Every year 325,000 Americans die from cardiac arrest, and around three-quarters of these deaths occur at home. Unlike a heart attack, where blood flow to the heart is restricted, cardiac arrest is a stopping of the heart beat. While heart attacks aren’t usually fatal, cardiac arrest almost always is: research has shown the survival rate to be as low as 2 percent.
Given these numbers, you’d think that automated external defibrillators (AEDs)—handheld devices that shock the heart back to its normal rhythm after cardiac arrest—would be indispensable for any household worried about its health. Philips, manufacturer of the nation’s only FDA-approved, no-prescription-needed AED, says as much on its website; the company insists that “anyone who wants a safer home” should buy its product.
But according to a just-released study from the New England Journal of Medicine (NEJM), having an AED at home actually doesn’t make you any safer. Researchers compared survival rates for a group of 7,001 patients who were organized—along with their spouses or companions—into two groups. 3,506 of them were trained to administer CPR and dial 911 in the case of cardiac arrest at home; the remaining 3,495 underwent the same training, but were also given an AED and trained to use it (i.e. placing the device against the patient’s chest and pressing a button to shock the heart back to its normal pace). The study found that overall survival rates were almost identical across the two groups.
The patients, who hailed from seven countries, were followed from January 2003 to October 2005. Over this period, 169 of them died from cardiac arrest: 84 in the group that received only CPR, and 85 in the group that also used AEDs. Both groups also saw the same number of successful resuscitations (19 in each). In other words, having an AED at home—and knowing how to use it—didn’t help to save lives.
Before going any further, it’s important to note that AEDs were only
applied in 32 of the 85 deaths in the AED-equipped group—so it’s not
that every death occurred in spite of the device. But this is small
comfort: the rarity of AED use suggests that (a) most cardiac arrests
at home are not witnessed by other people who can administer the device
and/or (b) even people trained to use the device often fail to do so.
Either way, the presence of an AED in your home is no guarantee of
Even when the gadget was used, its performance was less than
impressive. Of the 32 cases where AEDs were administered, 21 people
still died—a mortality rate of about sixty-six percent. If we look just
at unresponsive patients, i.e. those who were knocked out and thus in
the most serious need of an AED kick-start, the proportion who died
rises to almost three-quarters. It’s not that the AEDs
malfunctioned—when the equipment was applied, it worked properly. It
just that using the device usually was not enough to save a life.. And
isn’t that the point?
It would be unfair to say that AEDs are useless. Research has shown
them to be effective when emergencies occur in public places. One 2002 study
that looked at AEDs in Chicago airports found that, of the 18 recorded
cases of cardiac arrest over a two year period, 11 patients were
successfully resuscitated via AED—an impressive success rate of 61
percent. Another study from last year
suggested that AEDs in places like sports facilities and shopping
centers may double the survival rate for people who undergo cardiac
arrest in public.
But as compelling as these findings may be, they don’t really
confirm the efficacy of AEDs, especially at home. First, the public use
studies were not true clinical trials because they didn’t look at
whether AEDs were more effective than other options. We don’t know if,
for example, the placement of more paramedics in public places would
have proven similarly effective.
Further, the public studies had no target population, i.e. no
defined group that shared common characteristics (save being in the
same high-traffic area). But to understand if it makes sense for
individuals to purchase AEDs for their homes, we need target who is
most likely to benefit. We need to find out if the device is a sound
This week’s study did just that by focusing on a clearly defined
group of moderate-risk patients. All the participants had previously
had a heart attack—a loss of
blood supply to the heart—but didn’t have pacemakers installed (only
high-risk patients undergo that procedure). This means that the NEJM
study was precisely targeted, and is a better guide to understanding
who benefits from AEDs—or, as it turns out, who doesn’t.
No doubt the study’s findings come as an unpleasant surprise to
Philips. The company has done its best to gain medical credibility as a
resuscitation authority, mostly by shelling out money. Philips funds a
$100,000 joint fellowship with the American Heart Association (AHA) dedicated to postdoctoral research on resuscitation. According to the AHA’s annual report,
Philips also donated somewhere between $100,000 and $249,999 to the
organization between 2006 and 2007. Though the AHA hasn’t gone so far
as to formally endorse home ownership of AEDs, it appears to be warming
up to the idea: last month the organization’s manager of community
strategies for emergency cardiovascular care told the Albany Times-Union that having an AED at home would be “good for anyone.”
No doubt Philips jumped for joy at this statement. If device-makers
had their way, Americans would treat AEDs as we do smoke detectors–as
a must-have for every home. Consider this 2005 television
advertisement (below) for Philip’s AED product, dubbed the
“HeartStart.” It centers on a profoundly unsettling image: that of an
ambulance stuck in gridlock.
The message here is clear: it’s better to be safe than sorry. Buy an
AED because you never know how long it will take for help to arrive.
One YouTube user sums up this sentiment perfectly in a comment beneath
the video: “I love mine. Haven’t used it yet—but it’s there for us…”
Yet the NEJM study shows that, even if an AED is “there for you,” it
won’t help your chances of survival.
The incentive is strong for device-makers to insist otherwise. On Tuesday, The New York Times
noted that home sales for AEDs account for only 5 to 10 percent of the
outside-hospital AED market, which is currently pegged at $192 million.
In other words, there’s a lot of room for market growth.
Equally enticing is the opportunity to make fancier AEDs. DotMed,
a medical news business weekly, recently warned device-makers that as
“prices of AEDs are falling, manufacturers must consider producing
defibrillators with advanced functionalities that are more expensive in
order to increase their overall profit margins.” The end-goal is not
just to sell more devices, but also more expensive ones.
But an explosion of home AEDs wouldn’t be an effective strategy for saving lives—nor would it be cost-effective. A 2005 study
in the Journal of General Internal Medicine reviewed the literature on
AEDs and calculated that it would cost $5,175 per person to provide
them in-home to all 60-year olds in the U.S. For that investment, each
person would only see an extra .025 quality-adjusted life years, i.e.
additional years that a person lives—and lives well—after an
Obviously we can’t put a price on life; but if we can rely on a
resuscitation strategy that’s just as effective as AEDs but costs less,
then we should do so. The NEJM study suggests that we can, by investing
in more rigorous CPR and emergency training.
Of course, there’s not a lot of money to be made from such an
initiative, so it’s received relatively little attention. Instead, as
Dr. David Callans from UPENN noted in an editorial
accompanying Tuesday’s study, once again we are in a situation where
“marketing…[has] charg[ed] ahead of science.” AEDs already had become
a much-ballyhooed business proposition—even before the clinical
trial just published in the NEJM was done. And now, they have come up
short. But that probably won’t stop Philips.
Money has once again trumped medicine. As Callans told the Times on
Tuesday, the case of home AEDs represents “a great example of what is
wrong with American health care.”