Wednesday, 29 June 2016

How to get it wrong: Succinylcholine is associated with increased mortality when used for RSI in patients with severe traumatic brain injury

This is a fantastic study!

It is a fantastically bad study of how to perform research and come to wrong conclusions. It is so awful it makes one’s heart sink.

These authors performed a retrospect data-base review of patients who were intubated in their ED for traumatic brain injury. The main outcome was the difference in mortality when patients were intubated with either rocuronium or succinylcholine.

The results? No difference in mortality was found. Death occurred in 23% in each group.

Not satisfied with negative results, the authors conducted a post-hoc subgroup analysis and found that there was a difference in those with severe TBI. If you torture the data enough, it will talk.

Wooohooo... we can publish something!

They conclude, “in severely brain-injured patients undergoing RSI in the ED, succinlycholine was associated with increased mortality compared to rocurunium.”

This is totally nuts.

Regardless of the crazy analysis, all of the difference could easily be attributed to unmeasured confounding. This was not a randomized trial; therefore the patients given sux were very likely sicker.

Most experienced airway experts will tell you that they reach for sux when they want very rapid intubating conditions in sicker patients as compared to other neuromuscular blockers. Correcting for confounding (especially with a retrospective database) is far from an perfect science.

In the end, this is a small study with a high risk of bias that comes to unbelievable conclusions. Do we really believe a number needed to kill of 5 for succinylcholine in severe TBI!?!

There is so much I haven’t mentioned... the crazy power calculation, mixing association with causation, confusing subgroup analysis with stratification, neglecting the details of biological plausibility etc.

In 2005, John Ioannidis published his famous paper, “Why most published research findings are false.”

This study is a case in point. On so many levels, it is just wrong.

At best, it might raise a hypothesis for prospective testing. However, NOBODY should be changing their practice as a result of this paper.


Covering:

Patanwala AE, Erstad BL, Roe DJ, et al. Succinylchoine is associated with increased mortality when used for rapid sequence intubation of severely brain injured patients in the Emergency Department. Pharmacotherapy. 2016;36(1):57-63.



(Special thanks to Dr Mark Reeves, FANZCA and Dr Ryan Radeski for providing me with some of their insights. However they take no responsibility for the terrible nature of this post.) 

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