Resuscitation 91 (2015) A7–A8
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Editorial
Are out-of-hospital cardiac arrest survival rates improving?
It has been noted many times over the past 40 or so years that despite what seem like significant advances in the science of emergency medical services (EMS) generally and out-of-hospital cardiac arrest (OHCA) resuscitation specifically, little change has been seen in overall OHCA survival rates. A meta-analysis published as recently as 2010 noted that “survival from OHCA has not significantly improved in almost 3 decades, despite enormous efforts in research spending and the development of novel drugs and devices. The aggregate survival rate, recorded across various populations, is between 6.7% and 8.4%.”1 With the exception of several well-known and highly publicized EMS systems, few can claim survival rates of greater than 10% – and one system that can claim such a survival rate (Sydney, Australia) actually found a small decrease in survival between 2004–05 (12.3%) and 2009–10 (10.2%; absolute drop 2.1%, p = 0.015).2 But is this finally starting to change? This issue of Resuscitation reports on data from the Resuscitation Outcomes Consortium (ROC), a large multi-center US/Canadian project that is familiar to most readers.3 Examining nearly 50,000 patients managed by 139 different EMS agencies in 10 ROC cities/regions, the authors found that unadjusted survival increased from 8.2% in 2006 to 10.4% in 2010, with survival for witnessed cases found in shockable rhythms increasing from 23.5% to 30.3%.4 While this is encouraging news, one must ask: why were the improvements so modest? A 2.2% absolute improvement in overall survival is terrific if you happen to be one of those few “extra” patients who survived – but with the tremendous amount of effort being put into cardiac arrest research around the world, in the lab, field, ED, ICU, and elsewhere, why are not larger gains being seen? As it turns out, somewhat larger gains are being seen in some systems. The EMS system in Columbus, Ohio (USA) demonstrated improvement in unadjusted OHCA survival from 6.1% to 9.4% (absolute improvement 3.3%), and in survival for bystanderwitnessed, shockable-rhythm arrests from 24% to 30% following implementation of the 2005 AHA/ILCOR Guidelines.5 In a similar study of Guidelines 2005 implementation, the Wake County (North Carolina, USA) system cracked the 10% ceiling, with survival improvements from 4.2% to 11.5% for all arrests (absolute improvement 7.3%), and from 13.8% to 40.8% for witnessed, shockable-rhythm arrests.6 A statewide project in Arizona demonstrated survival gains from 1.8% to 5.4% (absolute improvement 3.6%) for all arrests and from 4.7% to 17.6% for witnessed, shockablerhythm arrests following implementation of minimally interrupted CPR.7
http://dx.doi.org/10.1016/j.resuscitation.2015.03.011 0300-9572/© 2015 Elsevier Ireland Ltd. All rights reserved.
So perhaps the question is instead why survival rates in the ROC systems are not increasing as quickly as those in some of these other systems. One contributing factor may be that in these ROC systems, for unknown reasons, the proportions of cases with three factors believed to be good prognostic indicators decreased over the study years. Shockable initial rhythms decreased (from 24.1% in 2006 to 21.5% in 2010), as did cases judged by the rescuers to be of noncardiac etiology (from 10.1% to 4.7%), although as the authors point out, this latter trend may be artificial, given that these data reflect EMS provider impressions only, with no autopsy data or physician impression of etiology included here. Cases occurring in public locations also decreased over time, from 16.1% to 13.7%, and it is well established that bystander CPR is more likely in arrests in public locations than in private residences.8 The 2010 meta-analysis by Sasson and colleagues very firmly re-established the value of both bystander CPR and shockable rhythms.1 The authors of the Sydney study cited above similarly noted a drop in the incidence of ventricular fibrillation (from 31.3% to 22.1%), and speculated that this might at least partially explain the decrease in OHCA survival that they documented.2 Two limitations in the ROC data presented in this issue are worth noting. First, neurologic outcomes were available only for those patients in the ROC PRIMED trial,9 and not for the other ROC Epistry patients, and thus are not reported. It is increasingly common to report cerebral performance scale data for survivors, to allow the reader to assess the quality of the outcome,10 especially since good cerebral performance at hospital discharge tends to predict good long-term survival.11 Second, no data on two important post-resuscitation care processes (therapeutic hypothermia and percutaneous coronary angiography) were available; however, any secular increase in the use of these treatment modalities over the years of the study would most likely bias the results toward even greater improvements in survival. Perhaps, though, a careful reading of both the Sasson metaanalysis and this analysis of thousands of patients from the ROC studies may give us a clue to what seems to becoming increasingly obvious. What is needed to increase survival in cardiac arrest is the science of the simple. The meta-analysis concluded that the strongest associations with survival were bystander or EMSwitnessed arrests, and the receipt of bystander CPR. These, together with shockable cardiac rhythm and return of spontaneous circulation in the field, comprised predictive resuscitation rules for EMS. But knowing that there were decreases (not increases) in most of these factors over the term of the ROC study, what might have led
A8
Editorial / Resuscitation 91 (2015) A7–A8
to the modest but apparently real increases in survival that do not accord with those in the meta-analysis? Perhaps we are seeing what could be termed Hawthorne survival? In the ROC sites, perhaps the very fact of the studies being performed changed not only the behavior of the EMS personnel,12,13 but also of some other components of the communities that hosted these studies. Given the 8–10% increase in mortality with each minute from cardiac arrest to defibrillation, it is axiomatic that when the median response time is 6–8 min, success must rest upon intervention by people other than EMTs; each of the first three links in the chain of survival must be operating to ensure increasing success in resuscitation, whatever the EMS system does when it intervenes. If we look at the standout systems that have achieved stellar success such as King County, Arizona, and Wake County, the largest effect tends to come from public health level interventions such as innovative schemes to exponentially increase community HP-CPR training, and the placement and geographic identification of AEDs. Studies from Japan demonstrating improvements in survival with optimization of dispatcher-aided CPR14 and the use of “hands-only” CPR15 support this position that consistent pre-EMS intervention is crucial to improving survival rates. The message from the Daya and Sasson studies seems to be that not only OHCA research but OHCA survival improvement has to be holistic, inclusive, and based in the society of which the EMS is only one part, and that true and lasting improvement relies on us convincing our communities across the world that OHCA resuscitation is their job as much as ours. Conflict of interest statement The authors have no conflicts of interest to disclose. References 1. Sasson C, Rogers MA, Dahl J, Kellermann AL. Predictors of survival from out-ofhospital cardiac arrest: a systematic review and meta-analysis. Circ Cardiovasc Qual Outcomes 2010;3:63–81. 2. Cheung W, Middleton P, Davies S, Tummala S, Thanakrishnan G, Gullick J. A comparison of survival following out-of-hospital cardiac arrest in Sydney Australia, between 2004–2005 and 2009–2010. Crit Care Resusc 2013;15:241–6. 3. Morrison LJ, Nichol G, Rea TD, et al. Rationale, development and implementation of the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest. Resuscitation 2008;78:161–9.
4. Daya M. Out-of-hospital cardiac arrest survival improving over time: results from the Resuscitation Outcomes Consortium (ROC). Resuscitation 2015;91:108–15. 5. Sayre MR, Cantrell SA, White LJ, Hiestand BC, Keseg DP, Koser S. Impact of the 2005 American Heart Association cardiopulmonary resuscitation and emergency cardiovascular care guidelines on out-of-hospital cardiac arrest survival. Prehosp Emerg Care 2009;13:469–77. 6. Hinchey PR, Myers JB, Lewis R, et al. Improved out-of-hospital cardiac arrest survival after the sequential implementation of 2005 AHA guidelines for compressions, ventilations, and induced hypothermia: the Wake County experience. Ann Emerg Med 2010;56:348–57. 7. Bobrow BJ, Clark LL, Ewy GA, et al. Minimally interrupted cardiac resuscitation by emergency medical services for out-of-hospital cardiac arrest. JAMA 2008;299:1158–65. 8. Jackson RE, Swor RA. Who gets bystander cardiopulmonary resuscitation in a witnessed arrest? Acad Emerg Med 1997;4:540–4. 9. Aufderheide TP, Nichol G, Rea TD, et al. A trial of an impedance threshold device in out-of-hospital cardiac arrest. N Engl J Med 2011;365:798–806. 10. Whitehead L, Perkins GD, Clarey A, Haywood KL. A systematic review of the outcomes reported in cardiac arrest clinical trials: the need for a core outcome set. Resuscitation 2015;88C:150–7. 11. Pachys G, Kaufman N, Bdolah-Abram T, Kark JD, Einav S. Predictors of longterm survival after out-of-hospital cardiac arrest: the impact of activities of daily living and cerebral performance category scores. Resuscitation 2014;85: 1052–8. 12. McCambridge J, Witton J, Elbourne DR. Systematic review of the Hawthorne effect: new concepts are needed to study research participation effects. J Clin Epidemiol 2014;67:267–77. 13. Campbell JP, Maxey VA, Watson WA. Hawthorne effect: implications for prehospital research. Ann Emerg Med 1995;26:590–4. 14. Goto Y, Maeda T, Goto Y. Impact of dispatcher-assisted bystander cardiopulmonary resuscitation on neurological outcomes in children with out-of-hospital cardiac arrests: a prospective nationwide, population-based cohort study. J Am Heart Assoc 2014;3:e000499. 15. Iwami T, Kitamura T, Kawamura T, et al. Chest compression-only cardiopulmonary resuscitation for out-of-hospital cardiac arrest with public-access defibrillation: a nationwide cohort study. Circulation 2012;126:2844–51.
David C. Cone ∗ Department of Emergency Medicine, Yale University School of Medicine, New Haven, CT, USA Paul M. Middleton Discipline of Emergency Medicine, University of Sydney, Sydney, New South Wales, Australia ∗ Corresponding author. E-mail address: [email protected] (D.C. Cone)
9 March 2015
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Editorial
Are out-of-hospital cardiac arrest survival rates improving?
It has been noted many times over the past 40 or so years that despite what seem like significant advances in the science of emergency medical services (EMS) generally and out-of-hospital cardiac arrest (OHCA) resuscitation specifically, little change has been seen in overall OHCA survival rates. A meta-analysis published as recently as 2010 noted that “survival from OHCA has not significantly improved in almost 3 decades, despite enormous efforts in research spending and the development of novel drugs and devices. The aggregate survival rate, recorded across various populations, is between 6.7% and 8.4%.”1 With the exception of several well-known and highly publicized EMS systems, few can claim survival rates of greater than 10% – and one system that can claim such a survival rate (Sydney, Australia) actually found a small decrease in survival between 2004–05 (12.3%) and 2009–10 (10.2%; absolute drop 2.1%, p = 0.015).2 But is this finally starting to change? This issue of Resuscitation reports on data from the Resuscitation Outcomes Consortium (ROC), a large multi-center US/Canadian project that is familiar to most readers.3 Examining nearly 50,000 patients managed by 139 different EMS agencies in 10 ROC cities/regions, the authors found that unadjusted survival increased from 8.2% in 2006 to 10.4% in 2010, with survival for witnessed cases found in shockable rhythms increasing from 23.5% to 30.3%.4 While this is encouraging news, one must ask: why were the improvements so modest? A 2.2% absolute improvement in overall survival is terrific if you happen to be one of those few “extra” patients who survived – but with the tremendous amount of effort being put into cardiac arrest research around the world, in the lab, field, ED, ICU, and elsewhere, why are not larger gains being seen? As it turns out, somewhat larger gains are being seen in some systems. The EMS system in Columbus, Ohio (USA) demonstrated improvement in unadjusted OHCA survival from 6.1% to 9.4% (absolute improvement 3.3%), and in survival for bystanderwitnessed, shockable-rhythm arrests from 24% to 30% following implementation of the 2005 AHA/ILCOR Guidelines.5 In a similar study of Guidelines 2005 implementation, the Wake County (North Carolina, USA) system cracked the 10% ceiling, with survival improvements from 4.2% to 11.5% for all arrests (absolute improvement 7.3%), and from 13.8% to 40.8% for witnessed, shockable-rhythm arrests.6 A statewide project in Arizona demonstrated survival gains from 1.8% to 5.4% (absolute improvement 3.6%) for all arrests and from 4.7% to 17.6% for witnessed, shockablerhythm arrests following implementation of minimally interrupted CPR.7
http://dx.doi.org/10.1016/j.resuscitation.2015.03.011 0300-9572/© 2015 Elsevier Ireland Ltd. All rights reserved.
