title: Lives saved by helicopter emergency medical services: an overview of literature.
abstract: BACKGROUND
  The objective of this review is to give an overview of literature on the survival benefits of Helicopter Emergency Medical Services (HEMS). The included studies were assessed by study design and statistical methodology.
  
  
  METHODS
  A literature search was performed in the National Library of Medicine's Medline database, extending from 1985 until April 2007. Manuscripts had to be written in English and describe effects of HEMS on survival expressed in number of lives saved. Moreover, analysis had to be performed using adequate adjustment for differences in case-mix.
  
  
  RESULTS
  Sixteen publications met the inclusion criteria. All indicated that HEMS assistance contributed to increased survival: Between 1.1 and 12.1 additional survivors were recorded for every 100 HEMS uses. A combination of four reliable studies shows overall mortality reduction of 2.7 additional lives saved per 100 HEMS deployments.
  
  
  CONCLUSIONS
  Literature shows a clear positive effect on survival associated with HEMS assistance. Efforts should be made to promote consistent methodology, including uniform outcome parameters, in order to provide sufficient scientific evidence to conclude the ongoing debate about the beneficial effects of HEMS.
authors.affiliation: Department of Surgery-Traumatology, Erasmus MC, University Medical Center, Rotterdam, Netherlands. a.ringburg@erasmusmc.nl
authors.forename: Akkie N
authors.initials: AN
authors.lastname: Ringburg
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Thomas
authors.forename: Ewout W
authors.initials: EW
authors.lastname: Steyerberg
authors.forename: Esther M M
authors.initials: EM
authors.lastname: van Lieshout
authors.forename: Peter
authors.initials: P
authors.lastname: Patka
authors.forename: Inger B
authors.initials: IB
authors.lastname: Schipper
mesh_terms: D017732:Air Ambulances; D004632:Emergency Medical Services / Q000592:standards*; D006801:Humans; D013534:Survival