FRIDAY, Feb. 3 (HealthDay News) -- While a clot-busting medication can often help stop a stroke in its tracks if it's given promptly, a new study finds that a high number of stroke victims continue to fail to get to the emergency room quickly enough to get the drug.

An analysis of about 115,000 patients who had strokes between 2005 and 2010 found that almost 44 percent didn't get to the hospital until more than 4.5 hours after the time they were known to first show symptoms. That's a sign of trouble: it's actually up from 39 percent in 2005.

Meanwhile, the percentage who got to the hospital within two hours fell from 40 percent in 2005 to 35 percent in 2010, another sign that more patients may be in danger from not getting prompt care.

Also, many patients chose to get themselves to the hospital instead of calling an ambulance, "boosting the risk that they won't get there in time to be able to take a clot-busting drug," said study co-author Dr. Mary George, a medical officer with the division for heart disease and stroke prevention at the U.S. Centers for Disease Control and Prevention.

The main message of the research is that more people need to learn about the warning signs of stroke, George said. According to the National Stroke Association, those symptoms appear suddenly and include numbness or weakness (especially on one side of the body); confusion or trouble speaking; trouble seeing out of one or both eyes; trouble with walking, dizziness, loss of balance or coordination; or severe headache with no known cause.

"They need to know that when any of that occurs, or when they even just think it is occurring, to call 911," George said. "It is really critical that they don't wait, that they don't sit around and say 'Let's see if this goes away in a couple of hours.'"

The study authors found that the percentage of patients who received treatment with tissue-plasminogen activator (tPA), a drug that breaks up blood clots, grew from 6.4 to 9.2 percent over the five years. The drug must be given promptly after a stroke and isn't appropriate for all kinds of strokes.

Research suggests that people who arrive at the hospital via ambulance are more likely to get the drug, George said. "They get there quicker, they get seen quicker and perhaps there's more of a sense of urgency."

There's no downside to providing more education about stroke, said Dr. David Liebeskind, a professor of neurology at the University of California, Los Angeles, who's familiar with the findings. But it may be difficult to convince more patients to come to the hospital promptly, he noted.

As for the rate of administration of the clot-busting drug, Liebeskind said that while "there are definitely more patients who could receive it," it takes a while for doctors to figure out what to do at the hospital because of the potential risks.

"These are difficult decisions, and a lot of factors are being weighed. That may cause a slight delay," he said.

The study was to be presented Friday at the American Stroke Association annual meeting in New Orleans.

Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information

For more about stroke, visit the U.S. National Library of Medicine.