Effects of salt substitutes on clinical outcomes: a systematic review and meta-analysis.

OBJECTIVES: The Salt Substitute and Stroke Study (SSaSS) recently reported blood pressure-mediated benefits of a potassium-enriched salt substitute on cardiovascular outcomes and death. This study assessed the effects of salt substitutes on a breadth of outcomes to quantify the consistency of the findings and understand the likely generalisability of the SSaSS results. METHODS: We searched PubMed, Embase and the Cochrane Library up to 31 August 2021. Parallel group, step-wedge or cluster randomised controlled trials reporting the effect of salt substitute on blood pressure or clinical outcomes were included. Meta-analyses and metaregressions were used to define the consistency of findings across trials, geographies and patient groups. RESULTS: There were 21 trials and 31 949 participants included, with 19 reporting effects on blood pressure and 5 reporting effects on clinical outcomes. Overall reduction of systolic blood pressure (SBP) was -4.61 mm Hg (95% CI -6.07 to -3.14) and of diastolic blood pressure (DBP) was -1.61 mm Hg (95% CI -2.42 to -0.79). Reductions in blood pressure appeared to be consistent across geographical regions and population subgroups defined by age, sex, history of hypertension, body mass index, baseline blood pressure, baseline 24-hour urinary sodium and baseline 24-hour urinary potassium (all p homogeneity >0.05). Metaregression showed that each 10% lower proportion of sodium choloride in the salt substitute was associated with a -1.53 mm Hg (95% CI -3.02 to -0.03, p=0.045) greater reduction in SBP and a -0.95 mm Hg (95% CI -1.78 to -0.12, p=0.025) greater reduction in DBP. There were clear protective effects of salt substitute on total mortality (risk ratio (RR) 0.89, 95% CI 0.85 to 0.94), cardiovascular mortality (RR 0.87, 95% CI 0. 81 to 0.94) and cardiovascular events (RR 0.89, 95% CI 0.85 to 0.94). CONCLUSIONS: The beneficial effects of salt substitutes on blood pressure across geographies and populations were consistent. Blood pressure-mediated protective effects on clinical outcomes are likely to be generalisable across population subgroups and to countries worldwide. TRIAL REGISTRATION NUMBER: CRD42020161077.

Cost-Effectiveness of a Household Salt Substitution Intervention: Findings From 20 995 Participants of the Salt Substitute and Stroke Study.

BACKGROUND: SSaSS (Salt Substitute and Stroke Study), a 5-year cluster randomized controlled trial, demonstrated that replacing regular salt with a reduced-sodium, added-potassium salt substitute reduced the risks of stroke, major adverse cardiovascular events, and premature death among individuals with previous stroke or uncontrolled high blood pressure living in rural China. This study assessed the cost-effectiveness profile of the intervention. METHODS: A within-trial economic evaluation of SSaSS was conducted from the perspective of the health care system and consumers. The primary health outcome assessed was stroke. We also quantified the effect on quality-adjusted life-years (QALYs). Health care costs were identified from participant health insurance records and the literature. All costs (in Chinese yuan [¥]) and QALYs were discounted at 5% per annum. Incremental costs, stroke events averted, and QALYs gained were estimated using bivariate multilevel models. RESULTS: Mean follow-up of the 20 995 participants was 4.7 years. Over this period, replacing regular salt with salt substitute reduced the risk of stroke by 14% (rate ratio, 0.86 [95% CI, 0.77-0.96]; P=0.006), and the salt substitute group had on average 0.054 more QALYs per person. The average costs (¥1538 for the intervention group and ¥1649 for the control group) were lower in the salt substitute group (¥110 less). The intervention was dominant (better outcomes at lower cost) for prevention of stroke as well as for QALYs gained. Sensitivity analyses showed that these conclusions were robust, except when the price of salt substitute was increased to the median and highest market prices identified in China. The salt substitute intervention had a 95.0% probability of being cost-saving and a >99.9% probability of being cost-effective. CONCLUSIONS: Replacing regular salt with salt substitute was a cost-saving intervention for the prevention of stroke and improvement of quality of life among SSaSS participants.

Effect of Salt Substitution on Cardiovascular Events and Death.

