Ankle-brachial index and 7-year ischemic stroke incidence: the ARIC study.
OBJECTIVE
Low ankle-brachial index (ABI), which is the ratio of tibial artery systolic blood pressure to brachial systolic artery pressure, is known to be a measure of lower limb peripheral artery disease as well as a marker for other cardiovascular disease events. The ability of ABI to predict incident ischemic stroke, however, is not established in population-based studies.


METHODS
ABI was measured in a cohort of 14 839 black and white men and women aged 45 to 64 years. Stroke incidence was calculated during approximately 7 years of follow-up.


RESULTS
A total of 206 incident strokes occurred. Adjusted stroke incidence rates were markedly higher for those in the lowest versus the highest categories of ABI for men, women, blacks, and whites. The proportional hazards regression model, adjusted for age, race, gender, and field center, showed an inverse linear trend between ABI and ischemic stroke incidence (P<0.0001). The lowest group (ABI <0.80) had a hazard ratio of 5.68 (95% CI 2.77 to 11.66). After adjustment for major risk factors in a multivariate model, the hazard ratio in the lowest group was elevated (1.93) but no longer statistically significant (95% CI 0.78 to 4.78). There was, however, still an indication of an overall inverse linear trend between ABI and incident stroke (P=0.03).


CONCLUSIONS
Low ABI was strongly associated with increased incidence of ischemic stroke, but the relationship was substantially reduced after adjustment for major cardiovascular risk factors.
Tsai
A W
AW
Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, USA.
Folsom
A R
AR
Rosamond
W D
WD
Jones
D W
DW
D044383:Black People; D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000379:methods*; D001916:Brachial Artery / Q000503:physiopathology; D002545:Brain Ischemia / Q000453:epidemiology* / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000503:physiopathology; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012307:Risk Factors; D017678:Sex Distribution; D020521:Stroke / Q000453:epidemiology* / Q000503:physiopathology; D013599:Systole; D016909:Tibial Arteries / Q000503:physiopathology; D044465:White People