Psychometric properties of Eysenck personality questionnaire-revised short scale (EPQ-R/S) in three large Czech cohorts: people with epilepsy, people with neurological and other disorders and non-clinical adults.

PURPOSE: The Czech version of the Eysenck Personality Questionnaire-Revised Short Scale (EPQ-R/S) has not been formally validated. This study examined its psychometric properties across two clinical cohorts and non-clinical subjects. METHODS: The total sample consisted of 2 560 participants: non-clinical adults (n = 382), patients with neurological and other disorders (PWND; n = 576), and patients with epilepsy (PWE; n = 1 602), aged 18-86 years. Internal consistency, item-level performance, and factorial validity were examined. Confirmatory factor analysis (CFA) and exploratory structural equation modelling (ESEM) with target rotation were performed. RESULTS: Extraversion (E) and Neuroticism (N) showed acceptable to good reliability across cohorts (α = 0.79-.85; ω = 0.89-.93). The Lie (L) scale showed lower but mostly acceptable reliability, whereas Psychoticism (P) showed weak item coherence and poor internal consistency, particularly in non-clinical adults and people with epilepsy. The theoretical four-factor CFA model showed poor fit, χ2(1074) = 15005.28, CFI = 0.643, TLI = 0.625, RMSEA = 0.076. A target-rotated ESEM solution was more interpretable but showed mixed fit, χ2(942) = 5198.66, TLI = 0.838, RMSEA = 0.042, RMSR = 0.030. A reduced two-factor CFA model for E and N showed a more coherent structure, χ2(251) = 3296.72, CFI = 0.900, TLI = 0.890, RMSEA = 0.072. Measurement invariance analyses across cohorts and gender supported threshold and loading invariance of this model based on changes in approximate fit indices. Women scored higher on N in both clinical subsamples, whereas no significant gender difference was found in the non-clinical sample. Among people with epilepsy, higher seizure frequency was associated with higher N, longer epilepsy duration with lower E, and monotherapy with lower N compared with polytherapy. N correlated strongly and positively with depressive symptoms and negatively with quality of life, supporting concurrent validity. CONCLUSIONS: The Czech EPQ-R/S E and N scales showed adequate psychometric properties and appear suitable for research and clinical use in neurological and epilepsy populations.