Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest

ResearchBlogging.org
 

I wrote about the start of the ALPS (Amiodarone, Lidocaine, Placebo Study) in 2012[1] and the results are now in.
 

In this randomized, double-blind, placebo-controlled, prehospital trial, we found that treatment with amiodarone or lidocaine did not result in a significantly higher rate of survival to hospital discharge or favorable neurologic outcome at discharge than the rate with placebo after out-of-hospital cardiac arrest caused by shock-refractory initial ventricular fibrillation or pulseless ventricular tachycardia. There were also no significant differences in these outcomes between amiodarone and lidocaine.[2]

 

The primary endpoint is that amiodarone does not improve survival to discharge and neither does lidocaine. However, the results are a bit more complicated than just throw out the drugs.

Two subgroups did have better outcomes, but as the authors appropriately point out, subgroup analysis requires a higher level of significance, because you are essentially getting extra shots at the goal for every subgroup. The more subgroups we have, the more likely that one of them will reach the p value of <0.05.  

We observed an interaction of treatment with the witnessed status of out-of-hospital cardiac arrest, which is often taken as a surrogate for early recognition of cardiac arrest, a short interval between the patient’s collapse from cardiac arrest and the initiation of treatment, and a greater likelihood of therapeutic responsiveness. Though prespecified, this subgroup analysis was performed in the context of an insignificant difference for the overall analysis, and the P value for heterogeneity in this subgroup analysis was not adjusted for the number of subgroup comparisons. Nonetheless, the suggestion that survival was improved by drug treatment in patients with witnessed out-of-hospital cardiac arrest, without evidence of harm in those with unwitnessed arrest, merits thoughtful consideration.[2]

 

Another important point is that the possibility of an effect was probably overestimated by the researchers. A much larger study would be needed to show this smaller effect.
 

Finally, the point estimates of the survival rates in the placebo group and the amiodarone group differed less than anticipated when the trial was designed, which suggests that the trial may have been underpowered. If amiodarone has a true treatment effect of 3 percentage points, approximately 9000 patients across the three trial groups would be needed to establish this difference in outcome with 90% power. Though seemingly small, a confirmed overall difference of 3 percentage points in survival with drug therapy would mean that 1800 additional lives could be saved each year in North America alone after out-of-hospital cardiac arrest.[2]

 

How could the top doctors in the field be so far off in their estimate?

We dramatically overestimate the good we do and we dramatically underestimate the harm we do. We are unreasonably optimistic.
 

Monty Hall problem vs medicine 1
Image credit.
 

We still do not have any evidence that anything other than compressions and defibrillation improve outcomes for adult patients with cardiac arrest, but we insist on using these treatments, because we believe in magic pills.

Should we consider giving amiodarone or lidocaine to only witnessed cardiac arrest patients or only EMS-witnessed cardiac arrest? Yes, but that is really just limiting the use of these drugs to those who have some weak evidence of benefit.

We are already giving too many treatments to too many patients, based on too little evidence.

That is assuming that we have any valid evidence at all. Medical ethics appears to be only for other people, because we don’t care enough to find out if our treatments work. We just make excuses for the harm we cause to our patients.

Footnotes:

[1] What Will Be the Next Standard Of Care We Eliminate
Wed, 28 Mar 2012
Rogue Medic
Article

[2] Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest
Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest.
Kudenchuk PJ, Brown SP, Daya M, Rea T, Nichol G, Morrison LJ, Leroux B, Vaillancourt C, Wittwer L, Callaway CW, Christenson J, Egan D, Ornato JP, Weisfeldt ML, Stiell IG, Idris AH, Aufderheide TP, Dunford JV, Colella MR, Vilke GM, Brienza AM, Desvigne-Nickens P, Gray PC, Gray R, Seals N, Straight R, Dorian P; Resuscitation Outcomes Consortium Investigators.
N Engl J Med. 2016 Apr 4. [Epub ahead of print]
PMID: 27043165

Free Full Text from NEJM

 
Kudenchuk, P., Brown, S., Daya, M., Rea, T., Nichol, G., Morrison, L., Leroux, B., Vaillancourt, C., Wittwer, L., Callaway, C., Christenson, J., Egan, D., Ornato, J., Weisfeldt, M., Stiell, I., Idris, A., Aufderheide, T., Dunford, J., Colella, M., Vilke, G., Brienza, A., Desvigne-Nickens, P., Gray, P., Gray, R., Seals, N., Straight, R., & Dorian, P. (2016). Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest New England Journal of Medicine DOI: 10.1056/NEJMoa1514204

.

Comments

  1. As usual, nothing but net. Thanks again for your scathing honesty and your brutal fearlessness.

  2. Another thing to consider: The amiodarone formulation they used (Nexterone) is one that has only been recently approved, not the standard Cordarone / Pacerone, and they chose it specifically because it doesn’t have the hypotensive effects of the standard formulations. So the amiodarone arm of the study is effectively useless except for those systems that have already switched to Nexterone.

Trackbacks

  1. […] great Rogue Medic  weighed in on the study earlier today.  His post Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest is well worth reading as is everything Rogue […]

  2. […] [2] Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest Mon, 04 Apr 2016 Rogue Medic Article […]

Speak Your Mind