Furthermore a consensus as to how to categorise or define levels of disability was lacking. An attempt to resolve this was published in the Lancet by Bryan Jennett and Sir Michael Bond, professors at the University of Glasgow, in their paper entitled "Assessment of outcome after severe brain damage". The aim of the Glasgow Outcome Scale was to use a limited number of exclusive categories that summarized the social capacity of patients rather than a prescribed list of disabilities.

Use of five categories was advocated at six months survival: 5. Good recovery when the patient resumes normal life and work but may suffer minor neuropsychological deficits; 4. Moderate disability when patients are able to independently care for themselves but may not resume work because of partial paralysis or difficulties with speech; 3. Severe disability when a patient is conscious but dependent upon another person for daily support because of a mental or physical disability; 2. Vegetative state when the patient shows unawareness with only reflex responses and periods of spontaneous eye opening usually assessed at one month after brain insult, and 1. Death.

These categories have proved invaluable in research comparing outcome in groups of patients. The use of narrower categories has subsequently been suggested in following individual patients.