Prognosis after severe head injury.

Prognosis depends on establishing a relationship between the patient's state in the early stages and the ultimate outcome. Both the severity of the initial damage (including early complications) and the degree of recovery need to be defined, but practical and statistical considerations impose a limit on the number of variables which can be manipulated. Variables chosen should be those likely to be relevant, and pilot studies are more reliable than intuition in indicating which items should be included. Data chosen should be of a kind likely to be readily available for most patients and should not therefore depend on complex laboratory investigation. The most reliable indicant of initial severity appears to be the depth and duration of coma or altered consciousness, and a scale has been devised for measuring these. Measures of outcome should include separate assessment of mental and physical disability as well as the overall social consequence of the brain damage. Prognosis should be expressed as the probability (mathematically expressed) that a patient will reach certain defined outcome categories, five of which are recognized in the present study. Predictions should begin only after initial resuscitative measures are complete (say six hours after ictus); they need not be limited to the early stages but can include estimates of the degree of further improvement expected in the light of progress in the early weeks after injuries. New methods of management cannot be critically assessed unless factors influencing prognosis are reliably identified and can be matched in comparative patient groups. An estimate of prognosis is also required for the selection of patients for intensive treatment, both in the acute and in the rehabilitation stage. Without such data there is a tendency to deploy an unduly high proportion of scarce resources on patients who have little prospect of recovery; this may deny the best chance of recovery to patients with severe, but less overwhelming, brain damage.