Urinary sodium excretion tied to mortality, cardiovascular events

Estimated urinary sodium excretion is positively associated with blood pressure and exhibits a possible J-shaped pattern of correlation with clinical outcomes, as shown in a study, noting the lowest risk among individuals with sodium excretion between 3 and 5 g/day.

A total of 39,366 individuals aged 35–70 years from 115 urban and rural communities in 12 centres across mainland China were included in the analysis. Trained research staff carried out the face-to-face interview to record baseline information based on questionnaires. They also collected morning fasting urine samples to estimate 24-h sodium excretion.

The researchers then performed multivariable frailty Cox regression, accounting for clustering by centre, to assess the relationship between estimated 24-h sodium excretion and the primary composite outcome of death and major cardiovascular events in a Chinese population.

Participants had a mean 24-h sodium excretion of 5.68 g/day. Overall, 3,080 (7.8 percent) individuals experienced the composite outcome after a median follow-up of 8.8 years; of these, 1,426 (3.5 percent) died and 2,192 (5.4 percent) developed cardiovascular events.

A positive association was found between 24-h sodium excretion and increased blood pressure. With 4–4.99 g/day as reference, a 24-h sodium excretion of either lower (<3 g/day) or higher (≥7 g/day) correlated with an increased risk of the composite outcome of death (hazard ratio [HR], 1.22, 95 percent confidence interval [CI], 1.01–1.49) and cardiovascular events (HR, 1.15, 95 percent CI, 1.01–1.30).

“A similar trend was observed between 24-h sodium excretion level and risk of death or major cardiovascular events,” the authors said.