Thursday 22 May 2014

Prehospital Stroke Thrombolysis... OMG!

What do you get when you put a mobile CT scanner, neurologist, radiology tech, paramedic, point-of-care lab, and a telemedicine unit in the back of an ambulance? At best a whole lot of wasted resources for marginal benefit.

The PHANTOM-S trial was conducted in Berlin, Germany and published in JAMA. It was designed to study the use of ambulance based thrombolysis (within 4.5 hours) for stroke as compared to conventional hospital based thrombolysis. The primary outcome was alarm-to-thrombolysis time. (This is obviously not a patient oriented outcome.) Secondary outcomes included overall thrombolysis rate, ICH rate after treatment, and 7 day mortality. Despite the title reporting to be a “randomized” trial it most certainly wasn’t. Not to be pedantic but the JAMA reviewers should know better.

The consent process is interesting to imagine. Think of the conversation and information provided by a neurologist who arrives on your doorstep with a mobile CT scanner and ready with tPA? In addition, they assumed consent in patients unable to communicate. Implied consent is fine if the therapy is of reasonable proven benefit without significant chance of harm. Many would argue that tPA for stroke does not fit this mould.

Results? It is absolutely no surprise that they were able to thrombolyse strokes quicker when it was done in the back of a million dollar ambulance. The mean alarm to treatment time was shortened by 25 minutes as compared to hospital based thrombolysis.

A close look at the data shows that this special ambulance with a stroke team was generally busy. On average they were dispatched 6 times in a (16 hour) day. Thrombolysis was performed in an amazing one third of strokes or about every other day. But in the quest for fast and faster treatment it is certain that they must have been treating a good number of stroke mimics.

The big question one must ask is what happens to the vast majority of patients who get thrombolysis of stroke? Answer...  absolutely nothing. No harm or benefit. If we consider a reasonable number needed to treat of 8 (this number is clearly arguable one way or another) then this fancy ambulance with mobile stroke team perhaps helped one patient about every two weeks. How many of these were actually helped by getting it 25 minutes faster? Regardless if you believe in the efficacy of stroke thrombolysis, it is absolutely clear that this is not an effective use of resources.



Ebinger M, Winger B, Wendt M, et al. Effect of the Use of Ambulance-Based Thrombolysis on Time to Thrombolysis in Acute Ischemic Stroke. A Randomized Clinical Trial. JAMA 2014;311(16):1622-1631.

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