Should sodium intake be restricted in chronic heart failure?

Castro-Guti�rrez, Victoria; Rada, Gabriel

doi:10.5867/medwave.2016.6696

Living FRIendly Summaries of the Body of Evidence using Epistemonikos (FRISBEE)

Medwave 2016;16(Suppl5):e6696 doi: 10.5867/medwave.2016.6696

Should sodium intake be restricted in chronic heart failure?

Victoria Castro-Guti�rrez, Gabriel Rada

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Abstract

Sodium restriction has been recommended in chronic heart failure for decades. However, the evidence about the benefit of this measure is not clear, and it might even increase risks. Searching in Epistemonikos database, which is maintained by screening multiple databases, we identified three systematic reviews incorporating 13 studies addressing the question of this article, 10 were randomized trials. We extracted data, combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded sodium restriction might increase mortality and the risk of hospital admission in chronic heart failure, but the certainty of the evidence is low.

Problem

High sodium intake increases morbidity and mortality, mainly in hypertensive people. Sodium restriction has also been recommended in chronic heart failure for decades, to diminish edema and to improve symptoms. However, it has been also postulated sodium restriction might increase the activity of renin-angiotensin and sympathetic systems through intravascular depletion, specially when combined with fluid restriction and diuretic therapy. Even though guidelines widely support this measure, existing evidence is controversial.

Methods

We used Epistemonikos database, which is maintained by screening multiple databases, to identify systematic reviews and their included primary studies. We extracted the information from the reviews, and with this information we generated a structured summary using a pre-established format, which includes key messages, a summary of the body of evidence (presented as an evidence matrix in Epistemonikos), meta-analysis of the total of studies, a summary of findings table following the GRADE approach and a table of other considerations for decision-making.

Key messages

Sodium restriction might increase mortality and the risk of hospital admission in chronic heart failure, but the certainty of the evidence is low.
The main guidelines widely recommend sodium restriction, and do not address the evidence suggesting it might be harmful.

About the body of evidence for this question

What is the evidence.
See evidence matrix in Epistemonikos later

We found three systematic reviews [1],[2],[3] incorporating 13 primary studies overall [4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16], including 10 randomized controlled trials [4],[5],[6],[7],[8],[9],[10],[11],[12],[13]. This table and the summary in general are based on the latter.

What types of patients were included

Ejection fraction was 22.5% in one trial [8], <35% in three trials [4],[5],[6], < 40% in one trial [13] and in five it was not reported [10],[12],[13],[14],[15].

NYHA functional class of included patients was the following:
In three trials it was II at 30 days post-discharge [4],[5],[6]; in one trial 72.6% were class II and 11.7% class III [7]; in one trial 17% class II and 83% class III [9]; in one 48.1 % II, 51.9% III or IV [10]; in one 90% II and 10% III [11]; in one I-III [12]; in one 24% II, 74% III [13]; and in one it was not reported [8].

What types of interventions were included

Three trials compared furosemide po + 120 mmol sodium per day versus furosemide po + 80 mmol sodium per day [4],[5],[6].

One trial compared providing general information versus providing information for a 2500 mg per day restriction [7].

Another trial compared a prescription of sodium 2000 mg per day versus 2000 mg per day + education by nutritionist [8].

One trial compared providing general information versus sodium restriction (2000-3000 mg/day and liquid 1.5 L + education) [9].

One trial compared provision of information + general care versus diet, education and sodium restriction 2000-3000mg per day [10].

One trial compared a restriction of 2300 versus 1500 mg per day [11].

One trial compared usual care versus diet, education and sodium restriction 2000-3000 mg per day [12].

Another trial compared provision of information about salt and fluid intake restriction versus fluid restriction 1500 cc per day and 5000 mg sodium per day restriction + nutritional support [13].

What types of outcomes
were measured

The primary studies measured several outcomes, but the systematic reviews identified grouped them as follows:

Mortality

Hospital admission

Summary of findings

The information about the effects of sodium restriction in chronic heart failure is based on only three trials including 775 patients for the outcome mortality and 578 for hospital admission [7],[8],[9]. The remaining trials were not incorporated in the meta-analysis of any of the reviews identified.

The summary of findings is the following:

Sodium restriction might increase mortality in chronic heart failure, but the certainty of the evidence is low.
Sodium restriction might increase the risk of hospital admission in chronic heart failure, but the certainty of the evidence is low.

Other considerations for decision-making

To whom this evidence does and does not apply

This evidence applies to patients with chronic heart failure with important decrease in ejection fraction (typically < 35%). The evidence presented in this summary does not allow recognizing a subgroup that might experience harm from sodium restriction, but clinically it is reasonable to anticipate it would occur in those with advanced heart failure.

About the outcomes included in this summary

We considered the two key outcomes for decision-making. These coincide with those presented in the systematic reviews identified.

