Urinary Sodium and Potassium Excretion and the Risk of Cardiovascular Events in CKD.

Abstract

Background: Kidney disease is a known, independent driver of cardiovascular disease. While dietary sodium and potassium intake, approximated via urinary excretion, are known cardiac risk factors in the general population, their role for prevention in persons with kidney disease is unclear. Thus, we studied the relationship between the ratio of urinary sodium-to-potassium excretion and incident cardiovascular disease in individuals with chronic kidney disease.

Methods: We included 2,342 adults with chronic kidney disease enrolled in the Chronic Renal Insufficiency Cohort free of cardiovascular disease on study entry. Urinary sodium and potassium were measured via 24-hour urine collection at the baseline visit. Primary study outcomes included atrial fibrillation [AF], heart failure (overall, reduced ejection fraction [HFrEF] and preserved ejection fraction [HFpEF]), and myocardial infarction [MI]. Incidence rates (with 95% confidence intervals) were calculated per 1000 person-years. Nested models were created using Cox regression and adjusted for sociodemographic data (age, sex and race/ethnicity), lifestyle habits (body mass index and cigarette smoking), medication use, medical comorbidities and renal characteristics.

Results: Among the study population, mean (SD) age was 56 (11) years and mean estimated glomerular filtrate rate was 51 (20) mL/min/1.73 m2. The highest quartile (versus lowest quartile) of urinary sodium-to-potassium ratio was associated with a 1.4-fold increased risk of overall HF (HR 1.44, CI 95% 1.05-1.98), 1.9-fold increased risk of HFrEF (HR 1.90, CI 95% 1.08-3.36) and 1.5-fold increased risk of AF (HR 1.48, CI 95% 1.03-2.13) after adjustment for the covariates above. We did not find an association with incident MI (HR 1.14, CI 95% 0.78-1.68) and HFpEF (HR 1.18, CI 95% 0.75-1.87).

Conclusions: A higher ratio of urinary sodium-to-potassium excretion was associated with incident AF and HF (particularly HFrEF), but not MI, in persons with chronic kidney disease. Dietary sodium and potassium represent possible modifiable risk factors for cardiovascular disease prevention in individuals with kidney disease.