Hospital Transfer for Stroke Thrombectomy Tied to Worse Outcomes

Damian McNamara

February 26, 2019

Interhospital transfers of patients with large-vessel occlusions who are candidates for endovascular therapy (EVT) are causing treatment delays and poorer outcomes, investigators report in a new study. The findings highlight the need for more efficient systems of care for stroke patients.

Investigators at Duke University Medical Center in Durham, North Carolina, found that 42.9% of stroke patients who received EVT and who were transferred from another hospital had inferior outcomes, including higher rates of in-hospital mortality and intracranial hemorrhage (ICH) and greater disability at discharge, compared with direct-transfer patients.

When patients with large-vessel occlusion come directly to a hospital that can perform mechanical thrombectomy, "their outcomes tend to be much better compared to patients who first have to go to a smaller hospital and are then transported to a large center," lead investigator Shreyansh Shah, MD, a critical care specialist and neurologist at Duke, told Medscape Medical News.

"They lose a lot of time in this transfer process. As you know, time is brain, so the delay in receiving the treatment causes worse outcomes," he added.

The study was published online January 31 in Circulation and was presented at the recent International Stroke Conference (ISC) 2019 in Honolulu, Hawaii.

Limited Capability

Although mechanical thrombectomy has been available for more than 15 years, the efficacy of early devices was limited, and initial patient outcomes were not always optimal, Shah said.

Over time, improved iterations of the devices were developed, and large-scale studies were conducted that compared EVT to more traditional stroke care. Results of several large trials showed "strong, positive data" favoring EVT, said Shah.

This surge in research supporting mechanical thrombectomy, in turn, increased its popularity and led to a sudden increase in demand for the procedure, he said.

However, mechanical thrombectomy requires a high level of expertise and infrastructure, Shah noted. He added that "there are a limited number of centers across the country that can perform this procedure."

The aim of the study was to describe the frequency and temporal trend of interhospital transfer for EVT in clinical practice, using the American Heart Association/American Stroke Association Get With the Guidelines–Stroke (GWTG-Stroke) program to promote quality and performance improvement.

"We hypothesize that following publications of pivotal trials demonstrating the benefit of EVT, there would be a substantial increase in the frequency of EVT occurring after interhospital transfer, further, that this transfer-in group would increasingly contribute to patients receiving EVT in the United States," the investigators write.

The researchers also evaluated the proportion of patients who received EVT following interhospital transfer and their outcomes in comparison with those of direct-arrival patients.

"Ours is the largest study to address the trend, frequency and outcomes of interhospital transfer for EVT," the researchers note.

Highlights Lack of Access

The initial cohort included 1,863,693 patients with ischemic stroke who were admitted to 2143 hospitals participating in the GWTG-Stroke voluntary registry.

The investigators analyzed data from January 2012 and December 2017. After exclusions, the final study cohort included 37,260 stroke patients who received care at 639 hospitals.

Results showed that 15,975 patients (42.9%) received EVT after transfer from another hospital during the study period.

The researchers also found that the number of patients who received EVT after interhospital transfer increased from 256 cases per quarter in the first quarter of 2012 to 1422 cases per quarter in the fourth quarter of 2017.

Interhospital transfer for the purpose of EVT significantly increased following the publication of pivotal randomized controlled trials showing the beneficial effects of this approach.

"This trend of increasing transfer-in EVT remained after normalizing for the number of hospitals providing EVT, indicating that it was not only due to the increasing number of EVT-providing hospitals," the researchers write.

"The big surprise of the study was how many patients are getting transferred," Shah said. The 42.9% interhospital transport rate "tells you the extent of the problem — how badly we lack access to endovascular therapy in this country, even now."

Inferior Outcomes

Unadjusted analyses indicated that, compared to the direct-arrival group, transferred patients had poorer in-hospital outcomes, including increased rates of in-hospital mortality and symptomatic ICH, along with a lower likelihood of independent ambulatory status at discharge and discharge to home.

