The Brain Trauma Foundation. The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Glasgow coma scale score.

When considering the use of the initial GCS for prognosis, the two most important problems are the reliability of the initial measurement, and its lack of precision for prediction of a good outcome if the initial GCS is low. If the initial GCS is reliably obtained and not tainted by prehospital medications or intubation, approximately 20% of the patients with the worst initial GCS will survive and 8-10% will have a functional survival (GOS 4-5).