Should out-of-hospital cardiac arrest be considered a public health problem and not a disease process? This is an extremely important question, as sudden cardiac arrest claims 330,000 lives each year in the United States and Canada. The patient population is so varied in age, underlying conditions, time to therapy and numerous other factors that it is less likely to be answered by randomized controlled trials.
Most public health problems, such as motor vehicle crashes or cigarette smoking, have made significant progress through a quality-improvement approach rather than randomized controlled trials. A quality-improvement process also could be used to advance resuscitation research. That is the argument proposed in an editorial titled “Cardiac Arrest and the Limitations of Clinical Trials” in the Sept. 1, 2011, issue of the New England Journal of Medicine by Arthur B. Sanders, MD, MHA, an emergency medicine physician and member of the University of Arizona Sarver Heart Center Resuscitation Research Group.
The Journal’s Sept. 1issue includes two analyses of potential improvements in the management of out-of-hospital cardiac arrest conducted by the Resuscitation Outcomes Consortium who reported on two randomized comparisons from the Prehospital Resuscitation Impedance Valve and Early Versus Delayed Analysis (ROC PRIMED).
One study was designed to address whether longer (3 minutes) or shorter (30 to 60 seconds) intervals of chest compressions were more effective prior to defibrillation. The second study looked at use of active or sham impedance threshold devices (ITD), designed to enhance venous return and cardiac output during cardiopulmonary resuscitation (CPR) by increasing the degree of negative intrathoracic pressure. In both instances, the researchers found no difference in outcomes for sudden cardiac arrest patients.
“Neither component showed one intervention to be superior to the other with respect to primary outcome of survival with satisfactory functional status,” wrote Dr. Sanders.
Although the studies are considered well designed, in both cases, Dr. Sanders points out that there was an issue of adherence to the intended protocol. “In the comparison of early versus later rhythm analysis, 32 percent of the early-analysis group and 40 percent of the later-analysis group did not have rhythm analysis performed within the planned time interval. In the comparison of active ITD versus sham ITD, almost 40 percent of participants did not have the ITD placed within the planned time interval. Since the ROC PRIMED trial was conducted by dedicated and committed investigators in a setting of rigorous training and retraining of emergency medical services (EMS) personnel, it seems likely that adherence to such timing targets would be even poorer in the community setting.”
Noting that many advances in resuscitation science were not subjected to randomized clinical trials, Dr. Sanders suggests using the alternative strategy of the continuous-quality-improvement model more commonly used in managing public health problems. This model was used in Arizona’s five-year analysis of data published in the Journal of the American Medical Association in October 2010. “After a statewide database of out-of-hospital cardiac arrests was developed, systemic changes that deviated from the standard guidelines were implemented, including an unconventional EMS protocol and layperson-administered compression-only CPR. As a result, the rate of survival nearly tripled and bystander-administered CPR increased,” says Dr. Sanders. He also pointed out that rural Wisconsin saw similar survival-rate improvements using this model.
“The ROC PRIMED trial illustrates that there are inherent limitations in even a well-designed, carefully executed clinical trial in advancing resuscitation science. Therefore, it is important that we re-assess the role of clinical trials and alternative strategies in improving the rate of survival from cardiac arrest. The goal of resuscitation is saving lives; research helps achieve this goal, but is not the goal itself,” says Dr. Sanders.
The University of Arizona Sarver Heart Center in Tucson, Ariz., emphasizes a highly interdisciplinary research environment fostering innovative translational or “bench-to-bedside” research. Working toward a future free of cardiovascular disease and stroke, the center’s more than 175 scientist and physician members collaborate with the goal of applying new findings from the basic sciences to the clinical arena as quickly as possible.