Incremental value of biochemical and echocardiographic measures in prediction of ischemic stroke: the Strong Heart Study.
OBJECTIVE
American Indians have high rates of stroke. Improved risk stratification could enhance prevention, but the ability of biochemical and echocardiographic markers of preclinical disease to improve stroke prediction is not well-defined.


METHODS
We evaluated such markers as predictors of ischemic stroke in a community-based cohort of American Indians without prevalent cardiovascular or renal disease. Laboratory markers included C-reactive protein, fibrinogen, urine albumin-to-creatinine ratio, and glycohemoglobin (HbA1c), whereas echocardiographic parameters comprised left atrial diameter, left ventricular mass, mitral annular calcification, and the ratio of early to late mitral diastolic velocities. Predictive performance was judged by indices of discrimination, reclassification, and calibration.


RESULTS
After adjustment for standard risk factors, only HbA1c, albuminuria, and left atrial diameter were significantly associated with first ischemic stroke. Addition of HbA1c, although not urine albumin-to-creatinine ratio, to a basic clinical model significantly improved the C-statistic (0.714 versus 0.695; P=0.044), whereas left atrial diameter modestly enhanced integrated discrimination improvement (0.90%; P=0.004), but not the C-statistic (0.701; P=0.528). When combined with HbA1c, left atrial diameter further increased integrated discrimination improvement (1.81%; P<0.001) but not the C-statistic (0.716). No marker achieved significant net reclassification improvement.


CONCLUSIONS
In this cohort at high cardiometabolic risk, HbA1c emerged as the foremost predictor of ischemic stroke when added to traditional risk factors, affording substantially improved discrimination, with a more modest contribution for left atrial diameter. These findings bolster the role of HbA1c in cardiovascular risk assessment among persons with glycometabolic disorders and provide impetus for further study of the incremental value of echocardiography in high-risk populations.
Weill Cornell Medical College, New York, NY, USA.
Maria G
MG
Karas
Richard B
RB
Devereux
David O
DO
Wiebers
Jack P
JP
Whisnant
Lyle G
LG
Best
Elisa T
ET
Lee
Barbara V
BV
Howard
Mary J
MJ
Roman
Jason G
JG
Umans
Jorge R
JR
Kizer
D000368:Aged; D000419:Albuminuria / Q000150:complications; D002545:Brain Ischemia / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism*; D002097:C-Reactive Protein / Q000032:analysis; D002318:Cardiovascular Diseases / Q000150:complications; D015331:Cohort Studies; D003404:Creatinine / Q000652:urine; D003627:Data Interpretation, Statistical; D004452:Echocardiography / Q000706:statistics & numerical data*; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis; D006321:Heart / Q000502:physiology*; D006325:Heart Atria; D006801:Humans; D007198:Indians, North American; D007674:Kidney Diseases / Q000150:complications; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D020521:Stroke / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism*
D002097:C-Reactive Protein; D003404:Creatinine; D005340:Fibrinogen; D006442:Glycated Hemoglobin