The difference in in-hospital mortality was not significant after adjustment for delay in initiation of EVT, but other outcomes in the transferred group remained inferior.

Table. Adjusted Stroke Outcomes for Transfer-In vs Direct-Arrival Patients

Endpoint Transfer-In Patients Direct-Arrival Patients Adjusted OR (95% CI)
In-hospital mortality (%) 14.7 13.4 1.01 (0.92 – 1.11)
Symptomatic ICH (%) 7.0 5.7 1.15 (1.02 – 1.29)
Independent ambulation at discharge (%) 33.1 37.1 0.87 (0.80 – 0.95)
Discharge to home (%) 24.3 29.1 0.82 (0.76 – 0.88)
OR, odds ratio; 95% CI, 95% confidence interval

 

Perhaps not surprisingly, patients who were transferred from one hospital to another for EVT experienced a longer interval between their last known well time and EVT. The median time was 289 min (interquartile range [IQR], 230 – 356), compared with 213 min (IQR, 159 – 280) in the direct-arrival group (P < .0001).

In contrast, the median door-to-EVT-initiation time was shorter for transferred patients, at 68 min (IQR, 40 – 110), vs 128 min (IQR, 92.0 – 176.0) for the direct-arrival group (P < .0001). This suggests that the longer overall interval for the transferred patients was "the result of longer transit times to reach the EVT providing hospitals," the authors note.

The proportion of patients who experienced a door-to-EVT-initiation time of 90 min or less also supported this result: 66% of transferred patients had a door-to-EVT time of 90 min or less, compared to 24% of those who arrived directly (P < .0001).

"This may reflect the benefit of pre-notification at the EVT center, enabling teams to prepare prior to the patient's arrival," the researchers note.

Potential Solutions

Use of mobile stroke units, smartphone apps, or telemedicine to identify potential thrombectomy candidates earlier could reduce the number of hospital-to-hospital transfers, said Shah.

"There are a lot of possible solutions, but many require technological progress before we can implement them," he added.

Additional training of emergency medical services (EMS) personnel to recognize the signs and symptoms of stroke caused by large-vessel occlusion might be the easiest strategy to implement immediately.

"So when EMS responds to a 911 call and takes a look at the patient, if they can quickly recognize...this patient is going to require mechanical thrombectomy, then they can transport that patient immediately to a center that can perform the procedure rather than taking them to the nearest ER," Shaw said.

Expanding EVT capabilities, developing tools for efficient triage, and quality improvement initiatives focused on increasing efficiency of the interhospital transfer process are needed to optimize outcomes for patients who receive EVT, the researchers note.

One caveat they add is that providing more EVT services "can improve access but will have to be balanced with the need for maintaining sufficient case volume and competence of EVT providers at these new centers."

The need to change the status quo will likely increase as advanced imaging expands the therapeutic window for providing mechanical thrombectomy, the investigators write. More time for treatment could mean more interhospital transfers, they add.

Future research could evaluate the proposed solutions. Shah said his team is working on a study that will determine the impact of additional EMS training on transfer rates.

"There are hospitals around us, all part of our network — unlike the big university hospital, they are not able to perform this procedure. We are training EMS personnel to bring these patients directly to us," he said.

"We want to see if that results in a decrease in interhospital transfers, and then maybe this can be replicated at other institutions across the country."

Timely Treatment Needed

Commenting on the findings for Medscape Medical News, Richard Krauthamer, MD, a radiologist at Torrance Memorial Medical Center, California, said the study underscores the importance of timely treatment.

"Precious time is lost if the patient needs a mechanical thrombectomy for a large-vessel occlusion and has to be transferred from a secondary facility rather then taken directly to a facility that can perform these procedures," Krauthamer added.

The study was funded by a grant from the American Heart Association/American Stroke Association to Shah. He and Krauthamer report no relevant financial relationships.

Circulation. Published online January 31, 2019. Abstract

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