Stroke among siblings in a biethnic community.

Background: Mexican Americans (MAs) have an increased risk of stroke compared with non-Hispanic whites (NHWs), especially at younger ages. Little is known regarding patterns of familial aggregation of stroke and whether familial risk assessment might prove a potentially useful tool in assessing stroke risk in this population. This study's objective was to estimate the sibling recurrence risk ratio (lambda(s)) for stroke and to compare this ratio between MAs and NHWs.

Methods: Stroke and transient ischemic attack (TIA) cases (n = 181) between the ages of 45 and 64 years were identified by a population-based stroke study in a biethnic Texas community. lambda(s) was calculated overall and by ethnicity.

Results: Siblings of ischemic stroke/TIA cases had a doubling in stroke risk compared to what would be expected based on national stroke prevalence estimates (lambda(s) = 1.92; 95% CI: 1.39-2.61). lambda(s) was 2.0 (95% CI: 1.39-2.81) among MA stroke/TIA cases and 1.66 (95% CI: 0.82-3.10) among NHW stroke/TIA cases.

Conclusion: The sibling recurrence risk for stroke was elevated in MA stroke/TIA cases suggesting that further ischemic stroke genetic studies across ethnicities may be warranted. In addition, a positive family history could prove a useful factor in the clinical setting for identifying MAs at increased stroke risk.