High sodium linked to increased cardiovascular risk in chronic kidney disease

In patients with chronic kidney disease (CKD), high urinary sodium excretion is associated with an increased risk of cardiovascular events, concludes a study in The Journal of the American Medical Association

The prospective cohort study included 3757 patients with CKD enrolled at seven sites in the Chronic Renal Insufficiency Cohort Study. Urinary sodium excretion was estimated from the mean of three 24-hour urinary samples and calibrated to the sex-specific mean of 24-hour urinary creatinine excretion in the study population. Urinary sodium was evaluated for association with a composite of cardiovascular disease events.

Fifty-five percent of patients were men; the mean age was 58 years old (2). At a median follow-up of 6.8 years, there were 575 patients with heart failure, 305 with myocardial infarction (MI), and 148 with stroke.

Quartiles of calibrated sodium excretion ranged from less than 2894 to greater than 4548 mg/24 hours. From the lowest to the highest quartile, cumulative incidence rates of cardiovascular events were 18.4 percent, 16.5 percent, 20.6 percent, and 29.8 percent. In the highest compared with the lowest quartile, rates of specific events were 23.2 versus 13.3 percent for heart failure, 10.9 versus 7.8 percent for MI, and 6.4 versus 2.7 percent for stroke. On multivariable analysis, hazard ratios were 1.36 for overall events, 1.34 for heart failure, and 1.81 for stroke; the association with MI was no longer significant.

Among patients with CKD, those with the highest level of sodium excretion were at increased risk of cardiovascular disease independent of other risk factors. The associations are similar across patient subgroups and independent of total caloric intake and systolic BP. “These findings, if confirmed by clinical trials, suggest that moderate sodium reduction among patients with CKD and high sodium intake may lower CVD risk,” the researchers conclude [Mills KT, et al. Sodium excretion and the risk of cardiovascular disease in patients with chronic kidney disease. JAMA 2016; 315:2200–2210].