title: Impact of Helicopter Emergency Medical Service in Traumatized Patients: Which Patient Benefits Most?
abstract: BACKGROUND
  The Helicopter Emergency Medical Service (HEMS) was established for the prehospital trauma care of patients. Improved rescue times and increased coverage areas are discussed as specific advantages of HEMS. We recently found evidence that HEMS exerts beneficial effects on outcomes for severely injured patients. However, it still remains unknown which group of trauma patients might benefit most from HEMS rescue. Consequently, the unique aim of this study was to reveal which patients might benefit most from HEMS rescue.
  
  
  METHODS
  Trauma patients (ISS ≥9) primarily treated by HEMS or ground emergency medical services (GEMS) between 2002 and 2012 were analysed using the TraumaRegister DGU. A multivariate regression analysis was used to reveal the survival benefit between different trauma populations.
  
  
  RESULTS
  The study included 52 281 trauma patients. Of these, 68.8% (35 974) were rescued by GEMS and 31.2% (16 307) by HEMS. HEMS patients were more severely injured compared to GEMS patients (ISS: HEMS 24.8±13.5 vs. GEMS 21.7±18.0) and more frequently suffered traumatic shock (SBP sys <90mmHg: HEMS 18.3% vs. GEMS 14.8%). However, logistic regression analysis revealed that HEMS rescues resulted in an overall survival benefit compared to GEMS (OR 0.81, 95% CI [0.75-0.87], p<0.001, Nagelkerke's R squared 0.526, area under the ROC curve 0.922, 95% CI [0.919-0.925]). Analysis of specific subgroups demonstrated that patients aged older than 55 years (OR 0.62, 95% CI [0.50-0.77]) had the highest survival benefit after HEMS treatment. Furthermore, HEMS rescue had the most significant impact after 'low falls' (OR 0.68, 95% CI [0.55-0.84]) and in the case of minor severity injuries (ISS 9-15) (OR 0.66, 95% CI [0.49-0.88]).
  
  
  CONCLUSIONS
  In general, trauma patients benefit from HEMS rescue with in-hospital survival as the main outcome parameter. Focusing on special subgroups, middle aged and older patients, low-energy trauma, and minor severity injuries had the highest survival benefit when rescued by HEMS. Further studies are required to determine the potential reasons of this benefit.
authors.affiliation: Department of Orthopedic Trauma at Aachen University and Harald Tscherne Laboratory, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany.
authors.forename: Hagen
authors.initials: H
authors.lastname: Andruszkow
authors.affiliation: Department of Trauma and Orthopedic Surgery, Berufsgenossenschaftliche Unfallklinik Frankfurt am Main, Friedberger Landstraße 430, 60389 Frankfurt am Main, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Schweigkofler
authors.affiliation: Institute for Research in Operative Medicine (IFOM), University of Witten/Herdecke, Ostmerheimer Str. 200, 51109 Cologne, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Lefering
authors.affiliation: Department of Orthopedic Trauma at Aachen University and Harald Tscherne Laboratory, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany.
authors.forename: Magnus
authors.initials: M
authors.lastname: Frey
authors.affiliation: Department of Orthopedic Trauma at Aachen University and Harald Tscherne Laboratory, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany.
authors.forename: Klemens
authors.initials: K
authors.lastname: Horst
authors.affiliation: Department of Orthopedic Trauma at Aachen University and Harald Tscherne Laboratory, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany.
authors.forename: Roman
authors.initials: R
authors.lastname: Pfeifer
authors.affiliation: Emergency Medical Service Aachen, Department of Anaesthesiology, University Hospital Aachen, RWTH Aachen University, Pauwelsstraße 30, Germany.
authors.forename: Stefan Kurt
authors.initials: SK
authors.lastname: Beckers
authors.affiliation: Department of Orthopedic Trauma at Aachen University and Harald Tscherne Laboratory, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany.
authors.forename: Hans-Christoph
authors.initials: HC
authors.lastname: Pape
authors.affiliation: Department of Orthopedic Trauma at Aachen University and Harald Tscherne Laboratory, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Hildebrand
mesh_terms: D000328:Adult; D000368:Aged; D017732:Air Ambulances / Q000706:statistics & numerical data; D000401:Aircraft; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009104:Multiple Trauma; D011446:Prospective Studies; D016019:Survival Analysis; D014193:Trauma Centers / Q000706:statistics & numerical data; D055815:Young Adult