Reliability and validity of the Korean version of the Scale for the Assessment of Thought, Language, and Communication

Abstract

BACKGROUND: Our study aimed to assess the inter-rater and test-retest reliability, as well as concurrent and convergent validity, of the Korean version of the Scale for the Assessment of Thought, Language, and Communication (TLC scale). METHODS: The factor solutions and psychometric properties of the Korean version of the TLC scale were evaluated among 167 schizophrenia inpatients (study subjects) at two sites in South Korea. Using Pearson's correlation, the concurrent and convergent validities of each of the factor solutions were represented by the correlations with the scores on the Clinical Language Disorder Rating Scale, Brief Psychiatric Rating Scale, Young Mania Rating Scale, and Calgary Depression Scale. Using receiver operating characteristics curves, the optimal cut-off score for the Korean version of the TLC scale to distinguish between study subjects with and without disorganized speech, was identified. RESULTS: The results showed that the Korean version of the TLC scale has a three-factor solution: fluent disorganization, speech emptiness, and speech peculiarity. In addition, the interrater reliability of the Korean version of the TLC scale was moderately good (intraclass correlation coefficient = 0.51) and its test-retest reliability was very good (Pearson's correlation coefficient = 0.94). For detecting the current presence of disorganized speech, the optimal cut-off total score on the TLC scale was proposed to be 8 points (sensitivity = 88.1%; specificity = 82.9%). LIMITATIONS: Psychometric tools covering cognitive functions were not used in our study. CONCLUSIONS: The Korean version of the TLC scale is a promising psychometric method for examining formal thought disorder (FTD) and disorganized speech in schizophrenia patients.