Conflicting measurements of depression in a substance abuse population

Methadone maintenance patients (N = 217) were administered a computerized screening version of the National Institute for Mental Health (NIMH) Diagnostic Interview Schedule (DIS), the Beck Depression Inventory (BDI) and the Addiction Severity Index (ASI) 2-4 weeks after treatment entry. Few differences were found between African-American, Hispanic, and Caucasian subjects. Only 1.7% of the patients met a lifetime diagnosis of major depressive disorder, and 1.4% qualified for a current diagnosis major depressive disorder. In contrast, 35.8% of the patients reported moderate to serious depression on the BDI during the previous week, and 19.3% reported serious depression during the previous month on the ASI (38.7% lifetime depression). Because moderate correlations were found between the DIS, the BDI, and the ASI measures of depression, there is some indication that they were tapping a similar construct. Therefore the lower rates of depression found with the DIS are probably attributable to its more stringent definition of depression. The findings tend to confirm previous literature indicating that the DIS, as contrasted with other structured psychiatric interviews, underestimates depression.