D espite several advances in resuscitation care over the last decade, in-hospital cardiac arrest (IHCA) remains common and is linked to poor survival. Approximately 200 000 hospitalized patients suffer IHCA and undergo cardiopulmonary resuscitation in the United States annually, with fewer than 20% surviving to discharge. Not surprisingly, a great deal of attention has been placed on reducing IHCA event rates and improving outcomes. Although there is some indication that this focus is improving risk-adjusted survival over time, little is understood about the underlying mechanisms behind these trends. It remains unknown what specific hospital factors or processes of care are responsible for delivering high-quality resuscitation care and what modifiable quality metrics best address outcomes. To begin to address these questions first requires the ability to identify the best hospitals. This is no easy task given the inherent heterogeneity of patients suffering IHCA— ranging from those with acute illnesses, such as acute myocardial infarction or sepsis, to those with chronic end-stage diseases like cancer. However, a risk-adjustment model for survival was recently developed and validated that included 9 clinical variables, using data gathered from nearly 50 000 patients within the Get With The Guidelines (GWTG)Resuscitation registry. Good discrimination and excellent calibration of the model permits it to be employed, for the first time, to facilitate benchmarking across hospitals as an initial step toward improving quality in resuscitation. The study published by Merchant et al in this edition of Journal of the American Heart Association (JAHA) builds on this critical work. It documents wide variability in risk-adjusted survival rates across hospitals. Based on data compiled from 135 896 index IHCA events at 468 hospitals within the GWTGResuscitation registry, the investigators found the observed median in-hospital survival rate for the bottom decile was 8.3% (range 0% to 10.7%) and for the top decile it was 31.4% (28.6% to 51.7%)—a nearly 4-fold difference. After adjusting for 36 predictors of in-hospital survival, significant variation remained across sites: the bottom decile with a median in-hospital survival rate of 12.4% (0% to 15.6%) versus the top decile with a median rate of 22.7% (21% to 36.2%). Only 24 of 46 hospitals (52%) remained in the top decile for IHCA survival after risk adjustment, which highlighted the importance of accounting for patient case-mix. Perhaps the most compelling finding was the median odds ratio for risk-adjusted in-hospital survival of 1.42 (95% CI 1.37 to 1.46). This statistic indicates a 42% difference in the odds of survival for patients with a similar case-mix at 2 different randomly selected hospitals. So why might such large variation in outcomes exist across hospitals? Resuscitation-specific factors remain to be fully elucidated and are not readily apparent from the study by Merchant et al. However, many possibilities have been suggested in prior studies. Duration of resuscitation varies across hospitals and may contribute to differences in survival. Based on our recent work, we found that patients at hospitals with longer durations of resuscitation had higher rates of return to spontaneous circulation (adjusted risk ratio 1.12, 95% CI 1.06 to 1.18, P<0.0001) and survival to discharge (1.12, 1.02 to 1.23, P=0.021), independent of measured patient characteristics. We also found that the median duration of resuscitation was just 20 minutes for nonsurvivors and many received shorter attempts. Importantly, these findings suggest that hospitals that reliably implement processes that systematically extend resuscitation care may have better outcomes. If so, duration of resuscitation could potentially serve as a quality metric for assessing IHCA care. However, further investigation is needed to establish the optimal duration of resuscitation attempts. Another resuscitation-specific factor that may contribute to a wide variation in case-survival may be time to defibrilThe opinions expressed in this article are not necessarily those of the editors or of the American Heart Association. From the Division of Cardiovascular Medicine, Department of Internal Medicine (S.S.S., B.K.N), Division of General Medicine, Department of Internal Medicine (L.M.C.), and Institute for Healthcare Policy and Innovation (L.M.C.), University of Michigan, Ann Arbor, MI; VA Ann Arbor Healthcare System, Ann Arbor, MI (L.M.C.). Correspondence to: Shashank S. Sinha, MD, University of Michigan Cardiovascular Center, 1500 East Medical Center Drive, SPC 5853, Ann Arbor, MI 48109-5853. E-mail: firstname.lastname@example.org J Am Heart Assoc. 2014;3:e000768 doi: 10.1161/JAHA.113.000768. a 2014 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.