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



This is a nationwide retrospective cohort analysis using the Nationwide Inpatient Sample (NIS). The NIS Subarachnoid Severity Scale was used to adjust for severity of SAH in multivariate logistic regression modeling.



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, 7787 (67.0%) were treated at a high-volume center compared with 3820 (32.9%) treated at a low-volume center. Patients treated at high-volume centers compared with low-volume centers were more likely to receive endovascular aneurysm control (58.5% vs 51.2%, P=.04), be transferred from another hospital (35.4% vs 19.7%, P<.01), be treated in a teaching facility (97.3% vs 72.9%, P<.01), and have a longer length of stay (14.9 days [interquartile range 10.3-21.7] vs 13.9 days [interquartile range, 8.9-20.1], P<.01). After adjustment for all baseline covariates, including severity of SAH, treatment in a high-volume center was associated with an odds ratio for death of 0.82 (95% confidence interval, 0.72-0.95; P<.01) and a higher odds of a good functional outcome (odds ratio, 1.16; 95% confidence interval, 1.04-1.28; P<.01).



After adjustment for severity of SAH, treatment in a high-volume center was associated with a lower risk of in-hospital mortality and a higher odds of a good functional outcome.
Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Room 2438, Jim Pattison Pavilion, 2nd Floor, 855 W 12th Ave, Vancouver, British Columbia, Canada V5Z 1M9; Harvard T.H. Chan School of Public Health, Harvard University, 677 Huntington Ave, Boston, MA 02115. Electronic address: bar890@mail.harvard.edu.
Barret
B
Rush
Department of Anesthesia, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada. Electronic address: kaliromano@gmail.com.
Kali
K
Romano
Division of Epilepsy, Department of Neurology, University of British Columbia, Vancouver, British Columbia, Canada. Electronic address: ashkanani63@hotmail.com.
Mohammad
M
Ashkanani
Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Room 2438, Jim Pattison Pavilion, 2nd Floor, 855 W 12th Ave, Vancouver, British Columbia, Canada V5Z 1M9; Department of Critical Care Medicine, Surrey Memorial Hospital, Surrey, BC, Canada. Electronic address: robmcdermid@telus.net.
Robert C
RC
McDermid
Beth Israel Deaconess Medical Center, Boston, MA, USA. Electronic address: lceli@bidmc.harvard.edu.
Leo Anthony
LA
Celi
D000328:Adult; D000368:Aged; D016208:Databases, Factual; D057510:Endovascular Procedures; D005260:Female; D006276:Health Facility Size; D017052:Hospital Mortality; D006760:Hospitalization; D061847:Hospitals, High-Volume / Q000706:statistics & numerical data*; D061846:Hospitals, Low-Volume / Q000706:statistics & numerical data*; D006780:Hospitals, Rural; D006784:Hospitals, Teaching / Q000706:statistics & numerical data; D006786:Hospitals, Urban; D006801:Humans; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010360:Patient Transfer / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013345:Subarachnoid Hemorrhage / Q000401:mortality / Q000628:therapy*
Case volume; Outcomes; Subarachnoid hemorrhage; United States
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