Balance between benefits and risks, and certainty of the evidence

Even though the certainty of the evidence is low, there would be an increase in mortality and hospital admissions, so the risk/benefit ratio is not favorable.

What would patients and their doctors think about this intervention

Confronted with an intervention difficult to adhere and potentially harmful, most patients and clinicians should be inclined against its use.
However, considering it is a measure widely recommended by experts and guidelines, and the certainty of the evidence is low, it is likely to find important variability in decision-making.

Resource considerations

The intervention does not carry important costs, although to achieve optimal adherence extra cost need to be considered.
However, given it might cause harm, the cost/benefit balance is not favorable.

Differences between this summary and other sources

One of the reviews, published in 2012, showed better outcomes without sodium restriction. The same authors retracted this afterwards since two included trials presented duplicate data, which could not be verified because these were lost due to a computer failure [2]. The reviews did arrive to conclusions similar to this summary. The other reviews identified, also agree in concluding the evidence is controversial and high-quality trials are needed.
Our summary does not agree with the main guidelines, which recommend sodium restriction to control symptoms and relieve congestion in heart failure with functional class III-IV [17]. The AHA guideline 2013 also recommends sodium restriction in patients with symptomatic heart failure to relieve congestive symptoms [18]. The guideline of the Heart Failure Society of America recommends sodium restriction (2000-3000 mg per day) in symptomatic heart failure, and considering a more intensive restriction in moderate to severe heart failure [19].

Could this evidence change in the future?

The probability that future evidence change the conclusions of this summary is high due to the level of uncertainty.
There are at least three ongoing trials according to the International Controlled Trials Registry Platform from the World Health Organization [20],[21],[22].
A new systematic review might contribute relevant information since all of the identified reviews have limitations. A deeper analysis of the completed trials and the incorporation of information of the ongoing trials might clarify the existing uncertainty.

How we conducted this summary

Using automated and collaborative means, we compiled all the relevant evidence for the question of interest and we present it as a matrix of evidence.

Follow the link to access the interactive version: Sodium restriction in chronic heart failure

Notes

The upper portion of the matrix of evidence will display a warning of “new evidence” if new systematic reviews are published after the publication of this summary. Even though the project considers the periodical update of these summaries, users are invited to comment in Medwave or to contact the authors through email if they find new evidence and the summary should be updated earlier. After creating an account in Epistemonikos, users will be able to save the matrixes and to receive automated notifications any time new evidence potentially relevant for the question appears.

The details about the methods used to produce these summaries are described here http://dx.doi.org/10.5867/medwave.2014.06.5997.

Epistemonikos foundation is a non-for-profit organization aiming to bring information closer to health decision-makers with technology. Its main development is Epistemonikos database (www.epistemonikos.org).

These summaries follow a rigorous process of internal peer review.

Conflicts of interest
The authors do not have relevant interests to declare.

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What is the evidence. See evidence matrix in Epistemonikos later	We found three systematic reviews [1],[2],[3] incorporating 13 primary studies overall [4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16], including 10 randomized controlled trials [4],[5],[6],[7],[8],[9],[10],[11],[12],[13]. This table and the summary in general are based on the latter.
What types of patients were included	Ejection fraction was 22.5% in one trial [8], <35% in three trials [4],[5],[6], < 40% in one trial [13] and in five it was not reported [10],[12],[13],[14],[15]. NYHA functional class of included patients was the following: In three trials it was II at 30 days post-discharge [4],[5],[6]; in one trial 72.6% were class II and 11.7% class III [7]; in one trial 17% class II and 83% class III [9]; in one 48.1 % II, 51.9% III or IV [10]; in one 90% II and 10% III [11]; in one I-III [12]; in one 24% II, 74% III [13]; and in one it was not reported [8].
What types of interventions were included	Three trials compared furosemide po + 120 mmol sodium per day versus furosemide po + 80 mmol sodium per day [4],[5],[6]. One trial compared providing general information versus providing information for a 2500 mg per day restriction [7]. Another trial compared a prescription of sodium 2000 mg per day versus 2000 mg per day + education by nutritionist [8]. One trial compared providing general information versus sodium restriction (2000-3000 mg/day and liquid 1.5 L + education) [9]. One trial compared provision of information + general care versus diet, education and sodium restriction 2000-3000mg per day [10]. One trial compared a restriction of 2300 versus 1500 mg per day [11]. One trial compared usual care versus diet, education and sodium restriction 2000-3000 mg per day [12]. Another trial compared provision of information about salt and fluid intake restriction versus fluid restriction 1500 cc per day and 5000 mg sodium per day restriction + nutritional support [13].
What types of outcomes were measured	The primary studies measured several outcomes, but the systematic reviews identified grouped them as follows: Mortality Hospital admission