New coma scale offers option to Glasgow
Ease of use, accurate prediction of mortality touted
Researchers at the Mayo Clinic College of Medicine in Rochester, NY, have created a new coma scale they say is superior to the commonly used Glasgow Coma Scale (GSC). The new scale, called the FOUR (Full Outline of UnResponsiveness) Score, is detailed in a recent article in the Annals of Neurology.1
The "four" in the title refers to the number of components in the test — eye response, motor response, brainstem reflexes, and respiration — and the maximum score that can be given in each component (ranked from 0-4, with 0 being the lowest score).
"There are major limitations with GCS," including the failure to assess the verbal score of intubated patients and the inability to test brainstem reflexes, says Eelco F.M. Wijdicks, MD, professor of neurology at Mayo Medical School and the lead author of the paper. "The findings do not really represent the neurologic status of the patient."
Alan Katz, MD, FACEP, assistant chair of the Department of Emergency Medicine at New York Hospital Queens in Flushing, agrees. "In general, the GCS is really being used beyond what it was designed to be used for," he says. "In the ’70s, when it first came out, we were supposed to look at patients for six hours post-injury; now it is used for points beyond that," Katz says. It has very low interrelator reliability, which indicates the extent of agreement among those rating that which is being studied. "Besides that, you can have the same score on your desk as would a [healthy] live person, or a drunk, or a severely injured person," Katz says.
New scale’s advantages
The GCS uses only eye response, motor response, and verbal response. Wijdicks says the new scale has added components "to give us a much better idea of how severe the brain damage is and of the expected prognosis of the patient." In addition, he says, his scale is simpler, as four is always the maximal number, while GCS has different numbers for different components.
"The eye components [of our scale], instead of only addressing eye opening, adds visual tracking, which would identify not only locked-in syndrome, but also a persistent vegetative state," Wijdicks says.
The most significant findings of his study include the fact that while the scale is more complex, it is very easily trained and learned, he adds. "The major finding is there is good interobserver agreement between ICU nurses, residents, and intensivists, and it is a better predictor of in-hospital mortality," Wijdicks says. For a GCS of 3, they found more than 20 scores in their new rating system that corresponded to that, "so we could identify many more subtleties, and we had a 20% better prediction of in-hospital mortality," he says. "That’s expected because our scale looks at the important component of brainstem reflexes, including signs of increased intracranial pressure — and the need to do something about it — and identifies difficulties with breathing."
At press time, Wijdicks said he was going to repeat the study in the ED in the next couple of weeks.
Support not universal
Wijdicks asserts enormous momentum for his scale since the paper was published, and he says several major institutions are adopting it. These facilities include Akron (OH) General Medical Center, which has just begun to use it in the ED and with Emergency Management Services and has plans to also use it in helicopter transport.
John Duldner, MD, FACEP, director of research in the Department of Emergency Medicine at Akron, says, "The GSC is a fine tool, but in certain situations, such as when the patient is intubated, you lose one-third of the value of the GCS [i.e., the verbal score] and you need another tool. Plus, if the patients are transferred to the ICU, the staff there will be able to repeat the test over time and do a numerical timeline of the patient’s condition."
Katz, however, has his doubts about how helpful the scale would be. In general, four components are harder to remember than three, and very few ED physicians even know the GCS components, he says. "Would you even remember four minutes after this exam if this was a 3 or if this was a 4? They are proud to say their interrater reliability is the same as that for GCS, but in multiple studies, I’ve seen no interrater reliability in GCS."
He does concede that having a measure of brainstem reflexes makes the FOUR Score more helpful than the GCS and that it makes sense that this measure helps more accurately predict in-hospital mortality. However, "you could just look at brain stem indicators and get rid of everything else," he says.
Wijdicks maintains, however, that this scale would give ED managers a more comprehensive patient evaluation. No scale replaces a neurological exam, he concedes, "but we took the bare essentials and put them in a scale while maintaining simplicity. That simplicity is its most important feature."
Katz strongly disagrees. "This is very difficult to memorize or to do," he asserts. "It will require a little bit more work to get anyone even on the same page, and in EDs it will be horrific."
Reference
- Wijdicks EFM, Bamlet WR, Maramattom BV. Validation of a new coma scale: The FOUR score. Ann Neurol 2005; 58(4):585-593.
Sources
For more information on coma scales, contact:
- John Duldner, MD, FACEP, Director of Research, Department of Emergency Medicine, Akron General Medical Center, 400 Wabash Ave., Akron, OH 44307. Phone: (330) 344-2044.
- Alan Katz, MD, FACEP, Assistant Chair, Department of Emergency Medicine, New York Hospital Queens, 56-45 Main St., Flushing, NY. Phone: (718) 670-1231.
- Eelco F.M. Wijdicks, MD, Professor of Neurology, Mayo Medical School, Rochester, MN. E-mail: [email protected].
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