Are the recommendation of sodium and fluid restriction in heart failure patients changing over the past years? A systematic review and meta-analysis.

Background: Heart failure (HF) is a growing problem for healthcare systems worldwide. Sodium and fluid restriction are non-pharmacological treatments recommended for patients with HF by several guidelines over the years, even without consensus.

Objective: To evaluate the effects of sodium and fluid restriction in patients with HF.

Methods: We searched MEDLINE, Embase, and Cochrane CENTRAL databases up to June 2020 and screened the reference lists of relevant articles. We included randomized controlled trials evaluating sodium and/or fluid restriction in patients with HF. We assessed three independent comparisons: (a) sodium restriction versus control; (b) fluid restriction versus control; and (c) sodium and fluid restriction versus control. Main outcomes of interest were all-cause mortality and hospitalization. Two independent reviewers selected studies and extracted data. We pooled the results using random-effects meta-analysis. We used the RoB 2.0 and the GRADE framework to assess risk of bias and quality of evidence.

Results: We included 16 studies totaling 3545 patients in our meta-analysis. Daily sodium intake was 1.5-2.4 g for the intervention group and >2.7 g for the control group, and daily fluid intake was 0.8-1.5 L for the intervention group and free oral fluid intake for the control group. Sodium restriction increased mortality (relative risk 1.92, 95% confidence interval 1.51 to 2.45, moderate quality of evidence) and hospitalization (relative risk 1.63, 1.11 to 2.40, low quality of evidence). Fluid restriction reduced mortality (relative risk 0.32, 0.13 to 0.82, low quality of evidence) and hospitalization (relative risk 0.46, 0.27 to 0.77, n = 331, low quality of evidence). The combination of sodium and fluid restriction did not significantly affect the risk of mortality (relative risk 0.92, 0.49 to 1.73, low quality of evidence) or the risk of hospitalization (relative risk 0.94, 0.75 to 1.19, low quality of evidence).

Conclusion: The combination of sodium and fluid restriction in clinical trials resulted in a null effect although results in the opposite direction were observed for each intervention independently. Combined sodium and fluid restriction are usually recommended for patients with HF. Our findings of sodium restriction harm, risk of mortality and hospitalization are consistent with publications from several clinical trial and physiologic explanations. A well-designed clinical trial nested by an implementation study is urgent for definitive sodium range recommendation, specially considering the change of currently guidelines, pushing up the cut-off of sodium restriction range.