Abstract 254: Absence of Evidence? A Systematic Review of Randomized Controlled Trials for In-hospital and Out-of-Hospital Cardiac Arrests

Abstract

Background: Cardiac arrests are a major public health problem worldwide. The extent and types of randomized clinical trials (RCTs) - our most reliable source of clinical evidence - that have been conducted in this patient population are unknown. We performed a systematic review of contemporary RCTs in cardiac arrest, with a focus on determining key differences between In-Hospital Cardiac Arrests (IHCA) and Out-of-Hospital Cardiac Arrests (OHCA), which have different epidemiological patterns and disease mechanisms. Methods: A computerized search query of Medline was performed using the terms “cardiac arrest” or “heart arrest” or “cardiopulmonary resuscitation” from 1995 to 2014, yielding a total of 1652 publications. After manual abstract review, 80 RCTs involving either IHCA or OHCA were then identified for inclusion in the final analysis. The following data were ascertained: number of patients, demographic information, blinded vs. unblinded, geography (US/non-US), single vs. multicenter, a positive or negative study outcome, and the type of intervention being studied. Results: There were a total of 80 RCTs with cardiac arrest performed containing 84,500 subjects between January 1, 1995 and December 31, 2014. Of these 80 RCTs, only 6 studies with 1143 total subjects involved IHCA whereas 74 studies with 83,357 total subjects pertained to OHCA (Table). All six studies with respect to IHCA were not performed in the U.S. In contrast, eight of the OHCA RCTs were performed both in the U.S. and abroad, 15 of the OHCA RCTs were performed in the U.S., and the remaining 51 studies were performed outside of the U.S. Four of the six IHCA studies were blinded, and two of the six IHCA studies were multicenter studies. In contrast, 29 of the OHCA RCTs were blinded and 39 of the OHCA RCTs were multicenter trials. Only two of the six IHCA RCTs demonstrated a positive study outcome and mortality benefit. Conversely, 39 of the 74 OHCA RCTs reported a positive study outcome but only 15 of the 74 OHCA RCTs had a survival benefit. Conclusion: We found limited evidence of high-quality RCTs in cardiac arrest with a striking paucity of evidence with respect to IHCA. Given key differences between IHCA and OHCA, further RCTs directly investigating IHCA are warranted to elucidate our understanding of the evaluation and management of these high-risk patients.