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February 1995

Subarachnoid Hemorrhage and Family History: A Population-Based Case-Control Study

Arch Neurol. 1995;52(2):202-204. doi:10.1001/archneur.1995.00540260108026

Objective:  To evaluate family history as a risk factor for subarachnoid hemorrhage.

Design and Setting:  A population-based case-control study in King County, Washington.

Subjects:  Cases consisted of 149 patients with spontaneous subarachnoid hemorrhage. Two control subjects who were matched to cases by gender and age within 5 years were identified for each case using random digit telephone dialing.

Main Measure:  Detailed information on family history was obtained through an in-person interview.

Results:  Some 11.4% of cases had a first-degree relative with a history of subarachnoid hemorrhage, compared with 6.4% of controls, yielding an odds ratio of 1.8 (95% CI, 0.92 to 3.7). The odds ratio for a positive family history among other relatives was 2.4 (95% CI, 1.1 to 5.2), likely reflecting family information bias. Findings were similar after adjustment was made for potential confounding variables, including cigarette smoking, a history of hypertension, and number of siblings and children.

Conclusion:  Although familial factors may be important in some families, overall they account for few cases of subarachnoid hemorrhage.