So perhaps the question is instead why survival rates in the ROC systems are not increasing as quickly as those in some of these other systems. One contributing factor may be that in these ROC systems, for unknown reasons, the proportions of cases with three factors believed to be good prognostic indicators decreased over the study years. Shockable initial rhythms decreased (from 24.1% in 2006 to 21.5% in 2010), as did cases judged by the rescuers to be of noncardiac etiology (from 10.1% to 4.7%), although as the authors point out, this latter trend may be artificial, given that these data reflect EMS provider impressions only, with no autopsy data or physician impression of etiology included here. Cases occurring in public locations also decreased over time, from 16.1% to 13.7%, and it is well established that bystander CPR is more likely in arrests in public locations than in private residences.8 The 2010 meta-analysis by Sasson and colleagues very firmly re-established the value of both bystander CPR and shockable rhythms.1 The authors of the Sydney study cited above similarly noted a drop in the incidence of ventricular fibrillation (from 31.3% to 22.1%), and speculated that this might at least partially explain the decrease in OHCA survival that they documented.2 Two limitations in the ROC data presented in this issue are worth noting. First, neurologic outcomes were available only for those patients in the ROC PRIMED trial,9 and not for the other ROC Epistry patients, and thus are not reported. It is increasingly common to report cerebral performance scale data for survivors, to allow the reader to assess the quality of the outcome,10 especially since good cerebral performance at hospital discharge tends to predict good long-term survival.11 Second, no data on two important post-resuscitation care processes (therapeutic hypothermia and percutaneous coronary angiography) were available; however, any secular increase in the use of these treatment modalities over the years of the study would most likely bias the results toward even greater improvements in survival. Perhaps, though, a careful reading of both the Sasson metaanalysis and this analysis of thousands of patients from the ROC studies may give us a clue to what seems to becoming increasingly obvious. What is needed to increase survival in cardiac arrest is the science of the simple. The meta-analysis concluded that the strongest associations with survival were bystander or EMSwitnessed arrests, and the receipt of bystander CPR. These, together with shockable cardiac rhythm and return of spontaneous circulation in the field, comprised predictive resuscitation rules for EMS. But knowing that there were decreases (not increases) in most of these factors over the term of the ROC study, what might have led
A8
Editorial / Resuscitation 91 (2015) A7–A8
to the modest but apparently real increases in survival that do not accord with those in the meta-analysis? Perhaps we are seeing what could be termed Hawthorne survival? In the ROC sites, perhaps the very fact of the studies being performed changed not only the behavior of the EMS personnel,12,13 but also of some other components of the communities that hosted these studies. Given the 8–10% increase in mortality with each minute from cardiac arrest to defibrillation, it is axiomatic that when the median response time is 6–8 min, success must rest upon intervention by people other than EMTs; each of the first three links in the chain of survival must be operating to ensure increasing success in resuscitation, whatever the EMS system does when it intervenes. If we look at the standout systems that have achieved stellar success such as King County, Arizona, and Wake County, the largest effect tends to come from public health level interventions such as innovative schemes to exponentially increase community HP-CPR training, and the placement and geographic identification of AEDs. Studies from Japan demonstrating improvements in survival with optimization of dispatcher-aided CPR14 and the use of “hands-only” CPR15 support this position that consistent pre-EMS intervention is crucial to improving survival rates. The message from the Daya and Sasson studies seems to be that not only OHCA research but OHCA survival improvement has to be holistic, inclusive, and based in the society of which the EMS is only one part, and that true and lasting improvement relies on us convincing our communities across the world that OHCA resuscitation is their job as much as ours. Conflict of interest statement The authors have no conflicts of interest to disclose. References 1. Sasson C, Rogers MA, Dahl J, Kellermann AL. Predictors of survival from out-ofhospital cardiac arrest: a systematic review and meta-analysis. Circ Cardiovasc Qual Outcomes 2010;3:63–81. 2. Cheung W, Middleton P, Davies S, Tummala S, Thanakrishnan G, Gullick J. A comparison of survival following out-of-hospital cardiac arrest in Sydney Australia, between 2004–2005 and 2009–2010. Crit Care Resusc 2013;15:241–6. 3. Morrison LJ, Nichol G, Rea TD, et al. Rationale, development and implementation of the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest. Resuscitation 2008;78:161–9.
