Depressive symptoms, health-related quality of life, and cardiac event-free survival in patients with heart failure: a mediation analysis.
OBJECTIVE
Health-related quality of life (HRQOL) and depressive symptoms both are associated with an adverse prognosis in heart failure (HF), although their associations with outcomes have been examined only in isolation. Therefore, it is unknown how HRQOL and depressive symptoms might interact in their associations with outcomes. The present study was conducted to determine whether the association between HRQOL and cardiac event-free survival is mediated by depressive symptoms in HF patients given that depressive symptoms are associated strongly with HRQOL.


METHODS
A total of 209 HF patients (61 ± 11 years, 24 % female, 49 % NYHA III/IV) participated. The Minnesota Living with HF Questionnaire and the Patient Health Questionnaire-9 were used to measure HRQOL and depressive symptoms, respectively. Patients were followed for a median of 357 days to determine cardiac event-free survival.


RESULTS
In Cox regression analysis, HRQOL [hazard ratio (HR) 1.013; 95 % confidence interval (CI) 1.001-1.026] and depressive symptoms (HR 1.075; 95 % CI 1.025-1.127) predicted cardiac event-free survival separately, controlling for demographic and clinical variables. HRQOL independently explained 38.7 % of the variance in depressive symptoms (p < 0.05; standardized β = 0.695) in a multiple regression. When HRQOL and depressive symptoms were entered in the model simultaneously, only depressive symptoms independently predicted cardiac event-free survival (HR 1.068; 95 % CI 1.001-1.139), demonstrating a mediation effect of depressive symptoms.


CONCLUSIONS
Depressive symptoms mediated the relationship between HRQOL and cardiac event-free survival. Interventions targeting HRQOL to enhance patient outcomes must also address patient depressive symptoms to be fully efficacious.
School of Nursing, K6/342 Clinical Sciences Center, University of Wisconsin-Madison, 600 Highland Ave., Madison, WI, 53792-2455, USA, kslee4@wisc.edu.
Kyoung Suk
KS
Lee
Terry A
TA
Lennie
Jia-Rong
JR
Wu
Martha J
MJ
Biddle
Debra K
DK
Moser
D000046:Academic Medical Centers; D000368:Aged; D015992:Body Mass Index; D003863:Depression / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology*; D018572:Disease-Free Survival; D017050:Episode of Care; D005260:Female; D006305:Health Status Indicators; D006333:Heart Failure / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D006764:Hospitals, Community; D006801:Humans; D053208:Kaplan-Meier Estimate; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011788:Quality of Life; D012111:Residence Characteristics; D012923:Social Class; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology