Reliability and validity of the Disability Rating Scale and the Levels of Cognitive Functioning Scale in monitoring recovery from severe head injury.

The Disability Rating Scale (DRS) and the Levels of Cognitive Functioning Scale (LCFS) are both widely used to monitor recovery from head injury, despite the total lack of published research on the reliability and validity of the LCFS, and the fragmented and incomplete reports on these characteristics of the DRS. Forty head-injured inpatients were evaluated with the DRS and LCFS four times weekly throughout their rehabilitation hospitalization. The DRS and LCFS were compared in terms of how consistently ratings could be made by different raters, how stable those ratings were from day to day, their relative correlation with Stover Zeiger (S-Z) ratings collected concurrently at admission, and with S-Z, Glasgow Outcome Scale (GOS), and Expanded GOS (EGOS) ratings collected concurrently at discharge, and finally in the ability of admission DRS and LCFS scores to predict discharge ratings on the S-Z, GOS, and EGOS. Results suggest that both scales possess significant degrees of test-retest and interrater reliabilities, and of concurrent and predictive validities, but the DRS surpasses the LCFS in nearly every regard. These results offer psychometric justification favoring the use of the DRS for monitoring recovery from head injury.