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Salt substitute reduced hypertension incidence by 55% in Peru
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PARIS — A pragmatic population-wide salt substitute strategy implemented in Peru, which consisted of 75% sodium chloride and 25% potassium chloride, contributed to reductions in both systolic and diastolic BP, especially in participants who were high risk, according to results from a study presented at the European Society of Cardiology Congress.
“We have to remind ourselves that even modest decreases in blood pressure at the population level brings us larger gains,” J. Jaime Miranda, MD, MSc, PhD, FFPH, research professor in the department of medicine and director of the CRONICAS Center of Excellence in Chronic Diseases at the Universidad Peruana Cayetano Heredia in Lima, Peru, said during the presentation. “This is the main message of this study.”
Researchers kept in mind the current state of discussing salt reduction with patients and how it can potentially be improved.
“We as doctors do a poor job at advising people. We tell people to reduce their salt consumption, and the effect of that advice is minimal,” Miranda said during the presentation. “That’s why we started to initiate this from a different angle. We wanted to go wide with the launch of a new product, a salt substitute to reduce blood pressure at the population level using a stepped-wedge cluster randomized design.”
The study focused on the area of Tumbes, Peru, which has an estimated population of 200,000 people and an estimated 25% poverty level. In addition, 27% of people older than 35 years had hypertension in 2010.
“This was our challenge; we needed to replace this,” Miranda said during the presentation. “We needed to compete and remove this use and introduce the salt substitute.”
In this study, 91.2% of people from the village were enrolled (n = 2,376; mean age, 43 years; 50% women) from six semirural villages. Participants with chronic kidney disease and heart disease were excluded.
From 2014 to 2017, researchers aimed to fully replace salt in the entire village with the salt substitute, which was provided free but in exchange of regular salt. The areas that were targets were places that used salt, including small shops, households, community kitchens and bakeries, restaurants and food vendors including street vendors.
Primary outcomes included systolic and diastolic BP, both of which were measured every 5 months. Measurements were taken for seven rounds. Secondary outcomes were hypertension incidence, defined as a systolic BP of at least 140 mm Hg and a diastolic BP of at least 90 mm Hg; changes in sodium levels and potassium secretion, which were assessed through 24-hour urine samples in a subsample of participants (n = 600); and both systolic and diastolic BP in patients who were high risk.
Formative research was conducted to identify the optimal flavor for the salt substitute, identify a target audience and to develop product identity. The final formulation of the salt substitute consisted of 75% sodium chloride and 25% potassium chloride.
“It is clearly known that potassium has an effect on palatability, so people don’t like it because it doesn’t have flavor,” Miranda said during the presentation.
The salt substitute was named Liz and featured an image of a local woman, as participants wanted to relate to it, Miranda said. It was packaged in transparent bags and a salt container for ease of use. A social marketing campaign was also performed that focused on the product itself, a door-to-door exchange of salt for the substitute and community activities to promote the product.
There were overall reductions in both systolic (–1.23 mm Hg; 95% CI, –0.38 to –2.07) and diastolic BP (–0.72 mm Hg; 95% CI, –0.1 to –1.34).
“There was no evidence that the effect of the intervention was modified over time, an important factor to consider given the nature and the characteristics of this type of study,” Miranda said during the presentation.
Reductions in systolic BP were greater in participants with hypertension (–1.92 mm Hg; 95% CI, –3.29 to –0.54) and in those older than 60 years (–2.17 mm Hg; 95% CI, –3.67 to –0.68).
The cumulative probability of developing hypertension in patients assigned the intervention vs. the control had an HR of 0.45 (95% CI, 0.34-0.66).
Urine samples in a random subsample of participants showed that there was no difference in sodium from baseline to the end of the study (3.94 g to 3.95 g; P = .93). There was also an increase in potassium during this time (1.97 g to 2.6 g; P < .001).
“My biggest fear was that as soon as we left the door, people would go and throw [the salt substitute] away,” Miranda said during the presentation.
Miranda closed the presentation with discussing how this may affect the achievement of hypertension goals.
“We’re contributing to decrease the gaps for attaining hypertension goals. We know that waiting to put people on medications and waiting to treat them properly is showing heavy failures. By reminding us that we have, at hand, population strategies that are effective, we are contributing toward these larger goals.” – by Darlene Dobkowski
Reference:
Miranda JJ. Hot Line Session 3. Presented at: European Society of Cardiology Congress; Aug. 31-Sept. 4, 2019; Paris.
Disclosure: Miranda reports no relevant financial disclosures.
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Carl J. Pepine, MD, MACC
This is very novel approach to population health that should catch the attention of our health care systems. The way that these investigators marketed the exchange of regular salt for the test preparation, the rural community chosen, and the activities conducted to promote the reduced sodium preparation serve as a model for others. Considering the prevalence of hypertension and its associated risks, a 2 mm Hg reduction in systolic BP could translate to a lot of lives spared a disabling stroke or HF.
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