STUDY: BLS better than ALS for trauma, stroke, respiratory distress

[Summit]

Outcomes of Basic Versus Advanced Life Support for Out-of-Hospital Medical Emergencies
Prachi Sanghavi, PhD; Anupam B. Jena, MD, PhD; Joseph P. Newhouse, PhD; and Alan M. Zaslavsky, PhD
http://annals.org/article.aspx?articleid=2456124
Annals of Internal Medicine - October 13th 2015

BLS had markedly superior outcomes vs ALS for trauma, stroke, and respiratory distress patients.
AMI patients had only a 1% better survival rate with ALS.

Sum of the samples was about 290K patients.

Population studied was non-rural.

Study funded by National Science Foundation, AHRQ, and National Institutes for Health

 

[DPM]

Poorly conducted study. Their determination of a "superior" outcome fails to take into account any sort of diagnosis or intervention that ALS can provide prior to the ER.

The study looks at Medicare billing, so only takes into account whether or not a call was billed as ALS or BLS, and not if the provider was ALS or BLS.

It's an urban only study, so response times are not a factor and all we have to do is drive to the ER and let them sort it out...

 

[Summit]

Poorly conducted study. Their determination of a "superior" outcome fails to take into account any sort of diagnosis or intervention that ALS can provide prior to the ER.

Poorer outcomes for being neurologically intact and alive are somehow are irrelevant because of the almighty ALS ability to diagnose and provide symptomatic relief?

The study looks at Medicare billing, so only takes into account whether or not a call was billed as ALS or BLS, and not if the provider was ALS or BLS.

Read the study. If it was dispatched as ALS, medicare allows ALS billing and the patient was placed in the ALS group.

It's an urban only study, so response times are not a factor and all we have to do is drive to the ER and let them sort it out...

The study was for NON-RURAL meaning areas that included a cluster of greater than 10,000 people were included. This encompasses 94% of the US population. The county I live in is classified as non-rural due to one "urban cluster" MICROPOLITAN district even though the county population density is 1% of a metro area.

No attempt was made to generalize this for extreme transport times or rural areas.

 

[DPM]

Intact neurological survival is not an excellent bench mark to go by for trauma patients, asthma patients etc. Symptom relief is a large part of the hospital treatment, so just because they don't die on the way to the hospital doesn't mean that PT care was not affected, and just because a PT can survive to the ER with BLS care does not mean that this should be the standard. In areas where rapid transport to a hospital is impossible, where does this leave our patients?

This study shows that respiratory, trauma etc patients that only require BLS pre hospital have better outcomes. Is it not saying that patients who are less sick have better outcomes?

 

[Underoath87]

Who would dispatch a BLS unit to any of those emergencies in the first place? Was it because the pt was not really suffering an emergency, and the ALS crew just transported them as a BLS pt?
Or is it because they were in a tiered system with few ALS units and the BLS unit just chucked them to the ED in 5 minutes for definitive treatment, rather than wait 30 minutes for ALS backup? Either of these would explain the skewed results and are not a fair comparison.

 

[DPM]

If EMD can triage your "trauma" to an ALPHA level then in many areas BLS can take them. The BLS group in this study is by design going to include more low acuity patients than the ALS group.

 

[Underoath87]

If EMD can triage your "trauma" to an ALPHA level then in many areas BLS can take them. The BLS group in this study is by design going to include more low acuity patients than the ALS group.

Which would simply mean that low acuity pt + BLS transport > high acuity pt + ALS interventions. Not really a surprise.

 

[chaz90]

Which would simply mean that low acuity pt + BLS transport > high acuity pt + ALS interventions. Not really a surprise.

Except that pesky mention of "propensity score weighting" means they used validated statistical methods to control for the confounding variable (baseline patient acuity) in this observational study. Since a randomized clinical trial of this size is probably impossible with ALS ingrained in EMS and considered the standard of care for high acuity patients, a RCT is probably impossible.

I'm still a little perplexed as to what may have caused the worsened outcomes for stroke and respiratory cases. I understand trauma a little bit as I imagine ALS likely took longer to transport and may have over administered IVF, but the other two are a bit surprising.

The percentages are small, but in a sample this large even a small change is compelling.

I think of the way I run a CVA call as an ALS provider, and the only ALS intervention I provide is an IV (occasionally x2) during transport and a lab draw. I do a 12 lead en route, and occasional suctioning during transport. Unless IVs are actually increasing mortality or other people are doing more things on scene, I really don't get it.

Respiratory cases are just as baffling. Inhaled beta agonists and anticholinergics are pretty well supported for asthmatics and COPD patients, and clearly a part of most hospital courses of treatment too. IV steroids, CPAP and BiPAP as necessary? I wouldn't think these should increase mortality either, judiciously applied.

