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ALS still doesn't appear to be better than BLS. This is Healthcare Triage News.

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ALS still doesn't appear to be better than BLS.  This is Healthcare Triage News.


Almost a year ago, we did an episode on how doing more for patients often does no good.  One of the examples I used was advanced life support or ALS versus basic life support, or BLS.  The basis for that video was a study that showed that patients with a cardiac arrest who had received ALS before coming to the hospital were less likely to survive to discharge than patients who had received BLS.  They were also less likely to survive to 90 days after discharge and they had worse neurological outcomes.

Many of the comments and e-mails I received after the video was released were incredulous.  People couldn't believe that this was possible.  After all, getting ALS from a paramedic must be better than just getting BLS.  A number of the more charged missives I received challenged me to demand only BLS myself if my life were in danger.

The more serious charges though picked at the methods.  Since this wasn't a randomized controlled trial, we can't establish causality.  It's possible that the sicker patients were the ones who got ALS and that's why their outcomes were worse.  It's true that the authors tried a number of sensitivity analyses to check for this, but it's still a legitimate concern.

Of course, a randomized controlled trial is likely never to happen.  One of the biggest reasons for that is that paramedics refuse to do it.  It's unethical, many believe, to randomize people to get BLS because they assume ALS must be better.  In fact, the Ontario Prehospital Advanced Life Support Trial, another cohort study of ALS versus BLS, was intended to be a randomized controlled trial, but the emergency medical services people refused to make it so for that very reason.  

When confronted with such a case, researchers must turn to the tools they have.  A more sophisticated analysis, using instrumental variables and propensity scores can help.  My blogmate Austin has written about those things extensively on our blog.  In a recent study, researchers did just that.  Outcomes of basic versus advanced life support for out of hospital medical emergenices.  To the research!

The older study that I discussed a year ago just looked at cardiac arrest.  This study, however, also looked at trauma, stroke, acute myocardial infarction, and respiratory failure.  The researchers did two main analyses.  In the first, they used propensity scores to match patients within counties to test how BLS performed against ALS.  It's still possible that dispatchers sent out ALS to worse cases than BLS, but they called the EMS systems to ask them directly if they did that, and found it didn't occur.  In that analyses, BLS outperformed ALS again.

In a second instrumental variable analysis, with respect to 90-day survival, those who received BLS had a 4.1% higher absolute chance to survive major trauma, 4.3% higher to survive stroke, 5.9% higher to survive an acute MI.  There was no significant difference with respect to respiratory failure.  

There will always be limitations to research and there are with this study.  It's possible that selection bias is still occurring, but the researchers were super careful.  They did more than one analysis.  The propensity score analysis could be biased if ALS went to sicker patients, but with most conditions, it'd be difficult to know what the severity is before sending out the ambulance.  The researchers further controlled for severity with respect to trauma and finally, the patients that got BLS were older and had more co-morbidities than those who got ALS.  It's hard to imagine this would bias the results against ALS.

They did falsification tests and found that ALS penetration wasn't associated with factors like non-emergent surgical mortality or intensive care mortality.  They even did sensitivity analyses to ensure that more BLS patients didn't die at the scene or en route to the hospital.  

Still, critics dismissed the results.  They declared, mostly without evidence, that ALS is sent to sicker patients, and look, nothing's a guarantee, but this analysis accounted for this critique.  It doesn't seem to make a difference.  For a long time, the tobacco companies were able to get away with saying that we never proved that smoking causes cancer since no RCT is available.  One will also never be done.  At some point, when we aren't going to get a randomized controlled trial, we have to start to accept the best evidence we can get.  We could still do a randomized controlled trial of ALS versus BLS, but if people refuse, and it looks like they probably will, then they should help design a study they'd accept and allow as enough evidence to consider the idea that ALS might be harmful.  Otherwise, they should consider that they might be unwilling to change their minds no matter what new data come to light.

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