or acute ischemic stroke? Thank you. Hi, ladies and gentlemen. Like I said, my name's Tom Peters. I'm from the University of Rochester Neurosurgery Program. Just here to talk to you about interhospital transfer for thrombectomy and ischemic stroke. So, as we all know, time is a brain. TPA can be given four and a half hours from ischemic onset. This is a very well-known figure from the original New England Journal paper showing improved outcomes in stroke scale, MRS, GOS, if TPA is given, within four and a half hours from ischemic onset. This has really led to a network of both primary and comprehensive stroke centers in the United States in somewhat of a hub-and-spoke model, and has really led to the attempt to improve delivery of stroke ischemic care to patients. That being said, multiple studies have come out recently, DAWN, Mr. Clean Escape, et cetera, shows that the efficacy of TPA in large vessel occlusions is really lacking, and the answer to that is obviously mechanical thrombectomy. That being said, all of this having happened, we still have a very large portion of the United States population without access to comprehensive stroke centers in a timely manner. These are two maps from the CDC websites showing on the top hospitalizations for ischemic stroke from 2012 to 2014, and on the bottom, hospitals with neurologic services over that same period. And if you look specifically in the southeastern portion of the United States, you see this huge, huge mismatch really highlighting that there is this lack of access. This is another paper that recently came out from Ben George, who I worked on this project with, showing an increase in inter-hospital transfers, ED to ED transfers specifically for ischemic stroke from 2006 to 2014. Those transferred more than doubled, and a huge proportion of them in that paper actually came from hospitals without neurologic services. It really underscores the need for improved helicopter transport, mobile stroke units to triage, and more specialized care there. Even with all of this information, the frequency and outcomes of mechanical thrombectomy for stroke patients undergoing inter-hospital transfer really remains unknown, so that's something that we sought to observe here. So what we did was a retrospective observational study of the NIS from 2009 to 2014, and we pulled out, using ICD-9 codes, adult patients with stroke diagnosis. We then excluded patients that were elective admissions, patients with outgoing acute care transfers, and admissions to hospitals that did not perform mechanical thrombectomy. That left us with 772,000 patients, and using those patients, we assessed trends with respect to thrombectomy transfers, predictors of thrombectomy transfer versus front door arrival thrombectomy, and short-term outcomes of transferred thrombectomy patients. The story here is a story of increasing utilization. So again, 772,000 patients, inter-hospital transfer stroke admissions increased steadily, so from 12.5% in 2009 up to 16.8% in 2014, and that's shown in these gray bars in this top figure here. There was also 16% of admitted transferred patients received TPA in 2009 compared to 20% in 2014. Mechanical thrombectomy increased in transferred patients. 4% received mechanical thrombectomy in 2009, up to 5.2% in 2014, shown in this. To break that down into absolute increases, what this comes out to is only one additional thrombectomy for every 15 additional transfer over those years, which really highlights an inefficiency, potentially highlights an inefficiency in this system. For those receiving TPA, that was 13.3% of stroke admissions. Percentage of TPA patients that were then transferred went from 18.8% in 2009 to 22% in 2014, and that's shown in this top figure. Excuse me, 3.2% of stroke admissions received mechanical thrombectomy in that time. Nearly one in four of them arrived via inter-hospital transfer, which really highlights maybe a region where increased referral pattern can be sought after if you target the suburban and rural territories. And while the number of transfer patients receiving thrombectomy increased over time, the proportion relative to front door thrombectomy remained unchanged, suggesting that really there's no increased utilization of thrombectomy by these transfer patients, again highlighting this inefficiency. The downside of being a transfer patient that receives a mechanical thrombectomy, there are greater odds of symptomatic intracranial hemorrhage and lower odds of discharge home. Obviously this is likely related to the fact that the time from ischemic onset to reperfusion is larger in these patients. That being said, there are no significant differences in multiple other metrics that we checked, including length of stay, hospital costs, inpatient mortality, et cetera. The take home here really for this project is that 15 to one number. So for every 15 increased transfers, or 15 increased transfers over that time frame, there's only one increased thrombectomy. Again, this really highlights a possible inefficiency in making us think that maybe we need to optimize these transfers and define the goal of the transfer at first. If the goal is actually to perform a thrombectomy on this patient, we're not doing the right job. If the goal is to get specialty and subspecialty care, maybe we are doing a better job of that. Again, one quarter of thrombectomies are transfers. This, again, might be this region of increased referral patterns if we target those areas. Notably, this data is all prior to recent thrombectomy trials, Don, Mr. Cleans, Escape, et cetera. And so, obviously, these trends will likely change over time and it costs increasing case volume with those changes. And then finally, the other take home is that we need to improve intervention delivery with rural or smaller metropolitan cases. So potentially, things like mobile stroke units or telemedicine to really kind of determine who's gonna benefit the most. And again, going back to optimizing those transfers, figuring out who's gonna be the best for those transfers. Limitations of this study were that it's a retrospective database study and that comes with all of the problems of a retrospective database study. It does lack MRS scores for these patients and long-term follow-up. And again, as just mentioned, this data is all prior to newer thrombectomy trials. And so, these numbers are probably going to change significantly in the near future. That being said, it is still a well-powered and generalizable description of the current state of both TPA and mechanical thrombectomy and their relationship to inter-hospital transfers. And really, future studies are just going to have to kind of take the same paradigm and study what the changes are, what the trends are, now that these newer trials have come out. So thank you to a couple people that have helped me out a lot of their questions. Thank you.

interhospital transfer

thrombectomy

ischemic stroke

TPA

stroke treatment