Which is to say – endorsing conclusions founded on sparse data is worse than simply admitting the limitations of our knowledge.
Clearly, if a patient requires blood, the more, the sooner, the better with severe injury. However, starting that transfusion outside a setting fully capable of assessing injury severity and physiology can mean wasted or inappropriate product use.
These authors attempt to show patients receiving blood in the pre-trauma center setting have markedly decreased mortality and traumatic coagulopathy. However, they do so using a retrospective database of patients from 2003 to 2010, of which only 50 patients received pre-trauma center transfusion, compared with 1,365 who did not. Additionally, there were diverse differences in ISS, base deficit, and total crystalloid and product transfusion. They subsequently attempt to control for this using logistic regression and by deriving a propensity-matched cohort – which then compares 35 patients with pre-hospital transfusion with 78 patients without, but still has diverse significant differences in initial physiology and total product transfusion.
So, because of all these intrinsic differences, all their reported odds ratios are adjusted after “controlling for confounders”. After all the statistical wrangling, “covariate-adjusted” 30 day survival was ~95% in the cohort with pre-trauma center transfusion, and ~88% in others. The propensity-matched results showed similar odds ratios. Unadjusted mortality in the cohorts is not presented.
Who knows what this really shows? The data used is retrospective, heterogenous and collected over the course of 8 years, their sample of pre-trauma center transfusions is tiny, and all their reported odds ratios required huge statistical adjustments. Pre-trauma center transfusions are probably helpful, if used judiciously, but this is not the study that shows it.
“Pretrauma Center Red Blood Cell Transfusion Is Associated With Reduced Mortality and Coagulopathy in Severely Injured Patients With Blunt Trauma”