Should uncontrollable worry be removed from the definition of GAD? A test of incremental validity.

In its current instantiation in DSM-IV, a diagnosis of generalized anxiety disorder (GAD) requires the presence of excessive and uncontrollable worry. It has been proposed that the uncontrollability criterion be removed from future editions of the DSM, primarily on the basis of empirical and conceptual overlap between excessiveness and uncontrollability and a relative lack of research on uncontrollability. However, no research has directly investigated the incremental validity of the uncontrollability criterion-that is, the extent to which uncontrollability predicts important clinical information over and above excessiveness. This question was examined in a community sample of 126 adults diagnosed with GAD. After controlling for excessiveness, uncontrollability explained a significant proportion of additional variance in a variety of relevant clinical measures, including GAD severity, clinician-rated anxiety, number and severity of comorbid disorders, and use of psychotropic medication and psychotherapy. The results remained statistically significant even when other features of GAD were controlled. By contrast, excessiveness did not significantly predict any clinical measure over and above uncontrollability. These findings suggest that uncontrollability contributes to the validity of the GAD diagnosis and should be retained as a core feature of pathological worry.