Validation of the geriatric anxiety inventory in a duloxetine clinical trial for elderly adults with generalized anxiety disorder

Background The Generalized Anxiety Inventory (GAI) has been developed for use in the assessment of anxiety symptoms in older adults (≥ 65 years), but previous validation work has not examined the psychometric qualities of the instrument in relation to treatment. The objective of this study was to examine the performance of the GAI for its internal reliability, convergent and divergent validity, and its sensitivity to treatment. Methods Elderly patients with generalized anxiety disorder (GAD) participated in a 10-week double-blind study of duloxetine treatment for patients with GAD. Anxiety symptoms were assessed with the Hamilton Anxiety Rating Scale (HAMA), the Hospital Anxiety and Depression Scale (HADS) anxiety and depression subscales, and the GAI. Internal reliability of the GAI was assessed with Cronbach's α. Correlations among the HAMA, HADS, and GAI scores were analyzed to determine convergent and divergent validity. Patients were also compared on remission status using recommended cut-off scores for the GAI. Results Patients with GAD, who were at least 65 years of age, were randomly assigned to double-blind treatment with either duloxetine (N = 151) or placebo (N = 140) for 10 weeks acute therapy. The mean change on the GAI was significantly greater with duloxetine compared with placebo treatment (-8.36 vs. -4.96, respectively, p ≤ 0.001). The GAI demonstrated good internal consistency, good convergent and divergent validity, but suggested cut-off values for caseness with the GAI did not correspond to remission status as measured by the HAMA. Conclusions Within an elderly patient population with GAD, the GAI demonstrated sound psychometric qualities and sensitivity to change with treatment.