title: Association between subarachnoid hemorrhage outcomes and number of cases treated at California hospitals.
abstract: OBJECTIVE
  Studies of several complex medical conditions have shown that outcomes are better at hospitals that treat more cases. We tested the hypothesis that patients with subarachnoid hemorrhage treated at high-volume hospitals have better outcomes.
  
  
  METHODS
  Using a database of all admissions to nonfederal hospitals in California from 1990 to 1999, we obtained discharge abstracts for patients with a primary diagnosis of subarachnoid hemorrhage who were admitted through the emergency department. Hospital volume, defined as the average number of subarachnoid hemorrhage cases admitted each year, was divided into quartiles. Rates of mortality, adverse outcomes (death or discharge to long-term care), length of stay, and hospital charges were computed by univariate analysis and by multivariable general estimating equations, with adjustment for demographic and admission characteristics.
  
  
  RESULTS
  A total of 12 804 patients were admitted for subarachnoid hemorrhage through the emergency departments of 390 hospitals. Hospital volumes varied from 0 to 8 cases per year in the first quartile to 19 to 70 cases per year in the fourth quartile. The mortality rate in the lowest volume quartile (49%) was larger than that in the highest volume quartile (32%, P<0.001). In multivariable analysis, the difference persisted (odds ratio comparing highest with lowest volume quartiles 0.57, 95% CI 0.48 to 0.67; P<0.001). At higher volume hospitals, lengths of stay were longer, and hospital charges were greater in univariate and multivariable models (all P<0.001). Only 4.8% of those admitted to hospitals in the lowest volume quartile were transferred to hospitals in the highest quartile.
  
  
  CONCLUSIONS
  In this study of discharge abstracts in California, hospitals that treated more cases of subarachnoid hemorrhage had substantially lower rates of in-hospital mortality. Few patients with subarachnoid hemorrhage are being transferred to high-volume centers.
authors.affiliation: School of Medicine, University of California, San Francisco, CA 94143-0114, USA.
authors.forename: Naomi S
authors.initials: NS
authors.lastname: Bardach
authors.forename: Shoujun
authors.initials: S
authors.lastname: Zhao
authors.forename: Daryl R
authors.initials: DR
authors.lastname: Gress
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lawton
authors.forename: S Claiborne
authors.initials: SC
authors.lastname: Johnston
mesh_terms: D002140:California; D015331:Cohort Studies; D003628:Database Management Systems; D003710:Demography; D005260:Female; D017722:Hospital Charges / Q000706:statistics & numerical data; D017052:Hospital Mortality / Q000639:trends; D006761:Hospitals / Q000592:standards* / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D017063:Outcome Assessment, Health Care; D010343:Patient Admission / Q000706:statistics & numerical data*; D010360:Patient Transfer / Q000706:statistics & numerical data; D012017:Referral and Consultation / Q000639:trends; D012041:Regional Medical Programs / Q000639:trends; D013345:Subarachnoid Hemorrhage / Q000191:economics / Q000401:mortality / Q000628:therapy*; D014600:Utilization Review