Clinical paperRegional variations in early and late survival after out-of-hospital cardiac arrest☆
Introduction
Regional variations in disease patterns have been described for a range of medical conditions including stroke, heart disease, diabetes, obesity and sepsis.1, 2, 3, 4, 5 Regional variations may signal potential differences in population characteristics, health behaviors, and access to, delivery or quality of healthcare, among other factors. Nichol et al. previously described regional variations in out-of-hospital cardiac arrest (OHCA) survival among sites of the Resuscitation Outcomes Consortium (ROC), finding survival to hospital discharge varying from 3.0% to 16.3%.6
To reduce disparities in OHCA survival, one must understand the underlying influences. Survival from OHCA requires timely out-of-hospital care complemented by quality post-arrest care in the hospital. Disparities in early and later survival may offer key perspectives to explain the observed regional variations in overall OHCA survival. For example, survival differences in the early period after cardiac arrest (e.g., within the first day) may reflect variations in out-of-hospital care such as timely 9-1-1 activation and the provision of bystander CPR. Differences in later survival (i.e., early survivors who progress to hospital discharge) may reflect differences in post-arrest care quality; for example, timely application of therapeutic hypothermia or cardiac catheterization, or the avoidance of premature withdrawal of care. In a prior effort using a different data set, we showed that while early OHCA survival was associated with out-of-hospital factors such as presenting ECG rhythm and resuscitation drug use; later long-term survival was associated with patient demographics such as age and sex.7 These perspectives could be useful to motivate or guide community-wide efforts to improve OHCA care and outcomes.
In an effort to characterize differences in out-of-hospital vs. in-hospital care, in this study we sought to describe regional variations in early and later survival after OHCA.
Section snippets
Study design
This study was an analysis of prospectively collected OHCA data from the ROC Epistry – Cardiac Arrest (“Epistry”).8 Data for the ROC Epistry were collected in conformance with United States Department of Health and Human Services regulations for the protection of human subjects and provisions of the Canadian Tri-Council Policy Statement: Ethical Conduct for Research Involving Humans. Additional reviews and approvals were obtained from the institutional review boards and research ethics boards
Results
During the study period there were 15,765 adult, non-traumatic OHCA. These patients included 3957 (25.9%) VF/VT, 11,336 (71.9%) non-VF/VT and 472 (3.0%) with unknown initial ECG rhythm (Table 1). Public OHCA location, bystander and EMS witnessed arrest, bystander CPR and AED use, and initial ECG rhythm varied across sites. Complete outcome and covariate data were available for 3763 VF/VT and 10,879 non-VF/VT patients. OHCA included in the analysis encompassed 219 EMS agencies and 216 hospitals.
Discussion
In this study we modeled OHCA survival as consisting of two successive elements: early survival (defined as surviving at least one calendar day from the event), followed by later survival (defined as early survivors who progress to hospital discharge). Under this conceptual model. early survival may reflect out-of-hospital and Emergency Department care, and later survival may reflect hospital-based post-arrest care. An analysis limited to overall OHCA survival cannot differentiate the relative
Limitations
The current data originate from a large, established multi-center OHCA network generalizeable across 264 EMS services and 287 hospitals from the US and Canada providing data for the years 2005–2007 and represent the best data available. Our definition of early survival included up to one-calendar day after the cardiac arrest, a period which may have included a time period as short as 24 h to as long as 48 h. The ROC Epistry – Cardiac Arrest data could not define shorter time intervals. It is
Conclusion
We observed regional disparities in early and later survival after out-of-hospital cardiac arrest. These observations suggest underlying regional differences in out-of-hospital care and post-arrest care. Community efforts to improve OHCA survival must address both early out-of-hospital as well as later in-hospital elements of care.
Financial support
The ROC is supported by a series of cooperative agreements to nine regional clinical centers and one Data Coordinating Center (5U01 HL077863-University of Washington Data Coordinating Center, HL077866-Medical College of Wisconsin, HL077867-University of Washington, HL077871-University of Pittsburgh, HL077872-St. Michael's Hospital, HL077873-Oregon Health and Science University, HL077881-University of Alabama at Birmingham, HL077885-Ottawa Health Research Institute, HL077887-University of Texas
Conflict of interest statement
The authors declare no conflicts of interest.
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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.07.013.