Assessing depression severity with a self-rated vs. rater-administered instrument in patients with epilepsy

Rationale: Up to 30-50% of individuals with epilepsy have depressive symptoms, which often complicate seizure management and reduce overall quality of life. To identify and manage depressive symptoms appropriately, clinicians need standardized instruments that can accurately identify and monitor those with clinically significant depression. The self-reported 9-item Patient Health Questionnaire (PHQ-9) has been used relatively widely to screen and monitor depression in epilepsy. The rater-administered Montgomery-Asberg Depression Rating Scale (MADRS) is a rater-administered instrument widely used in depression treatment trials but less widely applied in epilepsy. This secondary analysis from 2 epilepsy self-management clinical trials compared depression severity ratings using the PHQ-9 and the MADRS instruments.

Methods: Data for this analysis were derived from pooled baseline and longitudinal data from 2 prospective epilepsy self-management randomized controlled trials (RCTs). Both RCTs assessed depression with the PHQ-9 and the MADRS. For this analysis, total depression severity scores and case classification of individuals with no/minimal, mild, moderate/moderately severe, and severe depression were assessed using both PHQ-9 and MADRS.

Results: The sample contained 164 individuals with epilepsy. Demographic and clinical variables between the 2 studies were generally similar. There were 107 women (64.8%), 106 African-Americans (64.2%), and 51 Whites (30.9%). Individuals had epilepsy for an average of 22.1 (SD: 15.5). Mean past 30-day seizure frequency at baseline was 3.1 (SD: 11.6). Baseline mean PHQ-9 was 10.7 (SD: 6.80) with depression severity of 32 (19.6%) not or minimally depressed, 47 (28.8%) mildly depressed, 37 (22.7%) moderately depressed, 27 (16.6%) moderately severely depressed, and 20 (12.3%) severely depressed. Baseline mean MADRS severity was 18.5 (SD: 11.3) with 30 (18.8%) not or minimally depressed, 27 (16.9%) mildly depressed, 92 (56.1%) moderately depressed, and 11 (6.9%) severely depressed. The correlation between total PHQ-9 and total MADRS was 0.843 (p < .01) although case classification by depression severity varied somewhat between the two instruments.

Conclusions: Standardized measures to evaluate depression severity in people with epilepsy can help identify cases and monitor treatment. The PHQ-9 and MADRS both perform well in assessing depression in people with epilepsy although administration burden is less with PHQ-9 thus making it likely preferable for settings where time and epilepsy specialty resources are limited.