The Proportion of Dietary Salt Replaced with Potassium-Enriched Salt in the SSaSS: Implications for Scale-Up

Abstract

Background: The SSaSS (Salt Substitute and Stroke Study) recently reported definitive effects of a potassium-enriched salt on cardiovascular outcomes and death. Quantifying the amount of potassium-enriched salt used by trial participants is important for understanding the magnitude of the effect of potassium-enriched salt on risk reduction and how population-wide scale-up might be achieved. Methods: Baseline and annual 24-hour urine samples were collected from subgroups of participants in SSaSS throughout the 5-year follow-up. The mean difference in 24-hour potassium excretion between the 2 groups was used to estimate the quantity of potassium-enriched salt consumed in the intervention group. The corresponding projected difference in sodium intake between groups was calculated and compared with the observed difference. Results: The potassium-enriched salt group, compared to the regular salt group, had a mean increase in 24-hour urinary potassium excretion of 0.80 g/d (95% CI, 0.71–0.90), which equates to consumption of 8.8 g/d (95% CI, 7.8–9.9) of potassium-enriched salt. Based on 8.8 g/d potassium-enriched salt consumption, the projected difference in 24-hour urinary sodium excretion was −0.79 g/d. This compares to an observed difference of −0.35 g/d (95% CI, −0.55 to −0.15) and suggests that 72% of baseline regular salt intake was replaced by potassium-enriched salt. Conclusions: The smaller than anticipated between-group difference in sodium excretion likely results from the joint use of regular salt and potassium-enriched salt in the intervention group. Our findings suggest that even an incomplete replacement of regular salt with potassium-enriched salt can deliver significant health gains. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02092090.