BACKGROUND: Salt substitutes with reduced sodium levels and increased potassium levels have been shown to lower blood pressure, but their effects on cardiovascular and safety outcomes are uncertain. METHODS: We conducted an open-label, cluster-randomized trial involving persons from 600 villages in rural China. The participants had a history of stroke or were 60 years of age or older and had high blood pressure. The villages were randomly assigned in a 1:1 ratio to the intervention group, in which the participants used a salt substitute (75% sodium chloride and 25% potassium chloride by mass), or to the control group, in which the participants continued to use regular salt (100% sodium chloride). The primary outcome was stroke, the secondary outcomes were major adverse cardiovascular events and death from any cause, and the safety outcome was clinical hyperkalemia. RESULTS: A total of 20,995 persons were enrolled in the trial. The mean age of the participants was 65.4 years, and 49.5% were female, 72.6% had a history of stroke, and 88.4% a history of hypertension. The mean duration of follow-up was 4.74 years. The rate of stroke was lower with the salt substitute than with regular salt (29.14 events vs. 33.65 events per 1000 person-years; rate ratio, 0.86; 95% confidence interval [CI], 0.77 to 0.96; P = 0.006), as were the rates of major cardiovascular events (49.09 events vs. 56.29 events per 1000 person-years; rate ratio, 0.87; 95% CI, 0.80 to 0.94; P<0.001) and death (39.28 events vs. 44.61 events per 1000 person-years; rate ratio, 0.88; 95% CI, 0.82 to 0.95; P<0.001). The rate of serious adverse events attributed to hyperkalemia was not significantly higher with the salt substitute than with regular salt (3.35 events vs. 3.30 events per 1000 person-years; rate ratio, 1.04; 95% CI, 0.80 to 1.37; P = 0.76). CONCLUSIONS: Among persons who had a history of stroke or were 60 years of age or older and had high blood pressure, the rates of stroke, major cardiovascular events, and death from any cause were lower with the salt substitute than with regular salt. (Funded by the National Health and Medical Research Council of Australia; SSaSS ClinicalTrials.gov number, NCT02092090.).

Protocol for the economic evaluation of the China Salt Substitute and Stroke Study (SSaSS).

INTRODUCTION: Cardiovascular diseases (CVDs) are the leading causes of death and disability worldwide. Reducing dietary salt consumption is a potentially cost-effective way to reduce blood pressure and the burden of CVD. To date, economic evidence has focused on sodium reduction in food industry or processed food with blood pressure as the primary outcome. This study protocol describes the planned within-trial economic evaluation of a low-sodium salt substitute intervention designed to reduce the risk of stroke in China. METHODS AND ANALYSES: The economic evaluation will be conducted alongside the Salt Substitute and Stroke Study: a 5-year large scale, cluster randomised controlled trial. The outcomes of interest are quality of life measured using the EuroQol-5-Dimensions and major adverse cardiovascular events. Costs will be estimated from a healthcare system perspective and will be sought from the routinely collected data available within the New Rural Cooperative Medical Scheme. Cost-effectiveness and cost-utility analyses will be conducted, resulting in the incremental cost-effectiveness ratio expressed as cost per cardiovascular event averted and cost per quality-adjusted life year gained, respectively. ETHICS AND DISSEMINATION: The trial received ethics approval from the University of Sydney Ethics Committee (2013/888) and Peking University Institutional Review Board (IRB00001052-13069). Informed consent was obtained from each study participant. Findings of the economic evaluation will be published in a peer-reviewed journal and presented at international conferences. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT02092090).

Availability, Formulation, Labeling, and Price of Low-sodium Salt Worldwide: Environmental Scan.

BACKGROUND: Regular salt is about 100% sodium chloride. Low-sodium salts have reduced sodium chloride content, most commonly through substitution with potassium chloride. Low-sodium salts have a potential role in reducing the population's sodium intake levels and blood pressure, but their availability in the global market is unknown. OBJECTIVE: The aim of this study is to assess the availability, formulation, labeling, and price of low-sodium salts currently available to consumers worldwide. METHODS: Low-sodium salts were identified through a systematic literature review, Google search, online shopping site searches, and inquiry of key informants. The keywords "salt substitute," "low-sodium salt," "potassium salt," "mineral salt," and "sodium reduced salt" in six official languages of the United Nations were used for the search. Information about the brand, formula, labeling, and price was extracted and analyzed. RESULTS: A total of 87 low-sodium salts were available in 47 out of 195 (24%) countries worldwide, including 28 high-income countries, 13 upper-middle-income countries, and 6 lower-middle-income countries. The proportion of sodium chloride varied from 0% (sodium-free) to 88% (as percent of weight; regular salt is 100% sodium chloride). Potassium chloride was the most frequent component with levels ranging from 0% to 100% (potassium chloride salt). A total of 43 (49%) low-sodium salts had labels with the potential health risks, and 33 (38%) had labels with the potential health benefits. The median price of low-sodium salts in high-income, upper-middle-income, and lower-middle-income countries was US $15.00/kg (IQR 6.4-22.5), US $2.70/kg (IQR 1.7-5.5), and US $2.90/kg (IQR 0.50-22.2), respectively. The price of low-sodium salts was between 1.1 and 14.6 times that of regular salts. CONCLUSIONS: Low-sodium salts are not widely available and are commonly more expensive than regular salts. Policies that promote the availability, affordability, and labeling of low-sodium salts should increase uptake, helping populations reduce blood pressure and prevent cardiovascular diseases. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.1111/jch.14054.

