Study Debunks Operation to Prevent Strokes (The New York Times)
Source: The New York TImes
By Denise Grady
An operation that doctors hoped would prevent strokes in people with poor circulation to the brain does not work, researchers are reporting. A $20 million study, paid for by the government, was cut short when it became apparent that the surgery was not helping patients who had complete blockages in one of their two carotid arteries, which run up either side of the neck and feed 80 percent of the brain.
The surgery was a bypass that connected a scalp artery to a deeper vessel to improve blood flow to the brain.
The new study, published on Wednesday in The Journal of the American Medical Association, is the second in recent months to find that a costly treatment, one that doctors had high hopes for, did not prevent strokes. In September, researchers reported that stents being used to prop open blocked arteries deep in the brain were actually causing strokes. That study was also cut short.
Both the stents and the bypass operation seemed to make sense medically, and doctors thought they should work. Their failure highlights the peril of assuming that an apparent improvement on a lab test or X-ray, like better blood flow or a wider artery, will translate into something that actually helps patients, warned an editorial that accompanied the new findings. Only rigorous studies can tell for sure.
The editorial writer, Dr. Joseph P. Broderick, chairman of neurology at the University of Cincinnati College of Medicine, also cautioned that other stroke treatments were being used without sufficient study, particularly devices to remove clots. Dr. Broderick said doctors liked new technology, were paid well to use it and tended to believe in what they were doing, even without data.
The bypass operations were performed at 49 hospitals in the United States and Canada. All the patients given the surgery had had a stroke or transient ischemic attack (sometimes called a mini-stroke) during the previous 120 days, and were at high risk for another stroke. About 24,000 people a year in the United States were thought to be candidates for the operation.
But the study found that people who had the surgery, plus a strict regimen of drugs to lower their risk of stroke, fared no better than those who received the drugs alone. The drugs work by preventing blood clots and lowering cholesterol and blood pressure.
The surgery costs about $40,000, probably 10 times the price of a year’s worth of medicine to reduce the risk of stroke, according to Dr. William J. Powers, the lead author of the study and chairman of neurology at the University of North Carolina in Chapel Hill. But a successful operation would have been well worth the cost, he said, because it is even more expensive to take care of people who have suffered severe strokes.
Dr. David Langer, a brain surgeon and associate professor at the Hofstra North Shore-Long Island Jewish School of Medicine, said the study was well done and important.
“Surgeons don’t want to be doing bad operations,” Dr. Langer said. “Whenever you have a paper like this we’re all disappointed, because we like to operate. But in the end it’s a good thing.”
Dr. Langer predicted that the new information would lead to a reduction in the use of the bypass operation but would not wipe it out entirely because some patients, different from those in the study, could still be helped by it.
The new research was an effort to improve on an earlier study, published in 1985, which also found that the bypass operation did not work. Those results led Medicare to stop covering the operation for people with blocked carotids.
But many doctors had seen individual patients who seemed better after the surgery, and researchers wondered if the earlier study might have included too few high-risk patients who really might be helped by the surgery.
So this time, researchers used a sophisticated scanning technique to identify the 30 percent of patients with blockages who also had extremely low blood flow to the brain — a condition that a French researcher named “misery perfusion.” Only people with the lowest flow were included in the study; 97 received surgery and drugs, and 98 drugs alone. The researchers then monitored strokes.
After two years, there was no statistical difference between the two groups. In the surgery group, 21 percent had strokes, compared to 22.7 percent in the medicine-only group. A statistical analysis found that no benefit was likely to emerge even if the study went on, so it was stopped. The original plan would have treated about 180 more patients and cost an additional $10 million to $15 million, Dr. Powers said.
“I’ve probably put 30 years of my life into this question,” he said, but added that stopping the study was the right decision “if there is literally no chance we’re going show the surgery works.”
Tests showed that technically, the operation did what it was supposed to do: it improved blood flow to the brain. So why weren’t patients who had the surgery better off? It was because the operation itself caused strokes: 14.4 percent of the surgical patients had a stroke within a month of the operation, compared with a stroke rate of only 2 percent in the nonsurgical group during their first month in the study.
After the first month, surgical patients actually did have fewer strokes than would have been expected without the surgery — but any advantage was canceled out by the high stroke rate during that first month.
Dr. Powers said that the researchers pored over their data to see if they could find some clue to predict which patients would be most likely to have strokes soon after the surgery.
“We looked at 50 different factors to see if we could identify those people, and we couldn’t,” he said.
He said the idea that patients could be helped by improved blood flow was still valid — but researchers have to find a safer way to do it.
It was a letdown to find out that the operation did not work, Dr. Powers said.
“I like to tell myself that what was important was to get the answer,” he said. “Do I wish it had worked? Of course, because what we really want to do here is take better care of people. It’s a disappointment that after all this work we’re still no better at helping these people.”