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

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).

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.

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.

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.