Association Between Stroke Center Hospitalization for Acute Ischemic Stroke and Mortality

Abstract

CONTEXT: Although stroke centers are widely accepted and supported, little is known about their effect on patient outcomes. OBJECTIVE: To examine the association between admission to stroke centers for acute ischemic stroke and mortality. DESIGN, SETTING, AND PARTICIPANTS: Observational study using data from the New York Statewide Planning and Research Cooperative System. We compared mortality for patients admitted with acute ischemic stroke (n = 30,947) between 2005 and 2006 at designated stroke centers and nondesignated hospitals using differential distance to hospitals as an instrumental variable to adjust for potential prehospital selection bias. Patients were followed up for mortality for 1 year after the index hospitalization through 2007. To assess whether our findings were specific to stroke, we also compared mortality for patients admitted with gastrointestinal hemorrhage (n = 39,409) or acute myocardial infarction (n = 40,024) at designated stroke centers and nondesignated hospitals. MAIN OUTCOME MEASURE: Thirty-day all-cause mortality. RESULTS: Among 30,947 patients with acute ischemic stroke, 15,297 (49.4%) were admitted to designated stroke centers. Using the instrumental variable analysis, admission to designated stroke centers was associated with lower 30-day all-cause mortality (10.1% vs 12.5%; adjusted mortality difference, -2.5%; 95% confidence interval [CI], -3.6% to -1.4%; P < .001) and greater use of thrombolytic therapy (4.8% vs 1.7%; adjusted difference, 2.2%; 95% CI, 1.6% to 2.8%; P < .001). Differences in mortality also were observed at 1-day, 7-day, and 1-year follow-up. The outcome differences were specific for stroke, as stroke centers and nondesignated hospitals had similar 30-day all-cause mortality rates among those with gastrointestinal hemorrhage (5.0% vs 5.8%; adjusted mortality difference, +0.3%; 95% CI, -0.5% to 1.0%; P = .50) or acute myocardial infarction (10.5% vs 12.7%; adjusted mortality difference, +0.1%; 95% CI, -0.9% to 1.1%; P = .83). CONCLUSION: Among patients with acute ischemic stroke, admission to a designated stroke center was associated with modestly lower mortality and more frequent use of thrombolytic therapy.