Abstracts

Rationale: Depression is the most common, yet under-recognized & under-treated psychiatric co-morbidity in patients with epilepsy. One of the most significant obstacles to treatment may be the failure of adequate screening & diagnosis. The purpose of our study is to validate a widely used depression screening tool, the Patient Health Questionnaire (PHQ-9) by comparing it with the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) developed and validated specifically for patients with epilepsy. The PHQ-9 total score ranges from 0-27 and scores of 10 or greater have been found to correlate with major depression of at least a moderate degree. However, the PHQ-9 has not been specifically validated in epilepsy patients, where multiple somatic, cognitive or AED related side effects & epilepsy manifestations could falsely elevate the total PHQ-9 score. Methods: This is a prospective study where 60 clinically/EEG diagnosed epilepsy patients were interviewed to complete the PHQ-9 & NDDI-E in random order within a 24 hours period, mostly in the same sitting. The sensitivity & specificity of the PHQ-9 at cut-points defined in the literature was estimated & 95% C.I constructed. Various PHQ-9 score cut-points for a "PHQ-9 positive" screen of 10 thru 15 were compared to NDDIE score of >=15 (considered as "NDDI-E-positive"). Clinical, demographic, imaging, and EEG patient characteristics were collected. Results: There were only 20 patients (33.3%) who were on anti-depressant medications (ADM), including 9 who still had active depressive symptomatology (NDDIE score>=15). The mean number of ADM was 0.42, (range 0-3, median 0, standard deviation 0.7). Similarly for the anti-epileptic drugs (AEDs), the mean was 2.28 (range 0-5, median 2, standard deviation 1.2). The PHQ-9 mean score was 8.5 (range 0-26, median 7). Twenty seven patients (45%) had a PHQ-9 score of 10 or higher; while only 16 patients (27%) had a PHQ-9 score of 15 or higher. NDDIE mean score was 12, (range 6-22, median 12). A quarter of our cohort displayed active depressive symptomatology (NDDI-E score >=15) with only half of those being on any ADM. Details of other results are depicted in the attached table and charts. Conclusions: The prevalence of depression in epilepsy patients in our study is similar to the prior reported prevalence in the literature. Close to half the patients with active depression were not on any ADMs, and close to half the patients who were on depression treatment were not controlled suggesting challenges both with disease recognition and treatment. The PHQ-9 may be an alternative depression screening tool for patients with epilepsy, with optimal sensitivity and specificity achieved using cut-points of 11 or 12 rather than 10. This is significant as the validation of this widely used scale in the specific population of epilepsy patients will allow cross comparisons and larger scale cohort studies evaluating depression across the variety of neurological disorders.