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.
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.
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.
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 χ2 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.
The PHQ-8 demonstrated satisfactory validity and reliability; these results support its use to measure depressive symptoms in patients with heart failure.