Consistency of Blood Pressure Response to Potassium-Enriched Salt in the China Salt Substitute Study

Large between-person differences in blood pressure (BP) responses to sodium reduction, potassium supplementation, and potassium-enriched salt have been suggested by prior studies. However, limitations in research designs and misinterpretation of findings mean that overestimation of true between-person variation in response is likely.

Systolic BP (SBP) response during a 4-week run-in period on potassium-enriched salt was measured for 608 individuals. Participants were defined as apparently sensitive if SBP fell and apparently resistant if SBP was unchanged or rose. The effect of potassium-enriched salt compared with regular salt on SBP was then compared for apparently sensitive versus apparently resistant groups over a subsequent 12-month postrandomization period. A linear mixed model was used to determine how background within-person BP variability contributed to apparent between-person differences in BP response.

Apparent between-person variability in SBP response during run-in was substantial (mean SBP response, -13.7 [SD, 19.3; range, -80 to +56.5] mm Hg). Run-in identified 477 individuals as apparently sensitive and 131 as apparently resistant. Mean effects on SBP of potassium-enriched salt compared with regular salt over 12 months post-randomization were -2.2 mm Hg for apparently sensitive and -7.2 mm Hg for apparently resistant individuals, with no difference between the 2 groups (P=0.068). The mixed models identified no contribution of apparent run-in sensitivity to the observed between-person differences in postrandomization BP responses to potassium-enriched salt.

Individuals classified as responsive or resistant to potassium-enriched salt during initial exposure did not differ in their response to subsequent exposure.

URL: https://www.clinicaltrials.gov; Unique identifier: NCT00145756.