Urinary sodium and potassium excretion, mortality, and cardiovascular events

Abstract

BACKGROUND The optimal range of sodium intake for cardiovascular health is controversial. METHODS We obtained morning fasting urine samples from 101,945 persons in 17 countries and estimated 24-hour sodium and potassium excretion (used as a surrogate for in- take). We examined the association between estimated urinary sodium and potassium excretion and the composite outcome of death and major cardiovascular events. RESULTS The mean estimated sodium and potassium excretion was 4.93 g per day and 2.12 g per day, respectively. With a mean follow-up of 3.7 years, the composite outcome occurred in 3317 participants (3.3%). As compared with an estimated sodium ex- cretion of 4.00 to 5.99 g per day (reference range), a higher estimated sodium excre- tion (≥7.00 g per day) was associated with an increased risk of the composite out- come (odds ratio, 1.15; 95% confidence interval [CI], 1.02 to 1.30), as well as increased risks of death and major cardiovascular events considered separately. The association between a high estimated sodium excretion and the composite outcome was strongest among participants with hypertension (P=0.02 for interaction), with an increased risk at an estimated sodium excretion of 6.00 g or more per day. As compared with the reference range, an estimated sodium excretion that was below 3.00 g per day was also associated with an increased risk of the composite outcome (odds ratio, 1.27; 95% CI, 1.12 to 1.44). As compared with an estimated potassium excretion that was less than 1.50 g per day, higher potassium excretion was associ- ated with a reduced risk of the composite outcome. CONCLUSIONS In this study in which sodium intake was estimated on the basis of measured uri- nary excretion, an estimated sodium intake between 3 g per day and 6 g per day was associated with a lower risk of death and cardiovascular events than was either a higher or lower estimated level of intake. As compared with an estimated potassium excretion that was less than 1.50 g per day, higher potassium excretion was associ- ated with a lower risk of death and cardiovascular events. (Funded by the Popula -tion Health Research Institute and others.)