PASTA: Does Extra Paramedic Intervention Affect Stroke Outcome?

May 31, 2019

Enhanced paramedic assessment of patients with suspected acute ischemic stroke did not increase the rate or speed of thrombolysis in a new study but did result in reduced subsequent care costs that may represent better-informed treatment decisions, the authors report.

The Paramedic Acute Stroke Treatment Assessment (PASTA) study was presented at the recent 5th European Stroke Organisation Conference (ESOC) 2019, by Chris Price, MD, Newcastle University, UK.

"While our primary endpoint — the number of patients receiving thrombolysis — was negative, our results showed that enhanced paramedic involvement was linked to a nonsignificant improvement in outcomes at 90 days, gain in quality-adjusted life-years, and a significant reduction in health and social care costs," Price reported.

He described the results as "interesting and slightly puzzling." To Medscape Medical News he added: "While we haven't been able to improve the quantity of thrombolysis with this additional paramedic intervention, what we may have done is improve the selection of patients for thrombolysis, which then resulted in subsequent reduction in care costs."

The PASTA study evaluated the clinical and cost-effectiveness of an enhanced role of paramedics in the management of patients with suspected stroke.

"The enhanced paramedic role included conducting a more detailed clinical assessment of the patient estimating stroke severity and checking onset time of symptoms, and collecting additional information related to previous medical history," Price explained. 

"Then there was increased communication to the hospital team in the form of a structured handover of information about thrombolysis eligibility that paramedics had collected at the scene," he noted.  

In addition, paramedics stayed with the patient in the hospital for an additional 15 minutes to assist with practical tasks such as taking the patient for a scan. "Then they undertook a hospital response checklist to try and promote time and urgency of thrombolysis if the patient was eligible," he added.

The aim was to investigate whether such an intervention would improve the proportion of patients receiving thrombolysis, he said.

The study involved three ambulance services in the UK with 120 ambulance stations serving 15 hospitals. A cluster-randomized design was used so each ambulance station was randomized to either the additional care intervention or standard care.

Paramedics in the additional care group underwent 1 hour of training. 

The trial enrolled 1214 patients with suspected stroke within 4 hours of symptom onset — 500 assessed by paramedics trained to do the additional intervention and 714 by standard care paramedics.

Results showed that patients who received the additional intervention from paramedics were not more likely to be given thrombolysis. In contrast, there was a nonsignificant trend towards fewer patients in the intervention group receiving thrombolysis (39.4% vs 44.7%; odds ratio [OR], 0.81; P = .15)     

The average time from paramedic assessment to thrombolysis was 8.5 minutes longer for patients in the additional intervention group, which Price suggested was "probably reflective of the intervention."

However, after 90 days, there was a nonsignificant trend for fewer patients in the intervention group to be dead or dependent on others for personal care (mRS 3-6; adjusted OR, 0.86; P = .39).  

There was a small nonsignificant gain in quality-adjusted life-years (QALYs) for patients in the intervention group (0.006) and there was a significant reduction in costs for health and social care by an average of £1,105 brought about by shorter hospital stays, less rehabilitation, and less social care.

"The small nonsignificant QALY gain is an interesting finding, but the significant reduction in subsequent care costs implies there was some benefit that we were not able to measure," Price commented.

He suggested this may be identification of patients not suitable for thrombolysis.

"We know that generally at least 10% of people who receive thrombolysis for suspected stroke don't actually have a stroke. It may be that patients who are not appropriate for thrombolysis are spotted earlier on with this increased paramedic intervention," he noted. "Also the intervention may bring more clarification of time of symptom onset and just general better evaluation of the benefits versus harms of thrombolysis. In borderline cases this additional information could be very important."

Co-author, Gary Ford, MD, University of Oxford, UK, added: "This intervention didn't do what we thought it would do, but we have found some intriguing results. We think the improved information available from the paramedic intervention in this study while coming at the cost of extra time, is influencing decision-making and this may not just be on thrombolysis but also in general care."

Price concluded: "This study has raised awareness of the need for the best quality information possible when making time-critical decisions and highlighted how paramedics can influence that."

Ford noted that the team hopes to go on to study the role of paramedics in identifying stroke patients with large vessel occlusions who may be candidates for thrombectomy.

"What happens at many places at present is that the paramedics leave the patient at the first emergency department, then after it is realized the patient has a large vessel occlusion and a second ambulance is called back to transfer for thrombectomy," he said. "The experience of this trial can help us design a study for that situation with the same paramedic staying with the patient throughout."

Commenting on the study for Medscape Medical News was session comoderator Jesse Dawson, MD, Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK.

"This was an interesting study but showed that something we thought would have a big impact on process of care didn't actually save time or result in more patients receiving treatment," Dawson said.

On the reduced costs seen in the study, he commented: "We have to be slightly circumspect about cost-effectiveness data when the primary endpoint of the study is negative."

"It will be interesting to see more data on the characteristics of the patients involved, and if it is possible, to work out whether the intervention did actually save a small number of patients from a harmful outcome of thrombolysis when they had little chance of benefit, or whether the cost data were the play of chance."

The PASTA study was funded by the UK National Institute of Health Research.

ECOC 2019. Presented May 22.

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