Psychometric properties of the Generalized Anxiety Disorder 7-item scale in youth: Screening in a primary care sample

BACKGROUND: Anxiety disorders in youth are frequently underdiagnosed and untreated, partly due to a lack of screening in primary care. The Generalized Anxiety Disorder 7-item (GAD-7) scale is a brief self-report measure designed to screen for anxiety in primary care settings. However, little is known about the psychometrics of this scale with adolescents. METHODS: Participants included 579 youth age 11 to 17 years who received screening for depression in a primary care setting through a web-based application, VitalSign6, over a 4-year period. Psychometric analyses were completed based on classical test theory (CTT) and item response theory (IRT). RESULTS: Using CTT and IRT methods, the GAD-7 has a unidimensional structure with good psychometric properties. In addition, the IRT analysis demonstrates that items 1 and 2 are strongly associated with the total score, and thus are good choices as a 2-item screening tool. Convergent validity was demonstrated, with high correlations between the GAD-7 and other measures of anxiety, and discriminant validity was also demonstrated, with low correlations to measures of other psychological states. CONCLUSIONS: This psychometric evaluation of the GAD-7 provides support for the utility of this measure with adolescents. The GAD-2 is a good estimate of GAD-7 total score.