Czech adaptation of the CORE-OM: Selected psychometric properties

Objectives. The aim of the study was to adapt the CORE-OM measure to the Czech context and evaluate its psychometric properties. Sample and setting. CORE-OM, RSES, and SCL-90 were administered to 375 patients from four psychotherapy clinics (a clinical sample). Further, the first two measures were administered to 233 respondents from the general population (a non-clinical sample). Statistical analysis. The questionnaire structure was explored through an exploratory factor analysis, concurrent validity assessed using correlation with SCL-90 and RSES, and internal consistency using Cronbach's alpha. The difference between the clinical and the non-clinical samples was determined by the Mann-Whitney test and sensitivity to change was assessed by the Wilcoxon signed-rank test. Results. The factor analysis revealed a two-factor structure. However, the factor solution for the clinical and the non-clinical samples dif fered. In the clinical sample, the internal consistency of the Total Score was alpha = 0,933, the Total Score correlated r(s) = 0,80 with GSI SCL90 and r(s) = -0,51 with RSES. The measure successfully differentiated between the clinical and the non-clinical samples. Using the Total Score, the clinical cutoff score had a value of c = 1,349 and the Reliable Change Index had a value of RCI = 0,445. The sensitivity to psychotherapy change was adequate (r similar to -0,35 to -0,50 for individual clinics). Study limitation. The data was obtained through casual sampling and did not include outpatients or respondents with a psychotic disorder. Evaluation of sensitivity to change was based solely on self-report measures.