Validation of items on the NDDIE and PHQ-9 associated with suicidal ideation during suicidality screening in patients with epilepsy

Abstract

Purpose: This study was performed to validate individual items on the Neurological Disorders Depression Inventory for Epilepsy (NDDIE) and the Patient Health Questionnaire-9 (PHQ-9), as well as their total scores, during suicidality screening of patients with epilepsy (PWE). Methods: PWE were assessed with the Mini International Neuropsychiatric Interview (MINI), the NDDIE, and the PHQ-9. Moderate to high suicidality, as assessed by the Suicidality Module of the MINI, was considered the standard measurement. Each item and overall scores for the NDDIE and PHQ-9 were evaluated by receiver operating characteristic (ROC) curve analyses. The optimal cutoff criteria were identified as those with the highest Youden index. Results: Of the 213 participants, 20 (9.4%) had moderate to high suicidality. Item 4 on the NIDDE and item 9 on the PHQ-9, representing suicidal ideation, showed the best psychometric properties for suicidality. A cutoff of >1 for item 4 on the NDDIE showed an area under the ROC curve (AUC) of 0.853, a sensitivity of 90.0%, and a specificity of 72.0%. A cutoff >0 for item 9 on the PHQ-9 showed an AUC of 0.851, a sensitivity of 90.0%, and a specificity of 74.6%. The specificities and positive predictive values of item 4 on the NDDIE and item 9 on the PHQ-9 were higher in patients with depression than those in the overall patient population. Conclusion: Item 4 of NDDIE and Item 9 of PHQ-9 showed value in screening for suicidality. Use of these items may rapidly identify suicidality among PWE.