Validation of the Indian version of Neurological Disorders Depression Inventory for Epilepsy (NDDI-E)

The Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) is an efficient tool for rapid detection of depression, an important comorbid condition in persons with epilepsy (PWE). Since social and cultural differences can potentially affect the cutoff score of NDDI-E, in this study, the reliability and validity of the Indian version of the NDDI-E in PWE was determined.

After ethical clearance, 217 PWE above 18 years of age, on antiepileptic drugs (AEDs), attending neurology outpatient department (OPD) of All India Institute of Medical Sciences (AIIMS), New Delhi, India, were evaluated for depression using the NDDI-E (Indian version) and Mini International Neuropsychiatric Interview (MINI-Module A, version 6.0.0) as reference standard. Informed consent was taken before recruitment. Receiver operating characteristic (ROC) analysis and Cronbach's α, a measure of the internal consistency and reliability, were carried out to validate cutoff and questionnaire, respectively.

Of the 217 PWE (112 males/105 females), mean age of 28.6 ± 9.4 years, with generalized (69.1%) or focal seizures (30.9%), 41.5% and 10.6% were diagnosed with depression using MINI and NDDI-E Indian version (at cutoff >15), respectively. However, at a cutoff score of >11, the Indian version of NDDI-E had a sensitivity of 96.67%, a specificity of 84.25%, a positive predictive value of 81.31%, and a negative predictive value of 97.27%. ROC analysis showed an area under the curve (AUC) of 0.9547 (confidence interval (CI) 95% = 0.929-0.979; standard error (SE): 0.0127). With the Indian version of NDDI-E, the Cronbach's α value was 0.877.

A periodic assessment of PWE using a quickly administrable and reliable tool for screening depression is highly desirable given the high incidence. In the Indian population with a cutoff of >11, NDDI-E is a reliable and valid instrument to screen depression in PWE.