4. Daya M. Out-of-hospital cardiac arrest survival improving over time: results from the Resuscitation Outcomes Consortium (ROC). Resuscitation 2015;91:108–15. 5. Sayre MR, Cantrell SA, White LJ, Hiestand BC, Keseg DP, Koser S. Impact of the 2005 American Heart Association cardiopulmonary resuscitation and emergency cardiovascular care guidelines on out-of-hospital cardiac arrest survival. Prehosp Emerg Care 2009;13:469–77. 6. Hinchey PR, Myers JB, Lewis R, et al. Improved out-of-hospital cardiac arrest survival after the sequential implementation of 2005 AHA guidelines for compressions, ventilations, and induced hypothermia: the Wake County experience. Ann Emerg Med 2010;56:348–57. 7. Bobrow BJ, Clark LL, Ewy GA, et al. Minimally interrupted cardiac resuscitation by emergency medical services for out-of-hospital cardiac arrest. JAMA 2008;299:1158–65. 8. Jackson RE, Swor RA. Who gets bystander cardiopulmonary resuscitation in a witnessed arrest? Acad Emerg Med 1997;4:540–4. 9. Aufderheide TP, Nichol G, Rea TD, et al. A trial of an impedance threshold device in out-of-hospital cardiac arrest. N Engl J Med 2011;365:798–806. 10. Whitehead L, Perkins GD, Clarey A, Haywood KL. A systematic review of the outcomes reported in cardiac arrest clinical trials: the need for a core outcome set. Resuscitation 2015;88C:150–7. 11. Pachys G, Kaufman N, Bdolah-Abram T, Kark JD, Einav S. Predictors of longterm survival after out-of-hospital cardiac arrest: the impact of activities of daily living and cerebral performance category scores. Resuscitation 2014;85: 1052–8. 12. McCambridge J, Witton J, Elbourne DR. Systematic review of the Hawthorne effect: new concepts are needed to study research participation effects. J Clin Epidemiol 2014;67:267–77. 13. Campbell JP, Maxey VA, Watson WA. Hawthorne effect: implications for prehospital research. Ann Emerg Med 1995;26:590–4. 14. Goto Y, Maeda T, Goto Y. Impact of dispatcher-assisted bystander cardiopulmonary resuscitation on neurological outcomes in children with out-of-hospital cardiac arrests: a prospective nationwide, population-based cohort study. J Am Heart Assoc 2014;3:e000499. 15. Iwami T, Kitamura T, Kawamura T, et al. Chest compression-only cardiopulmonary resuscitation for out-of-hospital cardiac arrest with public-access defibrillation: a nationwide cohort study. Circulation 2012;126:2844–51.
David C. Cone ∗ Department of Emergency Medicine, Yale University School of Medicine, New Haven, CT, USA Paul M. Middleton Discipline of Emergency Medicine, University of Sydney, Sydney, New South Wales, Australia ∗ Corresponding author. E-mail address: [email protected] (D.C. Cone)
9 March 2015
