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. Author manuscript; available in PMC: 2019 Jan 16.
Published in final edited form as: Circulation. 2017 Oct 11;137(3):237–246. doi: 10.1161/CIRCULATIONAHA.117.029193

Figure 2. Cubic spline plots of the association between systolic blood pressure and usual sodium excretion, usual potassium excretion, and their ratio, among adults aged 20–69, NHANES 2014.

Figure 2

In Panel A, the y-axis shows difference in systolic blood pressure across sodium excretion values compared to a reference value of 2.58g (the midpoint of the lowest quartile). The overall association was significant (p<0.001) and the test of non-linear association was not significant (p=0.41). Panel B shows difference in systolic blood pressure across potassium excretion values compared to a reference value of 1.48g. The overall association was significant (p=0.007) and the test of non-linear association was not significant (p=0.13). Panel C shows difference in systolic blood pressure across sodium-to-potassium ratio values compared to a reference value of 2.27. The overall association was significant (p=0.006) and the test of non-linear association was not significant (p=0.28).