Psychometric Properties of the Korean Version of the Clinical Language Disorder Rating Scale (CLANG)

Objective: Our study aimed to measure inter-rater and test-retest reliability, concurrent and convergent validity, and factor solutions of the Korean version of the Clinical Language Disorder Rating Scale (CLANG). Methods: The Korean version of the CLANG for assessing thought, language, and communication, the Brief Psychiatric Rating Scale, Young Mania Rating Scale, and Calgary Depression Scale for Schizophrenia were used to evaluate language disorder, formal thought disorder, positive and negative symptoms, manic symptoms, and depressive symptoms, respectively, in 167 hospitalized patients with schizophrenia, The factor solution was obtained by the direct oblimin method. A receiver operating characteristic curve was used to find the optimal cut off score for discriminating schizophrenia patients with and without disorganized speech. Results: Inter-rater reliability was considered moderate (intraclass coefficient=0.67, F=3.30, p=0.04), and test-retest reliability was considered high (r=0.94, p<0.001). Five factors, namely, pragmatics, disclosure, production, prosody, and association, were identified. An optimal cut off score of 7 points with 84.5% sensitivity and 81.7% specificity was proposed for distinguishing schizophrenia patients with and without disorganized speech. Conclusion: Our findings suggest that the Korean version of the CLANG is a promising tool for evaluating language disorder in patients with schizophrenia.