Implantable defibrillators are truly life saving devices that have prevented sudden death in thousands of patients. No bigger than an iPod nano, the device can sense when the heart is beating irregularly and deliver an electrical jolt that kicks it back into proper rhythm. But like so many of medicine’s miracles, defibrillators are not always used on the right patients. According to a study published recently in the Journal of the American Medical Association, between 2006 and 2009 more than one-fifth of patients who got the $35,000 device almost certainly didn’t need it.

Each year, about 100,000 defibrillators are implanted, and the bill for the surgery comes to well over $50,000 a piece. That represents a nice profit for the hospital, and a fee of around $2,000 for the surgeon. But money is only the most obvious reason that a doctor might recommend a device to a patient who isn’t likely to get any benefit.

Guidelines have been developed to help surgeons decide which patients are likely to benefit from the device, and thus are appropriate candidates for the surgery. There’s always room for judgment, of course, and doctors are routinely faced with patients who don’t quite fit the criteria, but who might derive some benefit from the device. But at some hospitals, 40 percent or more of patients fell outside the guidelines, which stretches the concept of clinical judgment. In other cases, according to the authors, surgeons simply don’t know the guidelines, or had not studied the evidence enough to understand the rationale behind them.

Defibrillators are hardly the only expensive medical treatment being used on the wrong patients. At least one study found that as many as one quarter of angioplasties, a cardiac procedure, were done on inappropriate patients. Other studies suggest that as many as two-thirds of carotid endarterectomies, surgery to remove blockages from the carotid arteries in the neck, are as likely to harm the patient as help. About a third of CT scans are given to patients who don’t need them.

To many physicians and policy makers, the solution to such situations is more research and stricter guidelines.  If they could only define the perfect patient more narrowly, goes the thinking, doctors would be less likely to misuse the treatment. Yet even when a mountain of research studies have been published, as is the case of carotid endarterectomy, and the guidelines are spelled out in exquisite detail, physicians will always vary in their assessment of the evidence and their opinion about the value of the treatment to the patient in front of them.

The more ethical solution is for doctors to share the decision with their patients. Virtually any medical treatment entails risks as well as potential benefits, and patients need to understand the tradeoffs. Implantable defibrillators require surgery and a stay in the hospital. Should the patient’s heart begin to beat irregularly, the electrical impulse delivered by the device can be quite painful.  As a patient’s condition deteriorates over time, as it inevitably will, and his or her heart falters more often, the device may go off repeatedly. If the device is left on, it can cause terrible suffering around the time of death.

Different patients and their families will value the tradeoff between such risks and the possible benefits differently. Some of those who were implanted with the device, and who fell outside the appropriateness criteria, might well have said the risks are worth taking on the off chance that somehow the device would help them avoid death. But many others might have declined the surgery — if only they had they been given the choice. Most probably were not.

There’s a large body of medical literature showing that patients are routinely and woefully uninformed about the tradeoffs involved in elective treatments. This goes not just for implantable defibrillators, but also for treatments ranging from the prostate specific antigen, or PSA test for prostate cancer, to gastric bypass surgery for obesity, to cardiac stents for angina, or chest pain.

To be sure, some patients prefer to delegate such important decisions to their physicians, perhaps in the belief that “doctor knows best.” But more often, the physician simply has not been trained to explain complex medical information, doesn’t feel he or she has the time to do so, or assumes the patient’s values are the same as his or her own.

Yet when patients are given a chance to be fully informed, and to share the decision about an elective treatment with their doctors, they often make choices that are very different from those their physicians would have made for them. Clinical trials have shown that patients are less likely to want invasive procedures or devices when given a chance to be fully informed and share the decision.

Shared decision making represents a sea change in the practice of medicine, a democratization of the doctor-patient relationship. Young doctors need to be trained in the best way to convey medical information to patients, and they should learn to value the process of sharing decisions with their patients. Tools called “patient decision aids,” booklets, videos, and interactive web programs that offer balanced, clear information can help.  Patients, too, must understand that such choices are theirs to make.

The Affordable Care Act of 2010 contains provisions to promote the production of balanced decision aids and the process of shared decision making. Unfortunately, the act did not include the necessary funding.  Even so, shared decision making’s time has come. The nation can’t afford to waste money on surgeries and other treatments that patients would not have wanted had they been given a clear choice. But even more important than cost, patients deserve to be fully informed.

Shannon Brownlee is acting director of the New America Health Policy Program, blogs at The New Health Dialogue, and author of Overtreated: Why Too Much Medicine Is Making Us Sicker and Poorer.

Submit a guest post and be heard on social media’s leading physician voice.