Dietary salt reduction and cardiovascular disease rates in India: a mathematical model

Modelling health and economic impact of nutrition interventions: a systematic review

Diet related non-communicable diseases (NCDs), as well as micronutrient deficiencies, are of widespread and growing importance to public health. Authorities are developing programs to improve nutrient intakes via foods. To estimate the potential health and economic impact of these programs there is a wide variety of models. The aim of this review is to evaluate existing models to estimate the health and/or economic impact of nutrition interventions with a focus on reducing salt and sugar intake and increasing vitamin D, iron, and folate/folic acid intake. The protocol of this systematic review has been registered with the International Prospective Register of Systematic Reviews (PROSPERO: CRD42016050873). The final search was conducted on PubMed and Scopus electronic databases and search strings were developed for salt/sodium, sugar, vitamin D, iron, and folic acid intake. Predefined criteria related to scientific quality, applicability, and funding/interest were used to evaluate the publications. In total 122 publications were included for a critical appraisal: 45 for salt/sodium, 61 for sugar, 4 for vitamin D, 9 for folic acid, and 3 for iron. The complexity of modelling the health and economic impact of nutrition interventions is dependent on the purpose and data availability. Although most of the models have the potential to provide projections of future impact, the methodological challenges are considerable. There is a substantial need for more guidance and standardization for future modelling, to compare results of different studies and draw conclusions about the health and economic impact of nutrition interventions.

The effect of sodium restriction on iodine prophylaxis: a review

PURPOSE

Sodium is essential to life. However, its dietary excess is detrimental to the cardiovascular system, and sodium restriction is a crucial step in cardiovascular prevention. Iodine deficiency has been fought worldwide for decades, and substantial success has been achieved introducing the use of iodine-enriched salt. Nevertheless, areas of iodine deficiency persist around the world, both in developing and industrialized countries, and a major concern affecting dietary sodium reduction programs is represented by a possible iodine intake deficiency. There are substantial differences in the source of alimentary iodine among countries, such as iodized salt added, household tap water, seafood, or salt employed in packaged food. It is clear that a sodium-restricted diet can induce differences in terms of iodine intake, depending on the country considered. Moreover, iodine status has undergone relevant changes in many countries in the last years.

METHODS

Systematic review of literature evidence about the possible effects of sodium restriction on population iodine status.

RESULTS

To date, the available results are conflicting, depending on country, salt iodization policy, as well as time frame of data collection. However, to ensure an optimal iodine supply by salt fortification, without exceeding the current recommendation by World Health Organization for salt intake, seems to be an achievable goal.

CONCLUSION

A balanced approach may be obtained by an adequate iodine concentration in fortified salt and by promoting the availability of iodized salt for household consumption and food industry use. In this scenario, updated prospective studies are strongly needed.

Dietary Salt Reduction, Prevalence of Hypertension and Avoidable Burden of Stroke in Vietnam: Modelling the Health and Economic Impacts

Dietary salt reduction has been recommended as a cost-effective population-wide strategy to prevent cardiovascular disease. The health and economic impact of salt consumption on the future burden of stroke in Vietnam is not known.

Objective: To estimate the avoidable incidence of and deaths from stroke, as well as the healthy life years and healthcare costs that could be gained from reducing salt consumption in Vietnam.

Methods: This was a macrosimulation health and economic impact assessment study. Data on blood pressure, salt consumption and stroke epidemiology were obtained from the Vietnam 2015 STEPS survey and the Global Burden of Disease study. A proportional multi-cohort multistate lifetable Markov model was used to estimate the impact of achieving the Vietnam national salt targets of 8 g/day by 2025 and 7 g/day by 2030, and to the 5 g/day WHO recommendation by 2030. Probabilistic sensitivity analysis was conducted to quantify the uncertainty in our projections.

Results: If the 8 g/day, 7 g/day, and 5 g/day targets were achieved, the prevalence of hypertension could reduce by 1.2% (95% uncertainty interval [UI]: 0.5 to 2.3), 2.0% (95% UI: 0.8 to 3.6), and 3.5% (95% UI: 1.5 to 6.3), respectively. This would translate, respectively, to over 80,000, 180,000, and 257,000 incident strokes and over 18,000, 55,000, and 73,000 stroke deaths averted. By 2025, over 56,554 stroke-related health-adjusted life years (HALYs) could be gained while saving over US$ 42.6 million in stroke healthcare costs. By 2030, about 206,030 HALYs (for 7 g/day target) and 262,170 HALYs (for 5 g/day target) could be gained while saving over US$ 88.1 million and US$ 122.3 million in stroke healthcare costs respectively.

