Impact of Dietary Sodium Restriction on Heart Failure Outcomes

Abstract

Objectives: This study sought to evaluate the impact of sodium restriction on heart failure (HF) outcomes.

Background: Although sodium restriction is advised for patients with HF, data on sodium restriction and HF outcomes are inconsistent.

Methods: We analyzed data from the multihospital HF Adherence and Retention Trial, which enrolled 902 New York Heart Association functional class II/III HF patients and followed them up for a median of 36 months. Sodium intake was serially assessed by a food frequency questionnaire. Based on the mean daily sodium intake prior to the first event of death or HF hospitalization, patients were classified into sodium restricted (<2,500 mg/d) and unrestricted (≥2,500 mg/d) groups. Study groups were propensity score matched according to plausible baseline confounders. The primary outcome was a composite of death or HF hospitalization. The secondary outcomes were cardiac death and HF hospitalization.

Results: Sodium intake data were available for 833 subjects (145 sodium restricted, 688 sodium unrestricted), of whom 260 were propensity matched into sodium restricted (n = 130) and sodium unrestricted (n = 130) groups. Sodium restriction was associated with significantly higher risk of death or HF hospitalization (42.3% vs. 26.2%; hazard ratio [HR]: 1.85; 95% confidence interval [CI]: 1.21 to 2.84; p = 0.004), derived from an increase in the rate of HF hospitalization (32.3% vs. 20.0%; HR: 1.82; 95% CI: 1.11 to 2.96; p = 0.015) and a nonsignificant increase in the rate of cardiac death (HR: 1.62; 95% CI: 0.70 to 3.73; p = 0.257) and all-cause mortality (p = 0.074). Exploratory subgroup analyses suggested that sodium restriction was associated with increased risk of death or HF hospitalization in patients not receiving angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (HR: 5.78; 95% CI: 1.93 to 17.27; p = 0.002).

Conclusions: In symptomatic patients with chronic HF, sodium restriction may have a detrimental impact on outcome. A randomized clinical trial is needed to definitively address the role of sodium restriction in HF management. (A Self-management Intervention for Mild to Moderate Heart Failure [HART]; NCT00018005).

Keywords: Heart Failure Adherence and Retention Trial; heart failure; outcome; salt restriction; sodium restriction.

Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Absolute Standardized Differences in Baseline Covariates between Sodium Restricted and Unrestricted Patients Before and After Propensity Score Matching

HFrEF, heart failure with reduced ejection fraction; SF-36, 36-item short-form questionnaire of the medical outcome study; NYHA, New York Heart Association; ACEi, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker; HART, Heart Failure Adherence and Retention Trial

Figure 2. Impact of Sodium Restriction on Heart Failure Outcomes in the Propensity Matched Cohort

HR, hazard ratio; CI, 95% confidence interval; Adj HR, adjusted hazard ratios for covariates with >10% absolute standardized difference between the propensity-matched groups.

Figure 3. Impact of Sodium Restriction on Death or Heart Failure Hospitalization by Subgroups of the Propensity-Matched Cohort

HR, hazard ratio; CI, 95% confidence interval; HFrEF, heart failure with reduced ejection fraction; HFpEF, heart failure with preserved ejection fraction; CKD, chronic kidney disease; ACEi, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker

Figure 4. Impact of Sodium Restriction on Time-Varying Outcome Measures in the Propensity-Matched Cohort

The P values represent test of significance of between groups difference in the trajectory of time-varying outcome measures (group*time interaction), adjusted for covariates with >10% absolute standardized difference between the propensity-matched groups. SF-36, 36-item short form health survey † furosemide dose equivalent