February 27, 2008 — Slow walking speed was found to be a strong predictor of an increased risk for incident ischemic stroke among postmenopausal women independent of other established risk factors for stroke, according to the results of a study reported in the February 21 Online First issue of Stroke.

"Walking speed is a simple, reliable, and valid measure of functional status that has been shown to be strongly correlated with age-related outcomes and may be an indicator of subclinical cerebrovascular disease," write Aileen P. McGinn, PhD, from the Albert Einstein College of Medicine in Bronx, New York, and colleagues. "However, few studies have investigated the association of walking speed with risk of incident ischemic stroke."

The study cohort consisted of 13,048 postmenopausal women enrolled in the Women's Health Initiative who had no history of stroke at baseline. Mean age at baseline was 65 years. At follow-up, 264 of these women had had incident ischemic strokes.

The relationship between performance on a timed walking test and the risk for incident ischemic stroke was determined by Cox proportional hazards regression to obtain hazard ratios (HRs) and 95% confidence intervals (CIs) with multivariate adjustment for age, race or ethnicity, body mass index, waist-to-hip ratio, depression, arthritis, hypertension, smoking, systolic blood pressure, treated diabetes, hormone use, use of nonsteroidal anti-inflammatory drugs, aspirin use, self-reported general health, and history of coronary heart disease.

In this population, slower walking speed significantly predicted incident ischemic stroke. Compared with women in the fastest walking speed tertile, those in the slowest walking speed tertile had an increased risk for incident ischemic stroke (HR, 1.69; 95% CI, 1.21 - 2.36 after multivariate adjustment). This association was not changed significantly by additional adjustment for other physical function variables, such as grip strength and chair stands.

Limitations of the study include possible misclassification bias and failure to capture nonhospitalized patients with strokes.

"Slow walking speed was found to be a strong predictor of increased risk of incident ischemic stroke among postmenopausal women independent of other established risk factors for stroke," the study authors write. "Notably, the strength of the association of walking speed with incident ischemic stroke in this group of women is independent of and comparable, if not stronger, to established risk factors for stroke, including hypertension and diabetes."

The National Heart, Lung, and Blood Institute of the National Institutes of Health, US Department of Health and Human Services funded the Women's Health Initiative. The study authors have disclosed no relevant financial relationships.

Stroke. Published online February 21, 2008.

Clinical Context

Study Highlights

• Study subjects included those enrolled in the Women's Health Initiative, which included postmenopausal women between the ages of 50 and 79 years. Women with a history of alcohol or drug dependency or significant mental illness were excluded from participation, and the current analysis excluded subjects with a previous history of stroke.
• All subjects underwent a thorough health assessment at baseline, particularly for cardiovascular risk factors. Average physical activity was also measured, and a subset of participants were assessed for walking speed by measurement of the time it took to complete a 6-meter walk. Subjects also were assessed for repeated chair stands and handgrip strength.
• The main outcome of the study was the relationship between incident ischemic stroke and walking speed. Stroke was defined as the rapid onset of a persistent neurologic deficit lasting more than 24 hours and resulting from an arterial occlusion, and reports of stroke were adjudicated with the medical record. The main outcome was adjusted to account for other cardiovascular risk factors.
• 13,048 women were included in the current analysis, and the mean age was 65 years.
• Participants were divided into tertiles (> 1.24 meters per second, 1.06 - 1.24 meters per second, and < 1.06 meters per second) to help determine the relationship between walking speed and stroke.
• Women with faster walking speeds were generally younger, more likely to be white, taller, have better self-reported health, and have a lower body mass index and waist-to-hip ratio. Subjects with diabetes, hyperlipidemia, arthritis, and coronary heart disease had slower walking times, but subjects receiving hormone therapy had faster walking times.
• Participants with faster walking times had a lower mean systolic blood pressure.
• On multivariate adjusted models, the HR for subjects with a walking time between 1.06 and 1.24 meters per second was 1.29 for incident stroke vs women in the fastest tertile. This result was not statistically significant.
• For the slowest tertile in walking speed, the adjusted HR was 1.69 for incident stroke vs the fastest tertile. This result was statistically significant.
• The addition of grip strength and chair stands to the multivariable adjustment failed to significantly alter the main result of the study. However, the number of chair stands completed was inversely related to the risk for ischemic stroke. Grip strength did not affect the risk for stroke.

Pearls for Practice

• Reduced walking speed has previously been associated with an increased risk for falls, functional disability, hospitalizations, dementia, white matter hyperintensities and lacunar infarcts, and incident stroke among older adults.
• The current study demonstrates that reduced walking speed among older women can increase the risk for incident ischemic stroke.

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