Rationale: Depression is reported as a serious adverse event of antiviral therapy used to treat patients with hepatitis C (HCV); therefore, there is a need to identify a reliable and valid measure of depressive symptoms for this population.
Aims: To determine reliability, construct validity and predictive validity of the Center for Epidemiological Studies Depression Scale (CES-D) in a hepatitis C (HCV) population.
Ethical issues: Study reviewed/approved by the University Institutional Review Board and informed consent obtained.
Methods: Longitudinal design testing psychometric properties of the CES-D prior to treatment and 4 and 24 weeks postinitiation of treatment. Reliability was tested using Cronbach's coefficient alpha. Construct validity was tested, prior to therapy, using principal components factoring with varimax rotation. Predictive validity was tested using repeated measures analysis of variance (anova) of CES-D scores at 4 and 24 weeks postinitiation of treatment.
Results: Non-probability sample, 116 adult HCV patients [62 (53%) males and 54 (47%) females]. Reliability (Cronbach's alpha) = 0.88 pretreatment, 0.89 week 4 and 0.90 week 24. Construct validity testing revealed four factors: negative affect; positive affect; somatic; and depressed affect/somatic. Exception for two items, 'felt sad' and 'couldn't get going', all items loaded distinctly with correlation coefficients in the range of 0.51-0.84. Predictive validity testing revealed a statistically significant effect over time (P < 0.001) in the direction predicted (pretreatment x = 13.97; post 4 weeks x = 19.54 and 24 weeks x = 19.97).
Conclusions: The CES-D is a reliable and valid instrument to screen for depressive symptoms in HCV patients. The instrument detected the predicted increase in depression associated with HCV. Examination of the sensitivity and specificity is needed to determine the most accurate cut-off score.