Effects of salt substitution on cumulative blood pressure: a secondary analysis of the SSaSS

Abstract

The effect of a potassium-enriched salt substitute on cumulative blood pressure (BP) remains unclear. This study aimed to assess the long-term effects of a potassium-enriched salt substitute versus regular salt on cumulative and conventional measures of systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP) and pulse pressure (PP). We analyzed data from the Salt Substitute and Stroke Study (SSaSS), a 5-year cluster randomized controlled trial in rural of China with 20,995 participants. The intervention used salt substitute; controls used regular salt. BP was measured for all participants at baseline, among subsamples at 12-month intervals, and for all alive at 60 months. Cumulative BP was calculated as the average between baseline and follow-up measures multiplied by the time between them (mmHg × year). Linear mixed models were used to assess the effects of salt substitution on BP outcomes at each follow-up visit. After a mean 4.74 years of follow-up, salt substitute compared to the regular salt lowered the cumulative SBP with a mean (SD) of 740 (85) vs. 750 (87) mmHg×year. Salt substitute also lowered cumulative MAP and PP, with means (SD) of 560 (58) vs. 566 (59) mmHg×year, and 306 (67) vs. 313 (68) mmHg×year, respectively. Similar beneficial effects of the salt substitute were observed for traditional measurements of SBP, MAP, and PP. There was no difference in either cumulative DBP (434 vs. 437 mmHg × year) or traditional DBP (85 vs. 86 mmHg). Salt substitute significantly reduced cumulative and traditional SBP, MAP, and PP, but not DBP.

Trial registration

SSaSS ClinicalTrials.gov number: NCT0 2,092,090.