1. This study quantified sodium intake by measuring the 24-hour urinary sodium excretion, and found that among patients with chronic kidney disease (CKD), a greater level of sodium excretion (and thus higher sodium consumption) was associated with an increased incidence of cardiovascular disease (CVD).
2. Elevated sodium consumption was also found to be an independent risk factor for heart failure and stroke in patients with CKD.
Evidence Rating Level: 1 (Excellent)
Study Rundown: There is a well-established link between sodium consumption and blood pressure. However, less is known about the association between sodium consumption and the development of CVD. Patients with kidney disease are more sensitive to changes in sodium consumption as their kidneys are less able to excrete the cation, and there are theories that the increased rates of CVD among these patients is related directly to serum sodium levels and blood pressure. Thus, this study sought to characterize the relationship between sodium consumption and rates of CVD in patients with CKD. While previous studies have used dietary surveys to assess sodium intake, this study analyzed the 24-hour urinary excretion of sodium, which was previously shown to relate directly to sodium consumption.
The study found that increased levels of sodium intake was significantly associated with an increased risk of CVD events. After adjusting for covariates, the study further determined that the relationship between sodium consumption and CVD events was linear. Though this study is limited by the likely presence of several unmeasured confounders, it suggests that limiting sodium intake in patients with CKD can lead to better cardiovascular health, although more controlled studies are needed to confirm this finding.
Click to read the study in JAMA
Relevant Reading: Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomized trials.
In-Depth [prospective cohort]: This prospective cohort study was conducted at 7 centers in the United States between 2003 and 2013 and assessed the effect of sodium consumption on the development of CVD in patients with CKD. The study enrolled 3757 participants with CKD between the ages of 21 and 74 (mean age 58) and to quantify their baseline sodium intake, measured their 24-hour urine sodium excretion annually for three consecutive years. The cohort was then followed for at least 5 years and the rate of CVD events, including heart failure, myocardial infarction, and stroke, was analyzed.
Results showed that with greater urinary sodium excretion (and thus higher sodium consumption), increased the risk of composite CVD incidence, as well as the individual incidence of CHF, MI, and stroke. Comparing patients in the lowest and highest quartiles of sodium excretion, the incidence of CVD events was 18.4% and 29.8%, respectively (p < 0.001). Likewise the incidence of heart failure was 13.3% and 23.2% (p < 0.001), myocardial infarction 7.8% and 10.9% (p < 0.001), and stroke 7.8% and 10.9% (p < 0.001).
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