(HealthDay News) -- Neurologists say they've developed a quick test to assess the risk that someone who suffers a transient ischemic attack (TIA), or "mini stroke," will have a major stroke in the following 48 hours.
The test combines elements of two earlier predictive assessments. Those tests were designed to determine the risk of a stroke within seven and 90 days, respectively.
"We took each of the elements in those tests, combined them into a whole series of new scores, chose the best one, and validated them in new cohorts," said Dr. S. Claiborne Johnston, associate professor of neurology at the University of California, San Francisco, and lead author of a report in the journal The Lancet.
About 240,000 TIAs -- minor blockages in brain arteries -- are diagnosed in the United States each year, and up to 20 percent of them will be followed by a major stroke. It's important to assess the immediate danger, because half of those strokes will occur within the first two days after a TIA, Johnston said.
The new test can be administered in a few minutes, he added. It measures blood pressure, speech impairment, weakness on one side of the body, diabetes and age.
Using the tests on a large number of people who had TIAs showed that 21 percent were at high risk, meaning they had a 1-in-12 chance of having a stroke in the following 48 hours. Another 45 percent were classified as being at moderate risk, with a 4.1 percent chance of a stroke.
"This is the first large-scale study to validate these scores," Johnston said. "We are at a new level where we feel confident that the scores are useful in clinical practice in the Western world."
The test can help determine which patients should be hospitalized and which can safely be sent home, he said.
"We are hoping that neurologists, emergency physicians and primary care doctors will hear about this score and start using it widely," Johnston said. "Currently, it doesn't seem that physicians are making decisions based on risk. They are hospitalizing people whether they are at high risk or not."
Dr. Brett L. Cucchiara, assistant professor of neurology at the University of Pennsylvania, said he currently hospitalizes every patient who suffers a TIA. The reason, he said, is real doubt about the value of all risk-assessment tests.
His view of the new report is that it is "very interesting and suggests that this strategy may be useful." But, Cucchiara added, "we really need to see these kinds of findings replicated by an independent group before they are ready for prime time."
He pointed to a new Portuguese study, about to be published, that seems to have discredited an earlier stroke risk-assessment method.
"In their study, which was much larger, there was no predictive value at all," Cucchiara said. "I'm not sure these tests are proven enough to send patients home from the emergency room."
Another report in the same issue of the journal found that MRI is better than the commonly used CT scan for the detection of acute stroke.
The study of 356 patients, done at the U.S. National Institute of Neurological Diseases and Stroke, found that MRI detected stroke and brain hemorrhages more frequently than CT, and that MRI should be the preferred test, despite its extra cost.
Find out more on the symptoms and dangers of TIAs at the American Heart Association.