Transfer to High-Volume Centers Associated with Reduced Mortality after Endovascular Treatment of Acute Stroke

Background and Purpose - Some have argued that it may be beneficial to expand the availability of endovascular revascularization services to lower-volume hospitals to minimize the morbidity associated with transfer to larger endovascular centers. We compared the outcomes after revascularization of patients directly admitted to a low-volume center and those transferred to a high-volume center. Methods - We searched a national database of hospital-reported outcomes for patients who underwent endovascular revascularization for acute ischemic stroke. Hospitals were categorized as low, medium, or high procedural volume hospitals. Outcomes of inpatient admissions were collected and compared on the basis of admission source and hospital procedural volume. Results - A total of 118 institutions with 8533 patients were included. Mortality rate (14.9% versus 18.6%; P=0.049) and mortality index (1.1 versus 1.6; P=0.048) were significantly lower among directly admitted relative to transferred patients. For all patients, there were significant differences in institutional mortality rate (low: 19.7%, medium: 14.9%, high: 9.8%; P=0.003) and mortality index (low: 1.5, medium: 1.1, high: 0.8; P=0.004) between low-, medium-, and high-volume hospitals. For transferred patients to high-volume centers, both mortality rate (high: 10.0% versus low: 20.4%; P=0.005) and mortality index (high: 0.8 versus low: 1.5; P=0.034) were significantly lower than that observed for directly admitted patients to low-volume hospitals. Conclusions - We report a beneficial effect of treatment at high-volume hospitals in spite of the detrimental effects of transfer. These findings argue for the centralization of care.