Use, Temporal Trends, and Outcomes of Endovascular Therapy After Interhospital Transfer in the United States

Background: The use of endovascular therapy (EVT) in patients with acute ischemic stroke who have large vessel occlusion has rapidly increased in the United States following pivotal trials demonstrating its benefit. Information about the contribution of interhospital transfer in improving access to EVT will help organize regional systems of stroke care. Methods: We analyzed trends of transfer-in EVT from a cohort of 1 863 693 patients with ischemic stroke admitted to 2143 Get With The Guidelines-Stroke participating hospitals between January 2012 and December 2017. We further examined the association between arrival mode and in-hospital outcomes by using multivariable logistic regression models. Results: Of the 37 260 patients who received EVT at 639 hospitals during the study period, 42.9% (15 975) arrived at the EVT-providing hospital after interhospital transfer. Transfer-in EVT cases increased from 256 in the first quarter 2012 to 1422 in the fourth quarter 2017, with sharply accelerated increases following the fourth quarter 2014 (P<0.001 for change in linear trend). Transfer-in patients were younger and more likely to be of white race, to arrive during off-hours, and to be treated at comprehensive stroke centers. Transfer-in patients had significantly longer last-known-well-to-EVT initiation time (median, 289 minutes versus 213 minutes; absolute standardized difference, 67.33) but were more likely to have door-to-EVT initiation time of ≤90 minutes (65.6% versus 23.6%; absolute standardized difference, 93.18). In-hospital outcomes were worse for transfer-in patients undergoing EVT in unadjusted and in risk-adjusted models. Although the difference in in-hospital mortality disappeared after adjusting for delay in EVT initiation (14.7% versus 13.4%; adjusted odds ratio, 1.01; 95% CI, 0.92-1.11), transfer-in patients were still more likely to develop symptomatic intracranial hemorrhage (7.0% versus 5.7%; adjusted odds ratio, 1.15; 95% CI, 1.02-1.29) and less likely to have either independent ambulation at discharge (33.1% versus 37.1%; adjusted odds ratio, 0.87; 95% CI, 0.80-0.95) or to be discharged to home (24.3% versus 29.1%; adjusted odds ratio, 0.82; 95% CI, 0.76-0.88). Conclusions: Interhospital transfer for EVT is increasingly common and is associated with a significant delay in EVT initiation highlighting the need to develop more efficient stroke systems of care. Further evaluation to identify factors that impact EVT outcomes for transfer-in patients is warranted.