title: Does the Volume of Ischemic Stroke Admissions Relate to Clinical Outcomes in the Ontario Stroke System?
abstract: BACKGROUND
  Better outcomes have been found among hospitals treating higher volumes of patients for specific surgical and medical conditions. We examined hospital ischemic stroke (IS) volume and 30-day mortality to inform regionalization planning.
  
  
  RESULTS
  Using a population-based hospital discharge administrative database (2005/2006 to 2011/2012), average annual IS patient volumes were calculated for 162 Ontario acute hospitals. Hospitals were ranked and classified as small (<126), medium (126-202), and large (>202). Hierarchical multivariable logistic regression was used to estimate the odds of death within 7 and 30 days to account for the homogeneity in outcomes for patients treated at the same hospital. Overall, 73 368 patients were hospitalized for IS, and 30-day mortality was 15.3%. The mean (±SD) of annual hospitalizations for IS was 29 (31) for small-volume hospitals, 156 (20) for medium-volume hospitals, and 300 (78) for high-volume hospitals. High-volume hospitals admitted younger patients (mean [±SD] age, 73.0 [13.9] years) compared with medium- and small-volume hospitals (74.0 [13.2] and 75.5 [12.5] years, respectively; P<0.0001). Patients at small-volume hospitals were more likely than patients at high-volume hospitals to die at 30 days after an acute IS (adjusted odds ratio, 1.37; 95% confidence interval, 1.14-1.65).
  
  
  CONCLUSIONS
  Hospital IS volume is associated with 30-day mortality in Ontario. Patients admitted to hospitals with annual IS volumes <126 annually are more likely to die within 30 days than patients admitted to hospitals that see on average 300 patients annually. This finding supports centralizing care in stroke-specialized hospitals.
authors.affiliation: From the Institute for Clinical Evaluative Sciences (R.E.H., J.F., G.S., M.T.B.); Ontario Stroke Network (R.E.H., M.T.B.); College of Physicians and Surgeons of Ontario (K.H.); Department of Medicine, University of Toronto (G.S., M.T.B.); St. Michael's Hospital (G.S.); and Toronto Rehabilitation Institute, University Hospital Network (M.T.B.); Toronto, Ontario, Canada. ruth.hall@ices.on.ca.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Hall
authors.affiliation: From the Institute for Clinical Evaluative Sciences (R.E.H., J.F., G.S., M.T.B.); Ontario Stroke Network (R.E.H., M.T.B.); College of Physicians and Surgeons of Ontario (K.H.); Department of Medicine, University of Toronto (G.S., M.T.B.); St. Michael's Hospital (G.S.); and Toronto Rehabilitation Institute, University Hospital Network (M.T.B.); Toronto, Ontario, Canada.
authors.forename: Jiming
authors.initials: J
authors.lastname: Fang
authors.affiliation: From the Institute for Clinical Evaluative Sciences (R.E.H., J.F., G.S., M.T.B.); Ontario Stroke Network (R.E.H., M.T.B.); College of Physicians and Surgeons of Ontario (K.H.); Department of Medicine, University of Toronto (G.S., M.T.B.); St. Michael's Hospital (G.S.); and Toronto Rehabilitation Institute, University Hospital Network (M.T.B.); Toronto, Ontario, Canada.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Hodwitz
authors.affiliation: From the Institute for Clinical Evaluative Sciences (R.E.H., J.F., G.S., M.T.B.); Ontario Stroke Network (R.E.H., M.T.B.); College of Physicians and Surgeons of Ontario (K.H.); Department of Medicine, University of Toronto (G.S., M.T.B.); St. Michael's Hospital (G.S.); and Toronto Rehabilitation Institute, University Hospital Network (M.T.B.); Toronto, Ontario, Canada.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Saposnik
authors.affiliation: From the Institute for Clinical Evaluative Sciences (R.E.H., J.F., G.S., M.T.B.); Ontario Stroke Network (R.E.H., M.T.B.); College of Physicians and Surgeons of Ontario (K.H.); Department of Medicine, University of Toronto (G.S., M.T.B.); St. Michael's Hospital (G.S.); and Toronto Rehabilitation Institute, University Hospital Network (M.T.B.); Toronto, Ontario, Canada.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Bayley
mesh_terms: D000208:Acute Disease; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000453:epidemiology* / Q000401:mortality; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D061847:Hospitals, High-Volume / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario; D010351:Patient Discharge / Q000706:statistics & numerical data*; D044382:Population Groups; D012041:Regional Medical Programs; D020521:Stroke / Q000453:epidemiology* / Q000401:mortality; D016019:Survival Analysis
keywords: epidemiology; health services research; hospitals; outcome assessment (health care); stroke volume