Hospital volume and stroke outcome Does it matter? G. Saposnik, MD, MSc A. Baibergenova, MD, PhD M. O’Donnell, MD M.D. Hill, MD, MSc M.K. Kapral, MD, MSc V. Hachinski, MD, DSc On behalf of the Stroke Outcome Research Canada (SORCan) Working Group ABSTRACT Background: Although hospital– outcome relationships have been explored for a variety of proce- dures and interventions, little is known about the association between annual stroke admission volumes and stroke mortality. Our aim was to determine whether facility type and hospital volume was associated with stroke mortality. Methods: All hospital admissions for ischemic stroke were identified from the Hospital Morbidity database (HMDB) from April 2003 to March 2004. The HMDB is a national database that con- tains patient-level sociodemographic, diagnostic, procedural, and administrative information across Canada. Ischemic stroke was identified through patient’s principal diagnosis recorded us- ing the International Classification of Diseases (9 and 10). Multivariable analysis was performed with generalized estimating equations with adjustment for demographic characteristics, provider specialty, facility type, hospital volume, and clustering of observations at institutions. Results: Overall, 26,676 patients with ischemic stroke were admitted to 606 hospitals. Seven- day stroke mortality was 7.6% and mortality at discharge was 15.6%. Adverse outcomes were more frequent in patients treated in low-volume facilities (50 strokes/year) than in those treated in high volume facilities (100 to 199 and 200 strokes patients/year) (for 7-day mortality: 9.5 vs 7.3%, p  0.001; 9.5 vs 6.0%, p  0.001; for discharge mortality: 18.2 vs 15.2%, p  0.001; 18.2 vs 12.8%, p  0.001). The difference persisted after multivariable adjustment or when hospital volume was divided into quartiles. Conclusions: High annual hospital volume was consistently associated with lower stroke mortal- ity. Our study encourages further research to determine whether this is due to differences in case mix, more organized care in high-volume facilities, or differences in the performance or in the processes of care among facilities. Neurology ® 2007;69:1–1 Over the last two decades, much research has focused on the relationship between patient volumes in health services delivery and clinical outcomes. High patient volumes generally correlate with lower mortality, although most studies focus on diagnostic procedures or surgical interventions. 1 As a major contributor to premature death and disability, stroke represents an enor- mous global public health challenge. 2,3 Although clinical predictors of stroke mortality are well established, other health care determinants of clinical outcomes have not been E-Pub ahead of print at www.neurology.org. From the Stroke Program (G.S., V.H.), Department of Clinical Neurological Sciences, London Health Sciences Center, University of Western Ontario, Departments of Epidemiology (A.B.) and Medicine (M.O’D.), McMaster University, Hamilton, Departments of Medicine and Health Policy (M.K.K.), Management and Evaluation, University of Toronto, Division of General Internal Medicine and Clinical Epidemiology (M.K.K.), University Health Network, Toronto, University Health Network Women’s Health Program Toronto (M.K.K.), and Institute for Clinical Evaluative Sciences (M.K.K.), Toronto, Ontario, Stroke Research Unit (G.S.), Division of Neurology, Department of Medicine, St. Michael’s Hospital, University of Toronto, Ontario, and Stroke Unit (M.D.H.), Departments of Clinical Neurosciences, Medicine, and Community Health Sciences, University of Calgary, Alberta, Canada. Supported in part by a grant of the Heart Stroke Foundation of Canada (HSFC) and Canadian Institutes for Health Research (CIHR) given to Dr Gustavo Saposnik. Disclosure: We declare that we participated in the study and that we have seen and approved the final version. The authors report no conflicts of interest. Drs. Saposnik and Baibergenova had full access to the data and conducted the statistical analysis. Dr. Martin O’Donnell is supported by a grant from the CIHR. Dr. Moira Kapral is supported by a New Investigator Award from the CIHR and also received support from the Canadian Stroke Network and the University Health Network Women’s Health Program. Dr. Michael Hill is supported by the Heart and Stroke Foundation of Alberta/NWT/NU and the Canadian Institutes for Health Research. These grants were obtained based on competitive applications following publication of grant advertisements. The investigators acted as the sponsors of the study. None of the supporting agencies (HSFC, CSN, CIHR) had input on the design, access to the data, analyses, interpretation, or publication of the study. Address correspondence and reprint requests to Dr. G. Saposnik, Director of Stroke Research Unit, St. Michael’s Hospital, University of Toronto, 55 Queen St. E, Suite 9-31, Toronto, Ontario, Canada M5C 1R6 saposnikg@smh.toronto.on.ca Copyright © 2007 by AAN Enterprises, Inc. 1 Published Ahead of Print on July 18, 2007 as 10.1212/01.wnl.0000268485.93349.58