Comparative Effectiveness of Behavioural Sodium-Reduction Interventions for Intensive Systolic Blood Pressure Control in Populations with Elevated Blood Pressure: A Systematic Review and Network Meta-Analysis

<b>Background:</b> Globally, an estimated 1.4 billion people had hypertension in 2014, yet only just over 20% had controlled blood pressure, and about 580 million remained undiagnosed. Evidence indicates that salt substitutes facilitate meaningful blood-pressure reductions, yet their implementation remains restricted by social and healthcare constraints. The comparative effectiveness of alternative sodium-reduction interventions for elevated blood pressure remains unclear, limiting their introduction across diverse clinical and public health contexts. This study is registered with PROSPERO (CRD420251130153). <b>Methods:</b> We systematically searched PubMed, MEDLINE, and supplementary sources for randomised controlled trials (RCTs) published between 2000 and 2025. All behavioural sodium-reduction interventions among populations with elevated blood pressure, including hypertension, were included. The mean difference in systolic blood pressure (SBP) was the primary outcome, as evidence indicates that intensive control of SBP to levels below 120-130 mmHg is significantly associated with a reduced risk of major cardiovascular disease (CVD) and all-cause mortality. Network and subgroup pairwise meta-analyses were performed, with sensitivity analyses conducted to assess robustness of the findings and subgroup analyses used to explore clinical and public health factors influencing intervention effectiveness (clinical factors: blood pressure stage, trial duration, and medication status; public health factors: setting, implementation period, and country income level). <b>Results:</b> Of 10,404 records identified, 42 studies (46 trials, <i>n</i> = 46,771) were included. While the use of salt substitutes was ranked the most effective intervention in the network meta-analysis, with reductions of -6.78 mmHg (95% CI, -8.42, -5.14) compared to no intervention and -5.35 mmHg (95% CI, -7.89, -2.81) compared to conventional health education, self-monitoring devices and low-sodium diets, when combined with health education, demonstrated similar magnitudes of SBP reductions. Digital health education showed a larger point estimate for SBP reduction by -3.59 mmHg (95% CI -7.40 to 0.22) than conventional education (-1.43 mmHg; 95% CI -3.49 to 0.63), but both confidence intervals crossed zero, indicating no statistically significant difference. Subgroup analyses indicated that, except for trial duration, intervention setting, and country income level in specific intervention comparisons, clinical and public health factors did not generally account for differences in SBP reduction. No evidence of publication bias was observed, except between salt substitutes and no intervention and low-sodium diets and no intervention. <b>Conclusions:</b> Network meta-analysis ranked the use of salt substitutes as the most effective intervention, yet self-regulated interventions, such as low-sodium diets and self-monitoring devices, when combined with education-based sodium-reduction approaches, showed comparable point estimates for SBP reductions. Digital health education showed promise as a supportive adjunct to self-regulated interventions, although its effects were variable and require further quantification. These findings underscore the need for alternative sodium-reduction interventions supported by digital or conventional health education to improve blood pressure control. Health education on sodium reduction, including clinical counselling, should be viewed primarily as a complementary component that enhances other interventions.