Ischemic stroke subtypes: a population-based study of incidence rates among blacks and whites.
OBJECTIVE
Blacks have an excess burden of stroke compared with whites; however, data comparing ischemic stroke subtypes among the 2 groups are limited and typically involve relative frequencies. The objective of this study is to compare the incidence rates of ischemic stroke subtypes between blacks and whites within a large, representative, biracial population.


METHODS
The Greater Cincinnati/Northern Kentucky Stroke Study is designed to measure incidence rates and trends of all strokes within a well-defined, large, biracial population. Hospitalized cases were ascertained by International Classification of Disease (9th revision; ICD-9) discharge codes. Out-of-hospital events were ascertained by prospective screening of emergency department admission logs, review of coroners' cases, and monitoring all public health and hospital-based primary care clinics. A sampling scheme was used to ascertain events from nursing homes and all other primary care physician offices. All potential cases underwent detailed chart abstraction and confirmed by physician review. Based on all available clinical, laboratory, and radiographic information, ischemic stroke cases were subtyped into the following categories: cardioembolic, large-vessel, small-vessel, other, and stroke of undetermined cause. Race-specific incidence rates were calculated and compared after adjusting for age and gender, and standardizing to the 1990 US population.


RESULTS
Between July 1, 1993, and June 30, 1994, 1956 first-ever ischemic strokes occurred among blacks and whites in the study population. Small-vessel strokes and strokes of undetermined cause were nearly twice as common among blacks. Large-vessel strokes were 40% more common among blacks than whites, and there was a trend toward cardioembolic strokes being more common among blacks.


CONCLUSIONS
The excess burden of ischemic strokes among blacks compared with whites is not uniformly spread across the different subtypes. Large-vessel strokes are more common and cardioembolic stroke are as common among blacks, traditionally thought to be more common among whites.
Schneider
Alexander T
AT
Department of Neurology and The Neuroscience Institute, 231 Albert Sabin Way, University of Cincinnati, ML#0525, Cincinnati, Ohio 45267, USA. schneiar@ucmail.uc.edu
Kissela
Brett
B
Woo
Daniel
D
Kleindorfer
Dawn
D
Alwell
Kathleen
K
Miller
Rosemary
R
Szaflarski
Jerzy
J
Gebel
James
J
Khoury
Jane
J
Shukla
Rakesh
R
Moomaw
Charles
C
Pancioli
Arthur
A
Jauch
Edward
E
Broderick
Joseph
J
D000368:Aged; D044383:Black People / Q000706:statistics & numerical data*; D002545:Brain Ischemia / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D020521:Stroke / Q000145:classification* / Q000453:epidemiology / Q000208:ethnology*; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data*; D001741:Black or African American