Wheels rolling for exciting advance in stroke therapy?

Happy New Year, and welcome back to the sporadic blog known as AmboFOAM.  I thought I would start the year on a positive note, and what better way than by looking at one of the new initiatives happening here in Melbourne: an Australian first Stroke Ambulance!

So according to the press release, this looks like an ambulance, but is really like an emergency department on wheels (I’m not sure what to make of that, although my initial response was to feel vaguely offended…).  It will deliver life saving, brain saving, definitely not causing more ICH and early death, clot-busting drugs (I know, but stay with me here) to patients far quicker than if they were taken to hospital by regular old, non-emergency-department-on-wheels style ambulances.

This is probably true.  Indeed, it has been proven to be possible in other places: primarily Germany and the US.  Yep, this is an Australian first, but certainly not a world first.  However, the evidence from elsewhere is somewhat underwhelming.
There are some small feasibility studies (a couple of dozen patients enrolled, with no power to detect anything significant), and a large randomised trial (a couple of thousand patients enrolled)

The recurring theme is that with a stroke ambulance, it is absolutely possible to reduce door to needle time for tPA in stroke over traditional pathways.  Yay!

However, to date there has been no significant patient centered outcomes found.  So we can do it quicker, but this is not necessarily better for the patient.  Indeed, there seems to be some mixed data regarding time to treatment and outcome from stroke over all – there are papers that have shown an improvement with a systemwide approach to reducing door to needle time, but IST-3 (apparently one of the major trials supporting tPA for stroke despite a negative primary outcome ¯\_(ツ)_/¯) showed essentially no correlation with time (within the 6 hour timeframe used by the study)

I’m not convinced that delivering a shotgun approach with a controversial therapy quicker is the best way to go about things.  However with the rise of endovascular therapy for stroke, we at least have another pathway we can send patients down which may prove to have better outcomes for certain types of stroke.  The key will be better imaging to identify patients with the potential to benefit from either (or both) therapies.  This will likely be difficult, as a fair percentage of ischaemic strokes are cryptogenic, even with appropriate, detailed workup and imaging, but hopefully this strokebulance can contribute to better identifying salvageable strokes while there is still ischaemic penumbra to save.

Nevertheless!  Putting aside my (well founded) scepticism about tPA for stroke, and assuming that a strokebulance will improve outcomes (given the headline: AUSTRALIAN FIRST STROKE AMBULANCE TO SAVE LIVES, I’m guessing this is the assumption…), I still have some issues.

For the trial, there will be one strokebulance working in a small geographic area in Melbourne.  Even so, I imagine there will be many more strokes than a single strokebulance can get to in a day.  If we assume that the strokebulance is better than a boring old ambulance, how do we decide who gets that benefit?  This will be compounded if indeed we do discover a patient centered benefit (quicker doesn’t count if it doesn’t help the patient).  There are a great many strokes every day (over 13000 in Victoria in 2014), the length and breadth of the state.

Hopefully one benefit is that we will be able to gather data that will allow us to better identify clinically those patients who will benefit from early, aggressive intervention, regardless of whether a strokebulance is available or not (despite my scepticism, there must surely be a group; we just need to find them).  More importantly, we need to identify those patients over the phone to send the right resources immediately, which is a whole different ballgame.  If we need to send a regular old boring ambulance to a stroke for the patient to be clinically assessed first, we are likely to lose much of the benefit that may come from having a strokebulance respond: it may be better for the crew to load and go, especially if the trial is run close to major stroke hospitals.

So if you happen to have a stroke in Brunswick, you may be in luck (assuming the strokebulance is not already at a case), and you will get a strokebulance which will provide some benefit to you.  The real test though, is what happens if you have a stroke in Horsham.  Or Sale.  Or Wodonga.  Or Wycheproof.  If (and yes, it is a big if) the strokebulance does reduce mortality and morbidity, how do we extend that benefit to everyone, wherever they reside?  We risk further entrenching disadvantage for those outside of major metropolitan centers if we focus our resources on high end specialist intervention limited to major centers.

Even if we were to write off the rural sector (I know that this is NOT the attitude of AV, nor is it mine, I’m just thinking out loud here), and we did find a benefit (a patient benefit that is, not just squirting drugs quicker), it would still be interesting to see a cost/benefit analysis.  These platforms are expensive.  Like, really, really expensive.  And if they work, we would need a lot of them to provide appropriate cover, even if only in major centers.
Of course, stroke is a huge burden ($5 billion worth in 2012), so it is certainly feasible that strokebulances could be a cost effective means of reducing this burden.

Ultimately, tPA is not the be all and end all of stroke management (indeed, it never was: that honour goes to good medical care, nursing care, and most importantly, rehabilitation) and I struggle to see administering it quicker as the answer.  However, with the potential for furthering research into mechanical thrombectomy for clots, TXA for bleeds, and providing early access to high level care whatever the aetiology, there is still potential for the strokebulance to provide benefit to the people of Victoria.  As such, I hope my scepticism is ill placed, and I will be following the rollout of the strokebulance with interest.

 

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One Response to Wheels rolling for exciting advance in stroke therapy?

  1. Pingback: Australia’s First Stroke Ambulance! | Prehospital and Retrieval Medicine - THE PHARM dedicated to the memory of Dr John Hinds

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