Background: High sodium intake is a significant public health problem in the United States. Interventions that lower sodium intake can decrease blood pressure and improve cardiovascular outcomes. Restaurants and grocery stores are prime targets for intervention with about 77% of all sodium intake in the average US diet coming from processed and restaurant foods. Objective: This study proposes that a mobile app intervention that promotes low-sodium alternatives at grocery stores and restaurants will reduce dietary intake of sodium and improve confidence following a low-sodium diet in hypertension. Methods: In this single-center, prospective, open-label study, patients will be randomized to a mobile app or usual care for 8 weeks. We will randomize 50 patients (age>18 years) diagnosed with hypertension and on antihypertensive therapy for at least 3 months in a 1:1 manner stratified by gender. Study subjects will receive the mobile app, LowSalt4Life, or usual dietary advice for 8 weeks. LowSalt4Life provides a multifaceted intervention based on just-in-time contextual tailored messages at grocery stores and restaurants. The primary endpoint is the change in the estimated 24-hour urinary excretion of sodium from spot urine. Secondary outcomes include change in the sodium content of the food frequency questionnaire, confidence in following a low-sodium diet, urine chloride and creatinine dipsticks, and blood pressure. Results: The project was funded in May 2016 until April 2018. This trial is currently enrolling patients. To date, 26 of the 50 patients needed have been enrolled. Results will be available in the Spring of 2019. Conclusions: This randomized controlled trial will test the efficacy of just-in-time contextual tailored messages through a novel mobile app 8-week intervention on urinary sodium excretion in patients with hypertension. We will address a critical evidence gap in the care of patients with hypertension. If effective, this intervention could be scaled to assess effects on blood pressure and cardiovascular events in hypertension. Trial Registration: ClinicalTrials.gov NCT03099343; https://clinicaltrials.gov/ct2/show/NCT03099343 (Archived by WebCite at http://www.webcitation.org/735HNzKlQ) International Registered Report Identifier (IRRID): PRR1-10.2196/11282
Background: High dietary sodium intake is a significant public health problem in the United States. High sodium consumption is associated with high blood pressure and high risk of cardiovascular disease. Objective: The aim of this study was to evaluate the effect of a just-in-time adaptive mobile app intervention, namely, LowSalt4Life, on reducing sodium intake in adults with hypertension. Methods: In this study, 50 participants aged ≥18 years who were under treatment for hypertension were randomized (1:1, stratified by gender) into 2 groups, namely, the App group (LowSalt4Life intervention) and the No App group (usual dietary advice) in a single-center, prospective, open-label randomized controlled trial for 8 weeks. The primary endpoint was the change in the 24-hour urinary sodium excretion estimated from spot urine by using the Kawasaki equation, which was analyzed using unpaired two-sided t tests. Secondary outcomes included the change in the sodium intake measured by the food frequency questionnaire (FFQ), the 24-hour urinary sodium excretion, blood pressure levels, and the self-reported confidence in following a low-sodium diet. Results: From baseline to week 8, there was a significant reduction in the Kawasaki-estimated 24-hour urinary sodium excretion calculated from spot urine in the App group compared to that in the No App group (–462 [SD 1220] mg vs 381 [SD 1460] mg, respectively; P=.03). The change in the 24-hour urinary sodium excretion was –637 (SD 1524) mg in the App group and –322 (SD 1485) mg in the No App group (P=.47). The changes in the estimated sodium intake as measured by 24-hour dietary recall and by FFQ in the App group were –1537 (SD 2693) mg and –1553 (SD 1764) mg while those in the No App group were –233 (SD 2150) mg and –515 (SD 1081) mg, respectively (P=.07 and P=.01, respectively). The systolic blood pressure change from baseline to week 8 in the App group was –7.5 mmHg while that in the No App group was –0.7 mmHg (P=.12), but the self-confidence in following a low-sodium diet was not significantly different between the 2 groups. Conclusions: This study shows that a contextual just-in-time mobile app intervention resulted in a greater reduction in the dietary sodium intake in adults with hypertension than that in the control group over a 8-week period, as measured by the estimated 24-hour urinary sodium excretion from spot urine and FFQ. The intervention group did not show a significant difference from the control group in the self-confidence in following a low sodium diet and in the 24-hour urinary sodium excretion or dietary intake of sodium as measured by the 24-hour dietary recall. A larger clinical trial is warranted to further elucidate the effects of the LowSalt4Life intervention on sodium intake and blood pressure levels in adults with hypertension. Trial Registration: ClinicalTrials.gov NCT03099343; https://clinicaltrials.gov/ct2/show/NCT03099343