Psychometric validation of the 15-item Patient Health Questionnaire – Anxiety and Depression Scale (PHQ-ADS) to assess psychological distress in breast cancer survivors

Abstract

ObjectivePsychological distress persists amongst breast cancer survivors, so reliable assessment of symptoms is essential. The Patient Health Questionnaire Anxiety and Depression Scale (PHQ-ADS) is a composite measure of depression and anxiety and has been used to measure distress. This study aimed to evaluate the psychometric properties of the PHQ-ADS within breast cancer survivors. MethodBreast cancer survivors (N = 280) were recruited online and followed up at 12-months. Depression (PHQ-8) and anxiety (GAD-7) items formed the composite PHQ-ADS score. Additional measures included: distress thermometer (convergent validity), fear of cancer recurrence and COVID distress (discriminant validity), and self-compassion (predictive validity). Confirmatory factor analysis (CFA) using weighted least squares mean and variance adjusted estimation was undertaken. ResultsOne, two, and bifactor models underlying the PHQ-ADS were evaluated. The bifactor model had the most appropriate model fit overall. Omega hierarchical for the general distress factor was 0.914, accounting for 82% of explained variance. This suggests the PHQ-ADS is sufficiently unidimensional to warrant use of a total composite score. The PHQ-ADS demonstrated strong convergent and moderate discriminant validity. Self-compassion was an independent predictor of distress at 12-months. ConclusionsThe PHQ-ADS is a valid measure for psychological distress in breast cancer survivors prescribed hormone therapy.