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Short Circuit

Just how safe are medical devices? One doctor’s mission to find out.


Interviewer: HAL, you have an enormous responsibility on this mission, in many ways perhaps the greatest responsibility of any single mission element. You’re the brain and central nervous system of the ship, and your responsibilities include watching over the men in hibernation. Does this ever cause you any lack of confidence?

HAL: Let me put it this way, Mr. Amor. The 9000 series is the most reliable computer ever made. No 9000 computer has ever made a mistake or distorted information. We are all, by any practical definition of the words, foolproof and incapable of error.—2001: A Space Odyssey

    Unfortunately, most everyday consumer products aren’t as reliable as the supercomputer HAL was reputed to be (and as moviegoers know, even HAL turned out to be quite capable of error). If you purchased a cell phone or an IPOD during the holidays that malfunctioned, it was generally no big deal to get a replacement, provided you had a warranty and a sympathetic salesperson. If you wanted to gauge the reliability of items less easily replaceable and more expensive, such as automobiles, you could refer to various internet sites or Consumer Reports before buying. And in most cases, state and Federal laws offer a modicum of consumer protection as a back up.      

    But what happens when the device in question is one on which your life depends, such as a pacemaker, an implantable defibrillator or a stent that maintains the supply of nutrients to your heart by keeping your coronary artery open? With products such as these, even a minor malfunction could become life-threatening. And since every device is susceptible to design problems, manufacturing flaws or performance failures (like HAL), how do you know how reliable your stent is? How does your doctor know?          

    Enter Dr. William Maisel, a Harvard cardiologist. Maisel recently founded the Medical Device Safety Institute at Beth Israel Deaconess Medical Center in Boston, a nonprofit research center designed to provide patients and doctors with unbiased, understandable information about the safety of medical devices. The institute’s aim is to develop and transmit data on safety and performance that goes beyond what medical device manufacturers currently provide. Maisel also hopes to augment information provided by the Food and Drug Administration (FDA), which currently concentrates most of its efforts on premarket device evaluation and approval. The institute will provide greater information on postmarket device performance (adverse events that occur after patients receive devices) and off-label use (events that occur when doctors employ a device to treat patients for indications other than what the device was approved for).        

    At present, the FDA is in charge of the safety and effectiveness of medical devices in the United States. Medical devices are distinguished from drugs, which are also regulated by the FDA, by their mechanism of action. If the primary effect of the agent is obtained through chemical action within or on the body, the agent is a drug. If not, the agent is considered a device. (Products where there is an overlap, such as drug-containing coronary artery stents or antibiotic-containing bone cement are usually classified as devices.) Medical devices may be as simple as surgical gloves or as complicated as defibrillators or artificial heart valves.    

    In the past decade, there has been a tremendous upsurge in medical device development in the United States. There are an estimated 23,000 device manufacturers, creating 1,700 types of devices, comprising 500,000 different models. The large number of devices and models limits the FDA’s ability to determine the safety and effectiveness of any particular device. The problem of device regulation is even more difficult than drug regulation because the life cycle of a device is different than that of a drug. Once a drug is on the market, it is essentially the same, unchanged product that can be observed for a number of years. In contrast, devices like heart valves and knee replacements are constantly being tweaked and redesigned so that each redevelopment essentially represents a new product brought to market every few years. The Lipitor a patient takes today is the same compound it was a decade ago. The knee replacement a patient receives today is a much different product than it was in 1999.           

    In general, the FDA devotes greater attention to higher risk devices and those that, because of their innovative status, raise new questions of safety and effectiveness (heart valves receive more scrutiny than surgical gloves). Evaluation of these devices can be time-consuming and expensive, and the FDA must often rely on limited numbers of actual patient trials (in occasional cases there may be no human trials before a product is approved). The agency’s challenge is to keep product-to-market time as short as possible so that patients can receive the benefits of new devices while at the same time ensuring the safety of those same patients who receive these medical devices. This dual challenge means the evaluation of new devices is necessarily limited, especially where complications are rare or develop after years of use.                

    So that potentially high-benefit devices can reach market sooner, the FDA may shift its focus from premarket to postmarket evaluation. This means many patients can receive a new device that has little follow-up information associated with it. The current post-market surveillance system is a hodge-podge of reporting systems, studies, registries and databases. It’s primarily voluntary since it relies on the active participation of patients, doctors, health care facilities and manufacturers. Manufacturers, in particular, are obligated to report events they become aware of, but they are not required to actively seek out device malfunctions. There have been situations where a manufacturer discovers and reports a malfunction, but because they consider the malfunction’s underlying causes and mechanisms proprietary and confidential, they restrict outside access to critical information. The current structure of the postmarket reporting system has obvious limitations besides the health implications for patients, the economic implications for providers and manufacturers, especially when the FDA considers issuing a public health advisory, safety alert or product recall.                  

