Researchers at the University of Iowa and University of Michigan evaluated the value -- in terms of saving lives and the necessary costs to rescue people with cardiac arrest -- of installing defibrillators in various public locations. The team found that a defibrillator was a good investment if the specific location was expected to have at least one cardiac arrest every seven years, a slight extension of current American Heart Association guidelines. The findings, based on a comprehensive review of existing studies and data on defibrillator placements in the Seattle, Wash. area, appear in the September issue of the Journal of General Internal Medicine.
The study also found that locations such as large retail stores (1 in 2,000 annual probability of being used) and hotels (1 in 100 annual probability) apparently are not cost-effective candidates for defibrillator placement.
"Our conclusions support the American Heart Association recommendation that defibrillators should be placed in public locations where there is a one in five chance that the defibrillator will be used in a given year to treat a person with cardiac arrest," said Peter Cram, M.D., UI assistant professor of internal medicine and the study's principal investigator. "However, defibrillators also are being placed in a number of low-risk public locations where the money might be better to spent in other ways, such as improving the existing EMS program."
A. Mark Fendrick, M.D., professor of internal medicine at the University of Michigan and the study's senior author, identified the three crucial factors that should drive where a defibrillator should be placed: how many people are at the site, how long they are there, and whether those people are at risk for having cardiac arrest.
"In an ideal world, a defibrillator would be present wherever large numbers of high-risk people congregate," Fendrick said. "What concerns me is that instead of being routinely placed in high-risk locations such as crowded senior centers, these devices are frequently put in locations such as elementary schools, where their use is very unlikely."
Cram noted that, at the other end of the spectrum, international airports are a good place to have defibrillators because the sites are constantly in use.
"There are people there 24 hours a day, seven days week, they're densely populated and the population is at moderate risk. Evidence suggests that a defibrillator in an airport will be used once every two years," Cram said.
In contrast, public schools or houses of worship are generally sparsely populated for a limited number of hours each week with a low- to moderate-risk population. Yet many of these institutions are buying defibrillators.
According to the study, "it doesn't appear to make a whole lot of sense for these low-risk sites to have defibrillators," Cram said. Yet he understands the impulse for groups to buy the devices. After all, an estimated 250,000 people nationwide die each year from out-of-hospital cardiac arrest.
"For good reason, the public is worried about cardiac arrest. It is an extremely common cause of death in the United States," he said. "It is the individual's or organization's money, and if they want to buy a defibrillator, that's their choice. But the question is: Is that the best way to improve the well-being of your populations? Maybe not."
A better investment for low-risk sites might be to offer free counseling about smoking cessation or weight loss, provide free preventive health screenings or pay for effective services for those who cannot afford them, Cram said.
In a follow-up study, the researchers are surveying public schools to determine whether they are buying defibrillators and the number of cardiac arrests at the sites. Public schools are one of the markets that have been targeted very aggressively for defibrillator placement, Cram said.
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STORY SOURCE: University of Iowa Health Science Relations, 5137 Westlawn, Iowa City, Iowa 52242-1178
Journal
Journal of General Internal Medicine