Development of endovascular treatment networks should minimize delays and maximize experienced care, investigators say.
Transfer to high-volume centers remains the best way to ensure better survival among patients requiring an endovascular intervention for stroke, according to an analysis of a large US database. Thus, its authors say, future planning should aim for development of endovascular-capable centers that are strategically numbered and located, so that few patients endure excessively long transfer times while most centers maintain a high volume of cases.
“Transfer of stroke patients to centers capable of performing thrombectomy is common nowadays, as many small hospitals capable of administering the intravenous thrombolytic tPA (often by utilizing remote telestroke services) do not have the infrastructure and capabilities to provide 24/7 neuroendovascular coverage,” Maxim Mokin, MD, PhD, (University of South Florida, Tampa, FL), explained to Neurovascular Exchange in an email. And while studies show better outcomes at high-volume centers compared with low-volume centers, they also show deleterious effects associated with transfer.
According to lead author Lorenzo Rinaldo, MD, PhD (Mayo Clinic, Rochester, MN), the “study was essentially an attempt to reconcile these findings. [In] planning endovascular networks, is transfer something to be minimized or is there nevertheless a benefit of transfer to experienced institutions?”
For their paper published online March 23, 2017, ahead of print in Stroke, Rinaldo and colleagues used a national database of hospital-reported outcomes from 118 institutions to identify 8,533 patients who underwent endovascular revascularization for acute ischemic stroke between October 2012 and June 2016. Each hospital’s procedural volume was categorized as low (< 27 cases), medium (27 to < 132 cases), or high (> 132 cases).
Both the mortality rate (14.9% vs 18.6%; P = 0.049) and the ratio of observed to expected mortality (mortality index 1.1 vs 1.6, P = 0.048) were lower among patients who were directly admitted to an endovascular-capable center compared with those who were transferred.
In addition, both mortality was lower at the higher-volume centers.
Outcome by Hospital Procedural Volume
|
|
Low |
Medium |
High |
P Value |
|
Mortality Rate |
19.7% |
14.9% |
9.8% |
0.003 |
|
Mortality Index |
1.5 |
1.1 |
0.8 |
0.004 |
When patients were transferred to high-volume centers, both mortality rate (10.0% vs. 20.4%, P = 0.005) and mortality index (0.8 vs. 1.5, P = 0.034) were lower than for direct admission to low-volume hospitals.
According to Rinaldo, the findings suggest that “increasing the number of endovascular centers in order to decrease the need for transfer may not necessarily improve patient outcomes.”
Based on these results, Mokin agreed, high-volume centers seem to achieve better outcomes despite travel time. Speculating as to why this might be the case, he noted that high-volume centers offer more skilled operators, access to the most advanced technology, better patient selection, and top-notch, specialized perioperative care.
Another factor, Rinaldo said, is that “studies of the effect of institutional case volume on outcomes after endovascular stroke therapy have shown reduced mean time to revascularization at high-volume centers, which likely mitigates at least some of the temporal delay associated with transfer.”
Finding the Sweet Spot
Rinaldo argued against “simply increasing the number of hospitals with endovascular capabilities. Clearly, the challenge will be in finding the ‘sweet spot’ in which a majority of patients have access to a high-volume institution but do not have transfer from too remote a location to get there.”
He pointed out that an important limitation to the study, however, is that mortality was the sole outcome, whereas functional outcome would be more informative.
Mokin also noted that the study lacks information on important patient characteristics, including stroke severity, location of large vessel occlusion, and time from symptom onset to recanalization.
“While we found that transfer to high-volume centers for stroke care may be beneficial, transfer inevitably delays care and thus creates a suboptimal situation,” Rinaldo concluded. “A key area for research will be in methods to identify potential endovascular candidates prior to admission to nonendovascular centers, allowing initial triage to facilities with endovascular capabilities and obviating the need for transfer in the first place. Secondly, more research is needed into understanding the benefit of treatment at high-volume centers.”
Sources:
Rinaldo L, Brinjikji W, Rabinstein AA. Transfer to high-volume centers associated with reduced mortality after endovascular treatment of acute stroke. Stroke. 2017;Epub ahead of print.
Disclosures:
Rinaldo and Mokin report no relevant conflicts of interest.
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- Ischemic Stroke Patients Require Faster Transit to Comprehensive Stroke Centers, Researchers Assert
