Written by Clay Smith
Spoon Feed
A new lethal triad performs better than the old one for 28-day mortality in trauma patients. But the “new” is simply a reframing of the classic and doesn’t appear that helpful.
Like New Coke… it should be better, but does it beat the Classic?
The classic lethal triad in trauma is coagulopathy (INR >1.5), hypothermia (<35ºC), and acidosis (pH <7.2).
A revised triad consists of:
- Major Criterion:
Fibrin/fibrinogen degradation product, FDP >90 μg/mL) - Minor Criteria
1) Metabolic acidosis (base excess, BE < −3 mmol/L)
OR 2) Hypothermia (<36°C)
An earlier study found that meeting the major criterion or two minor criteria was 80.7% sensitive and 66.8% specific for predicting 28-day trauma mortality.
They retrospectively applied this triad to an external population, using a previously collected dataset (J-OCTET 2) with 1,177 severely injured Japanese patients from 23 institutions. Those with missing data were excluded, leaving just 770 (65%) from the original cohort. In this highly select population, the triad performed moderately well for 28-day mortality: 80.6% sensitivity, 64.4% specificity, AUC 0.77 (when the major criterion or both minor criteria were met). This outperformed the classic triad: sensitivity 2.8%, specificity 99.8%, AUC 0.68.
This study has some major issues. First, the new triad is awfully similar to the old: coagulopathy, hypothermia, and acidosis. Is there an actionable change with these new criteria? For the old triad, we would fix coagulopathy, warm them up, and improve perfusion. For the new criteria, what changes in that action plan? Next, it is subject to serious risk of confounding. Finally, exclusion of those with missing data is problematic.
How will this change my practice?
Some things are classic for a reason. Coagulopathy, hypothermia, and acidosis is easier to recall than: major criterion: fibrin/fibrinogen degradation product, FDP >90 μg/mL); minor criteria: metabolic acidosis (base excess, BE < −3 mmol/L) OR hypothermia (<36°C). I see that this triad performs better, but I’m not sure it’s helpful for changing our practice.
Source
External validation of the revised lethal triad criteria for appropriate strategic decision making. J Trauma Acute Care Surg. 2025 Sep 4. doi: 10.1097/TA.0000000000004782. Epub ahead of print. PMID: 40905980.
