Introduction: Repetitive negative thinking (RNT) is reported in a wide variety of emotional disorders, although it is most often associated with either depression or anxiety disorders, assessed as symptoms of rumination and worry. Early detection of indicators for RNT across disorders is needed. To this end we explored the psychometric properties of a transdiagnostic measure, i.e., the Swedish version of the brief Repetitive Thinking Questionnaire (RTQ-10), in adults (n = 674, age: 18 years or older). Methods: Participants completed an online battery of questionnaires measuring RNT, anxiety, depression and levels of positive and negative affect, satisfaction with life, metacognitive beliefs, and sick leave. Reliability and validity were evaluated with Cronbach's alpha, item and scale correlations, factor analysis (including multigroup analysis), and multiple linear regression analysis. Principal component analysis and exploratory factor analysis were first carried out to identify the number of latent factors. Confirmatory factor analysis was then used to assess the model fit of a single latent factor. Results: Analyses supported a single-factor solution. Results showed that the reliability was excellent. The single-factor model was robust, except across levels of distress that did not support scalar invariance. Negative metacognitive beliefs, negative affect, and anxiety were strong covariates demonstrating convergent validity. Negative and weaker correlations with life satisfaction, positive affect, and physical symptoms contributed to the discriminant validity. Conclusion: This study showed that the instrument is robust in a population with various degrees of affective symptoms and distress. These results provide additional psychometric support for the RTQ-10 as a transdiagnostic measure. It can be administered online to assess RNT as a risk factor for emotional disorders.
