Depressive and anxiety disorders in chronic hepatitis C patients: reliability and validity of the Patient Health Questionnaire.

UNLABELLED: Depression and anxiety in patients with hepatitis C virus (HCV) infection influence their health-related quality of life and their adherence to antiviral treatment.
OBJECTIVE: To study the psychometric properties of the Patient Health Questionnaire (PHQ) as a screening instrument for depression and anxiety in HCV patients.
METHODS: Criterion validity, using the structured clinical interview for DSM-IV-Axis I (SCID-I) to diagnose depression and anxiety disorders as diagnostic standard, was evaluated for both summed and algorithm-based PHQ in 500 HCV patients. Correlations with quality of life (Short-Form-36 Health Survey; SF-36) and severity of illness (Hospital Anxiety and Depression Scale; HADS) were calculated to assess construct validity. Test-retest reliability and patients' reaction to the PHQ were assessed in 120 HCV patients.
RESULTS: Twenty-three percent of patients (N=114) had a psychiatric disorder (any depressive disorder=18.2%; major depressive disorder=6.4%; generalized anxiety disorder=7.0% and panic disorder=5.8%). The questionnaire demonstrated good test-retest reliability for any depressive disorder (k=.847), major depressive disorder (k=.784), generalized anxiety disorder (k=.787), panic disorder (k=.848), and for any psychiatric disorder (k=.847). There was good agreement between PHQ and SCID-I diagnoses (for any PHQ disorder, k=.821; overall accuracy=90.43%, sensitivity=83.84%; specificity=97.01%). Patients with any PHQ disorder had higher impairment on the SF-36 (p<.001). HADS depression and anxiety scores showed high correlations with PHQ depression (p<.001) and anxiety (p<.001) scores respectively. PHQ administration was well accepted by 97% of patients.
CONCLUSIONS: The Spanish version of the PHQ is a reliable, valid, and useful screening instrument to detect depression, generalized anxiety and panic disorders in HCV patients.