Change in mean salt intake over time using 24-h urine versus overnight and spot urine samples: a systematic review and meta-analysis.

BACKGROUND: Little is known about the capacity of overnight and spot urine samples to estimate changes in mean salt intake over time. The objective of this review was to compare the estimates of change in mean population salt intake based on 24-h urine and overnight/spot urine samples. METHODS: Studies were systematically identified through searches of peer-reviewed databases (Medline, Embase, Global Health, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews) and grey literature. Studies that reported estimates of mean salt intake for at least two time points based on both 24-h and overnight/spot urines were deemed eligible. The capacity of overnight/spot urine samples to estimate the change in mean salt intake was assessed both at the individual-study level and overall through random-effects meta-analyses. The level of heterogeneity was assessed through the I2 statistic. Subgroup and sensitivity analyses were conducted to explore possible sources of heterogeneity, and check the robustness of the findings from the primary analysis. RESULTS: A total of 1244 records were identified, 50 were assessed as full text, and 14 studies met the criteria, capturing data on 7291 participants from seven countries. Nine and five studies collected overnight and spot urines, respectively. The comparison of the change in mean salt intake between 24-h and overnight/spot urines showed some inconsistencies at the individual study-level. The pooled mean change in salt intake was - 0.43 g/day (95% CI - 1.16 to 0.30; I2 = 95%) using 24-h urines, and - 0.22 g/day (- 0.65 to 0.20; I2 = 87%) using overnight/spot urines, with a pooled difference-in-differences between the two methods of 0.27 g/day (- 0.23 to 0.77; I2 = 89%). Subgroup analyses showed substantial heterogeneity for most subgroups. Sensitivity analyses did not change the effect observed in the primary analysis. CONCLUSION: The evidence for the capacity of overnight/spot urines to estimate changes in mean salt intake over time is uncertain. More research where overnight/spot urines are collected in parallel with 24-h urines is needed to enable a more in-depth evaluation of these alternative approaches to estimating change in mean salt intake.

The effectiveness, feasibility, and acceptability of low-sodium salts worldwide: An environmental scan protocol.

Excess sodium intake elevates blood pressure and risk for cardiovascular diseases. The use of low-sodium salts is a potentially cost-effective strategy to counter the rising global burden of cardiovascular diseases. This research aimed to understand the potential scale-up of low-sodium salt interventions by examining the availability of low-sodium salts globally, synthesizing evidence about the effectiveness of low-sodium salt interventions, and identifying the challenges and opportunities associated with implementing low-sodium salt interventions. This study consists of three parts. The first part is a systematic online search of low-sodium salts. The authors will use the advanced search functions of search engines and online shopping sites to execute the search. The second part is a systematic review of academic literature on the use of low-sodium salts. A meta-analysis will be performed to quantify the effectiveness of low-sodium salt interventions. The third part is key informant interviews to understand the challenges of implementing low-sodium salt interventions. Key informants will include policymakers, academic researchers, and salt industry representatives. The list of key informants will be generated through purposive sampling and snowball sampling based on the completed online search and the systematic review. The interview guides will be developed based on the RE-AIM (Reach, Effective, Adoption, Implementation, and Maintenance) framework. The study received ethics approval from the University of New South Wales Human Research Ethics Advisory Panel (HC190921). Findings will be disseminated with academics and policymakers through a peer-reviewed journal and conference presentations.

Mapping the contribution and strategic distribution patterns of neuroimaging features of small vessel disease in poststroke cognitive impairment.

OBJECTIVES: Individual neuroimaging features of small vessel disease (SVD) have been reported to influence poststroke cognition. This study aimed to investigate the joint contribution and strategic distribution patterns of multiple types of SVD imaging features in poststroke cognitive impairment. METHODS: We studied 145 first-ever ischaemic stroke patients with MRI and Montreal Cognitive Assessment (MoCA) examined at baseline. The local burdens of acute ischaemic lesion (AIL), white matter hyperintensity, lacune, enlarged perivascular space and cross-sectional atrophy were quantified and entered into support vector regression (SVR) models to associate with the global and domain scores of MoCA. The SVR models were optimised with feature selection through 10-fold cross-validations. The contribution of SVD features to MoCA scores was measured by the prediction accuracy in the corresponding SVR model after optimisation. RESULTS: The combination of the neuroimaging features of SVD contributed much more to the MoCA deficits on top of AILs compared with individual SVD features, and the cognitive impact of different individual SVD features was generally similar. As identified by the optimal SVR models, the important SVD-affected regions were mainly located in the basal ganglia and white matter around it, although the specific regions varied for MoCA and its domains. CONCLUSIONS: Multiple types of SVD neuroimaging features jointly had a significant impact on global and domain cognitive functionings after stroke on top of AILs. The map of strategic cognitive-relevant regions of SVD features may help clinicians to understand their complementary impact on poststroke cognition.