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 (t(318) = -5.05, p < .001) supported construct validity. Conclusion The PHQ-9 is a reliable, valid measure of depressive symptoms in patients with heart failure.