Obviously this study didn't look for the reasons in differences, and those are the big questions. Are these common medical interventions truly harmful to patients, or are we as paramedics that bad at deciding when to apply them?

 

[chaz90]

The temptation we're faced with is always going to be following the knee jerk reaction of "poorly designed study" when faced with results that aren't necessarily positive towards our career. There may be problems with this study design, but anything showing statistically significant results with hundreds of thousands of patients reviewed at least deserves some critical review.

 

[Summit]

If EMD can triage your "trauma" to an ALPHA level then in many areas BLS can take them. The BLS group in this study is by design going to include more low acuity patients than the ALS group.

They used severity scores and statistical analysis methods to test for confounders and sample differences to see if the exact things you pointed out were the issue.

Do you really think the 3 PhDs and 1 MD PhD from Harvard Medical School didn't think of those things and that the peer review board for the Annals of Internal Medicine didn't consider it before publishing?

Thank heavens you don't need to read a study to dismiss it.

READ. THE. STUDY.

 

[DPM]

Except that pesky mention of "propensity score weighting" means they used validated statistical methods to control for the confounding variable (baseline patient acuity) in this observational study...

When the authors analysed their own data using different methods (propensity score analysis vs instrumental variable analysis) they had different and contradicting results. So it may seem knee jerk, but when their own methods come up with contradictions then it's hard to take it seriously.

 

[Summit]

When the authors analysed their own data using different methods (propensity score analysis vs instrumental variable analysis) they had different and contradicting results. So it may seem knee jerk, but when their own methods come up with contradictions then it's hard to take it seriously.

Where did they say that? DID YOU READ THE STUDY? YES OR NO?

Here is a relevant excerpt from the discussion section (emphasis added):

For 3 of the 4 conditions we studied, unadjusted survival rates were higher among patients receiving BLS despite these patients being older and having more comorbid conditions on average than those receiving ALS. After adjustment, these outcome differences persisted; we found similar or better health outcomes associated with prehospital BLS than ALS in all of our analyses for major trauma, stroke, and respiratory failure. Because these high-acuity conditions necessitate early optimization of care, one would have expected any advantage of ALS over BLS to manifest itself in these diagnoses. Although ALS may be expected to improve outcomes because of early treatment, the opposite may occur in practice if ALS is associated with delays in hospital management or iatrogenic injury (3, 5–7, 31). We used 2 methodological approaches to adjust for potential confounders of comparisons between BLS and ALS outcomes. One analysis used propensity score methods to balance observed characteristics. This approach is susceptible to confounding by any unobserved patient characteristics associated with survival and ALS use; however, because ambulance dispatch protocols prioritize ALS for the conditions we studied, such individual-level confounding is plausibly minimal. Our second approach used the instrumental variable of county-level variation in overall ALS prevalence to predict the likelihood that a patient would receive ALS. This approach is less susceptible to confounding by unobserved patient characteristics but is subject to confounding by associations between rates of ALS use and other county characteristics that affect mortality. However, our falsification tests suggest that such confounding is unlikely
...
With the exception of patients who had AMI, BLS was associated with outcomes similar to or significantly better than ALS using both methodological approaches. Survival after AMI was substantially better with BLS than ALS in instrumental variable analysis (between 4 and 8 percentage points across all time points), but the propensity score analysis found higher survival with ALS than BLS (between 1 and 2 percentage points at 90 days, 1 year, and 2 years). We did several sensitivity analyses (Appendixes 9 to 16 of the Supplement), none of which changed the direction or significance of our main findings. Our findings are consistent with other evidence for cardiac arrest (Appendix 17 of the Supplement) and trauma (4, 5, 7, 10 – 18). Little prior evidence, however, exists for patients with stroke, AMI, and respiratory failure.
...
Our study has several limitations. Selection bias may confound our findings if patients receiving ALS and BLS differ in unobserved illness severity or in the quality of hospital care that they receive. To address this issue, we did 2 types of analyses that are subject to different types of confounding. The propensity score analysis would be biased toward finding worse outcomes associated with ALS if ALS providers were dispatched to patients with greater unobserved illness severity. Interviews we conducted with 45 state emergency medical service representatives, however, indicate that, if available, ALS would routinely be dispatched for many of the conditions that we investigated. As a result, the decision to dispatch ALS providers may plausibly be uncorrelated with unobserved illness severity for conditions other than trauma; for trauma, we controlled for severity. Moreover, BLS patients were older and had more comorbidities than ALS patients, which suggests that any unobserved differences in severity may actually have biased our results against BLS. The instrumental variable analysis could be confounded if counties with poorer quality hospital care had higher ALS penetration. Our falsification tests found no association of ALS penetration with nonemergent surgical mortality or nonemergent intensive care unit mortality at the county level. Although these tests increase confidence in our results, we had no way of directly assessing the quality of care for emergency patients that was not susceptible to potential confounding by characteristics of ambulance services. Estimates and significance tests under the propensity score analysis could be subject to bias if ALS providers evaluated a patient and then selectively provided care and billed at the BLS level for less acute cases. Given substantial reimbursement differences between ALS and BLS, it is unlikely that ALS providers billed at BLS rates because Medicare allows billing at the ALS level if assessment by ALS-trained providers was considered necessary at dispatch. Further, analysis of survival differences in 2005 claims, which distinguish ALS claims billed at the BLS level, showed little sensitivity to whether this small group was categorized as ALS or BLS (Appendix 15 of the Supplement). Finally, significance tests under the instrumental variable analysis would still be valid in this case as long as higher rates of ALS claims reflect higher utilization rates of ALS providers, although estimates of the effect magnitude might be biased. Because our sample included only patients with hospital claims, another potential limitation may be that more BLS patients died at the scene or en route to the hospital. In sensitivity analyses that considered these cases, however, the direction and significance of our findings were unchanged (Appendixes 10 and 11 of the Supplement).

