@article {900, title = {Factors associated with geographic variations in stroke incidence among older populations in four US communities.}, journal = {Stroke}, volume = {37}, year = {2006}, month = {2006 Aug}, pages = {1980-5}, abstract = {

BACKGROUND AND PURPOSE: In the Cardiovascular Health Study (CHS), we previously observed lower stroke incidence in Allegheny County, PA compared with the other 3 study sites. The purpose of this study was to study possible reasons for the lower stroke incidence in Allegheny County.

METHODS: CHS participants 65 years or older who were stroke-free at baseline (n=5639) were followed between 1989 to 1990 and 2000 for the development of stroke. Risk factors at baseline and their subsequent control were compared among both groups. Site-specific hazard ratios for stroke incidence were calculated using Cox regression models.

RESULTS: The unadjusted hazard ratio for total stroke incidence in Forsyth County, NC; Sacramento County, CA; and Washington County, MD combined compared with Allegheny County, PA was 1.74 (95\% CI: 1.42, 2.14). After adjustment for age and other traditional risk factors, there was modest reduction of the excess hazard in non-Allegheny sites compared with Allegheny County (hazard ratio=1.52, 95\% CI: 1.17, 1.98). Between baseline and the seventh-year visits, control of hypertension, diabetes, lipids, smoking, atrial fibrillation and transient ischemic attack were similar across sites. White matter grade > or = 3 on the baseline brain MRI was less common in Allegheny County (25.8\% versus 36.3\%, respectively; P<0.001) and accounted for 25\% of the excess hazard in non-Allegheny sites compared with Allegheny County.

CONCLUSIONS: Site differences in stroke risk factors at baseline and subsequent control only partially explain site differences in stroke incidence. White matter grade as a possible integrated measure of exposure and control of risk factors may help in explaining geographic variations in stroke incidence.

}, keywords = {Aged, Brain, California, Female, Humans, Incidence, Magnetic Resonance Imaging, Male, Maryland, North Carolina, Pennsylvania, Proportional Hazards Models, Risk Assessment, Risk Factors, Stroke}, issn = {1524-4628}, doi = {10.1161/01.STR.0000231454.77745.d9}, author = {El-Saed, Aiman and Kuller, Lewis H and Newman, Anne B and Lopez, Oscar and Costantino, Joseph and McTigue, Kathleen and Cushman, Mary and Kronmal, Richard} }