Mortality rates after subarachnoid hemorrhage: variations according to hospital case volume in 18 states.

OBJECT: The goal of this study was to determine whether a hospital's volume of subarachnoid hemorrhage (SAH) cases affects mortality rates in patients with SAH. For certain serious illnesses and surgical procedures, outcome has been associated with hospital case volume. Subarachnoid hemorrhage, usually resulting from a ruptured cerebral aneurysm, yields a high mortality rate. There has been no multistate study of a diverse set of hospitals to determine whether in-hospital mortality rates are influenced by hospital volume of SAH cases.
METHODS: The authors conducted an analysis of a retrospective, administrative database of 16,399 hospitalizations for SAH (9290 admitted through emergency departments). These hospitalizations were from acute-care hospitals in 18 states representing 58% of the US population. Both univariate and multivariate analyses were used to assess the case volume-mortality rate relationship. The authors used patient age, sex, Medicaid status, hospital region, data source year, hospital case volume quartile, and a comorbidity index in multivariate generalized estimating equations to model the relationship between hospital volume and mortality rates after SAH. Patients with SAH who were treated in hospitals in which low volumes of patients with SAH are admitted through the emergency department had 1.4 times the odds of dying in the hospital (95% confidence interval 1.2-1.6) as patients admitted to high-volume hospitals after controlling for patient age, sex, Medicaid status, hospital region, database year, and comorbid conditions.
CONCLUSIONS: Patients with a diagnosis of SAH on their discharge records who initially presented through the emergency department of a hospital with a high volume of SAH cases had significantly lower mortality rates. Concentrating care for this disease in high-volume SAH treatment centers may improve overall survival.