The catatonia rating scale I--development, reliability, and use.

The study objective is to present reliability data on the Catatonia Rating Scale (CRS). The CRS is a 21-item clinician-administered rating scale. Items are individually defined and are scored from 0 (absent) to 4 (severe). A definition for each degree of severity is provided for each item. The diagnostic threshold for catatonia is 4 symptoms rated at least 2 (moderate). The CRS requires, at most, 45 minutes to administer. Reliability data were evaluated in a sample of 120 inpatients, 71 of whom were catatonic. Ratings were performed by 4 pairs of raters. Interrater reliability was high (Pearson correlation coefficient = .91 to .99, intraclass correlation coefficient = .94 to .99). Internal consistency was very good (Cronbach's alpha = .8890). Analysis of individual items showed that all were frequently endorsed and occurred across a wide range of severity. The CRS is a reliable rating scale for the diagnosis of catatonia. Advantages of the scale, areas of use, and clinical implications are discussed.