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.

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