Dokuz Eylül thought disorder assessment scale: A reliability and validity study

Available thought disorder (TD) scales used in schizophrenia research are limited to positive and negative TD dimensions and do not adequately assess the full spectrum of TD. Moreover, TD evaluation scales are often time-consuming, relying on diverse visuals, forms, or lengthy structured interviews. Therefore, a new TD scale that can be administered during routine psychiatric interviews and that evaluates TD more comprehensively is needed. This study aimed to develop a more complete TD scale for assessing TD in patients with schizophrenia during psychiatric interviews.

This study examines the reliability and validity of the new Dokuz Eylül Thought Disorder Scale (DEU-TDS). The study included 130 schizophrenia patients and 35 controls. Reliability was assessed via Cronbach's α, test-retest, and inter-rater reliability. Validity was evaluated through exploratory factor analysis - which tested a theoretically hypothesised three-factor structure comprising Positive TD, Negative TD, and Pragmatic Comprehension Disorder - and correlations with established scales.

Inter-rater reliability was excellent (Pearson r = 0.987 across two raters in 34 patients; ICC = 0.985 in a five-rater concordance analysis). Three factors (positive, negative, pragmatic TD) accounted for 73.2% variance. Strong correlations with PANSS, SAPS, and TLI were found.

The DEU-TDS demonstrates promising psychometric properties as a multidimensional tool for evaluating TD in patients with schizophrenia, though replication in larger and more diverse samples is needed before definitive conclusions about its clinical utility can be drawn.