Psychometrics of the PHQ-9 as a measure of depressive symptoms in patients with heart failure

Background: Depression in patients with heart failure commonly goes undiagnosed and untreated. The Patient Health Questionnaire-9 (PHQ-9) is a simple, valid measure of depressive symptoms that may facilitate clinical assessment. It has not been validated in patients with heart failure. Aims: To test the reliability, and concurrent and construct validity of the PHQ-9 in patients with heart failure. Methods: A total of 322 heart failure patients (32% female, 61 ± 12 years, 56% New York Heart Association class III/IV) completed the PHQ-9, the Beck Depression Inventory-II (BDI-II), and the Control Attitudes Scale (CAS). Results: Cronbach's alpha of .83 supported the internal consistency reliability of the PHQ-9 in this sample. Inter-item correlations (range .22-.66) and item-total correlation (except item 9) supported homogeneity of the PHQ-9. Spearman's rho of .80, (p < .001) between the PHQ-9 and the BDI-II supported the concurrent validity as did the agreement between the PHQ-9 and the BDI-II (Kappa = 0.64, p < .001). At cut-off score of 10, the PHQ-9 was 70% sensitive and 92% specific in identifying depressive symptoms, using the BDI-II scores as the criterion for comparison. Differences in PHQ-9 scores by level of perceived control measured by CAS (t318 = -5.05, p < .001) supported construct validity. Conclusion: The PHQ-9 is a reliable, valid measure of depressive symptoms in patients with heart failure.