To study the psychometric properties of the Patient Health Questionnaire (PHQ) as a screening instrument for depression and anxiety in HCV patients.
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.
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.
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.