Psychometric properties of the Intolerance of Uncertainty Scale-12 in generalized anxiety disorder: Assessment of factor structure, measurement properties and clinical utility

•First study to assess the factor structure of the IUS-12 in a sample with GAD.•Bifactor type (two-factor testlet) model demonstrated best fit for the IUS-12.•Only the IUS-12 total score should be interpreted.•The IUS-12 demonstrated good validity and reliability.•The IUS-12 showed responsivity to treatment and clinical utility.