Conclusion: Achieving the national salt reduction targets could result in substantial population health and economic benefits. Estimated gains were larger if the WHO salt targets were attained and if changes can be sustained over the longer term. Future work should consider the equity impacts of specific salt reduction programs.

Attributable Burden and Expenditure of Cardiovascular Diseases and Associated Risk Factors in Mexico and other Selected Mega-Countries

BACKGROUND

This paper describes the health and economic burden of cardiovascular diseases (CVD) in Mexico and other mega-countries through a review of literature and datasets.

METHODS

Mega-countries with a low (Nigeria), middle (India), high (China/Brazil/Mexico), and very high (the U.S.A./Japan) human development index were included. The review was focused on prevalence of dyslipidemias and CVD economic impact and conducted according to the PRISMA statement. Public datasets of CVD indicators were explored.

RESULTS

Heterogeneity in economic data and limited information on dyslipidemias were found. Hypertriglyceridemia and hypercholesterolemia were higher in Mexico compared with other countries. Higher contribution of dietary risk factors for cardiovascular mortality and greater probability of dying prematurely from CVD were observed in developing countries. From 1990-2016, a greater decrease in cardiovascular mortality in developed countries was registered. In 2015, a CVD expense equivalent to 4% of total health expenditure was reported in Mexico. CVD ranked first in health expenditures in almost all these nations and the economic burden will remain significant for decades to come.

CONCLUSIONS

Resources should be assured to optimize CVD risk monitoring. Educational and medical models must be improved to enhance CVD diagnosis and the prescription and adherence to treatments. Long-term benefits could be attained by modifying the food system.

Potential impact of a modest reduction in salt intake on blood pressure, cardiovascular disease burden and premature mortality: a modelling study

Objective

To assess the potential impact of reduction in salt intake on the burden of cardiovascular disease (CVD) and premature mortality in Cameroon.

Methods

Using a multicohort proportional multistate life table model with Markov process, we modelled the impact of WHO's recommended 30% relative reduction in population-wide sodium intake on the CVD burden for Cameroonian adults alive in 2016. Deterministic and probabilistic sensitivity analyses were conducted and used to quantify uncertainty.

Results

Over the lifetime, incidence is predicted to decrease by 5.2% (95% uncertainty interval (UI) 4.6 to 5.7) for ischaemic heart disease (IHD), 6.6% (95% UI 5.9 to 7.4) for haemorrhagic strokes, 4.8% (95% UI 4.2 to 5.4) for ischaemic strokes and 12.9% (95% UI 12.4 to 13.5) for hypertensive heart disease (HHD). Mortality over the lifetime is projected to reduce by 5.1% (95% UI 4.5 to 5.6) for IHD, by 6.9% (95% UI 6.1 to 7.7) for haemorrhagic stroke, by 4.5% (95% UI 4.0 to 5.1) for ischaemic stroke and by 13.3% (95% UI 12.9 to 13.7) for HHD. About 776 400 (95% UI 712 600 to 841 200) health-adjusted life years could be gained, and life expectancy might increase by 0.23 years and 0.20 years for men and women, respectively. A projected 16.8% change (reduction) between 2016 and 2030 in probability of premature mortality due to CVD would occur if population salt reduction recommended by WHO is attained.

Conclusion

Achieving the 30% reduction in sodium intake recommended by WHO could considerably decrease the burden of CVD. Targeting blood pressure via decreasing population salt intake could translate in significant reductions in premature CVD mortality in Cameroon by 2030.

Sources of Dietary Salt in North and South India Estimated from 24 Hour Dietary Recall

Recent data on salt intake levels in India show consumption is around 11 g per day, higher than the World Health Organization's (WHO) recommended intake of 5 g per day. However, high-quality data on sources of salt in diets to inform a salt reduction strategy are mostly absent. A cross-sectional survey of 1283 participants was undertaken in rural, urban, and slum areas in North (n = 526) and South (n = 757) India using an age-, area-, and sex-stratified sampling strategy. Data from two 24-h dietary recall surveys were transcribed into a purpose-built nutrient database. Weighted salt intake was estimated from the average of the two recall surveys, and major contributors to salt intake were identified. Added salt contributed the most to total salt intake, with proportions of 87.7% in South India and 83.5% in North India (p < 0.001). The main food sources of salt in the south were from meat, poultry, and eggs (6.3%), followed by dairy and dairy products (2.6%), and fish and seafood (1.6%). In the north, the main sources were dairy and dairy products (6.4%), followed by bread and bakery products (3.3%), and fruits and vegetables (2.1%). Salt intake in India is high, and this research confirms it comes mainly from added salt. Urgent action is needed to implement a program to achieve the WHO salt reduction target of a 30% reduction by 2025. The data here suggest the focus needs to be on changing consumer behavior combined with low sodium, salt substitution.

