: Esteves
authors.forename: Márcia R
authors.initials: MR
authors.lastname: Noya
mesh_terms: D054058:Acute Coronary Syndrome / Q000401:mortality*; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil / Q000453:epidemiology; D004812:Epidemiologic Methods; D017809:Fatal Outcome; D005260:Female; D006470:Hemorrhage / Q000150:complications / Q000401:mortality*; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged