How To Remember Glasgow Coma Scale
SEE RELATED ARTICLE, P. 143.
It is now beyond reasonable dispute that the standard 13-point Glasgow Coma Calibration (GCS) (score range 3 to 15) is unnecessarily complicated for out-of-hospital field assessment, and that information technology can be merely as effectively replaced with whatever one of several simpler subset versions of itself. Such functional equivalence has been reported repeatedly and is now farther confirmed by a rigorous meta-analysis by Chou et al
one
- Chou R.
- Totten A.M.
- Carney N.
- et al.
Predictive utility of the total Glasgow Coma Scale versus the motor component of the Glasgow Blackout Scale for identification of patients with serious traumatic injuries: a systematic review and meta-analysis.
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in this result of Annals. Indeed, last year Annals published the single largest study on this topic, which ended that the GCS could be effectively replaced with the single binary decision point GCS motor score less than vi, ie, "Patient does not follow commands."
The total GCS was never intended for trauma prognostication
and has been established equally unreliable, unnecessarily complex, hard to utilize in exercise, statistically inappropriate,
,
and with accuracy similar to that of more elementary approaches.
Currently, out-of-hospital personnel are required to calculate a full GCS score on every injured patient, an unnecessary burden that requires more minimal time and a reference bill of fare
to enhance accuracy. Why has this complicated task persisted in modern out-of-hospital intendance? Supporting reasons include inertia, tradition, and the illusory sense of psychological guild provided past a seemingly precise tool.
,
,
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Guidelines for field triage of injured patients: recommendations of the National Adept Panel on field triage, 2011.
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A final justification is the notion that the GCS is statistically superior to replacement measures. This latter assertion is flawed, and we will rebut information technology in this editorial.
Investigators have used ii separate analytic approaches to measure the GCS. The first contrasts the accuracy of binary thresholds, eg, how does a single cut point of a simplified scale compare with the trauma middle triage threshold GCS score of less than or equal to xiii stipulated by the National Field Trauma Guidelines?
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- Sasser S.1000.
- Hunt R.C.
- Faul K.
- et al.
Guidelines for field triage of injured patients: recommendations of the National Adept Panel on field triage, 2011.
- PubMed
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Enquiry reporting this uncomplicated dissimilarity of relative sensitivities and specificities has found simplified measures to be functionally equivalent to the total GCS. Equally an instance, in the Table we provide mortality data from the largest bachelor study from Kupas et al,
in which the total GCS score less than or equal to 13 is statistically more than sensitive and statistically less specific than GCS motor score less than 6. Nevertheless, the absolute differences (2.v% and ii.0%) are small and finer weigh each other. Indeed, the overall accuracy (a measure that equally weights sensitivity and specificity) favors GCS motor score less than six.
Table Near-identical relative test performance of 2 field triage thresholds in predicting mortality (taken from Kupas et al).
| Threshold | Sensitivity, % | Specificity, % | Accuracy, % |
|---|---|---|---|
| GCS score ≤thirteen: National Field Trauma Guidelines | 69.eight | 88.1 | 87.1 |
| GCS motor score <6: "patient does not follow commands" | 67.3 | 90.1 | 88.8 |
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The 2nd GCS analytic approach is to plot receiver operating characteristic (ROC) curves and to summate the expanse under these curves. (Run into this Annals Journal Club article for an overview and critique of this technique.
) Using the area under the curve to quantify predictive performance effectively considers all scale thresholds along the curve simultaneously, in contrast to the previously mentioned binary technique that considers only unmarried thresholds. Studies reporting ROC areas under the curve take typically shown statistical superiority of the full GCS—just on the gild of just a few percentage points or less of the full area, which many argue is below reasonable thresholds of clinical importance.
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,
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- Gill M.
- Steele R.
- Windemuth R.
- et al.
A comparison of five simplified scales to the out-of-hospital Glasgow Blackout Scale for the prediction of traumatic encephalon injury outcomes.
- Crossref
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,
12
- Thompson D.O.
- Hurtado T.R.
- Liao K.G.
- et al.
Validation of the Simplified Motor Score in the out-of-hospital setting for the prediction of outcomes after traumatic brain injury.
- Google Scholar
In the Figure, we provide the same mortality prediction instance every bit in the Table; note that plots of the 2 sensitivity and specificity combinations are next and thus functionally equivalent. However, when the full ROC curves are contrasted, the total GCS score has a statistically significantly greater expanse under area the curve than does the GCS motor subscale score—by a 2.8% margin. (For simplicity, nosotros use mortality equally our example, but this same discussion equally applies to slight differences in area nether the bend noted for other trauma outcomes such as emergency intubation, brain injury, and neurosurgical intervention.)
