Glasgow Coma Scale (GCS)

Purpose

The Glasgow Coma Scale (GCS) was developed to describe the depth and duration of impaired consciousness or coma. In this measure, three aspects of behaviour are independently measured: motor responsivenessThe ability of an instrument to detect clinically important change over time.
, verbal performance, and eye opening. The GCS can be used with individuals with traumatic brain injury, strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More, non-traumatic coma, cardiac arrest, and toxic ingestions.

In-Depth Review

Purpose of the measure

The Glasgow Coma Scale (GCS) was developed to describe the depth and duration of impaired consciousness or coma. In this measure, three aspects of behaviour are independently measured: motor responsivenessThe ability of an instrument to detect clinically important change over time.
, verbal performance, and eye opening. The GCS can be used with individuals with traumatic brain injury, strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More, non-traumatic coma, cardiac arrest, and toxic ingestions.

Available versions

The GCS was published in 1974 by Graham Teasdale and Bryan J. Jennett. In 1976, Teasdale and Jennett distinguished between “normal” and “abnormal” flexion, which increased the “best motor response” item by one point.

Features of the measure

Items:

The GCS is comprised of three components: 1) Best eye response, which is believed to indicate whether the arousal mechanisms in the brainstem are active; 2) Best verbal response, which is believed to be the most common definition of the end of a coma, or the recovery of consciousness; and 3) Best motor response, which is thought to be associated with central nervous system functioning. Each component has a number of grades starting with the most severe. Best eye response has 4 grades; Best verbal response has 5 grades; Best motor response has 6 grades.

Best eye response (E)

1. No eye opening
2. Eye opening in response to pain (patient responds to pressure on the patient’s fingernail bed; if this does not elicit a response, supraorbital and sternal pressure or rub may be used).
3. Eye opening to speech (not to be confused with an awaking of a sleeping person; such patients receive a score of 4, not 3).
4. Eyes opening spontaneously

Best verbal response (V)

1. No verbal response
2. Incomprehensible sounds (moaning but no words).
3. Inappropriate words (random or exclamatory articulated speech, but no conversational exchange).
4. Confused (the patient responds to questions coherently but there is some disorientation and confusion).
5. Oriented (patient responds coherently and appropriately to questions such as the patient’s name and age, where they are and why, the year, month, etc.).

Best motor response (M)

1. No motor response
2. Extension to pain (decerebrate response: rigid adduction and extension of the arms, legs stiffly extended, downward pointing of the toes, backward arching of the head, wrists pronated and fingers flexed).
3. Flexion in response to pain (decorticate response: arms flexed, or bent inward on the chest, the hands are clenched into fists, and the legs extended).
4. Withdraws from pain (pulls part of body away when pinched; normal flexion)
5. Localizes to pain (purposeful movements towards changing painful stimuli; e.g. hand crosses mid-line and gets above clavicle when supra-orbital pressure applied).
6. Obeys commands (the patient does simple things as asked).

Scoring:

In the GCS, each of the component scores as well as the sum of the components are considered. The total score is out of 15-points, with lower scores indicating more severe impairment. The lowest possible GCS total score is 3, indicating deep coma or death, and the highest possible score is 15, indicating a fully awake individual. The total score of the GCS is calculated by summing E + V + M.

The score is expressed in the form GCS (total score) = score on E + score on V + score on M. For example, GCS 9 = E2 V4 M3 indicates a total score of 9, a score of 2 on Best eye response (E), a score of 4 on Best verbal response (V), and a score of 3 on Best motor response (M). Note: For a patient who is intubated, the V is expressed as V intubated.

Interpretation of the GCS total score is as follows:

• Minor head injury = 13-15
• Moderate head injury = 9-12
• Severe head injury (coma) = 8 or less

Time:

Not reported.

Subscales:

The GCS has 3 subscales: Best eye response, Best motor response, and Best verbal performance.

Equipment:

Only a pencil and the test are needed.

Training of administrator:

Although no training is required to administer the GCS, one study examined whether the GCS can be used reliably and accurately by inexperienced examiners and found that experienced medical personnel can use the measure with extremely high levels of accuracy and reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of "true" variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to "noise" in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
, but inexperienced examiners may create significant errors, especially in the intermediate levels of consciousness, when the detection of neurologic changes is critical to patient monitoring"The process of checking the task over time for ‘quality control’ and the adjustment of behavior" (Stuss, 2009, p. 9-10)
(Rowley & Fielding, 1991). Thus, it is recommended that the inexperienced examiner be supervised by an expert when completing the GCS.

