Validity of the Hospital Anxiety and Depression Scale and Patient Health Questionnaire-9 to screen for depression in patients with coronary artery disease.

Depression is common but frequently undetected in patients with coronary artery disease (CAD). Self-report screening instruments for assessing depression such as the Hospital Anxiety and Depression Scale (HADS) and the Patient Health Questionnaire-9 (PHQ-9) are available but their validity is typically determined in depressed patients without comorbid somatic illness. We investigated the validity of these instruments relative to a referent diagnostic standard in recently hospitalized patients with CAD.