    Maisel’s interest in device safety came a decade ago as a result of his work as a cardiologist specializing in electrophysiology. As part of his daily practice, he implanted pacemakers and defibrillators and consequently he would receive notification of device recalls. At one point, he became curious and tried to ascertain the overall national recall rates for pacemakers and defibrillators. He found this data extremely difficult to come by, but his diligence ultimately paid off. He was surprised to find the number of patients who had their devices recalled numbered in the thousands.                

    He published this data and went a step further by trying to ascertain how many products had actually malfunctioned as opposed to just being recalled (recall is simply a marker of possible malfunction). In some cases, the FDA might have been conservative and recalled “safe” products, and in other cases, it may not have acted quickly enough. The results, once again hard to access, indicated one could not predict the actual safety of the device from the recall rate. He realized if this information was difficult for him to obtain with his level of diligence, it was virtually impossible for practicing physicians and the general public. This provided the impetus for him to found the institute, which has several purposes—to discover how safe devices actually are, to encourage greater scientific rigor on device evaluation, to report the results to the health care community and to protect patients with prudent decisions based on the information.       

    His work in several high-profile safety issues has established Maisel as one of the leaders in the field. He played an important role in the collaboration between the FDA, doctors and manufacturers of defibrillators and pacemakers in developing guidelines on public safety alerts for malfunction risks. He chaired a 2006 FDA panel on the long-term thrombosis risks of drug-coated cardiac stents and last year published an important paper in the New England Journal of Medicine about the possibility of lead fracture in a popular model of implantable defibrillator (which could result in failure to defibrillate). He’s currently working on the potential for wireless interference on pacemakers and defibrillators. Maisel and his coworkers presented research at the most recent American Heart Association Meeting indicating that if headphones for portable digital music (MP3) players, like the iPod, were placed within an inch of pacemakers or implantable defibrillators, the devices might malfunction.    

    While his current work is primarily in his field of cardiology, he hopes the institute will ultimately branch out into product safety in other specialties such as orthopedic surgery. “Ideally, if you or your mother needed a knee replacement, hopefully we would be able to provide you with factual, independent information as to which model works best,” Maisel says.                        

    His efforts have met with raised eyebrows in some quarters from those who feel the public disclosure of safety information may create undue anxiety inpatients. An editorial in the Wall Street Journal observed that ”the real danger to public health is the overreaction to medical risk.” It went further to speculate that some patients, worried about device malfunction, might forego beneficial procedures.     

    Maisel counters these concerns, saying, “We can do a better job of protecting consumers with better information and more scientific rigor.” Attempting to put the question of safety in proper perspective, he says, “These issues are never black and white…the issue is how careful we are looking for these things or how well we predict where trouble might arise…when you are putting a potentially life-sustaining product out to hundreds of thousands of people in the case of a lead or millions in the case of a stent, it is predictable that you are going to want to know how the device is performing. I just think we need to do a better job of anticipating which products are going to need better data collected.”                               

    The doctor has made a concerted effort to maintain his independence from device manufacturers. Unlike many physicians who supplement their incomes by working with the manufacturers, Maisel does no consulting and takes no money from the industry. This independence from industry means it is not always easy to raise funds for the studies he wishes to pursue. Consequently, the funding for the institute comes from philanthropy and non-industry grants. On the opposite end of the spectrum, unlike physicians who allow anti-industry prejudice to influence their scientific findings, Maisel bears no especial animus to industry. He understands their importance to drug and device development and actually wants them to succeed, as long as success is defined as producing better and safer products.                

    Medicine needs more physicians like Maisel, researchers with patients’ best interests at heart who maintain a healthy skepticism but are also not Luddites where medical progress is concerned. “In many respects, medical devices are the poster child for modern medicine,” Maisel says. “Physicians and patients expect innovation and new technologies can provide amazing benefits. But there are risks and things can go wrong. The push and pull of modern technology comes with a cost.”    

    That cost of modern technology? Just ask those astronauts from 2001: A Space Odyssey who were on the mission guided by HAL.                                 

    The website for Dr. Maisel and the Medical Device Safety Institute is www.medicaldevicesafety.org. It contains information about the institute, including details on their latest research along with comprehensible information for patients about device safety.

Published: February 08, 2009
Issue: February 2009 Design Issue