martes, 20 de diciembre de 2011

NLM Director's Comments Transcript - Stroke Bypass Surgery & Better Evidence: MedlinePlus

NLM Director's Comments Transcript
Stroke Bypass Surgery & Better Evidence: 12/19/2011

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Picture of Dr. LindbergGreetings from the National Library of Medicine and
Regards to all our listeners!
I'm Rob Logan, Ph.D. senior staff National Library of Medicine for Donald Lindberg, M.D, the Director of the U.S. National Library of Medicine.
Here is what's new this week in MedlinePlus.listen
After reviewing two years of surgeries within 49 different North American hospitals, the study's six researchers found no statistical differences between 97 patients (who received a bypass intended to improve blood flow to the brain plus medications) and 98 other participants (who only received post mini-stroke medications, such as anti-clotting, blood pressure, and cholesterol lowering drugs).
Specifically, 21 percent of the patients who received bypass surgery and medications died or had a stroke compared to 22.7 percent of participants who only received drug therapy. Moreover, some evidence suggested medications were more clinically efficacious; 30 days after bypass surgery 14.4 percent of patients had a stroke compared with two percent who received only medications.
In contrast with previous studies, the researchers used an image scanning technique to determine if participants who had a mini-stroke also experienced a very low blood flow to the brain. The latter increases the risk of a second and more significant stroke. The bypass operation, called the extracranial-intracranial arterial bypass, attaches a blood vessel from the scalp to blood vessels within the brain.
In reporting about the study, the New York Times explained physicians were optimistic about the tested bypass procedure because it was seen as a creative option to increase blood flow when mini-stroke patients experience a significant blockage of arterial pathways in the neck. However, the clinical trial's authors stopped the current study (that was scheduled to continue with 180 more patients) when the results showed the procedure did not result in comparative post-surgical benefits.
The New York Times added the $40,000 cost of the bypass operation was a factor in stopping the trial early. The clinical trial was sponsored by the National Institute of Neurological Disorders and Stroke.
The study's authors explain their research additionally underscores the importance of using randomized clinical trials – compared to less rigorous protocols – to assess the clinical efficacy of this and some other stroke procedures. The authors write the clinical trial (and we quote): 'reaffirms(s) the hazard of using even the most carefully studied historical controls to infer therapeutic efficacy and the necessity of performing randomized controlled trials to establish clinical benefit' (end of quote).
A perceptive editorial accompanying the clinical trial article adds broader acute stroke therapy is at a critical juncture where the use of some therapy is proceeding with (and we quote) 'little scientific evidence of clinical efficacy' (end of quote).
Ironically at a time when clinical evidence is desirable, the editorial's authors explain the capacity to expand randomized clinical trials for stroke patients seems impeded. The editorial's authors write (and we quote): 'even though no device has proven clinically effective for the treatment of acute ischemic stroke [or mini-strokes], a substantial proportion of the stroke interventional community in the United States is seemingly unwilling to enroll patients into ongoing acute interventional randomized trials' (end of quote).
The editorial's authors add the clinical trial indirectly raises an underlying problem; some post-stroke intervention procedures used in U.S. hospitals receive increasing reimbursement even though there may be a dearth of rigorous evidence regarding their clinical efficacy.
The editorial's authors call for an alignment of clinical science and the reimbursement for stroke procedures. They add (and we quote) 'physicians who provide care for patients with stroke must recognize the current lack of evidence for clinical efficacy of endovascular therapy and enroll patients in randomized trials' (end of quote). explains a stroke occurs when the blood flow to your brain stops.'s stroke health topic page explains the mini-strokes assessed in the JAMA article occur when the blood supply to the brain is briefly interrupted. explains drug therapy using blood thinners is the most common treatment for stroke. More information about stroke medications, provided by NIH Senior Health, is available within the 'tutorials' section of's stroke health topic page.'s stroke health topic page additionally contains research summaries, which are available in the 'research' section. Links to the latest pertinent journal research articles are available in the 'journal articles' section.
To find's stroke health topic page, type 'stroke' in the search box on's home page, then, click on 'stroke (National Library of Medicine).'
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NLM Director's Comments Transcript - Stroke Bypass Surgery & Better Evidence: MedlinePlus
A bypass surgical procedure (intended to improve blood circulation in the brain and prevent a more serious stroke) is no more effective than widely available stroke medications, finds a study recently published in the Journal of the American Medical Association. In addition, the study's authors (and an accompanying editorial) note the research suggests a need for acute stroke research and practice that is better supported by rigorous, randomized clinical trials.

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