(HealthDay News) – Having a sibling who has had a stroke significantly increases the familial stroke risk by at least 60%.

Katherine Kasiman, of the Karolinska Institutet in Stockholm, and colleagues identified incident ischemic stroke cases from 1987–2007 in the Swedish Hospital Discharge and Cause of Death Registers and linked them to their stroke-free siblings (study participants) to form exposed sib-pairs. Up to five unexposed sib-pairs from the Multi-Generation Register were matched to each exposed sib-pair by birth and year of stroke to include a total of 30,735 exposed and 152,391 unexposed participants.

The researchers found that, for exposed participants, the overall risk of incident ischemic stroke was significantly increased (relative risk [RR], 1.61). Risk was higher in full siblings versus half siblings (RR, 1.64 vs. 1.41). There was nearly a two-fold increase in familial risk of early ischemic stroke when exposed to early ischemic stroke (RR, 1.94).

“There was 60% increased risk for ischemic stroke in individuals having a sibling with prior stroke. The familial effect was even higher for full sibling relations,” the authors write. “Familial effects were observed in both male and female individuals, and we found no differential effects depending on the sex of either of the siblings.”

Full Text (subscription or payment may be required)