Does the Volume of Ischemic Stroke Admissions Relate to Clinical Outcomes in the Ontario Stroke System?

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.

Methods And 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.