Measuring Depressive Symptoms in Heart Failure: Validity and Reliability of the Patient Health Questionnaire–8

BACKGROUND: Depressive symptoms are common in patients with heart failure, but few investigators have reported the validity and reliability of measures of depressive symptoms among these patients. OBJECTIVES: To evaluate the validity and reliability of a measure of depressive symptoms, the Patient Health Questionnaire-8 (PHQ-8), among 249 patients with chronic heart failure. METHODS: As part of a larger study, patients completed the PHQ-8 and the Living With Heart Failure Questionnaire. New York Heart Association class was assessed as a measure of the severity of heart failure. Construct validity of the PHQ-8 was evaluated by confirmatory factor analysis, Pearson correlation coefficients, and analysis of variance. Internal consistency reliability was estimated by using the Cronbach α. RESULTS: The sample was 63% men, with a mean age of 63 years, and 67% reported their race as white. Construct validity of the PHQ-8 was supported. The confirmatory factor analysis model reflected the emotional and somatic dimensions of depressive symptoms and displayed a good fit with the data. The χ(2) value of the PHQ-8 was 24.75 with 18 degrees of freedom (P =.13) and the goodness-of-fit index was 0.98. The PHQ-8 was significantly correlated with the total and subscale scores on the Living With Heart Failure Questionnaire (P <.001 for all correlations). Differences in the PHQ-8 scores were found among New York Heart Association classes (F=20.4, P<.001). The PHQ-8 internal consistency reliability (Cronbach α) was 0.82. CONCLUSIONS: The PHQ-8 demonstrated satisfactory validity and reliability; these results support its use to measure depressive symptoms in patients with heart failure.