Impact of hospital case-volume on subarachnoid hemorrhage outcomes: a nationwide analysis adjusting for hemorrhage severity

Abstract Objective There have been suggestions that patients with subarachnoid hemorrhage (SAH) have a better outcome when treated in high volume centers. Much of the published literature on the subject is limited by an inability to control for severity of SAH. Methods A nationwide retrospective cohort analysis utilizing the Nationwide Inpatient Sample. The Nationwide Inpatient Sample Subarachnoid Severity Scale was employed to adjust for severity of SAH in multivariate logistic regression modelling. Results The records of 47,911,414 hospital admissions from the 2006-2011 NIS samples were examined. There were 11,607 patients who met inclusion criteria for the study. Of these, 7,787 (67.0%) were treated at a high volume center, compared to 3820 (32.9%) treated at a low volume center. Patients treated at high-volume centers compared to low-volume centers were more likely to receive endovascular aneurysm control (58.5% vs 51.2%, p=0.04), be transferred from another hospital (35.4% vs 19.7%, p