Dietary Potassium Intake and Risk of Chronic Kidney Disease Progression in Predialysis Patients with Chronic Kidney Disease: A Systematic Review.

The prevalence of chronic kidney disease (CKD) is increasing and dietary interventions may be a strategy to reduce this burden. In the general population, higher potassium intake is considered protective for cardiovascular health. Due to the risk of hyperkalemia in CKD, limiting potassium intake is often recommended. However, given that poor cardiovascular function can cause kidney damage, following a low-potassium diet may be deleterious for patients with CKD. The aim of this systematic review was to summarize the evidence on dietary potassium intake and CKD progression. Multiple databases were searched on 7 June 2019 and data were managed with Covidence. No intervention trials met the inclusion criteria. Eleven observational studies met the inclusion criteria (10 post hoc analyses, 1 retrospective cohort), representing 49,573 stage 1-5 predialysis patients with CKD from 41 different countries. Of the 11 studies, 6 studies reported exclusively on early CKD (stage 1-2), 4 studies separately reported analyses on both early and late (stage 3-5) CKD, and 2 studies reported exclusively on late CKD. A total of 9 studies reported risk of disease progression in early CKD; in 4 studies high potassium intake was associated with lower risk, while in 2 studies the low intake showed a higher progression of risk, and 3 studies reported no relation. In late CKD, results are mixed: 2 studies suggested benefit of higher potassium intake and 1 suggested benefit of lower potassium intake, whereas 3 studies were neutral. These results should be interpreted with caution, as considerations preventing firm conclusions include 1) the overall low range of dietary potassium intake, with all studies reporting an average intake below the 2004 Kidney Disease Outcomes Quality Initiatives guidelines, and 2) the method used to assess potassium intake in most studies (i.e., urine) in late stages of CKD. Ideally, well-controlled intervention studies are needed to understand how dietary potassium intake is linked to CKD progression.

Effect of Salt Substitution on Cardiovascular Events and Death.

BACKGROUND: Salt substitutes with reduced sodium levels and increased potassium levels have been shown to lower blood pressure, but their effects on cardiovascular and safety outcomes are uncertain. METHODS: We conducted an open-label, cluster-randomized trial involving persons from 600 villages in rural China. The participants had a history of stroke or were 60 years of age or older and had high blood pressure. The villages were randomly assigned in a 1:1 ratio to the intervention group, in which the participants used a salt substitute (75% sodium chloride and 25% potassium chloride by mass), or to the control group, in which the participants continued to use regular salt (100% sodium chloride). The primary outcome was stroke, the secondary outcomes were major adverse cardiovascular events and death from any cause, and the safety outcome was clinical hyperkalemia. RESULTS: A total of 20,995 persons were enrolled in the trial. The mean age of the participants was 65.4 years, and 49.5% were female, 72.6% had a history of stroke, and 88.4% a history of hypertension. The mean duration of follow-up was 4.74 years. The rate of stroke was lower with the salt substitute than with regular salt (29.14 events vs. 33.65 events per 1000 person-years; rate ratio, 0.86; 95% confidence interval [CI], 0.77 to 0.96; P = 0.006), as were the rates of major cardiovascular events (49.09 events vs. 56.29 events per 1000 person-years; rate ratio, 0.87; 95% CI, 0.80 to 0.94; P<0.001) and death (39.28 events vs. 44.61 events per 1000 person-years; rate ratio, 0.88; 95% CI, 0.82 to 0.95; P<0.001). The rate of serious adverse events attributed to hyperkalemia was not significantly higher with the salt substitute than with regular salt (3.35 events vs. 3.30 events per 1000 person-years; rate ratio, 1.04; 95% CI, 0.80 to 1.37; P = 0.76). CONCLUSIONS: Among persons who had a history of stroke or were 60 years of age or older and had high blood pressure, the rates of stroke, major cardiovascular events, and death from any cause were lower with the salt substitute than with regular salt. (Funded by the National Health and Medical Research Council of Australia; SSaSS ClinicalTrials.gov number, NCT02092090.).