Ane can imagine a well-intentioned out-of-hospital policymaker looking at this statistically pregnant 2.eight% margin and using it to justify retentivity of the full GCS. Even if the statistical reward is slight, perhaps, given many thousands of patients, this slender difference might upshot in a rare but real result for some. Even so, such hopeful thinking is invalid for 2 reasons.
First, the practical, bodily application of the GCS for out-of-infirmary trauma triage does non use all thresholds simultaneously, equally is mathematically assumed past ROC area under curve analyses. Instead, the National Field Trauma Guidelines are binary: Patients with a GCS score less than or equal to xiii are to exist transported to a trauma center.
Such unmarried thresholds parallel the human cognitive process because out-of-hospital personnel and emergency physicians most certainly do not consider all GCS points simultaneously in their clinical decisionmaking. And, as previously mentioned, any evidence of slight statistical superiority in existing research disappears when pragmatic, actual thresholds are applied.
The second objection confronting the ROC effect is evident when the right side of the Figure is viewed. The 2.eight% marginal difference in area under the curves lies virtually exclusively in a wide range that is absent actual data points. The ROC graphic process has interpolated examination operation to include all imaginary decision thresholds between a total GCS score of 14 and fifteen, and between a GCS motor score of v and six. From the Figure, we tin can readily visualize the relative sensitivities and specificities for portions of the curve attributable to fictional GCS values such equally 14.25, 14.v, and 14.75. For the GCS, such noninteger values have no meaning because this calibration is ordinal and not continuous, and thus it is effectively nonsense to use solid lines to connect the points. As a outcome, whatever deviation in calculated area under these lines is also nonsense.
A potent limitation of the ROC technique is that the calculation of area under the curve weights as all portions of the curve, including segments not germane to bodily clinical decisionmaking.
It is evident from inspection of the Effigy that the GCS curves are quite similar in the central portions in which actual clinical decisionmaking occurs. Curve differences elsewhere are non relevant and thus tin only exist misleading. Statistical techniques are available for comparing partial areas nether ROC curves
only are unnecessary here, given the visual similarity already discussed.
The meta-analysis reported in this result by Chou et al includes aggregate ROC comparisons that show slightly greater ROC area nether the curve for the full GCS. As evidenced by the Effigy and this discussion, readers should not be misled into believing that the differences are clinically relevant or important.
Functionally, any 1 of several simpler subset versions of the GCS tin can supercede the total score for out-of-hospital trauma triage, and the simplest and thus about efficient of these alternatives is the single conclusion signal of Kupas et al,
"Patient does not follow commands." The literature evidence is now more than than compelling, and it is past fourth dimension for such reform.
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Published online: February 04, 2017
Footnotes
Supervising editor: Michael L. Callaham, Medico
Authorship: All authors adjure to coming together the four ICMJE.org authorship criteria: (i) Substantial contributions to the conception or design of the piece of work; or the acquisition, analysis, or interpretation of information for the piece of work; AND (2) Drafting the work or revising it critically for of import intellectual content; AND (3) Final blessing of the version to be published; AND (4) Understanding to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of whatever part of the work are appropriately investigated and resolved.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in whatever mode related to the discipline of this article as per ICMJE conflict of involvement guidelines (see www.icmje.org). The authors have stated that no such relationships exist. Drs. Green, Haukoos, and Schriger are paid editors for Annals.
Dr. Callaham was the supervising editor on this article. Dr. Greenish did not participate in the editorial review or conclusion to publish this article.
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DOI: https://doi.org/10.1016/j.annemergmed.2016.12.016
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- Predictive Utility of the Total Glasgow Coma Scale Versus the Motor Component of the Glasgow Blackout Scale for Identification of Patients With Serious Traumatic Injuries
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The motor component of the Glasgow Blackout Scale (mGCS) has been proposed as an easier-to-utilize alternative to the full GCS (tGCS) for field assessment of trauma patients past emergency medical services. We perform a systematic review and meta-analysis to compare the predictive utility of the tGCS versus the mGCS or Simplified Motor Scale in field triage of trauma for identifying patients with adverse outcomes (inhospital mortality or severe brain injury) or who underwent procedures (neurosurgical intervention or emergency intubation) indicating need for high-level trauma intendance.
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