Clinical paperInter-hospital variability in post-cardiac arrest mortality☆
Introduction
Overall survival after cardiac arrest is poor,1, 2 and has remained largely unchanged over time.3, 4 Furthermore, despite international efforts to develop and disseminate cardiac arrest treatment guidelines, significant outcome variability persists among individual emergency medical service (EMS) systems and hospital. Reported rates of survival to hospital discharge range from 1% to 31% after out-of-hospital cardiac arrest2, 5 and 0% to 42% after in-hospital cardiac arrest.6 Although numerous pre-arrest,3, 7, 8 and intra-arrest9, 10, 11, 12, 13, 14, 15 factors contribute to this variability, much less is known about the relative contribution of post-cardiac arrest care.
Post-cardiac arrest care is now recognized as a critical link in the chain of survival.16, 17 Therapeutic hypothermia and formalized post-cardiac arrest treatment protocols decrease morbidity and mortality.18, 19, 20, 21 However, substantial inter-hospital variability in mortality of patients that achieve initial return of spontaneous circulation (ROSC) has been reported.8, 22 Mortality differences have been associated with hospital-based factors as well as patient care factors.23, 24 Although likely to be a universal phenomenon, all of these data are from sites outside the United States (US).
The goal of this study was to examine within the US health care system the variability in mortality of patients that achieve initial ROSC after cardiac arrest. Documenting inter-hospital variability of post-cardiac arrest mortality is the first step in understanding the role of post-cardiac arrest care in the overall chain of survival. Ultimately, identifying the sources of variability is essential to optimize post-cardiac arrest care. This study utilized a large clinical intensive care unit (ICU) database to determine site-dependent variability in adjusted in-hospital mortality and the association between mortality and hospital case volume.
Section snippets
Study design and patients
We conducted a retrospective cohort study using the Acute Physiology and Chronic Health Evaluation (APACHE) IV database (Cerner Corporation, Kansas City, MO). APACHE is an ICU clinical information system used by participating hospitals within the US for benchmarking and quality improvement.25 Patient demographics, admission source, primary admission diagnosis, and detailed laboratory and physiologic variables are collected in the first 24 h of ICU admission. Trained clinical coordinators
Study population
The initial dataset contained 5386 post-arrest patients in 57 hospitals. We excluded 215 patients in 18 very low volume hospitals, resulting in 39 hospitals in the final sample (Table 1). Just over half of the hospitals were academic hospitals (26%) or community hospitals with housestaff (33%). Most hospitals were located in the southeast (44%), west (28%), or midwest (21%). The median number of hospital beds at each facility was 384 (IQR 280–650), and the median number of cardiac arrest
Discussion
We demonstrate inter-hospital variability in severity adjusted post-cardiac arrest mortality in patients admitted to the ICU after successful resuscitation from cardiac arrest. In addition, we observed an inverse relationship between the volume of cardiac arrest patients treated in the ICU and in-hospital mortality. These findings are consistent with previous work that has demonstrated wide variability in post-cardiac arrest mortality outside the US,22, 23, 24 and the relationship between
Conclusions
In-hospital mortality varies significantly among patients admitted to US intensive care units after initial resuscitation from cardiac arrest, and one potential source of outcome variability is patient volume. These results suggest the need for additional research to delineate best-practices and to optimize post-cardiac arrest care. If variability in patient care is found to be causal, then development, dissemination and implementation of comprehensive post-cardiac arrest care guidelines should
Conflict of interest
BGC & JK have no pertinent disclosures. RMM serves on the BLS Subcommittee of the American Heart Association Emergency Cardiac Care Committee as a fellow. AAK is an employee of Cerner Corporation and owns shares of Cerner stock. RWN serves on the ACLS Subcommittee of the American Heart Association Emergency Cardiac Care Committee.
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2008.09.001.