Commentary:Automatic External Defibrillator Study

According to recent reports in December 2003, new research shows that AEDs may not be as effective as originally thought (see news item at right). In the editorial below, Laurie Potter, RN discusses the trial data. This article cites two studies recently done that raise questions not only about automatic external defibrillator (AED) cost effectiveness, but also on their ability to improve the patient s chance of survival to hospital discharge. These are necessary and important questions to ask as technology use grows in the medical field. Both of these studies appeared in a recent issue of the British Medical Journal. In the second study listed, the researchers estimated the cost per life year gained with AED use. The basis for this cost estimate was arrived at by applying data from 17 sites over a 7-year period, measuring time to treatment, and applying all treatment received in three minutes or less to the AED category, for a total of 5.4 arrests annually. Based on these numbers, they documented an increase in survival to hospital discharge of only two percent. Utilizing this data, the cost of AED use was determined to exceed acceptable limits. The first study compared differing regions. The AEDs were given to first responders such as the police and fire department in half the regions. The other half had manual defibrillation available with the ambulances only. These regions switched every four months. They came up with an increase in survival with an AED of only three percent. The cutoff for this study was defibrillation within five minutes, which was accomplished in 9% of the AED group as opposed to 1% in the ambulance group. It does state that the average difference in time to treatment between the two groups was less than two minutes, and the average response time for first responders was 10 minutes. They note that the delay in time to call, call handling, and delay in dispatching severely reduced the benefits of the first responders with the conclusion that there is a need to optimize dispatch procedures to save more lives. The assessment that there is only modest survival benefits seen with AEDs does not seem to be supported by multiple other studies, just one of which was reported at the American Heart Association s (AHA) Scientific Sessions in Orlando in November 2003. This study concluded that placing AEDs in office buildings and shopping malls and training people to use them can increase chances of survival by as much as 50%. In another study, AEDs were mounted in plain view at 1-minute intervals in Chicago s O Hare and Midway airports. In the first 10 months, fourteen cardiac arrests occurred, with 12 of the 14 in ventricular fibrillation. Nine of these were resuscitated with an AED and had no brain damage. Another study trained half of the group in CPR only; the other half were trained in both CPR and AED use. After two years, twice as many survivals occurred in the group with the AEDs as in the group who used CPR alone. According to the AHA, sudden cardiac death occurs over 680 times per day in the United States. The most common cause is a heart attack that results in ventricular fibrillation. Eighty percent of these occur in the home, but twenty percent are in public places where bystander intervention is critical to survival. With brain damage occurring in 4-6 minutes of the arrest, early restoration of circulation is a priority. The recent guidelines in public training for CPR have them make sure 911 is being called before starting CPR, recognizing the importance of early defibrillation to the restoration of that circulation. Placing the AEDs at appropriate sites where immediate defibrillation is not available from professionals and training the lay public in their use seems to be supported by these other studies. Analysis of the cost of the AED or any medical therapy as compared to its benefit is always ongoing and important. Larger and ongoing studies can continue to assess this cost. The additional analysis of the cost of caring for those that do survive with brain damage, as compared to those who survive without, may also be of benefit for comparison.

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wo new European studies have suggested that the use of automated external defibrillators (AEDs) in patients suffering an out-of-hospital cardiac arrest produces only a modest increase in survival and does not represent good value for the money. Both studies are published in the December 6, 2003 issue of the British Medical Journal. The first study, conducted in the Netherlands, investigated whether giving AEDs to police and firefighters the emergency services that normally arrive at the scene before an ambulance and thus are known as first responders could improve survival of cardiac-arrest victims.¹ The researchers, led by Dr. Anouk van Alem from the Academic Medical Centre in Amsterdam, the Netherlands, found that much of the potential benefit of dispatched first responders using AEDs was limited by time lost in decision making, incorrect decisions in the emergency medical dispatch center, and delays in communication between dispatch centers. In the study, they gave defibrillators to half the police and half the firefighters in the city of Amsterdam and the surrounding area. The other half did not have AEDs and just performed CPR if they arrived at the scene before an ambulance (controls). Results showed that 243 patients were included in the AED area and 226 patients in the control area. The first shock was delivered more quickly in the area in which the first responders had AEDs, with median time intervals between collapse and first shock of 668 seconds vs. 769 seconds. More patients in the AED area had return of spontaneous circulation and more were admitted alive to the hospital, but there was not a significant difference in the number of patients discharged alive from the hospital: 18% in the AED area and 15% in the control area. In an interview with Heartwire, van Alem said the reason that there was little difference in survival in this study appeared to be the late arrival of the first responders. The police or firefighters arrived at the scene an average of 101 seconds before the ambulance. Although 101 seconds could be enough to show a difference in survival if this was in the first few minutes after cardiac arrest, in this study the first responders arrived an average 10 minutes from collapse to shock, and the chances of reviving anyone 10 minutes after a cardiac arrest are very small, she explained. She suggested that the focus now needs to shift to improving the dispatch process. In this study, the median delay from receipt of call to dispatch of the ambulance was 120 seconds, and the delay to dispatch of the police/firefighters was 180 seconds. So the first responders arrived at the scene before the ambulance, even though they were dispatched 60 seconds later, van Alem commented. Time delays occur at dispatch centers as they first call an ambulance and then the police. It would be better if these processes were integrated and only one call was necessary to inform all emergency services. This happens in some US states only one call goes out to all emergency services and whoever is nearest gets there first. This saves time, she added. The researchers note that according to the 2000 guidelines, delivery of the first shock within five minutes of receipt of a call to the emergency medical system is a high-priority goal. In the experimental group, nine percent of cases met this criterion vs. 1% in the control group. In the experimental group, twenty percent would have had a shock delivered within five minutes of the call if first responders had been dispatched simultaneously with the ambulance, they write. We have shown that it is not enough just to provide the police and firefighters with AEDs, but that we need to also optimize the dispatch procedure to save more lives, van Alem concluded. In the second study, a team led by Dr. Andrew Walker from the University of Glasgow, United Kingdom, calculated the cost efficiency of placing defibrillators in all major airports, railway stations, and bus stations across Scotland.² They developed an economic model that compared the costs of increased accident and emergency attendances, increased hospital bed days, and the purchase and maintenance of defibrillators and training in their use with the life-years gained calculated from increased discharges from hospital and mean survival after discharge. The researchers came up with a cost per life-year gained of £29,625 ($49,625) and a cost per quality-adjusted life-year (QALY) gained of £41,146. They conclude that The cost per QALY calculated for public-place defibrillators represents poorer value for money than some alternative strategies for improving survival after prehospital cardiopulmonary arrest, such as the use of other trained first responders. The figure exceeds the commonly discussed cutoff levels for funding in the UK and US of £30,000 and $50,000 per QALY, respectively. Walker et al. caution, however, that their conclusions require corroboration from prospective studies, adding that We support the view of the American Heart Association that evidence of clinical and cost effectiveness from randomized controlled trials is required before further expansion of public-place defibrillators can be justified.