Impact of Self-monitoring of Salt Intake by Salt Meter in Hypertensive Patients (SMAL-SALT)

Hypertension is one of the most common chronic medical conditions. The concerned sequelae are the cardiovascular complications, especially acute myocardial infarction and stroke. In Thailand, the incidence of hypertension is increasing each year. Many clinical studies found that salt intake over the reference level (>5 g/day) would result in elevated blood pressure (BP) and long-term morbidity. Dietary salt reduction campaigns were unsuccessful, in part, due to time limitation in the clinic, lacking of awareness, and the higher threshold to detect salt taste in chronic high salt ingestion. Salt meter is a device used to detect sodium content in daily food. It will facilitate monitoring and control of salt intake. The 24-hour urinary sodium excretion is an acceptable method to reflect the quantity of sodium intake. This study aimed to compare the efficacy of salt meter plus dietary education compared with education alone in terms of salt intake reduction, blood pressure, salt taste sensitivity, and vascular consequence.

Study Overview

• Status: Unknown
• Conditions: Hypertension; Salt; Excess
• Intervention / Treatment: Device: Salt-meter; Behavioral: Education

Detailed Description

A randomized-controlled trial was conducted in hypertensive patients whose BP was uncontrolled (systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg) despite therapy or antihypertensive-naïve. Patients were randomized to receive salt meter to use in conjunction with dietary education (group A) or receive education only (group B), and were followed up for 8 weeks. Dietary education was provided by certified dietician without awareness of patients' allocation. The primary endpoint was change in 24-hour urinary sodium excretion. Changes in BP, salt taste sensitivity threshold, cardio-ankle vascular index (CAVI), as well as motivation to maintain low salt diet were also analyzed.

• Study Type: Interventional
• Enrollment (Anticipated): 100
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Thailand
  • Bangkok, Thailand, 10400
    • Faculty of Medicine, Ramathibodi Hospital, Mahidol University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Mean SBP 140-179 mmHg or mean DBP 90-109 mmHg (average 3 times)
• Diagnosed of hypertension for at least 3 months
• No adjustment of antihypertensive agents for at least 1 month
• 24h Urine sodium ≥ 90 mmol/day
• eGFR ≥ 45 ml/min/1.73 sq.m.

Exclusion Criteria:

• eGFR < 45 ml/min/1.73 sq.m.
• UACR > 300 mg/g
• Serum potassium > 6.0 mmol/l
• Serum sodium < 135 mmol/l
• Unable to collect 24-hour urine

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Salt-meter; Patients received salt-meter in conjunction with dietary education by trained dietician to help monitoring the salt content in food, as well as usual care by their primary physicians.	Device: Salt-meter; Salt-meter, developed by Faculty of Engineering at Mahidol University, is a device to measure sodium chloride content in the food and reflects to user with number and symbols for easy-understanding.; Behavioral: Education; Program dietary education by certified dietician who did not know the patients arm allocation.
Active Comparator: Control; Patients received dietary education by trained dietician and usual care by their primary physicians.	Behavioral: Education; Program dietary education by certified dietician who did not know the patients arm allocation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
24-hour urinary sodium excretion	Change in 24-hour urinary sodium excretion from baseline	8 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in systolic and diastolic blood pressure	Changes in systolic and diastolic blood pressure from baseline	8 weeks
Improvement in salt taste sensitivity by evaluating the salt detection or recognition thresholds	Using the different saline concentration in solution. Starting from the lowest to higher concentration, the point when the patient can differentiate from distilled water is called "detection threshold", and the point that patient can identify salty taste is called "recognition" threshold.	8 weeks
Change in cardio-ankle vascular index (CAVI)	Change in cardio-ankle vascular index (CAVI) from baseline	8 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of patients with hypertensive emergency	Number of patients documented to have hospitalisation for hypertension treatment including hypertensive emergency requiring intravenous antihypertensive agents.	8 weeks
Questionnaire about motivation to maintain low salt diet	Scale from 0 to 10 to estimate self motivation for taking low salt strategy at baseline and at 8 weeks	after 8 weeks

Collaborators and Investigators

• Sponsor: Mahidol University

Publications and helpful links

General Publications

• Mente A, O'Donnell MJ, Rangarajan S, McQueen MJ, Poirier P, Wielgosz A, Morrison H, Li W, Wang X, Di C, Mony P, Devanath A, Rosengren A, Oguz A, Zatonska K, Yusufali AH, Lopez-Jaramillo P, Avezum A, Ismail N, Lanas F, Puoane T, Diaz R, Kelishadi R, Iqbal R, Yusuf R, Chifamba J, Khatib R, Teo K, Yusuf S; PURE Investigators. Association of urinary sodium and potassium excretion with blood pressure. N Engl J Med. 2014 Aug 14;371(7):601-11. doi: 10.1056/NEJMoa1311989.
• Cook NR, Kumanyika SK, Cutler JA, Whelton PK; Trials of Hypertension Prevention Collaborative Research Group. Dose-response of sodium excretion and blood pressure change among overweight, nonhypertensive adults in a 3-year dietary intervention study. J Hum Hypertens. 2005 Jan;19(1):47-54. doi: 10.1038/sj.jhh.1001775.
• MacGregor GA, Markandu ND, Sagnella GA, Singer DR, Cappuccio FP. Double-blind study of three sodium intakes and long-term effects of sodium restriction in essential hypertension. Lancet. 1989 Nov 25;2(8674):1244-7. doi: 10.1016/s0140-6736(89)91852-7.
• Piovesana Pde M, Sampaio Kde L, Gallani MC. Association between Taste Sensitivity and Self-Reported and Objective Measures of Salt Intake among Hypertensive and Normotensive Individuals. ISRN Nutr. 2012 Oct 24;2013:301213. doi: 10.5402/2013/301213. eCollection 2013.
• Kusaba T, Mori Y, Masami O, Hiroko N, Adachi T, Sugishita C, Sonomura K, Kimura T, Kishimoto N, Nakagawa H, Okigaki M, Hatta T, Matsubara H. Sodium restriction improves the gustatory threshold for salty taste in patients with chronic kidney disease. Kidney Int. 2009 Sep;76(6):638-43. doi: 10.1038/ki.2009.214. Epub 2009 Jun 10.

Study record dates

Study Major Dates

• Study Start (Actual): July 11, 2017
• Primary Completion (Anticipated): February 21, 2020
• Study Completion (Anticipated): February 28, 2020

Study Registration Dates

• First Submitted: February 11, 2020
• First Submitted That Met QC Criteria: February 25, 2020
• First Posted (Actual): February 27, 2020

Study Record Updates

• Last Update Posted (Actual): February 27, 2020
• Last Update Submitted That Met QC Criteria: February 25, 2020
• Last Verified: February 1, 2020

More Information

Terms related to this study

• Keywords: hypertension; uncontrolled; salt, excess; salt meter
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Hypertension
• Other Study ID Numbers: 04-60-21

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No