A comparison of the dimensionality of the Hamilton Rating Scale for anxiety and the DSM-5 Anxious-Distress Specifier Interview

The Hamilton Rating Scale for Anxiety (HAM-A) is one of the most widely used measures for assessing anxiety in research settings. However, it has been criticized for its inclusion of items that assess depressive symptoms. The DSM-5 Anxious Distress Specifier Interview (DADSI), developed as one assessment tool for measuring anxiety among depressed patients, demonstrates similar validity when compared with the HAM-A. However, its underlying factor structure has never been explored. The goal of the current study, therefore, was to compare the underlying factor structures of the HAM-A and the DADSI among clinically depressed (n = 576) and non-depressed (n = 146) patient samples. While two- and three-factor structures of the HAM-A fit similarly well among patients with a current major depressive episode, the three-factor structure-with anxiety and depressive symptoms forming separate factors-fit best among patients without a current major depressive episode. The DADSI was best represented by a single-factor model in both groups. The DADSI showed stronger associations with anxiety and somatic symptoms than with depressive symptoms of the HAM-A. These findings add to the characterization of the DADSI, and further highlight an important consideration for the use of HAM-A as a measure of anxiety in outcome studies.