Sunday, February 17, 2013
A Cardiac Conundrum
From Harvard Magazine:
The first randomized clinical trial of bypass surgery’s efficacy, using data from a collaboration of Veterans Administration hospitals, was not published until 1977. Such trials were then becoming the gold standard of medical research (and still are). “Surgeons said trials were totally unnecessary, as the logic of the procedure was self-evident,” says Jones. “You have a plugged vessel, you bypass the plug, you fix the problem, end of story.” But the 1977 paper showed no survival benefit in most patients who had undergone bypass surgery, as compared with others who’d received conservative treatment with medication. “There was a firestorm of controversy,” Jones says. “There was lots of money, institutional power, and lots of lives at stake. The surgeons dismissed the trial for technical reasons. So, many other trials were done, all more or less showing the same thing: bypass surgery improved survival for a few patients with the most severe forms of coronary artery disease, but for most others it relieved symptoms but did not extend lives.” The results raise a philosophical question of the goal of medical treatment: alleviating symptoms or lengthening lives? “How much is it worth investing in a surgical procedure, with all its risks,” he asks, “if all you’re doing is relieving symptoms?”
The advent of angioplasty in the 1980s complicates the story. With angioplasty, instead of bypassing the plugged artery, “you use a balloon to compress the plug,” Jones explains, “and (as it’s done today) you leave a stent behind to keep the blood vessel open, and so restore blood flow to the heart.” Like bypass surgery, angioplasty went from zero to 100,000 procedures annually with no clinical trial to assess long-term outcomes—based on the logic of the procedure and patients’ reports of how much better they felt. Yet the first clinical trials, which appeared in the early 1990s, showed no survival benefit of elective angioplasty as compared with medication.
...Furthermore, “patients are wildly enthusiastic about these treatments,” he says. “There’ve been focus groups with prospective patients who have stunningly exaggerated expectations of efficacy. Some believed that angioplasty would extend their life expectancy by 10 years! Angioplasty can save the lives of heart-attack patients. But for patients with stable coronary disease, who comprise a large share of angioplasty patients? It has not been shown to extend life expectancy by a day, let alone 10 years—and it’s done a million times a year in this country.” Jones adds wryly, “If anyone does come up with a treatment that can extend anyone’s life expectancy by 10 years, let me know where I can invest.” “The gap between what patients and doctors expect from these procedures, and the benefit that they actually provide, shows the profound impact of a certain kind of mechanical logic in medicine,” he explains. “Even though doctors value randomized clinical trials and evidence-based medicine, they are powerfully influenced by ideas about how diseases and treatments work. If doctors think a treatment should work, they come to believe that it does work, even when the clinical evidence isn’t there.”
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