Benefit of Helicopter Emergency Medical Services on trauma patient mortality in the Netherlands?

N. Hoogerwerf, MD PhD, Medical Coordinator HEMS, Radboud University Medical Center, Nijmegen. J.P. Valk, MD, Medical Coordinator HEMS, University Medical Center Groningen. R.J. Houmes MD, Medical Coordinator HEMS Rotterdam H.M. Christiaans MD, Medical Coordinator HEMS, VU University Medical Center Amsterdam. L.M.G. Geeraedts jr. MD, Department of Surgery, VU University Medical Center Amsterdam. P. Schober MD PhD, HEMS and Department of Anesthesiology, VU University Medical Center Amsterdam. E.S.M. de Langede Klerk MD PhD, dept Epidemiology and Biostatistics, VU University Medical Center E.M.M. Van Lieshout PhD, Research coordinator Trauma Surgery Erasmus MC Rotterdam G.J. Scheffer MD PhD, Head of Anesthesiology, Radboud University Medical Center, Nijmegen. D. Den Hartog MD PhD, trauma surgeon, Head of Trauma center South West Netherlands