An examination of the intolerance of uncertainty scale-short version (IUS−12) in Spanish adolescents: alternative models, versions, and their associations on psychological distress, experiential avoidance, and risk of suicide

Intolerance of uncertainty (IU) is a key transdiagnostic risk factor, and the IUS-12 is the most commonly used measure. However, the structural validity of the IUS-12 remains debated and unexplored among adolescents. Using a sample of 966 adolescents, we tested alternative factor models of the IUS-12 using confirmatory factor analysis, confirmatory bifactor analysis, and exploratory structural equation modeling. Structural equation modeling was used to test criterion validity regarding psychological distress, experiential avoidance, and suicide risk. The unidimensional model showed poor fit. While the confirmatory bifactor model showed superior fit indices, it presented serious validity threats. These results fail to support the unidimensionality of IU. Conversely, the ESEM model with two latent factors (Prospective and Inhibitory IU) provided the most valid representation, accounting for item complexity and revealing that Inhibitory IU drove the association with maladaptive outcomes. Additionally, content analysis revealed conceptual weaknesses in several items, prompting the proposal of a refined IUS-6. The ESEM framework is recommended for the IUS-12 to capture the complexity of IU. However, as its complexity can limit its operability, the parsimonious IUS-6 may be preferable for specific purposes. Findings suggest that behavioral inhibition is the critical target for intervention in adolescents.