Clot busters via mobile stroke units: AHA release is fuzzy on key details

Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The release briefly mentions the issue of costs with this statement: “Its better outcomes could offset the increased costs of a mobile stroke unit.”

We thought the release would have been better if it had noted the nominal cost of clot busting drugs as well as the cost of a CT scanner and additional personnel essential to mobile stroke units, which would be considerable.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The release does describe the benefits using numbers, but it does so in such a way that readers could be misled. The entire study only included 658 stroke patients. Half received a clot-busting drug at the hospital and half received it in the ambulance. And yet when presenting the benefits, the release presents them as a rate, saying that “three months after stroke, 182 out of every 1,000 patients treated before arriving at hospital were less disabled, including 58 patients who had zero disability, compared to people who received treatment after reaching the hospital.”

How a rate like this based on just 329 patients (half of the total cohort) was derived is never explained, and the description makes it sound like there were thousands of patients in the study.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The news release does a reasonable job explaining the basics of the study, though this description falls below some earlier language that has the potential to mislead. It says:

Researchers analyzed results from 658 stroke patients who were treated with tPA — a drug that dissolves blood clots. About half of the participants received the clot-busting drug at the hospital, and half received it while still in the ambulance.

It also notes that the findings were “presented at the American Stroke Association’s International Stroke Conference 2017.” What’s missing from this is the fact that the findings likely only received limited peer review, since they were not published in a journal.

Very low in the release — but at least it was included — it says that the findings did not quite achieve statistical significance. At least that’s how we’re interpreting it. The statement itself is a bit vague, saying,

“The findings bordered on statistical significance, suggesting that future clinical trials with a greater number of patients are needed to show similar benefits.”

The lack of statistical significance, even with caveats, merits a Not Satisfactory for evidence. Moreover, the release doesn’t tell us why in this apparent re-analysis of the results, only about two-thirds of the patients from the original study were included.

Does the news release establish the availability of the treatment/test/product/procedure?

Not Satisfactory

Availability is not addressed beyond UCLA’s Mobile Stroke Rescue Program, which collected the data for the study.

It would have been good to mention that specialist-staffed mobile stroke units have been popping up in different parts of the country over the last 3-4 years. They are mainly affiliated with larger medical centers and funded by private donations.

Does the news release establish the true novelty of the approach?

Not Satisfactory

The release does not adequately establish the novelty of the study or the findings. It does briefly allude to previous research: “Past research showed the sooner that a clot-busting tPA drug is given after an ischemic stroke – one in which a clot is blocking blood flow – the better patients fare.”

There have been around a dozen trials on mobile stroke units in recent years, appearing primarily in neurology journals. Some examples:

• Cerejo, R., et al. (2015) “A Mobile Stroke Treatment Unit for Field Triage of Patients for Intraarterial Revascularization Therapy,”Journal of Neuroimaging, 25(6), 940–945
• Fassbender, K., et al. (2013) “Streamlining of prehospital stroke management: The Golden Hour,”Lancet Neurology, 12(6), 585–596
• Walter, S., et al. (2012) “Diagnosis and treatment of patients with stroke in a mobile stroke unit versus in hospital: A randomised controlled trial,”Lancet Neurology, 11(5), 397–404
• Walter, S., et al. (2010) “Bringing the hospital to the patient: First treatment of stroke patients at the emergency site,”PLoS ONE, 5(10), e13758
• Weber, J.E., et al. (2013) “Prehospital thrombolysis in acute stroke: Results of the PHANTOM-S pilot study,”Neurology, 80(2), 163–168