Diagnosis of depression in former injection drug users with chronic hepatitis C

This study seeks to define the performance characteristics of 2 common depression screening tests and how psychiatric diagnoses affect adherence to treatment.

Hepatitis C virus is common in former injection drug users (IDU). Many former IDUs have depression, which may complicate treatment, and are often denied therapy.

Ninety patients with chronic hepatitis C virus and reported IDU were recruited from a Hepatology Clinic in Seattle. Subjects completed the Beck Depression Inventory (BDI) and Patient Health Questionnaire-9 (PHQ-9) before antiviral therapy. A psychiatrist administered the Mini International Neuropsychiatric Interview as the "gold standard." Adherence was measured by self-report of missed doses.

The BDI and PHQ-9 were highly correlated (r=0.75). Using a BDI score of ≥20 and a PHQ-9 score of ≥10, 39% and 52%, respectively, were misclassified as being depressed, as compared with the Mini International Neuropsychiatric Interview. Maximal sensitivity (85.7%) and specificity (82.6%) was achieved using a BDI score cutoff of 31, with an area under the curve of 0.82. For the PHQ-9, a cutoff of 14 yielded the best sensitivity (85.7%) and specificity (73.9%) with an area under the curve of 0.84. Adherence to at least 80% of medications was achieved by the majority.

Subjects reported good adherence and outcomes despite a high level of psychiatric comorbidity. The BDI and PHQ-9 were highly correlated but both tended to overdiagnose depression. A high score on BDI or PHQ-9 should not be the sole basis for withholding treatment. These patients should be evaluated by a psychiatrist to make an informed decision.