Figure 3. Contour step three. Tree Plots of land regarding Alterations in Systolic and you may Diastolic Blood pressure level having The 1-grams Increase in dating for seniors Salt Excretion.
The relationship of estimated sodium excretion with systolic blood pressure was nonlinear, with a significantly steeper slope for the association at a level of sodium excretion of more than 5 g per day (2.58 mm Hg per gram of sodium; 95% CI, 2.38 to 2.78; P<0.001 for the comparison of the slope with a slope of 0) than at a level of excretion of 3 to 5 g per day (1.74 mm Hg per gram; 95% CI, 1.29 to 2.19; P<0.001) or less than 3 g per day (0.74 mm Hg per gram; 95% CI, –0.36 to 1.84; P=0.19) (P<0.001 for interaction) ( Figure 2A and Figure 3A ). Similar results were observed for diastolic blood pressure (P<0.001 for interaction) ( Figure 2B and Figure 3B ).
A significant inverse association between estimated potassium excretion and systolic blood pressure was observed after adjustment for covariates (P<0.001) (Fig. S3 in the Supplementary Appendix). For each increment of 1 g in estimated potassium excretion per day, there was a decrement of 0.75 mm Hg in systolic blood pressure (P<0.001) and a decrement of 0.06 mm Hg in diastolic blood pressure (P=0.33). The decrements were larger after correction for regression dilution bias (1.08 mm Hg and 0.09 mm Hg, respectively). There was a stronger inverse relationship between potassium excretion and blood pressure in China than in the other geographic regions studied (P<0.001 for interaction).
After adjustment for covariates, a strong and linear association was observed between the estimated sodium-to-potassium ratio and systolic blood pressure (P<0.001 for trend) and between the sodium-to-potassium ratio and diastolic blood pressure (P<0.001 for trend), although the slope of this association was significantly steeper in China than in other countries (P<0.001 for interaction). A 1-SD increment in the estimated sodium-to-potassium ratio (of 3.26) was associated with increments of 2.30 mm Hg in systolic blood pressure and 0.78 mm Hg in diastolic blood pressure (P<0.001 for both comparisons). The highest blood pressures were observed in the group with the highest estimated sodium excretion and the lowest estimated potassium excretion (difference from group with lowest sodium excretion and highest potassium excretion, 12 mm Hg in systolic pressure and 5 mm Hg in diastolic pressure; P<0.001 for interaction) ( Figure 4 ).
Exclusion of the 8637 participants with cardiovascular disease (who had an increment of 2.11 mm Hg in systolic blood pressure per 1-g increment in sodium excretion), the 14,856 participants receiving antihypertensive therapy (who had an increment of 2.24 mm Hg per gram), or the 43,042 participants from China (who had an increment of 2.10 mm Hg per gram) did not materially alter the findings of association. Estimated sodium excretion was more strongly associated with increased systolic and diastolic blood pressure in persons with hypertension (increment of 2.49 mm Hg in systolic pressure per gram) than in those without hypertension (1.30 mm Hg in systolic pressure per gram; P<0.001 for interaction) ( Figure 3A and 3B ). There was also a significant trend according to age, with a steeper slope of association with estimated sodium excretion in persons older than 55 years of age (2.97 mm Hg in systolic pressure per gram) than in those 45 to 55 years of age (2.43 mm Hg per gram) or those younger than 45 years of age (1.96 mm Hg per gram; P<0.001 for interaction) ( Figure 3A and 3B ). Higher estimated potassium excretion was associated with a steeper inverse relationship with systolic and diastolic blood pressure among persons with increased levels of estimated sodium excretion, as well as among older persons, those with hypertension, and those with an increased body-mass index (P<0.001 for interaction for all comparisons).