Accepted for/Published in: JMIR mHealth and uHealth
Date Submitted: Dec 3, 2020
Date Accepted: May 7, 2021
A mobile health salt-reduction intervention for people with hypertension: results of a feasibility randomised controlled trial
ABSTRACT
Background:
A high salt diet is a risk factor for hypertension and cardiovascular disease, therefore reducing dietary salt intake is a key pillar of prevention strategies. There are few effective salt-reduction interventions suitable for delivery in the primary care setting, where the majority of the management and diagnosis of hypertension occurs.
Objective:
The aim of this study is to assess the feasibility of a complex behavioural intervention to lower salt intake in people with raised blood pressure and test the trial procedures for a randomised controlled trial to investigate intervention effectiveness.
Methods:
This feasibility study was an unblinded, randomised controlled trial of a mobile health intervention versus a salt reduction advice leaflet (control). The intervention was developed using the Behaviour Change Wheel and comprised individualised brief advice from a healthcare professional with use of the SaltSwap app. Participants with an elevated blood pressure recorded in clinic, were recruited through primary care practices in the United Kingdom. Primary outcomes assessed feasibility of progression to a larger trial including follow-up attendance, fidelity of intervention delivery, and app use. Secondary outcomes objectively assessed salt intake (measured via 24-hour urine collection), salt content of purchased foods and blood pressure. Qualitative outcomes were assessed using the think-aloud method and process outcomes were also evaluated.
Results:
All progression criteria were met; follow up attendance (96%), intervention fidelity (81%) and app use (87%). There was no evidence that the intervention significantly reduced the salt content of purchased foods, salt intake or blood pressure, however, process and qualitative outcomes demonstrated that the trial design is feasible, the intervention is acceptable to both individuals and practitioners and positively influenced salt intake behaviours.
Conclusions:
The intervention was acceptable and feasible to deliver within primary care; the trial procedures were practicable and there is sufficient signal of efficacy to change salt intake. With some improvements to the intervention app, a larger trial to assess intervention effectiveness for reducing salt intake and blood pressure in primary care is warranted. Clinical Trial: ISRCTN 20910962
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