“The good news is that the millions of dollars spent on clinical trials to clarify who really benefits from stroke prevention surgery (carotid endarterectomy) appears to have paid off – the percentage of cases done for inappropriate reasons has fallen from 32 percent in the 1980s to 10.6 percent in 1997-1998. Unfortunately, the bad news is that one in ten operations are still done in situations where the risks may outweigh the benefits, ” says lead study author Ethan A. Halm, M.D. MPH, assistant professor of health policy and medicine at Mount Sinai School of Medicine, New York. The study was funded by the federal Agency for Healthcare Research and Quality.
“If our results are typical of practice in the United States, then approximately 14,000 operations are performed annually for inappropriate reasons,” he says.
Carotid endarterectomy removes plaque in the neck arteries that supply blood to the brain. A study of 2,124 carotid endarterectomy surgeries done at six hospitals in New York State during a two-year period in late 1990s found that 84.9 percent of the surgeries were done for appropriate reasons; 10.6 percent were done for inappropriate reasons, and 4.5 percent were performed for uncertain reasons.
Researchers also found that the type of patients who have carotid endarterectomy has shifted dramatically. The procedure was developed to prevent strokes in patients with neurologic symptoms, but three-quarters of all cases were done on patients without symptoms. “This is cause for concern because, even though asymptomatic patients may have significant narrowings in their carotid arteries, they have less to gain compared to patients with neurologic symptoms. The yearly risk of stroke from those asymptomatic narrowings is very low in most cases,” Halm says.
Researchers also found that a subset of asymptomatic patients who have multiple cardiac risk factors had rates of death or stroke related to the procedure that exceeded the recommended threshold. “You don’t want to cause a stroke while trying to prevent a stroke, and our data indicate that for asymptomatic patients with multiple cardiac problems the risks of the procedure outweigh the benefits, even in the most experienced surgical hands,” Halm adds.
“Physicians need to focus more attention on assessing the patient’s cardiovascular risk factors for having a stroke or dying during surgery when balancing the benefits and harms of carotid endarterectomy among asymptomatic patients,” he says.
Moreover, since narrowing of the carotid arteries often occurs at the same time as similar narrowing in heart vessels, “there is an ongoing debate about which should be done first: the neck, the heart, or a one-stop-shopping approach in which both the neck and heart problems are fixed at the same time. Based on this study, he says, “the combination surgery is not the answer because the rate of dying or having a stroke with the combined procedure was 10.3 percent.”
In the early 1980s, enthusiasm for the procedure was high even though there was no strong evidence that it actually prevented strokes and saved lives, he says. In the late 1980s, studies found that complications rates were higher than expected, and a large study by the RAND Corporation indicated that one third of the cases were inappropriate.
“These studies had a chilling effect, and procedure rates declined sharply,” Halm says.
After the RAND study, several large randomized controlled trials (RCTs) were conducted that indicated carotid endarterectomy could prevent stroke if patients were carefully selected and the surgeons had low complication rates. That created a new boom in surgeries.”
In their analysis, Halm and colleagues revisited the appropriateness issue to determine if practices have really changed following the widespread dissemination of the RCTs findings.
The researchers developed a list of 1,557 mutually exclusive indications for carotid endarterectomy. A panel of nationally recognized experts in vascular surgery, neurosurgery, neurology, internal medicine, neuroradiology and vascular medicine then rated the appropriateness of each indication. Surgery was considered appropriate when the benefits exceeded the risks of the procedure. It was considered uncertain when the benefits and risks were equal and considered inappropriate while the risks outweighed the benefits.
The research team evaluated the appropriateness of surgery for 2,124 patients seen from January 1, 1997 to December 31, 1998. The patients were treated in moderate- to high-volume hospitals by 67 different surgeons. Most of the patients were elderly, white and had Medicare insurance. They also had other health problems such as hypertension and coronary artery disease.
The presence of other serious diseases was cited as a determining factor in 46.6 percent of the cases judged inappropriate while 28 percent of them were found to have carotid narrowings that did not warrant surgery. Among the inappropriate cases, 70 percent were asymptomatic patients.
Overall, the combined rate of death or nonfatal stroke within 30 days of surgery for patients with symptoms was 5.47 percent. The rate was 2.26 percent in patients without symptoms having the carotid endarterectomy alone and 10.3 percent for patients without symptoms having carotid endarterectomy and coronary bypass.
Halm’s co-authors are Mark R. Chassin, M.D. MPP, MPH; Stanley Tuhrim, M.D.; Larry H. Hollier, M.D.; A. John Popp, M.D.; Enrico Ascher, M.D.; Herbert Dardik, M.D.; Glenn Faust, M.D. and Thomas S. Riles, M.D.