Elsevier

Resuscitation

Volume 83, Issue 7, July 2012, Pages 862-868
Resuscitation

Clinical paper
Increasing hospital volume is not associated with improved survival in out of hospital cardiac arrest of cardiac etiology,☆☆

https://doi.org/10.1016/j.resuscitation.2012.02.006Get rights and content

Abstract

Background

Resuscitation centers may improve patient outcomes by achieving sufficient experience in post-resuscitation care. We analyzed the relationship between survival and hospital volume among patients suffering out-of-hospital cardiac arrest (OHCA).

Methods

This prospective cohort investigation collected data from the Cardiac Arrest Registry to Enhance Survival database from 10/1/05 to 12/31/09. Primary outcome was survival to discharge. Hospital characteristics were obtained via 2005 American Hospital Association Survey. A hospital's use of hypothermia was obtained via direct survey. To adjust for hospital- and patient-level variation, multilevel, hierarchical logistic regression was performed. Hospital volume was modeled as a categorical (OHCA/year  10, 11–39, ≥40) variable. A stratified analysis evaluating those with ventricular fibrillation or pulseless ventricular tachycardia (VF/VT) was also performed.

Results

The cohort included 4125 patients transported by EMS to 155 hospitals in 16 states. Overall survival to hospital discharge was 35% among those admitted to the hospital. Individual hospital rates of survival varied widely (0–100%). Unadjusted survival did not differ between the 3 hospital groups (36% for ≤10 OHCA/year, 35% for 11–39, and 36% for ≥40; p = 0.75). After multilevel adjustment, differences in survival across the groups were not statistically significant. Compared to patients at hospitals with ≤10 OHCA/year, adjusted OR for survival was 1.04 (CI95 0.83–1.28) among 11–39 annual volume and 0.97 (CI95 0.73–1.30) among the ≥40 volume hospitals. Among patients presenting with VF/VT, no difference in survival was identified between the hospital groups.

Conclusion

Survival varied substantially across hospitals. However, hospital OHCA volume was not associated with likelihood of survival. Additional efforts are required to determine what hospital characteristics might account for the variability observed in OHCA hospital outcomes.

Introduction

Out-of-hospital cardiac arrest (OHCA) is a major public health problem with an overall mortality of approximately 90% across North America.1 Although prehospital interventions remain an important cornerstone of resuscitation, growing evidence indicates the implementation of specialized post-arrest care can positively affect outcome. In-hospital treatments such as therapeutic hypothermia and early cardiac catheterization provide opportunities to meaningfully improve survival.2, 3, 4

The impact of post-arrest care provides a rationale for the development of cardiac “resuscitation centers”, modeled after trauma centers in the United States (US).5, 6, 7 Some states such as Arizona and Minnesota, have either implemented or are planning to implement such systems of care. These efforts have been complemented by scientific consensus recommendations designed to inform and support the development of resuscitation centers.7 Higher patient volume is associated with improved survival in some medical and traumatic conditions and with success rates for certain surgical procedures.8, 9, 10, 11, 12, 13 However, there is limited data on the role of hospital volume and OHCA survival.14, 15, 16

In this investigation, we evaluated the relationship between annual OHCA hospital volume and survival to assess the hypothesis that increasing hospital volume of OHCA patients is associated with improved survival.

Section snippets

Study design

This is a cohort investigation of prospectively collected data from the Cardiac Arrest Registry to Enhance Survival (CARES). Started in 2005, CARES is an OHCA registry that has grown each year as new communities, hospitals, and EMS agencies join. As of June 2011, CARES includes 73 EMS agencies serving 40 communities in 23 states and more than 340 hospitals. Details of the registry have been described previously.17, 18 In brief, CARES is a surveillance-based and quality assurance registry

Results

At the time of this analysis, 20,018 patients were in the CARES registry, after applying exclusion criteria, 4125 patients were available for analysis (Fig. 1). Patient characteristics are presented in Table 1.

Those patients taken to the high volume centers were more likely to be African-American and less likely to be of other race (Table 2). Hospital characteristics associated with survival were: number of annual admissions; trauma designation; presence of a cardiac catheterization lab; as

Discussion

In this multicenter, multicity observational study, we did not observe a significant association between increasing OHCA hospital volume and survival in OHCAs of suspected cardiac etiology. While some hospital characteristics, such as trauma center designation and a hospital's use of therapeutic hypothermia, were associated with improved outcomes in OHCA patients, their role with survival requires further exploration. It is possible that the impact of specific hospital attributes, such as the

Conclusion

Although survival varied considerably across hospitals, we observed that receiving hospital OHCA patient volume was not associated with survival to hospital discharge in those with presumed cardiac etiology. Additional efforts are required to determine what hospital characteristics account for the wide variability observed in hospital survival and neurological outcomes following resuscitation from out-of-hospital cardiac arrest.

Funding source

The primary author MTC has funding support from the National Research Program of the American Heart Association (Award # 0835250N).

The Cardiac Arrest Registry to Enhance Survival (CARES) is funded by grant support from the Centers for Disease Control and Prevention (CDC) and Emory University.

Neither funding source had any role in the study design, collection, analysis, interpretation of the data, nor the writing or submission of the manuscript.

Disclosures

None to report.

Conflict of interest statement

None of the authors has any financial and/or personal relationship with people and/or organizations that could inappropriately influence this work.

Acknowledgements

We thank the more than 70 EMS Agencies and more than 340 Hospitals in the CARES registry for all that they do as well as the contributions that their hard work has contributed to this project.

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    A Spanish translated version of the abstract of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2012.02.006.

    ☆☆

    Presented in Poster form at 2011 Society for Academic Emergency Medicine National Research Meeting, Boston, MA, June 2011.

    g

    On behalf of the CARES Surveillance Group. See Appendix A.

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