Abstract
Background: Although a low-sodium diet (LSD) is important in self-management of patients with heart failure (HF), the impact of LSD on event-free survival has not been investigated. Depressive symptoms predict worse event-free survival, in part, by affecting adherence to self-management. However, there are few investigations of the relationship among depressive symptoms, adherence to the LSD, and event-free survival.
Purpose: The purpose of this study was to determine the relationships among adherence to the LSD, depressive symptoms, and event-free survival.
Methods: A total of 254 patients (57% male, 62 +/- 14 years, 52% New York Heart Association class III/IV, ejection fraction of 36% +/- 14%) were recruited from outpatient HF clinics in Korea. Twenty-four-hour urinary sodium excretion was collected as an indicator of patient adherence to the LSD. Patients were grouped based on the cut point of 3 g of urinary sodium excretion. Depressive symptoms were assessed by the Korean version of Beck Depression Inventory, and patients were split into 2 groups at the cutoff of the Korean version of Beck Depression Inventory. Event-free survival for 12 months was determined by medical records. Hierarchical Cox proportional hazards regression was used to determine the association of depressive symptoms and adherence to 3-g sodium intake on event-free survival.
Results: After controlling for age, sex, etiology of HF, body mass index, New York Heart Association class, ejection fraction, N-terminal B-type natriuretic peptide, and total comorbidity score, nonadherence to 3-g sodium intake (hazard ratio = 1.56, 95% confidence interval = 1.05-2.32) and depressive symptoms (hazard ratio = 2.21, 95% confidence interval = 1.47-3.33) independently predicted event-free survival. Patients with sodium intake higher than 3 g and with depressive symptoms demonstrated a 3.7 times higher risk for cardiac events compared with patients with sodium intake lower than 3 g and without depressive symptoms (P < .001).
Conclusion: Improvement of adherence to the LSD and treatment for depressive symptoms could improve event-free survival.