Implementation of Regional Prehospital Stroke Protocol Increases Rates of EVT
The association of increased EVT rates was noted with the initiation of online training and EMS dissemination of the policy in September 2018, 2 months in advance of formal implementation of prehospital protocol.
Tareq Kass-Hout, MD
Primary stroke centers and comprehensive stroke centers (CSCs) that implemented prehospital EMS transport policy were associated with an a significant, rapid, and sustained increase in the rate of endovascular treatment (EVT) for eligible patients with acute ischemic stroke (AIS), according to findings from a retrospective multicenter study.
Lead author Tareq Kass-Hout, MD, assistant professor of neurology, University of Chicago Medicine, and colleagues concluded that the results “provide further evidence to support the development of regional strategies to direct patients with suspected LVO (large vessel occlusion) to CSCs and thrombectomy-capable centers when feasible.”
The study used interrupted time series (ITS) analysis to compare treatment rates before and after implementation of prehospital EMS transport protocol in 7709 patients with AIS arriving at 15 primary stroke centers and 8 CSCs. Data from December 1, 2017, to August 31, 2018 (9-month preimplementation period) and from September 1, 2018, to May 31, 2019 (9-month postimplementation period) were used.
Prehospital Protocol
Patients with suspected stroke within 6 hours of symptom onset were subsequently assessed using the 3-item stroke scale (31-SS) a simple prehospital LVO screening tool that assesses 3 parameters, including level of consciousness, gaze, and motor function. Those who had scores of at least 4 were then triaged as having suspected LVO and recommended for transport to the closest CSC if the additional transport time did not exceed 15 minutes compared with transport to the closest primary stroke center.
In May 2018, the Illinois Department of Public Health approved the Chicago EMS System Transport of Stroke Patient Policy and Protocol with criteria for triage and transport to CSCs. EMS education using both live and web-based training modules was rolled out September 2018, with an official launch in November 2018. The newly implemented policy did not change the selection criteria for EVT at the CSCs.
Staff and physicians received education on emergency department protocols for vessel imaging in patients with suspected stroke presenting within 6 hours of onset, data collection using the Get With The Guidelines-Stroke program (GWTG-Stroke), and the definition of LVO per GWTG-Stroke criteria. To improve quality of care and monitor patients with AIS, hospitals were required to report data into the GWTG-Stroke database.
Efficacy Data
Of the 7709 patients with stroke, 663 (mean age, 68.5 years [standard deviation (SD), 14.9]) with AIS arrived within 6 hours of stroke onset by EMS transport. In the postimplementation compared with the preimplementation periods, the rate of EVT increased 2.8-fold (13.6% [95% CI, 10.4-17.6] vs 4.8% (95% CI, 3.0-7.8]; P <.001). Using ITS analyses, investigators observed a step increase in EVT use by 7.15% within 1 month of implementation (P = .04) with no slope change before (0.16%; P = .71) or after (0.08%; P = .89).
There was also an association with increased EVT overall (preimplementation, 4.9% [95% CI, 4.1-5.8]; postimplementation, 7.4% [95% CI, 7.5-8.5]; P <.001) and in the 6-hour window (11.2% [95% CI, 9.6-14.4] vs 17% [95% CI, 14.4-20]; P = .01), but not in the 6- to 24-hour window (5.6% [95% CI, 4.1-7.7] vs 6.1% [95% CI, 4.6-8.2]; P = .77). Investigators concluded that awareness of extended window EVT trial results may have also contributed to the association with increased EVT rates in the region.
"It is also possible that training on advanced vessel imaging and implementation of computed tomographic angiography protocols for patients with suspected AIS in primary stroke centers and CSCs, which occurred in advance of our protocol implementation, increased LVO detection and therefore EVT rates. However, prehospital CSC transport policies should be linked to emergency department protocols for rapid neurovascular evaluation, including advanced imaging, to have their intended association with treatment rates,” the study authors wrote.
For those who arrived by EMS within the 6- to 24-hour window, there were no differences in the rates of EVT pre- and postimplementation. This remained true for those who arrived during the same time frame by interhospital transfer or walk-in.
Door to groin puncture times, captured in 12 of 22 patients who received EVT and arrived by EMS in the preimplementation period, and in 64 of 74 patients in the postimplementation period show no differences (median, 123.0 minutes [interquartile range (IQR), 51-150] vs 123.5 minutes [IQR, 61.5-181]; P = .91).
