Recurrence of depressive disorders after interferon-induced depression

Interferon alpha (IFN-alpha)-treated patients commonly develop depression during the therapy period. Although most IFN-alpha-induced depressive disorders achieve remission after IFN-alpha therapy, no studies have examined the long-term mood effects of IFN-alpha treatment. We conducted a 12-year population-based cohort study of hepatitis C virus (HCV)-infected patients who were older than 20 years and had received IFN-alpha therapy. The sample was obtained from the Taiwan National Health Insurance Research Database. The cohort included patients with and without IFN-alpha-induced depression, matched randomly by age, sex and depression history, at a ratio of 1: 10. The follow-up started after the last administration of IFN-alpha and was designed to determine the incidence of recurrent depressive disorder after IFN-alpha therapy. A total of 156 subjects were identified as having IFN-alpha-induced depression and achieving full remission after IFN-alpha therapy. The overall incidence of recurrent depressive disorders among patients with and without IFN-alpha-induced depression was 56.8 (95% confidence interval (CI), 42.4-76.1) and 4.1 (95% CI, 2.9-5.8) cases, respectively, per 100 000 person-years, Po0.001. The adjusted hazard ratios for recurrent depressive disorder were 13.5 (95% CI, 9.9-18.3) in the IFN-alpha-treated cohort and 22.2 (95% CI, 11.2-44.2) in the matched cohort for IFN-alpha-induced depression patients after adjusting for age, sex, income, urbanization and comorbid diseases. IFN-alpha-induced depression was associated with a high risk of recurrent depression. It was not a transient disease and might be considered an episode of depressive disorder. Continuation therapy might be considered, and further research is needed.