Methods: Cox proportional hazards analyses, adjusting for known stroke risk factors, were used to examine familial concordance in three groups: (1) members of the original Framingham cohort using reported parental stroke death; (2) members of the Framingham Offspring Study and their parents (members of the original Framingham Study); and (3) sibships within the original Framingham cohort.

Results: We found no association between stroke or transient ischemic attack among original cohort members and their reported parental stroke death (n=4933; relative risk [RR]=1.07). Using verified cases of parental stroke or transient ischemic attack, the Offspring analyses revealed that both paternal (n=1762; RR=2.4; 95% confidence interval [CI], 0.96 to 6.03) and maternal (n=2074; RR=1.4; 95% CI, 0.60 to 3.25) histories were associated with an increased risk. Parental history of coronary heart disease was strongly associated with stroke or transient ischemic attack among Offspring Study members (RR=3.33; 95% CI, 1.27 to 8.72). Sibling history of stroke or transient ischemic attack was not associated with stroke or transient ischemic attack among original cohort members, although a non-statistically significant increased risk associated with sibling history of atherothrombotic brain infarction was observed (RR=1.8; 95% CI, 0.68 to 4.94).

Conclusions: These analyses suggest that parental history of stroke may be a risk factor for stroke. As more stroke or transient ischemic attack events develop among the Offspring Study members, it will be valuable to reexamine these associations.