BACKGROUND AND PURPOSE: To identify risk factors for subarachnoid hemorrhage 
(SAH) and intracerebral hemorrhage, we designed a case-control study of men and 
women 18 to 49 years of age (the Hemorrhagic Stroke Project [HSP]). This report 
focuses on SAH.
METHODS: Patients were recruited from 44 hospitals in the United States. Cases 
with SAH must have had a ruptured aneurysm documented by angiography or surgery. 
Two controls, identified by random digit dialing and matched to each patient for 
age, sex, race, and telephone exchange, were sought for each case subject.
RESULTS: Between 1994 and 1999, 425 patients with SAH were enrolled in HSP, and 
312 cases met the criteria for aneurysmal SAH. The present analyses also 
included 618 matched controls. Of the 312 cases, 66% were current cigarette 
smokers compared with 30% of controls (adjusted odds ratio [OR], 3.73; 95% CI, 
2.67 to 5.21). Cocaine use within the previous 3-day period was reported by 3% 
of cases and no controls (bivariate exact OR, 24.97; 95% exact CI, 3.95 to 
infinity; adjusted estimate not calculable). Other independent risk factors in 
the multivariable model included hypertension (adjusted OR, 2.21; 95% CI, 1.48 
to 3.29), low body mass index (OR, 1.59; 95% CI, 1.08 to 2.35), primary family 
history of hemorrhagic stroke (OR, 3.83; 95% CI, 1.73 to 8.46), caffeine in 
pharmaceutical products (OR, 2.48; 95% CI, 1.19 to 5.20), lower educational 
achievement (OR, 2.36; 95% CI, 1.44 to 3.87), and nicotine in pharmaceutical 
products (adjusted estimate not calculable).
CONCLUSIONS: Aneurysmal SAH may be largely a preventable disease among the young 
and middle-aged because several prevalent risk factors can be modified by 
medication (eg, hypertension) or behavioral change (eg, cigarette smoking, 
cocaine use). The association of caffeine and nicotine in pharmaceutical 
products and aneurysmal SAH warrants further study.