The significance of intolerance of uncertainty in generalized anxiety disorder: possible models and development of a German version of the intolerance of uncertainty scale

Background: Intolerance of uncertainty (IU) has recently been discussed as an important factor the development and maintenance of generalized anxiety disorder (GAD). So far, an adequate instrument to assess IU in German is missing. Objective: What are the psychometric properties of the German intolerance of uncertainty scale? What is it underlying factor structure? Is it possible to shorten the instrument? Is it possible to replicate the new factor structure in an independent sample? How much variance of worrying (PSWQ) can IU explain? Is it possible to integrate IU with other relevant constructs into a theoretical model of GAD? Methods: The factor structure of the German translation of the IU scale was analyzed in a group of students (N = 682) using exploratory factor analysis. On this basis, a shortened version of the IU scale (IU-18) was developed. The factor structure of this instrument was confirmed in a second independent student sample (N = 540). In order to validate the construct, we calculated a regression model predicting worrying. Results: The new IU-18 scale measures three replicable factors ("reduced ability to act due to IU", "burden due to IU" and "vigilance due to IU"). The subscales "burden" and "vigilance" of the IU-18 scale, four scales of the meta cognitions questionnaire, as well as gender, all significantly predict worrying. Conclusions: IU can be measured reliably. Against the background of these results we present a theoretical model of GAD that integrates IU, metacognitions concerning worrying, and the avoidance theory of worrying.