Effects and associated behaviour change techniques of ehealth-based interventions on sodium reduction among adults: a systematic review and meta-analysis

Objective: To evaluate the effects of eHealth-based interventions on sodium and blood pressure reduction in adults, and identify study characteristics and behaviour change techniques (BCTs) associated with greater sodium reduction effects. Design and method: A systematic review and meta-analysis of randomised controlled trials (RCTs) was conducted in 5 databases including RCTs published from January 2000 to September 2022. The 24-hour urinary sodium (24HUNa, primary outcome of this review), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were meta-analysed using random-effects models. I2 statistic was used to assess heterogeneity among studies, with I2 > 50% considered substantial heterogeneity. Publication bias and robustness of the results were evaluated by the Egger test and sensitivity analysis, respectively. The contents of sodium reduction interventions were mapped to BCT Taxonomy (V1). Subgroup analyses of 24HUNa were performed according to study characteristics, including participants’ health status (hypertension vs. heart failure vs. healthy adults), urinary measurement (24-hour urine vs. spot urine), trial period (1-6 months vs. 7-12 months vs. 13-18 months), intervention mode (individual- vs. group-based), and BCTs. Results: Twenty-eight RCTs (5720 participants, mean age: 54.72 ± 10.80) were included. eHealth-based interventions significantly reduced 24HUNa (mean difference, MD = - 0.34 g/24 hours, 95% CI: - 0.45 to - 0.23; I2 = 49%, equivalent to 0.85 g/salt reduction per day) and SBP (MD = - 2.84 mmHg, 95% CI: - 4.02 to - 1.66; I2 = 35%), but not DBP (MD = - 0.93 mmHg, 95% CI: -1.95 to 0.08; I2 = 56%). No publication bias was detected. The effects on 24UHNa and SBP remained significant in sensitivity analyses. Twenty-nine BCTs were identified and predominantly were goal setting and behaviour feedback. Subgroup analyses showed using BCTs (goal setting, problem solving, feedback on behaviour, self-monitoring of behaviour, instruction on how to perform the behaviour, or demonstration of the behaviour) associated with a large significant reduction in sodium intake. No significant differences were observed for other study characteristics. Conclusions: eHealth-based interventions effectively reduced sodium intake and SBP in adults. The identified useful BCTs for sodium reduction should be tested in future trials.