Clinical paperPost-resuscitation care and outcomes of out-of-hospital cardiac arrest: A nationwide propensity score-matching analysis☆
Introduction
Out-of-hospital cardiac arrest (OHCA) is a major cause of unexpected deaths worldwide.1 The outcomes of OHCA have been improving thanks to the evidence-based cardiopulmonary resuscitation guidelines followed by numerous clinical and communities’ efforts in the chain of survival,2, 3 while most other outcomes have remained low.1
Post-resuscitation care procedures include more active post-resuscitation care (APRC) procedures, such as mild therapeutic hypothermia (MTH), active cardiac care (ACC) including percutaneous coronary intervention (PCI), coronary artery bypass surgery (CABG), and the insertion of an implantable cardioverter-defibrillator (ICD)/pacemaker (PM), as well as the usual conservative post-resuscitation care (CPRC) procedures, including stabilization of vital signs using vasopressors, ventilation support, general supportive care, glucose control and antiepileptic management.4 Of these procedures, APRC procedures are challenging options in many hospital settings because they require more multidisciplinary approaches and more advanced skills, as well as much greater resources than are required for the usual intensive conservative care for critically ill patients.
In 2003, the American Heart Association issued a guideline recommending that MTH be used to treat cardiac arrest with shockable rhythm,5 and the AHA subsequently incorporated the procedure into its 2005 treatment guidelines,6 such that it finally became the 5th link in the chain of survival that is emphasized in post-cardiac arrest care.4 Active cardiac care, such as with PCI/CABG and ICD/PM, has also been proven to result in better outcomes in OHCA survivors in advanced hospital settings.7, 8
However, a larger proportion of hospitals still prefer to provide only CPRC rather than APRC9, 10, 11 due to unclear indications when selecting treatment options, cultural barriers, lack of interdisciplinary cooperation, lack of resources and knowledge, and cost issues.12, 13 This applies to the current care systems, except for the urban academic medical centers, in Korea. APRC might not be considered as a single treatment option but rather as a multidisciplinary treatment care bundle, which can provide a higher standard care accompanying the procedure itself. There have been few studies on how many patients have been treated, which patients have been treated, and what size of effects has been found with APRC, particularly on a nationwide level.
Post-resuscitation care options are too dynamic and complex, according to patients’ statuses by time period, to implement each protocol or treatment option easily and step by step in clinical practice.4, 14 Hospitals cannot provide treatment options such as MTH or ACC unless there is a dedicated multidisciplinary active post-resuscitation care team with a great amount of experience, skill and resources. A combined procedure (PCI with MTH), as well as each individual procedure, for OHCA was reported to be safe and effective in small case series15, 16 or in a population series.17 Many combinations of treatment options, such as MTH and CABG, MTH with ICD, and PCI followed by PM or ICD, can be considered according to the patient's status. However, combinations can only be chosen by clinicians when they are available. For example, although the clues are very ambiguous for diagnosing ST elevation in MI in a clinical setting, the clinician can choose PCI if he or she has access to additional cardiologic intervention teams in real time. This accessibility can be a proxy measure of organized bundles of post-resuscitation care. Therefore, APRC can be regarded as a proxy of accessibility to a particular comprehensive post-resuscitation care level to a larger extent than can each segmented procedure provided to patients in most other studies.
The objective of this study was to determine the effects of active post-resuscitation care procedures, including MTH and ACC (PCI/CABG, and ICD/PM), on the outcomes of OHCA in a nationwide, population-based OHCA survivor cohort.
Section snippets
Study setting
The Korean emergency medical services (EMS), which is a single-tiered, government-based system, provides a basic-to-intermediate service level of ambulance services from the sixteen provincial headquarters of the national fire department and supports a population of approximately 50 million.18, 19 Ambulance crews can administer CPR at the scene and during transport with automatic external defibrillation and advanced airway management under direct medical control. Advanced cardiac life support is
Demographic findings
Among the 64,155 EMS-assessed OHCA patients with available outcomes, 44,794 adult patients with presumed cardiac etiologies were enrolled after excluding patients with non-cardiac etiologies (n = 17,970) and pediatric (n = 1391) patients. Of these enrollees, 4557 patients survived to admission and were used for the final analysis. There were no patients with a normal alert mental state among the 496 patients (10.9%) receiving ROSC before arriving at the ED. Of these survivors, 1599 (35.1%) cases
Discussion
This study aimed to determine the association between APRC and improved outcomes at the nationwide level. We found the APRC group showed a significantly higher survival to discharge rate (adjusted OR = 2.17) and a good neurological discharge rate in the total cohort (Adjusted OR = 2.54). Significant associations were found in the propensity score-matched cohort.
Previous studies showed a wide variation in the proportion of cases receiving MTH in OHCA. A recent survey study from Italy reported that
Limitations
This study has several limitations to the interpretation of its results and the generalization of these results to other settings. First, this study was not a controlled trial but was a retrospective, observational study. APRC might be selected for patients with a higher likelihood of survival, although we tried to match the risk using propensity scores. Second, the study setting was different from the paramedic level of EMS systems such as those in North American or European communities. A
Conclusion
In this nationwide, observational cohort study, OHCA victims who received any APRC including either MTH or ACC treatment options showed significantly better outcomes than those who only received CPRC. These findings might support the systemic inclusion of the fifth link in the chain of survival to improve the outcomes of OHCA. Prospective studies are needed to strengthen the outcome of APRC.
Conflict of interest statement
No conflicts of interest for all authors are in this study.
Previous presentation
This paper was presented at the National Association of Emergency Medical Services Physician annual congress in January 2011 and at the American Heart Association Resuscitation Science Symposium in Los Angeles in 2012.
Acknowledgement
This study was supported by the National Emergency Management Agency of Korea and the Korean Centers for Disease Control and Prevention. The study was funded by the Korean Centers for Disease Control and Prevention (2008–2011).
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2013.02.010.