Evidence-based improvement of the National Trauma Triage Protocol: The Glasgow Coma Scale versus Glasgow Coma Scale motor subscale

Abstract

Background: Ideal triage uses simple criteria to identify severely injured patients. Glasgow Coma Scale motor (GCSm) may be easier for field use and was considered for the National Trauma Triage Protocol (NTTP). This study evaluated performance of the NTTP if GCSm is substituted for the current GCS score ≤ 13 criterion.

Methods: Subjects in the National Trauma Data Bank undergoing scene transport were included. Presence of NTTP physiologic (Step 1) and anatomic (Step 2) criteria was determined. GCSm score ≤ 5 was defined as a positive criterion. Trauma center need (TCN) was defined as Injury Severity Score (ISS) > 15, intensive care unit admission, urgent operation, or emergency department death. Test characteristics were calculated to predict TCN. Area under the curve was compared between GCSm and GCS scores, individually and within the NTTP. Logistic regression was used to determine the association of GCSm score ≤ 5 and GCS score ≤ 13 with TCN after adjusting for other triage criteria. Predicted versus actual TCN was compared.

Results: There were 811,143 subjects. Sensitivity was lower (26.7% vs. 30.3%), specificity was higher (95.1% vs. 93.1%), and accuracy was similar (66.1% vs. 66.3%) for GCSm score ≤ 5 compared with GCS score ≤ 13. Incorporated into the NTTP Steps 1 + 2, GCSm score ≤ 5 traded sensitivity (60.4% vs. 62.1%) for specificity (67.1% vs. 65.7%) with similar accuracy (64.2% vs. 64.2%) to GCS score ≤ 13. There was no difference in the area under the curve between GCSm score ≤ 5 and GCS score ≤ 13 when incorporated into the NTTP Steps 1 + 2 (p = 0.10). GCSm score ≤ 5 had a stronger association with TCN (odds ratio, 3.37; 95% confidence interval, 3.27-3.48; p < 0.01) than GCS score ≤ 13 (odds ratio, 3.03; 95% confidence interval, 2.94-3.13; p < 0.01). GCSm had a better fit of predicted versus actual TCN than GCS at the lower end of the scales.

Conclusion: GCSm score ≤ 5 increases specificity at the expense of sensitivity compared with GCS score ≤ 13. When applied within the NTTP, there is no difference in discrimination between GCSm and GCS. GCSm score ≤ 5 is more strongly associated with TCN and better calibrated to predict TCN. Further study is warranted to explore replacing GCS score ≤ 13 with GCSm score ≤ 5 in the NTTP.

Level of evidence: Prognostic study, level III.

Figure 1

ACS COT and Centers for Disease Control NTTP, 2011. Reproduced from Sasser et al. Adaptations are themselves works protected by copyright. So in order to publish this adaptation, authorization must be obtained both from the owner of the copyright in the original work and from the owner of copyright in the translation or adaptation.

Figure 2

Predicted TCN plotted versus actual TCN through the range of scores for GCS (3–15) and GCSm (1–6). The dotted diagonal line represents perfect calibration. The more linear line of the GCSm model indicates calibration better than that of the GCS model through the range of scores to predict TCN, particularly at the lower end of the scales.

Figure 3

Residual plot over the range of scores for GCS (3–15) and GCSm (1–6) versus actual TCN. The y-axis displays the residuals or deviation from the regression line in linear regression. The dotted line at zero represents perfect linear relationship in linear regression. GCSm demonstrates lower residuals and higher r² compared with GCS, indicating a more linear relationship between predicted and actual TCN in GCSm.