title: Incidence, etiology and predictors of adverse outcomes in 43,315 patients presenting to the Emergency Department with syncope: an international meta-analysis.
abstract: BACKGROUND
  Syncope remains challenging for Emergency Department (ED) physicians due to difficulties in assessing the risk of future adverse outcomes. The aim of this meta-analysis is to establish the incidence and etiology of adverse outcomes as well as the predictors, in patients presenting with syncope to the ED.
  
  
  METHODS
  A systematic electronic literature review was performed looking for eligible studies published between 1990 and 2010. Studies reporting multivariate predictors of adverse outcomes in patients presenting with syncope to the ED were included and pooled, when appropriate, using a random-effect method. Adverse events were defined as 'incidence of death, or of hospitalization and interventional procedures because of arrhythmias, ischemic heart disease or valvular heart disease'.
  
  
  RESULTS
  11 studies were included. Pooled analysis showed 42% (CI 95%; 32-52) of patients were admitted to hospital. Risk of death was 4.4% (CI 95%; 3.1-5.1) and 1.1% (CI 95%; 0.7-1.5) had a cardiovascular etiology. One third of patients were discharged without a diagnosis, while the most frequent diagnosis was 'situational, orthostatic or vasavagal syncope' in 29% (CI 95%; 12-47). 10.4% (CI 95%; 7.8-16) was diagnosed with heart disease, the most frequent type being bradyarrhythmia, 4.8% (CI 95%; 2.2-6.4) and tachyarrhythmia 2.6% (CI 95%; 1.1-3.1). Palpitations preceding syncope, exertional syncope, a history consistent of heart failure or ischemic heart disease, and evidence of bleeding were the most powerful predictors of an adverse outcome.
  
  
  CONCLUSIONS
  Syncope carries a high risk of death, mainly related to cardiovascular disease. This large study which has established the most powerful predictors of adverse outcomes, may enable care and resources to be better focused at high risk patients.
authors.affiliation: University of Turin, Division of Cardiology, Italy. fabrizio.dascenzo@gmail.com
authors.forename: Fabrizio
authors.initials: F
authors.lastname: D'Ascenzo
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Biondi-Zoccai
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Reed
authors.forename: Gelareh Z
authors.initials: GZ
authors.lastname: Gabayan
authors.forename: Masaru
authors.initials: M
authors.lastname: Suzuki
authors.forename: Giorgio
authors.initials: G
authors.lastname: Costantino
authors.forename: Raffaello
authors.initials: R
authors.lastname: Furlan
authors.forename: Andrea
authors.initials: A
authors.lastname: Del Rosso
authors.forename: Francois P
authors.initials: FP
authors.lastname: Sarasin
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Sun
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Modena
authors.forename: Fiorenzo
authors.initials: F
authors.lastname: Gaita
mesh_terms: D004632:Emergency Medical Services / Q000379:methods*; D004636:Emergency Service, Hospital / Q000639:trends; D006801:Humans; D015994:Incidence; D038622:Internationality; D015337:Multicenter Studies as Topic / Q000379:methods; D011237:Predictive Value of Tests; D016032:Randomized Controlled Trials as Topic / Q000379:methods; D012307:Risk Factors; D013575:Syncope / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D016896:Treatment Outcome