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Surgery designed to prevent strokes doesn't, study finds

November 08, 2011|By Karen Kaplan, Los Angeles Times/For the Booster Shots blog
  • The bypass surgery was intended to steer blood around a blocked artery in the brain to prevent future strokes. The results were no better than using medicine alone.
The bypass surgery was intended to steer blood around a blocked artery in… (Powers, W. J. et al. JAMA…)

A surgery that seemed like an obvious way to prevent additional strokes in people who already had a first stroke is actually no better than therapy based on drugs alone, according to a new study in the Journal of the American Medical Assn.

The surgery in question is called extracranial-intracrannial arterial bypass surgery. It was designed to improve blood flow in the internal carotid artery, one of the main sources feeding the brain. In the procedure, doctors attach a new vessel to route blood around a blockage in the artery that could otherwise lead to a stroke. How could it not work?

Actually, in a study published back in 1985, this very approach failed to show any benefit for patients. But critics of that trial said it didn’t make any effort to identify the subset of stroke patients who would be most likely to benefit from the procedure.

Enter the Carotid Occlusion Surgery Study, or COSS, which zeroed in on patients who had a stroke caused by poor blood flow in the internal carotid artery within the previous 120 days. Before the trail was stopped, researchers at 49 centers recruited 195 patients. All of them got the “best medical therapy” available to treat their strokes. In addition, 97 of them got the surgery and the other 98 did not.

It turned out that in both groups, 20 patients had a repeat stroke (on the same side as the prior stroke) within 2 years of joining the study. There were also no statistically significant differences in the risk of having another stroke anywhere in the brain, a disabling or fatal stroke of any kind, or death from any cause.

What gives? In the JAMA paper, the researchers give the credit to “improvements in medical therapy.”

The moral of the story is to never assume that something works just because logic tells you that it should. “These observations reaffirm .. the necessity of performing randomized controlled trials to establish clinical benefit,” the researchers wrote.

The entire study is online here.

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