Depressive symptoms in heart failure: Independent prognostic factor or marker of functional status?

The prognostic potential of depressive symptoms independent of somatic features of heart failure severity has repeatedly been demonstrated. However, patient-reported functional status has rarely been accounted for in these studies. Thus, it has remained unclear to what extent the predictive power of depressive symptoms may mirror functional status. We therefore aimed to evaluate the prognostic value of depressive symptoms adjusting for patient-reported functional status in a large, well-characterized sample of patients with systolic heart failure.

Eight hundred sixty-three patients, 67±12 years old, 72% men, and 42% with New York Heart Association functional classes III/IV, who participated in the extended Interdisciplinary Network Heart Failure (INH) study were investigated. We assessed depressive symptoms using the Patient Health Questionnaire (PHQ-9) and patient-reported functional status with the Kansas City Cardiomyopathy Questionnaire (KCCQ). Data on survival was obtained after a follow-up of 18 months (100% complete).

Depressive symptoms predicted mortality risk (HR per PHQ-9 scale point=1.07, 95% CI 1.04-1.09, p<.001), even after adjustment for heart failure severity and co-morbidities (HR=1.04, 95% CI 1.01-1.07, p=.017). However, they were no longer significant predictors (HR=1.01, 95% CI 0.98-1.05, p=0.46) after additional adjustment for patient-reported functional status, which proved predictive of mortality risk (HR=0.90, 95% CI 0.82-0.99, p=.025).

Our results suggest that the association of depressive symptoms with functional status may at least partly explain the prognostic potential of depressive symptoms.