Sunday, 30 July 2017

Mortality rates of severe TBI: impact of direct vs. non-direct transfer

There are potential benefits to transfer patients with suspected severe traumatic brain injury (TBI) directly to a trauma centre and bypass smaller local hospitals. The tertiary centres likely have more experience and expertise to manage these patients well.

But of course, this must be balanced by potential harm of prolonged transportation prior to hospital evaluation and resource implications.  

This study sought to answer which strategy is best for these patients; go to the small centres first or direct transfer to the trauma centre?

This was a registry review of patients (with no chart extraction methods reported) presenting to a level 1 trauma centre in New York. 171 patients with GCS<8 (severe TBI) were directly transferred as compared to 92 that were transferred after going to a local hospital.

The primary outcome was mortality. Can’t argue with this outcome…

Results?

There was an observed 19% mortality rate for direct transfer vs. 36% for secondary transfer.  To be clear, this was an absolute difference of 16% or a NNT of 6 for mortality.

The only thing that springs to my mind is, “holy shit!”

But wait…

This is sounds too good to be true. So, what’s wrong?

This was not a randomized trial. Therefore, this observational study will inevitably have some underlying confounders between the groups. Did they make any attempt at controlling or analysing for confounding?

No.

To be fair, they did mention that the patients undergoing direct transfer had higher injury severity scores (ISS) but this is only a single measure and far from perfect.

I strongly suspect the cohort of patients undergoing secondary transfer were vetted at the local centres and found to be genuinely quite sick. Many likely had complete primary surveys and pan-scans. They kept the patients that were ok and only transferred the sickest ones. So of course, this group was going to have worse outcomes than those who were not screened by doctors.

But, for many reasons I could be wrong.

Unfortunately, a good RCT would be very tricky to undertake. In addition, it would arguably fail on feasibility, ethics and issues of external validity.

What should we conclude?

This study does not add much to our understanding of this complex question. It has the capacity to be grossly misinterpreted. 

Great one for journal club… but afterward you might feel like you have your own TBI.


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