Still a long way to go in diagnostic evaluation of all patients who suffer ischemic strokes

Sep 27 2005

Women who survive a stroke are less likely than men to get crucial tests of their heart and neck arteries that can help improve their treatment and reduce their risk of a second stroke, a new University of Michigan study finds.

And while those tests appear to be under-used in all stroke patients no matter what their gender, the difference in testing between men and women may help explain why women tend to have a worse long-term outcome from stroke, including a higher death rate. The study is published in the Sept. 27 issue of the journal Neurology.

The findings, from a study of 1,234 stroke patients treated in Texas community hospitals, show that there's still a long way to go in diagnostic evaluation of all patients who suffer ischemic strokes. About 88 percent of all strokes are ischemic, which means they're caused by blood clots traveling to the brain or by blockages in the carotid arteries in the neck that supply blood to the brain.

One in every seven people who has a stroke will have another one within a year. The study looked at the use of tests that can cut that risk, by assessing the potential for blood clots to form in the heart, and the health of the carotid arteries. The results of such tests can guide doctors to prescribe preventive treatment and help patients understand what they must do to prevent a second stroke.

"Diagnostic evaluations that should be done on every ischemic stroke patient still aren't being performed on a third to a half of patients, and they're less likely to be performed on women," says senior author Lewis Morgenstern, M.D., director of the Stroke Program in the U-M Cardiovascular Center. "Intervention is needed to increase access to quality stroke care for all patients, but especially women."

Morgenstern, a stroke neurologist who leads the Brain Attack Surveillance in Corpus Christi, or BASIC, study from which the new data were gathered, is a professor in the Departments of Neurology, Neurosurgery and Emergency Medicine at the U-M Medical School and a professor of epidemiology at the U-M School of Public Health.

The new paper is based on detailed analysis of records from a random sample of 381 patients, 220 of them female and half of them Mexican-American.

It found that women were 36 percent less likely than men to receive an echo-cardiogram of their heart, a test similar to pregnancy ultrasound that creates a movie of the heart and can looks for clot-producing conditions and other problems. Women were also 43 percent less likely to have exams of their carotid arteries, which can become narrowed by cholesterol plaque that blocks blood flow and spawns clots.

The gender difference in testing rates was still present in the study even after the researchers took into account factors such as age, ethnicity, insurance status, stroke risk factors, stroke severity, blood pressure and atrial fibrillation, a heart rhythm condition that encourages the formation of clots in the heart.

There were no significant differences by gender in the use of electrocardiogram, or EKG, to examine heart rhythm, and the use of MRI (magnetic resonance imaging) and CT (computed tomography) scans to examine the brain.

Says lead author and neurology research associate Melinda Smith Cox, M.P.H., "Previous studies have shown that the rate of stroke is lower in women than in men, but that women have worse outcomes than men. Our results may give us a reason for that disparity." Sixty-two percent of American stroke deaths are in women, though a higher percentage of men suffer strokes at any age.

The new paper is the fourth from U-M researchers to show gender differences in some aspect of stroke. Previously, they've shown that stroke death is more common in women than in men in Texas, and that women reach the hospital later than men and are triaged for emergency treatment more slowly than men -- findings that have major implications for ischemic stroke because the most effective treatment, a drug called tPA, must be administered within three hours of the onset of a stroke.

In 2003, they showed that women were much more likely than men to report "non-traditional" symptoms of stroke such as headache, face pain and limb pain; disorientation and change in consciousness; and chest pain or shortness of breath. Traditional stroke symptoms include sudden changes in sensation, walking ability, balance, motor functions (including paralysis of one side of the body), speech, language abilities, facial muscles, vision and dizziness.

Currently, the U-M team is conducting an in-depth prospective study of stroke symptoms, treatment and outcomes among patients treated at U-M hospitals, looking for any gender differences.

The BASIC study, funded by the National Institutes of Health, is a population-based study focusing on stroke awareness, incidence, treatment and outcomes in Nueces County, Texas, which has a high proportion of second- and third-generation Mexican Americans and two main community hospital systems but no academic medical center.

The new paper is based on data from stroke patients treated between Jan. 1, 2000 and Dec. 31, 2002. After the random sample of patients was selected from among all ischemic stroke patients, stroke neurologists went through their medical records and documented the subtype of ischemic stroke, demographic and medical characteristics, and diagnostic tests conducted after the stroke. They also retrieved pre-stroke records for patients whose hospital records mentioned that an exam had been performed in the days before the stroke. If a person had more than one ischemic event during the study period, only the first one was analyzed.

Both the men and women in the study were equally likely to have been admitted to the hospital with a confirmed or strongly suspected diagnosis of ischemic stroke -- eliminating the possibility that the difference in testing was due to differences in diagnosis.

In all 57 percent of men and 48 percent of women had either a trans-thoracic echocardiogram (called a TTE for short) or a trans-esophageal echocardiogram (TEE) to look at their hearts. TTEs are performed using an ultrasound device outside the body, while TEEs use a scope inserted down the throat to get a better look at the heart.

Just over 70 percent of men had some form of test to evaluate their carotid arteries, either an ultrasound scan, an invasive X-ray exam called an angiogram, or an MRI carotid exam. By contrast, 62 percent of women had a carotid exam of some sort. National experts advise that all ischemic stroke patients whose strokes are thought or known to affect the part of the brain fed by the carotid arteries (so-called anterior circulation strokes) should have carotid evaluation.