One step closer to a global tool for rapid screening of major depression in epilepsy: Validation of the French NDDI-E

•The NDDI-E is a screening questionnaire used for detecting major depressive episode in epilepsy.•This study translates and validates the French NDDI-E.•The psychometric properties of the French NDDI-E were satisfactory.•The French NDDI-E showed a cutoff score of > 15, which was similar to the original version.•The sensitivity was 0.88, the specificity was 0.88, and the negative predictive value was 0.95.

ObjectiveDepression in people with epilepsy (PWE) is underdiagnosed and undertreated. The Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) is a screening questionnaire used for detecting major depressive episode (MDE) in PWE, and is already validated in 10 languages. However a version in French, one of the world's widely spoken languages, was, until now, lacking. We aimed to translate and validate the French NDDI-E.MethodsThis study was performed under the auspices of the ILAE. People with epilepsy > 18 years of age were recruited from 2 specialist epilepsy units in Marseille, France. Two native French speakers and 2 native English speakers performed a forward-backward translation. The Mini International Neuropsychiatric Interview (MINI) was performed as the gold standard, and the Center for Epidemiological Studies Depression symptoms index (CES-D) was performed for external validity. Data were compared between PWE with MDE and PWE without MDE using the chi-square test and Student's t-test. Internal structural validity, external validity, and receiver operator characteristics were analyzed.ResultsTesting was performed on 116 PWE: mean age = 40.39 years (SD = 13.83, range: [18-81] years old); 58.6% (68) were women; 87.1% had focal epilepsy. Using the MINI, we found that 33 (28.4%) patients had current MDE and that 15 (12.9%) patients had dysthymia; also, we found that 37 (31.9%) patients presented suicidal ideation and/or behavior. Cronbach's alpha coefficient was 0.838, indicating satisfactory internal consistency. Correlation between the NDDI-E and the CES-D scores was high (r(116) = 0.817, p < 0.0001), indicating good external validity. Receiver operator characteristic analysis showed an area under the curve of 0.958 (95% CI = 0.904-0.986), (p < 0.0001), indicating good capacity of the NDDI-E to detect MDE (defined by MINI). The cutoff for maximal sensitivity and specificity was 15. The mean NDDI-E score in PWE with MDE was 18.27 (SD = 2.28), and the mean NDDI-E score in PWE without MDE was 10.61 (SD = 3.63).SignificanceThis study validated the French NDDI-E, with a cutoff score of 15/24 for MDE, similar to previous studies, and reinforces the NDDI-E as a global tool for detection of MDE.