Alternative form of the GCS:

The GCS cannot be used with children, especially below the age of 36 months. This is due to the verbal performance component which is likely to be poor in even a healthy child. Thus, the Pediatric Glasgow Coma Scale (Reilly, Simpson, Sprod, & Thomas, 1988) was developed as an alternative to the GCS.

The Pediatric Glasgow Coma Scale can be obtained at the following website:

https://www.mdcalc.com/pediatric-glasgow-coma-scale-pgcs

Client suitability

Can be used with:

The GCS can be used with clients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More. However, the National Institutes of Health StrokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More Scale (NIHSS), developed specifically for use with a strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More population may be a more useful assessment of consciousness in this population.

Should not be used with:

• Clients with dysphasiaImpaired speech with difficulty or inability to put words in their proper order. This disorder affects the power of expression (speech, writing or signs) or loss of the power of comprehension (spoken or written language). More severe forms of dysphasia are called aphasia.
  , aphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury.
  An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada), and clients who are intubated will have a reduced score on the verbal response scale resulting in a reduced total GCS score but a normal level of consciousness. This should be taken into account when interpreting the GCS results in these individuals. Although it has been suggested that the verbal score be omitted in these clients, and an 8-level (3 to 10) modified GCS be used (Prasad, 1996; Prasad & Menon, 1998), the results of a larger study has suggested that the verbal subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
  still be included because it adds important prognostic information (Weir, Bradford, & Lees, 2003).
• In clients with hemiparesis, ensure that the motor scale is being applied to the less affected arm so that a “best” response can be obtained.
• The GCS should be administered prior to administration of a sedative or paralytic agent, or after these drugs have been metabolized. Airway, breathing, and circulation should be assessed and stabilized prior to administering the GCS.

In what languages is the measure available?

The GCS has been translated into Chinese and is available online at the following
website: http://www.coma.ulg.ac.be/medical/acute.html

Summary

What does the tool measure?	To describe the depth and duration of impaired consciousness or coma.
What types of clients can the tool be used for?	The GCS can be used with individuals with traumatic brain injury, cerebrovascular events, nontraumatic coma, cardiac arrest, and toxic ingestions.
Is this a screeningTesting for disease in people without symptoms. or assessment tool?	Assessment
Time to administer	Not reported.
Versions	Pediatric Glasgow Coma Scale
Other Languages	Chinese
Measurement Properties
ReliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of “true” variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to “noise” in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .	Internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. More: One study examined the internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. More of the GCS and reported excellent internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. More. Inter-rater: Two studies examined the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept. of the GCS using kappa statistics. One study reported adequate inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept. and the other reported excellent inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept. for all three GCS subscales.
ValidityThe degree to which an assessment measures what it is supposed to measure.	Criterion: Predictive: Three studies examined the predictive validityA form of criterion validity that examines a measure’s ability to predict some subsequent event. Example: can the Berg Balance Scale predict falls over the following 6 weeks? The criterion standard in this example would be whether the patient fell over the next 6 weeks. of the GCS. One reported that the GCS adequately predicted strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More mortality. One study reported that the total GCS score predicted acute mortality with 87% accuracy using just the Best eye response and Best motor response subscales, and with 88% accuracy using all three subscales. One study reported that the GCS was able to predict both 2-week mortality and 3-month recovery from strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More. Construct: Convergent: One study examined the convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other. of the GCS with the 60-Second Test (SST) and reported an excellent correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation. using Spearman’s rho.
Floor/Ceiling Effects	No studies have examined floor/ceiling effects of the GCS in patients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More.
SensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also “Specificity.” /Specificity	Not reported.
Does the tool detect change in patients?	One study examined the responsivenessThe ability of an instrument to detect clinically important change over time. of the GCS and reported that it had poor sensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also “Specificity.” to change.
Acceptability	Caution should be used in interpreting the scores of intubated clients, or clients with dysphasiaImpaired speech with difficulty or inability to put words in their proper order. This disorder affects the power of expression (speech, writing or signs) or loss of the power of comprehension (spoken or written language). More severe forms of dysphasia are called aphasia. or aphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury. An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada).
Feasibility	The GCS is a short measure that requires no additional equipment. Although training is not required, it is recommended as the measure is more reliable when completed by an experienced clinician. The scale is simple to score and cutoffs are well established in this measure.
How to obtain the tool?	The GCS is available free online from the following website: http://www.strokecenter.org/professionals/stroke-diagnosis/stroke-assessment-scales/

Psychometric Properties

Overview

We conducted a literature search to identify all relevant publications on the psychometric properties of the GCS in individuals with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More. We identified only three studies specifically examining the GCS in strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More (Weir et al., 2003; Prasad & Menon, 1998; Weingarten, Bolus, Riedinger, Maldonado, Stein, & Ellrodt, 1990). Thus, in this review we will present psychometric data from studies examining neurological patients that include patients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More.

