Low Sodium Diets Increase Mortality and Readmission Rate in Patients with Systolic Heart Failure Taking Daily Diuretics

EBM Focus - Volume 8, Issue 5

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Guidelines from the Heart Failure Society of America (HFSA) recommend daily sodium intake of 2-3 g in most patients with heart failure, and suggest limiting sodium intake to < 2 g daily in cases of moderate-severe heart failure (J Card Fail 2010 Jun;16(6):e1). These recommendations have been based largely on observational data. A Cochrane review in 2011 identified a single randomized trial evaluating low sodium diets in patients with heart failure taking high-dose furosemide, and found an association between low sodium and increased mortality (Cochrane Database Syst Rev 2011 Jul 6;(7):CD009217). A new systematic review compared low sodium vs. normal sodium diets with data from 6 randomized trials including 2,747 patients with heart failure with a broader mix of diuretic treatment dosages.

In all trials, patients were randomized to a low-sodium diet of 1.8 grams daily vs. a normal sodium diet of 2.8 grams daily. Most trials had a fluid restriction for all patients of 1 liter daily. Furosemide doses (IV or oral) ranged from a low of 50-125 mg twice daily in 1 trial with 1,771 patients to a high of 500-1000 mg twice daily in 2 trials.

Compared to normal sodium diets, low sodium diets significantly increased all-cause mortality (risk ratio [RR] 1.95, 95% CI 1.66-2.29), heart failure-related mortality (RR 2.23, 95% CI 1.77-2.81) and heart failure readmissions (RR 2.1, 95% CI 1.67-2.64) (level 1 [likely reliable] evidence). The numbers needed to harm (NNH) were 6-12 for all-cause mortality and 2-7 for readmission. Low sodium diets were also associated with increased risk of sudden death (RR 1.72, 95% CI 1.21-2.44) (Heart 2013 Jan 24 early online).

In the largest trial, with the most clinically applicable furosemide dosing, the low sodium diet was associated with increased mortality (23.8% vs. 12.9%, p < 0.0001, NNH 9) and increased heart failure readmissions (34.2% vs. 18.5%, p < 0.0001, NNH 6) in follow-up of 57 months. In this trial, the normal sodium group received hypertonic saline solution 150 mL with each furosemide infusion (Am J Med Sci 2011 Jul;342(1):27).

For more information, see the Heart failure topic in DynaMed.