Studies on the association between sodium-to-potassium (Na/K) ratio changes and blood pressure (BP) changes among older adults are limited. This 7-year longitudinal study examined the association between Na/K ratio changes (evaluated using spot urine tests) and BP changes among older Japanese adults. Data were collected from 432 participants (mean age: 70.3±4.4; range: 65−84 years) in 2012 and 2019. Changes in BP and the Na/K ratio over 7 years were calculated by subtracting baseline values from values noted during a follow-up survey. The median systolic and diastolic BP (SBP) and (DBP) changes after 7 years were 4 (IQR, −7, 14) and −1 (IQR, −9, 5) mmHg, respectively. The median Na/K ratio was changed during the follow-up period by −0.2 (IQR, −1.3, 0.7). A generalized linear model indicated that Na/K ratio changes were positively associated with SBP (B = 2.03, p < 0.001) and DBP (B = 0.62, p = 0.021) changes. In the non-antihypertensive medication-using group, urinary Na/K ratio changes were associated with SBP and DBP changes (B = 2.39, p = 0.001; B = 0.99, p = 0.033). In the antihypertensive medication user group, urinary Na/K ratio changes were associated with SBP changes (B = 1.62, p = 0.015). We confirmed the association between changes in the Na/K ratio and changes in BP.
Keywords: blood pressure changes; older adults; salt intake; sodium-to-potassium ratio.