Emergency Transfusion Score (ETS)

During the initial phases of trauma resuscitation, one of the most complex tasks for the Resuscitationist is making the decision to activate the Massive Transfusion Protocol. While clinician gestalt is highly sensitive, the specificity is variable leading to large rates of either over or undertriage. While some argue, "it's better to be safe than sorry", buying into a liberal transfusion approach (overtriage) is dangerous not only to the patient (TRALI, TACO, anaphylactoid reactions), but also to the institution ($$$). Thus, over the last decade, a multitude of prediction tools were developed. One score I just became familiar with is the Emergency Transfusion Score (ETS).

What is it?

• The ETS contains 9 predictive values (all of differing weights ['coefficients']) based on regression analysis of retrospectively collected data from 1,103 patients admitted to a single institution over a 4-year period. [1]
• ETS was later validated again by Kuhne et al with prospectively collected data from 481 patients on admission to a single-institution over a 17-month period. [2]
• Data from the latter validation concluded that an ETS ≥ 3 is a positive test and the massive transfusion protocol should therefore be initiated. 

What are the variables?

Variable		Coefficient	p Value
Age (years)			< 0.001
	20 - 60	0.5
	> 60	1.5
Admission from scene of accident		1	< 0.004
Injury mechanism
	Traffic Accident	1	< 0.002
	Fall > 3m	1
Systolic Blood Pressure
	0-90 mmHg	2.5	< 0.001
	90-120 mmHg	1.5
Pelvic Ring Disruption		1.5	< 0.001
Abdominal Free Fluid (FAST)		2	< 0.001

How did ETS perform? [2]

	ETS ≥ 2	ETS ≥ 3	ETS ≥ 4
Sensitivity	100%	97.5%	84.2%
Specificity	44.2%	68%	92.5%
PPV	11.5%	22.2%	31.4%
NPV	100%	99.7%	98.4
LR+	1.79	3.16	11.23
LR-	0	0.04	0.17

Conclusion

The ETS has been proven on 2 occasions to be moderately accurate in the prediction in the need (or lack of need) for massive transfusion. Kuhne et al [2] claimed that their institution was able to save a substantial amount of blood (176 MT+ vs 481 MT+) and money ($97,600 USD saved) compared to their traditional "clinician gestalt" approach. Obviously, it seems like their "standard" approach is wildly liberal so it would be wise to interpret these savings carefully in your institution.

Having said that, 3 caveats with ETS are:

1. Remembering the coefficient variable at the bedside without some form of a checklist would be daunting.
2. ETS has not been validated to be used in patients with penetrating trauma.
3. The ETS and the ABC Score perform similarly, however the ABC score is much easier to perform/remember. 

At the end of the day, I'm still partial to the ABC score.

Bibliography:

1. Ruchholtz et al."The Emergency Room Transfusion Score (ETS): Prediction of Blood Transfusion Requirement in Initial Resuscitation after Severe Trauma" Transfusion Medicine 2006, 16(1):49–56
2. Kuhne et al."Emergency Transfusion Score (ETS): A Useful Instrument for Prediction of Blood Transfusion Requirement in Severely Injured Patients" World J Surg 2008, 32(6):1183–8