APPROPRIATE USE OF THE GLASGOW COMA SCALE IN INTUBATED PATIENTS - A LINEAR-REGRESSION PREDICTION OF THE GLASGOW VERBAL SCORE FROM THE GLASGOW EYE AND MOTOR SCORES

The Glasgow Coma Scale (GCS) has been shown to be a valuable tool in a ssessing the neurologic and physiologic status of critically ill patie nts. Unfortunately, the GCS requires assessment of the verbal response of the patient and this can be blocked by intubation. The purpose of this study was to assess the ability of a regression model based upon the eye and motor components of the GCS to accurately predict the verb al response of the GCS. The primary hypothesis was that the verbal res ponse could be derived from the motor and eye responses of the GCS. Me thods: Data were collected prospectively in an intensive care unit com puter data base, Patients were divided into training and test data set s. Linear regression was used to derive a model of verbal score from t he motor and eye scores of the GCS in the training data set. Correlati on between the actual and the predicted verbal scores was calculated. Results: A total of 2,521 GCS assessments were available for analysis. The second order multiple regression model was an accurate predictor of the verbal score (Pearson's Correlation r = 0.9, R(2) = 0.8,p = 0.0 001) in 1,463 observations in the training data set. Second Order Mult iple Regression Model: Estimated GCS Verbal = (2.3976) + [GCS Motor x (-0.9253)] + [GCS Eye x (-0.9214)] + [(GCS Motor)(2) x (0.2208)] + [(G CS Eye)(2) x (0.2318)] where r = 0.91, R(2) = 0.83, and p = 0.0001. Th e accuracy of this model was confirmed by comparing the predicted verb al score to the actual verbal score in the test data set (n = 736, r = 0.92, R(2) = 0.85, p = 0.0001) Conclusions: The GCS is a useful tool in the intensive care unit and a critical part of the APACHE II assess ment of patient acuity. GCS has been shown to be a useful tool in its own right as a predictor of outcome in the critically ill. Its use is limited with intubation. (See Segatore M, Way C: Heart Lung 21:548, 19 92; and Lieh-Lai MW, Theodorou AA, Sarnaik AP, et al: J Pediatr 120:19 5,1992.) The present study demonstrates that a relatively simple regre ssion model can use the eve and motor components of the GCS to predict the expected verbal component of the GCS, thus allowing the calculati on of the GCS sum score in intubated patients.