CHAPTER 31: JFK COMA RECOVERY SCALE-REVISED (CRS-R)

Description

The JFK Coma Recovery Scale (CRS) by Giacino et al. (1991) is a standardized instrument designed to measure the neurobehavioral function in persons with disorders of consciousness and was developed to more fully characterize and monitor patients functioning at level I (generalized response) to level IV (confused-agitated response) on the Rancho Los Amigos Levels of Cognitive Functioning Scale (Giacino & Kalmar, 2004; Giacino, Kalmar, & Whyte, 2004). Revised in 2005 by Giacino and Kalmar, modifications included the addition of new items, merging of items found to be statistically similar in terms of their ability to differentiate patients’ neuro-behavioral status, the deletion of some items demonstrating poor fit, and renaming of items to provide better face validity for the behaviors they represent. The current CRS-Revised (CRS-R) comprises 6 subscales that quantify such things as auditory function and visual function where during assessment the individual is graded on their ability to react to specific stimuli such as localization to sound, object recognition, localization to noxious stimulation, oral reflexive movement, and attention (Wilde, Whiteneck, et al., 2010). There are a total of 23 scoring choices and each of the 6 subscales uses a Likert scale where scores can range from 0 to 6. The lowest score on each subscale typically represents basic reflexive activity while the highest items suggesting cognitively mediated behaviors (Giacino & Kalmar, 2005). The assessment takes approximately 10 minutes to complete where higher scores suggest increased cerebral ability/activity.

Psychometrics

A convenience sample of 80 subjects in a specialized coma intervention program found inter-rater reliability to be high (r = 0.84) with the lowest score for the visual subtest at 0.80 (Giacino et al., 2004). Test-retest reliability for the total score was also high (r = 0.94) with the lowest reliability for the oromotor/verbal subscale at 0.70, while total scores on the CRS-R were shown to correlate well with total scores on the original CRS at 0.97 as well as with the Disability Rating Scale (0.90) (Giacino et al., 2004). A study by Kalmar and Giacino (2005) of 20 subjects determined inter-rater reliability to be r = 0.84, test–retest reliability to be r = 0.94, and internal consistency to be α = 0.83. A convenience sample of 31 subjects found that inter-rater and test-retest reliabilities had a range of r = 0.65 to 0.82 with 2 raters over a 3-day period (Lovstad et al., 2010). A study of 44 patients who were clinically diagnosed as being in a vegetative state (VS), the CRS-R detected signs of awareness in 18 patients (41%) suggesting that they were actually in a minimally conscious state not VS (Schnakers et al., 2009). Misdiagnosis was greater for chronic patients than for acute patients and the behavioral signs detected in those misdiagnosed primarily included purposeful eye movements such as visual fixation and visual pursuit (Schnakers et al., 2009).

Advantages

The CRS-R is a relatively brief/simple assessment to administer. There is a fair amount of research in support of its use in clinical practice and it is an excellent way to track change in a person’s consciousness level over time. The CRS-R is based on the first 4 levels of the Rancho Los Amigos Levels of Cognitive Functioning Scale thereby making it more sensitive to a person’s level of consciousness across the levels pertaining to generalized response up to the confused–agitated response. No certifications are required and administration time is less than 10 minutes. CRS-R has also been translated to 11 languages suggesting it is a culturally relevant outcome measure.

Disadvantages

The detection of slight degrees of brain activity (i.e., an auditory startle or visual startle) required at the lowest levels of the assessment may be difficult for some individuals, which can lead to misdiagnosis or poor inter-rater reliability between clinicians.

Administration

During assessment, the client is presented with a stimuli and is scored on their ability to perform or react to that stimuli which typically occurs based on their level of consciousness. The assessment comprises 6 subtests that gauge a person’s (1) auditory, (2) visual, (3) motor, (4) oromotor/verbal, (5) communication, and (6) arousal functioning. Each subtest uses a variable Likert scale ranging from 0 to 6, in which higher scores indicate increasing levels of consciousness. Total scores range from 0 to 23. Example items include eye movement commands where the clinician asks the subject to look at object #1 then look at object #2, as well as limb movement commands in which the clinician asks the subject to take object #1 and #2 and then kick object #1 and #2.

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