Incidence, epidemiology, and treatment of aneurysmal subarachnoid hemorrhage in 12 midwest communities.

Only 8 studies have investigated the incidence and epidemiology of aneurysmal subarachnoid hemorrhage (aSAH) in the United States. This is the first investigation in Indiana, which has some of the highest rates of tobacco smoking and obesity in the nation. The authors prospectively identified 441 consecutive patients with aSAH from 2005 to 2010 at 2 hospitals where the majority of cases are treated. Incidence calculations were based on US Census populations. Epidemiologic variables included demography; risk factors; Hunt and Hess scale; Fisher grade; number, location, and size of aneurysms; treatment type; and complications. Overall incidence was 21.8 per 100,000 population. Incidence was higher in women, increased with age, and did not vary by race. One third to half of patients were hypertensive and/or smoked cigarettes at the time of ictus. Variations by count were partially explained by Health Factor and Morbidity Rankings. Complications varied by treatment. These findings deviate from estimates that 6-16 per 100,000 people in the United States will develop aSAH and are double the incidence in a Minnesota population between 1945 and 1974. The results also deviate from the worldwide estimate of 9.0 aSAHs per 100,000 person-years. The predictive value of variations in Health Factor and Morbidity Rankings implicates the importance of future research on multivariate biopsychosocial causation of aSAH.