%0 Journal Article
%T Prediction of 24-hour sodium excretion from spot urine samples in South African adults: a comparison of four equations
%J -
%D 2019
%R https://doi.org/10.1038/s41371-019-0210-2
%X Repeated 24-hour urine collection is considered to be the gold standard for assessing salt intake. This is often impractical in large-population studies, especially in low¨Cmiddle-income countries. Equations to estimate 24-hour urinary salt excretion from a spot urine sample have been developed, but have not been widely validated in African populations. This study aimed to systematically assess the validity of four existing equations to predict 24-hour urinary sodium excretion (24UNa) from spot urine samples in a nationally representative sample of South Africans. Spot and 24-hour urine samples were collected in a subsample (n£¿=£¿438) of participants from the World Health Organisation Study on global AGEing and adult health (SAGE) Wave 2 in South Africa in 2015. Measured 24UNa values were compared with predicted 24UNa values from the Kawasaki, Tanaka, INTERSALT and Mage equations using Bland¨CAltman plots. In this subsample (mean age 52.8£¿¡À£¿16.4 years; body mass index 30.2£¿¡À£¿8.2£¿kg/m2; 76% female; 73% black African; 42% hypertensive), all four equations produced a significantly different population estimate compared with the measured median value of 6.7£¿g salt/day (IQR 4.4¨C10.5). Although INTERSALT underestimated salt intake (£¿3.77£¿g/d; £¿1.64 to £¿7.09), the other equations overestimated by 1.28£¿g/d (£¿3.52; 1.97), 6.24£¿g/d (2.22; 9.45), and 17.18£¿g/d (8.42; 31.96) for Tanaka, Kawasaki, and Mage, respectively. Bland¨CAltman curves indicated unacceptably wide levels of agreement. Use of these equations to estimate population level salt intake from spot urine samples in South Africans is not recommended
%U https://www.nature.com/articles/s41371-019-0210-2