 

[DPM]

They say with AMI that BLS is better when they use instrumental variable analysis, but that ALS is better when propensity score analysis is used. You even bolder that section. These two analyses contradict each other.

Likewise, propensity score analysis found better outcomes with BLS for respiratory failure, yet instrumental variable analysis found no survival difference.

So far I've only been able to read what is published for free, but I'm hoping to get a full copy shortly.

 

[Summit]

This might be a seperate thread...

Does your employer give you access to key resources like journals, pharm db, and other ebp resources like uptodate?

 

[EpiEMS]

Comparable to OPALS results (except for respiratory distress) and to the primary author's prior paper, I think...

I cannot say I'm entirely surprised about trauma & stroke, but respiratory distress is surprising. However...consider my conjecture:
1) ALS providers may be using interventions unsuccessfully/inappropriately
or
2) Key interventions could be performed at both ALS & BLS levels
or
3) Incremental inerventions are being performed at ALS level that just don't work
or any combination of 1, 2, and 3...

 

[chaz90]

This might be a seperate thread...

Does your employer give you access to key resources like journals, pharm db, and other ebp resources like uptodate?

No. I believe we have access to journals as needed if requested for a specific research/special project we're working on, but for the most part, no.

In all fairness, most wouldn't be interested. Some even complain about the pre-hospital applications of some of the con-ed sessions we do get. We paramedics tend to be a little narrow minded and shortsighted at times.

 

[DPM]

No. I believe we have access to journals as needed if requested for a specific research/special project we're working on, but for the most part, no.

In all fairness, most wouldn't be interested. Some even complain about the pre-hospital applications of some of the con-ed sessions we do get. We paramedics tend to be a little narrow minded and shortsighted at times.

...and the Annals of Internal Medicine isn't exactly the most applicable journal to our field [emoji6]

 

[chaz90]

...and the Annals of Internal Medicine isn't exactly the most applicable journal to our field [emoji6]

Well, I don't quite know how this article found a home in this specific journal, but I'd certainly say this subject is relevant.

 

[Carlos Danger]

Just a few comments, observations, and predictions:

1. Assuming the methodology employed here is sound (and the safe bet is that it is), this is a study that absolutely should not be ignored, if for no other reason than its sheer size. However, many will still ignore it.

2. The findings are roughly in agreement with previous studies - we all know that most ALS interventions have never been shown to positively impact outcomes - which means that no one should be surprised by this. It is not breaking news.

3. People are always quick to play the "poorly conducted" card - often before they even know how it was conducted - when the stated conclusions don't support their own biases. It's always fascinating to see people who don't know the first thing about statistical methods and who never even read clinical research suddenly become experts in how research should be conducted when the findings threaten one of their sacred cows.

4. I doubt anyone is going to use this study to support a claim that ALS is worthless and never brings any value. That isn't what this study says. For instance, the effects of ALS analgesia were not even addressed, so the "but what about analgesia!?!?!" argument that is always thrown out in response to any criticism of ALS has no meaning here.

 

[EBMEMT]

Somone started 2nd thread. their link is to an article that descrines the study and includes video presentation.

http://emtlife.com/threads/als-increases-mortality-bls-cheaper-and-better-outcomes.42496/