The epidemiology of admissions of nontraumatic subarachnoid hemorrhage in the United States.

BACKGROUND

Subarachnoid hemorrhage (SAH) is the cause of 5% to 10% of strokes annually in the United States.

OBJECTIVE

To study the incidence and mortality trends of admissions of SAH from 1979 to 2008 using a nationally representative sample of all nonfederal acute-care hospitals in the United States: The National Hospital Discharge Survey.

METHODS

The sample was obtained from the hospital discharge records according to the International Classification of Disease, 9th Revision, Clinical Modification code 430.

RESULTS

We reviewed data on approximately 1 billion hospitalizations in the United States over a 30-year study period and identified 612,500 cases of SAH, which was more common in women (relative risk 1.71, 95% confidence interval 1.7-1.72) and nonwhite persons than white persons (relative risk 1.46, 95% confidence interval 1.4-1.5). The estimated incidence rate of admission after SAH was 7.2 to 9.0 per 100,000/year and did not significantly change over the study period. Overall, in-hospital mortality after SAH fell from 30% during the period from 1979 to 1983 to 20% during the subperiod from 2004 to 2008 (P = .03) and was lower in larger treating hospitals. The average days of care for SAH hospitalizations decreased, but the rate of discharge to long-term care facilities increased.

CONCLUSION

The incidence rate of admission after SAH has remained stable over the past 30 years. Total deaths and in-hospital mortality after SAH have decreased significantly. In-hospital mortality after SAH is lower in larger treating hospitals.