Birthplace differences in stroke rates among coronary heart disease patients: is variation explained by recognized risk factors?

Background: The incidence of stroke varies among ethnically and culturally diverse groups.
Objectives: To examine the ethnic-geographic patterns of stroke incidence in men and women with coronary heart disease in Israel, focusing on the extent to which this variability can be explained by known differences in risk factors for stroke.
Methods: Patients with documented coronary heart disease were followed for 6-8 years for incident cerebrovascular events. Baseline medical evaluation included assessment of vascular risk factors and measurements of blood lipids. Among 15,052 patients, 1110 were identified with any incident ischemic cerebrovascular event by ICD-9 codes, of whom 613 had confirmed ischemic stroke or transient ischemic attack.
Results: A major excess of ischemic cerebrovascular events among Israeli Arab women as compared to males, and an inverse finding among Israeli born Jews, were noted. The high risk in the Arab population in Israel reflected an unfavorable risk profile, since predicted rates by multivariate analysis and observed rates were 69 and 68 per 1000, respectively. High ischemic cerebrovascular event rates were identified among patients born in the Balkan countries and North Africa (89 and 90 per 1000), but unfavorable risk factor levels of these individuals did not explain them. Most trends appeared similar in male and female patients. A comparison of observed and accepted-according-to-risk-profile rates of ischemic cerebrovascular events yielded significant differences (P = 0.04), consistent with an additional role of geographic/ethnic origin resulting from factors that remain unrecognized, or with variables unassessed in this study.
Conclusions: We identified an ethnic diversity in stroke risk among the Israeli born in different parts of the world beyond what could be expected on the basis of differences in known risk factors. These findings call for detailed research aimed at identifying additional differences in the risk profile of patients with atherothrombotic disease exposed to an increased risk of stroke.