title: Association of Bystander Cardiopulmonary Resuscitation and Survival According to Ambulance Response Times After Out-of-Hospital Cardiac Arrest.
abstract: BACKGROUND
  Bystander-initiated cardiopulmonary resuscitation (CPR) increases patient survival after out-of-hospital cardiac arrest, but it is unknown to what degree bystander CPR remains positively associated with survival with increasing time to potential defibrillation. The main objective was to examine the association of bystander CPR with survival as time to advanced treatment increases.
  
  
  METHODS
  We studied 7623 out-of-hospital cardiac arrest patients between 2005 and 2011, identified through the nationwide Danish Cardiac Arrest Registry. Multiple logistic regression analysis was used to examine the association between time from 911 call to emergency medical service arrival (response time) and survival according to whether bystander CPR was provided (yes or no). Reported are 30-day survival chances with 95% bootstrap confidence intervals.
  
  
  RESULTS
  With increasing response times, adjusted 30-day survival chances decreased for both patients with bystander CPR and those without. However, the contrast between the survival chances of patients with versus without bystander CPR increased over time: within 5 minutes, 30-day survival was 14.5% (95% confidence interval [CI]: 12.8-16.4) versus 6.3% (95% CI: 5.1-7.6), corresponding to 2.3 times higher chances of survival associated with bystander CPR; within 10 minutes, 30-day survival chances were 6.7% (95% CI: 5.4-8.1) versus 2.2% (95% CI: 1.5-3.1), corresponding to 3.0 times higher chances of 30-day survival associated with bystander CPR. The contrast in 30-day survival became statistically insignificant when response time was >13 minutes (bystander CPR vs no bystander CPR: 3.7% [95% CI: 2.2-5.4] vs 1.5% [95% CI: 0.6-2.7]), but 30-day survival was still 2.5 times higher associated with bystander CPR. Based on the model and Danish out-of-hospital cardiac arrest statistics, an additional 233 patients could potentially be saved annually if response time was reduced from 10 to 5 minutes and 119 patients if response time was reduced from 7 (the median response time in this study) to 5 minutes.
  
  
  CONCLUSIONS
  The absolute survival associated with bystander CPR declined rapidly with time. Yet bystander CPR while waiting for an ambulance was associated with a more than doubling of 30-day survival even in case of long ambulance response time. Decreasing ambulance response time by even a few minutes could potentially lead to many additional lives saved every year.
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.). shahzleen@gmail.com.
authors.forename: Shahzleen
authors.initials: S
authors.lastname: Rajan
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Mads
authors.initials: M
authors.lastname: Wissenberg
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Fredrik
authors.initials: F
authors.lastname: Folke
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Steen Møller
authors.initials: SM
authors.lastname: Hansen
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Gerds
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Kristian
authors.initials: K
authors.lastname: Kragholm
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Carolina Malta
authors.initials: CM
authors.lastname: Hansen
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Lena
authors.initials: L
authors.lastname: Karlsson
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Freddy K
authors.initials: FK
authors.lastname: Lippert
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Lars
authors.initials: L
authors.lastname: Køber
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Gunnar H
authors.initials: GH
authors.lastname: Gislason
authors.affiliation: From Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark (S.R., F.F., C.M.H., L.K.); Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Denmark (M.W.); Emergency Medical Services Copenhagen, University of Copenhagen, Ballerup, Denmark (M.W., F.F., F.K.L.); Department of Clinical Epidemiology, Aalborg University Hospital, Denmark (S.M.); Department of Biostatistics, University of Copenhagen, Denmark (T.A.G.); Department of Anesthesiology & Clinical Medicine, Aalborg University Hospital, Denmark (K.K.); Duke Clinical Research Institute, Duke University, Durham, NC (C.M.H.); Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark (L.K.); The National Institute of Public Health, University of Southern Denmark, Copenhagen (G.H.G.); and Department of Health, Science and Technology, Aalborg University, Denmark (C.T.-P.).
authors.forename: Christian
authors.initials: C
authors.lastname: Torp-Pedersen
mesh_terms: D000328:Adult; D000368:Aged; D000552:Ambulances; D024201:Bystander Effect; D016887:Cardiopulmonary Resuscitation; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy*; D011930:Reaction Time; D012042:Registries; D016019:Survival Analysis; D013997:Time Factors
keywords: cardiac arrest; cardiopulmonary resuscitation; epidemiology; survival