Validation of the Russian version of neurological disorders depression inventory for epilepsy (NDDI-E)

To translate and validate the English version of the Neurologic Depression Disorders Inventory in Epilepsy (NDDI-E) into the Russian language as an instrument for rapid detection of major depressive episodes (MDE) for patients with epilepsy (PWE) from Russian Federation.

One hundred and 75 consecutive PWE were included in the study. All patients were assessed with Mini-International Neuropsychiatric Interview (MINI 6.0.0), Hospital Anxiety and Depression Scale (HADS) and the Russian version of NDDI-E. Chi-square, Fisher's exact and Mann-Whitney tests were used to compare PWE with and without MDE. We analyzed internal structural validity, external validity, and receiver operator characteristics.

None of the participants had any difficulties in understanding the questions of NDDI-E. The internal consistency of the inventory was satisfactory (Cronbach's ά = 0.856). Correlation between the NDDI-E and the HADS scores was moderate (r = 0.64, P < 0.001), indicating acceptable external validity. NDDI showed good capacity to detect MDE, with area under the curve of 0.919 (95% CI = 0.868-0.955; standard error: 0.019; P < 0.001). An optimal cut-off point with the highest Yuden's index (J = 0.699) was  > 12. At this point NDDI-E showed sensitivity of 88.16% (95% CI = 78.7%-94.4%), specificity of 81.82% (95% CI = 72.8%-88.9%), positive predictive value of 59.3% (95% CI = 48.8%-69.0%), negative predictive value of 95.8% (95% CI = 92.5%-97.7%).

Russian version of NDDI-E is an affordable and fast screening tool with a good combination of sensitivity and specificity.