Floor/Ceiling Effects

Not reported.

Reliability

Internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. More:
Mayer, Dennis, Peery, Fitsimmons, Du, Bernardini, Commichau, et al. (2003) examined the internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. More of the GCS in 171 patients in the neurointensive care unit. Cronbach’s alpha was found to be excellent (alpha = 0.83).

Test-retest:
Not reported.

Inter-rater:
Gill, Reiley, and Green (2004) examined the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the GCS in 116 emergency department patients with various diagnoses (10 clients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More, 9% of the sample). Two attending emergency physicians independently assessed the GCS within 5 minutes of each other while blinded to each other’s scores. Kappa statistics were calculated for each of the GCS subtests and the total score. Best eye response had adequate inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
(weighted k = 0.72) as did Best verbal response (weighted k = 0.48) and Best motor response (weighted k = 0.40). The agreement percentage for total GCS was 32% (Kendall’s T-b = 0.74; Spearman rho = 0.86; Spearman rho2 = 75%). Agreement percentage for GCS Best eye response was 74% (T-b = 0.72; Spearman rho = 0.76; Spearman rho2 = 57%), verbal 55% (T-b = 0.59; Spearman rho = 0.67; Spearman rho2 = 44%), and motor 72% (T-b = 0.74; Spearman rho = 0.81; Spearman rho2 = 65%).

Mayer et al. (2003) examined the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the CGS in 64 patients in the neurointensive care unit. The GCS was administered by 2 or 3 examiners within 5 to 10 minutes of each other. Examiners were blinded to each other’s scores. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
was excellent for the total GCS (weighted k = 0.91), Best visual response (weighted k = 0.86), Best motor response (weighted k = 0.91) and Best verbal response (weighted kappa = 0.76).

Validity

Content:

Not available.

Criterion:

Concurrent:
No gold standardA measurement that is widely accepted as being the best available to measure a construct.
exists against which to compare the GCS.

Predictive:
Weingarten et al. (1990) examined whether the GCS was as accurate in predicting strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More mortality as APACHE II (Knaus, Draper, Wagner, & Zimmerman, 1985), a scale that consists of the GCS score plus 11 other physiological variables, age, and a chronic health evaluation. 246 patients hospitalized with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More, including 49 oversampled mortalities were included in the study. The GCS was found to adequately predict strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More mortality, and was found to be as accurate as the APACHE II score in predicting strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More mortality with the oversampled mortalities (r = -0.50 and r = 0.50, respectively) and after excluding the oversampled mortalities (r = -0.40 and r = 0.39, respectively).

Prasad and Menon (1998) compared the predictive accuracy of three alternative strategies for verbal scoring in 275 patients with acute strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More who were either intubated or had dysphasiaImpaired speech with difficulty or inability to put words in their proper order. This disorder affects the power of expression (speech, writing or signs) or loss of the power of comprehension (spoken or written language). More severe forms of dysphasia are called aphasia.
. The total GCS score predicted acute mortality with 87% accuracy using just the Best eye response and Best motor response subscales, versus 88% accuracy with all three subscales. Thus, the authors concluded that the verbal subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
could be excluded from the total GCS score without loss of predictive value in clients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More.

Weir, Bradford, and Lees (2002) examined the ability of the GCS to predict 2-week mortality and 3-month recovery (survival, living at home) in a large cohort of individuals with acute strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More. The results of 1217 patients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More (including 349 patients with dysphagiaDifficulty, discomfort or pain in swallowing due to problems in nerve or muscle control. It is common in patients who have had a stroke. Dysphagia ranges from slight discomfort to complete inability to swallow. Dysphagia may compromise nutrition and hydration and may lead to aspiration pneumonia and dehydration.
) were analyzed. Area under the receiver operating curve (AUC) was used by the authors to compare versions of the GCS. The results of the AUC calculations indicated that the total GCS score had a greater AUC than the GCS without the verbal score for predicting 2-week mortality. This was apparent for all participants together (AUC = 0.78 for the total GCS score; 0.76 for the GCS without the verbal score) and for only the participants with dysphasiaImpaired speech with difficulty or inability to put words in their proper order. This disorder affects the power of expression (speech, writing or signs) or loss of the power of comprehension (spoken or written language). More severe forms of dysphasia are called aphasia.
(AUC = 0.72 for total GCS score; 0.71 for the GCS without the verbal score). Similarly, the total GCS score was also better than the GCS without the verbal score for predicting 3-month recovery in all participants (AUC = 0.71 for the total GCS score; 0.67 for the GCS without the verbal score) and in participants with dysphasiaImpaired speech with difficulty or inability to put words in their proper order. This disorder affects the power of expression (speech, writing or signs) or loss of the power of comprehension (spoken or written language). More severe forms of dysphasia are called aphasia.
only (AUC = 0.74 for the total GCS score; 0.70 for the GCS without the verbal score). These results suggest that in contrast to the findings by Prasad and Menon (1998), the verbal subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
should not be excluded in clients with dysphasiaImpaired speech with difficulty or inability to put words in their proper order. This disorder affects the power of expression (speech, writing or signs) or loss of the power of comprehension (spoken or written language). More severe forms of dysphasia are called aphasia.
since it adds important prognostic information. These results also suggest that the total GCS score can predict early mortality and 3-month recovery and that the GCS better predicted the outcome of early mortality than the outcome of 3-month recovery.

