Elsevier, Epilepsy & Behavior, (57), p. 211-216, 2016
DOI: 10.1016/j.yebeh.2016.02.015
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Objective: Generalized anxiety disorder (GAD) in people with epilepsy (PWE) is underdiagnosed and undertreated. The GAD-7 is a screening questionnaire to detect GAD. However, the usefulness of the GAD-7 as a screening tool in PWE remains to be validated. Thus, we aimed to: (1) validate the GAD-7 in French PWE and (2) assess its complementarity with regard to the previously validated screening tool for depression, the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E). Methods: This study was performed under the auspices of the ILAE Commission on Neuropsychiatry. People with epilepsy >18 years of age were recruited from the specialist epilepsy unit in Marseille, France. The Mini-International Neuropsychiatric Interview (MINI) was performed as gold standard, and the Penn State Worry Questionnaire (PSWQ) and the NDDILE were performed for extemal validity. Data were compared between PWE with/without GAD using Chi2 Lest and Student's L-Lest. Internal structural validity, external validity, and receiver operator characteristics were analyzed. A principal component factor analysis with Varimax rotation was performed on the 13 items of the GAD-7 (7 items) plus the NDDI-E (6 items). Results: Testing was performed on 145 PWE: mean age = 39.38 years old (SD = 1401, range: 18-75); 63.4% (92) women; 75.9% with focal epilepsy. Using the MINI, 49 (33.8%) patients had current GAD. Cronbach's alpha coefficient was 0.898, indicating satisfactory internal consistency. Correlation between GAD-7 and the PSQW scores was high (r (145) = .549, P- D001), indicating good external validity. Factor analysis shows that the anxiety investigated with the GAD-7 and depression investigated with the NDDI-E reflect distinct factors. Receiver operator characteristic analysis showed area under the curve of 0.899 (95% CI 0.838-0943, P