Reliability and validity of the dimensional features of generalized anxiety disorder.

The reliability and validity of the dimensional features of generalized anxiety disorder (GAD) were examined in a diverse sample of 508 outpatients with anxiety and mood disorders who underwent two independent administrations of the Anxiety Disorders Interview Schedule for DSM-IV: Lifetime version (ADIS-IV-L; Di Nardo, Brown, & Barlow, 1994). Inter-rater reliability was higher in the full sample than in patients with current GAD. Additionally, the presence of a mood disorder weakened inter-rater reliability. We also explored the unique contribution of excessiveness and uncontrollability of worry to various clinical outcomes and found that excessiveness predicted anxiety, depression, and stress self-report measures, and uncontrollability predicted clinical severity and number of diagnoses. Findings are discussed with regard to their implications for the classification of GAD (e.g., utility of dimension-based assessment to improve the classification of psychological disorders).