Construct:

Convergent/Discriminant:
Mayer et al. (2003) examined the convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the GCS with the 60-Second Test (SST) in 171 patients in the neurointensive care unit using Spearman’s rho. The GCS and SST had an excellent correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
(Spearman’s rho = 0.72).

Known groups:
Not examined.

Responsiveness

Mayer et al. (2003) examined the responsivenessThe ability of an instrument to detect clinically important change over time.
of the GCS in 36 patients in the neurointensive care unit. Patients underwent a baseline testing, followed by 1-13 follow-up encounters performed every 12-24 hours. The neurologistThis team member is responsible for “the diagnostic evaluation, medical treatment, prevention of stroke recurrence, patient and family education, staff and trainee education, research, program evaluation.”(Suggested by Philips et al, 2002)
performed a brief standardized examination and provided a global clinical impression of change in level of consciousness (better, the same, or worse) compared with the prior encounter. According to the global impression of a neurologistThis team member is responsible for “the diagnostic evaluation, medical treatment, prevention of stroke recurrence, patient and family education, staff and trainee education, research, program evaluation.”(Suggested by Philips et al, 2002)
, patients improved in 24% and worsened in 26% of the 187 follow-up examinations. SensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also “Specificity.”
of the GCS to these changes in level of consciousness was poor (46%).

References

• Gill, M. R., Reiley, D. G., & Green, S. M. (2004). Interrater Reliability of Glasgow Coma Scale Scores in the Emergency Department. Ann Emerg Med, 43, 215-223.
• Knaus, W. A., Draper, E. A., Wagner, D. P., & Zimmerman, J. E. (1985). APACHE II: A severity of disease classification system. Crit Care Med, 13, 818-829.
• Lenfant, F., Sobraques, P., Nicolas, F., Combes, J. C., Honnart, D., Freysz, M. (1997). Use of Glasgow Coma Scale by anesthesia and intensive care internists in brain injured patients. Ann Fr Anesth Reanim, 16, 239-243.
• Mayer, S. A., Dennis, L. J., Peery, S., Fitsimmons, B. -F., Bernardini, G. L., Commichau, C., Eldaief. (2003). Quantification of lethargy in the neuro-ICU: The 60-Second Test, Neurology, 61(4), 543-545.
• Prasad, K. (1996). The Glasgow Coma Scale: A critical appraisal of its clinimetric properties. Journal of Clinical Epidemiology, 49(7), 755-763.
• Prasad, K. & Menon, G. R. (1998). Comparison of three strategies of verbal scoring of the Glasgow Coma Scale in patients with stroke. Cerebrovasc Dis, 8, 79-85.
• Reilly, P., Simpson, D., Sprod, R., Thomas, L. (1988). Assessing the conscious level in infants and young children: A paediatric version of the Glasgow Coma Scale.Child’s Nerv Syst, 4(1), 30-33.
• Rowley, G, Fielding, R. (1991). Reliability and accuracy of the Glasgow Coma Scale with experienced and inexperienced users. Lancet, 337, 535-538.
• Teasdale, G., Jennett, B. (1974). Assessment of coma and impaired consciousness. A practical scale. The Lancet, 2(7872), 81-84.
• Teasdale, G. M., & Jennett, B. (1976). Assessment and prognosis of coma after head injury. Acta Neurochir (Wien), 34, 45-55.
• Warlow, C. P., Dennis, M. S., van Gijn, D., Hankey, G. J., Sandercock, P., Bamford, J. M., et al. (2001). Stroke: A Practical Guide to Management (2nd ed.). Malden, MA: Blackwell Publishing.
• Weir, C. J., Bradford, A. P., & Lees, K. R. (2003). The prognostic value of the components of the Glasgow Coma Scale following acute stroke. Q J Med, 96, 67-74.

See the measure

How to obtain the GCS:

The GCS is available at the following website:
http://www.strokecenter.org/trials/scales/glasgow_coma.html