Evaluation of reliability and validity of the Persian version of the Neurological Disorders Depression Inventory for Epilepsy (P-NDDI-E).

ABSTRACT

INTRODUCTION: Major depression is common among people with epilepsy (PWE), but it is underdiagnosed. The aim of the present study was to assess the reliability and validity of the Persian version of the Neurological Disorders Depression Inventory for Epilepsy (P-NDDI-E) as a screening tool for major depression in patients with epilepsy. METHOD: A total of 210 patients suffering from epilepsy have been assessed using the NDDI-E and the Beck Depression Inventory-II (BDI-II) with no difficulty in understanding or answering the Persian version of the questionnaire. Patients identified as depressed under BDI-II underwent a psychiatric evaluation to confirm depression according to 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD) criteria. RESULT: According to the BDI-II and the ICD-10 criteria, major depression was diagnosed in 75 patients (32% men, 68% women). Cronbach's α coefficient was 0.826, suggesting a very good internal consistency. The receiver operating characteristic analysis showed an area under the curve of 0.90 (95% confidence interval [CI] = 0.86-0.94, standard error [SE] 0.02, p < 0.001). A cutoff of ≥14 resulted in an 83% sensitivity, an 80% specificity, a 70.1% positive predictive value, and an 88.6% negative predictive value. A significant and positive correlation between the P-NDDI-E and the BDI-II was shown (Spearman's ρ = 0.604, p < 0.001). DISCUSSION: The P-NDDI-E could be used as a reliable and valid instrument in detecting major depression in PWE.