Accepted for/Published in: JMIR mHealth and uHealth
Date Submitted: Oct 19, 2022
Date Accepted: Jan 19, 2023
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
A sodium reduction smartphone app and reduced sodium salt for adults with hypertension: Findings from the SALTS randomized controlled trial
ABSTRACT
Background:
Even modest reductions in blood pressure (BP) can have important impacts for population-level morbidity and mortality from cardiovascular disease (CVD). Two promising approaches are (1) the SaltSwitch smartphone application (app), which enables users to scan the barcode of a packaged food using their smartphone camera and receive an immediate, interpretive traffic light nutrition label on-screen alongside a list of healthier, lower salt options in the same food category, and (2) reduced sodium salts (RSS’s), which are an alternative to regular table salt being lower in sodium and higher in potassium but with a similar mouthfeel, taste, and flavor.
Objective:
Our aim was to determine whether 12 weeks intervention with a sodium reduction package comprising the SaltSwitch smartphone app and a RSS could reduce urinary sodium excretion in adults with high BP.
Methods:
A two-arm, parallel, randomized controlled trial was conducted in New Zealand (NZ; target n=326). Following a two-week baseline period, adults who owned a smartphone and had high BP (≥140/85 mmHg) were randomized in a 1:1 ratio to intervention (SaltSwitch smartphone app + RSS) or control (generic heart-healthy eating information from The Heart Foundation of NZ). The primary outcome was 24-hour urinary sodium excretion at 12 weeks estimated via spot urine. Secondary outcomes were urinary potassium excretion, BP, the sodium content of food purchases, and intervention use and acceptability. Intervention effects were assessed blinded by intention-to-treat analyses using generalized linear regression adjusting for baseline outcome measures, age, and ethnicity.
Results:
One-hundred and sixty-eight adults were randomized (n=84 per group) between May 2019 and February 2020. Challenges associated with the COVID-19 pandemic and smartphone technology detrimentally impacted recruitment. The adjusted mean difference (95% CI) between groups for 24-hour urinary sodium excretion was 547 (-331, 1424) mg, 24-hour urinary potassium excretion was 132 (-1083, 1347) mg, systolic BP was -0.66 (-3.48, 2.16) mmHg, and the sodium content of food purchases was 73 (-21, 168) mg/100g. Most intervention participants used the SaltSwitch app (75%) and RSS (94%). SaltSwitch was used on six shopping occasions, and ~1/2 tsp per week of RSS was consumed per household during the intervention.
Conclusions:
In this randomised controlled trial of a salt-reduction package we found no evidence that dietary sodium intake was reduced in adults with high BP. The negative findings may be due to lower-than-anticipated engagement with the trial intervention package. However, implementation and COVID-19-related challenges meant the trial was underpowered and it is possible that a real effect may have been missed. Clinical Trial: Australian New Zealand Clinical Trials Registry #ACTRN12619000352101. Universal Trial #U1111-1225-4471.
Citation
Request queued. Please wait while the file is being generated. It may take some time.
Copyright
© The authors. All rights reserved. This is a privileged document currently under peer-review/community review (or an accepted/rejected manuscript). Authors have provided JMIR Publications with an exclusive license to publish this preprint on it's website for review and ahead-of-print citation purposes only. While the final peer-reviewed paper may be licensed under a cc-by license on publication, at this stage authors and publisher expressively prohibit redistribution of this draft paper other than for review purposes.