Comparing Strategies to Prevent Stroke and Ischemic Heart Disease in the Tunisian Population: Markov Modeling Approach Using a Comprehensive Sensitivity Analysis Algorithm

BACKGROUND

Mathematical models offer the potential to analyze and compare the effectiveness of very different interventions to prevent future cardiovascular disease. We developed a comprehensive Markov model to assess the impact of three interventions to reduce ischemic heart diseases (IHD) and stroke deaths: (i) improved medical treatments in acute phase, (ii) secondary prevention by increasing the uptake of statins, (iii) primary prevention using health promotion to reduce dietary salt consumption.

METHODS

We developed and validated a Markov model for the Tunisian population aged 35-94 years old over a 20-year time horizon. We compared the impact of specific treatments for stroke, lifestyle, and primary prevention on both IHD and stroke deaths. We then undertook extensive sensitivity analyses using both a probabilistic multivariate approach and simple linear regression (metamodeling).

RESULTS

The model forecast a dramatic mortality rise, with 111,134 IHD and stroke deaths (95% CI 106567 to 115048) predicted in 2025 in Tunisia. The salt reduction offered the potentially most powerful preventive intervention that might reduce IHD and stroke deaths by 27% (-30240 [-30580 to -29900]) compared with 1% for medical strategies and 3% for secondary prevention. The metamodeling highlighted that the initial development of a minor stroke substantially increased the subsequent probability of a fatal stroke or IHD death.

CONCLUSIONS

The primary prevention of cardiovascular disease via a reduction in dietary salt consumption appeared much more effective than secondary or tertiary prevention approaches. Our simple but comprehensive model offers a potentially attractive methodological approach that might now be extended and replicated in other contexts and populations.

Knowledge and behaviors related to dietary salt and sources of dietary sodium in north India

Sodium, an element needed for the normal human physiology is known to be associated with high blood pressure and other consequences if consumed in excess. The assessment of knowledge and behavior related to sodium that is consumed in the form of salt plays an important role in the control of cardiovascular diseases. To control the intake of sodium, dietary sources of sodium need to be identified. To address this, a community-based cross-sectional study was conducted among women aged 20 to 59 years in north India, where knowledge, attitude, and behavior questionnaire given by the World Health Organization and 24-h dietary recall were used. The mean age of the participants was 34.5 years, and the majority of them were homemakers. Approximately, 80% of the participants believed that high salt diet causes serious health problems, and only 5% of the participants were aware of the existence of a recommendation for daily salt intake. Less than 20% of the participants took measures to control their salt intake. Vegetable-based dishes were found to be the major contributors to the daily salt intake followed by pulse-based and cereal-based dishes. This is because of the high quantity in which they are consumed. Food cooked at home contributed to 90% of the daily salt intake. To control the salt intake, we should cut- down the discretionary salt use. Dietary advice should be customized to the individual, and the family physician plays an important role in this. Behavioral change is the need of the hour to control the epidemic of non-communicable diseases.

Salt sensitivity and its implication in clinical practice

Hypertension (HTN) is a complex multi-factorial disease and is considered one of the foremost modifiable risk factors for stroke, heart failure, ischemic heart disease and renal dysfunction. Over the past century, salt and its linkage to HTN and cardiovascular (CV) mortality has been the subject of intense scientific scrutiny. There is now consensus that different individuals have different susceptibilities to blood pressure (BP)-raising effects of salt and this susceptiveness is called as salt sensitivity. Several renal and extra-renal mechanisms are believed to play a role. Blunted activity of the renin–angiotensin–aldosterone system (RAAS), adrenal Rac1-MR-Sgk1-NCC/ENaC pathway, renal SNS-GR-WNK4-NCC pathway, defect of membrane ion transportation, inflammation and abnormalities of Na⁺/Ca²⁺ exchange have all been implicated as pathophysiological basis for salt sensitive HTN. While salt restriction is definitely beneficial recent observation suggests that treatment with Azilsartan may improve salt sensitivity by selectively reducing renal proximal tubule Na⁺/H⁺ exchange. This encourages the future potential benefits of recognizing and therapeutically addressing the salt sensitive phenotype in humans.

Cost and cost-effectiveness of a school-based education program to reduce salt intake in children and their families in China

Objective

The School-based Education Program to Reduce Salt Intake in Children and Their Families study was a cluster randomized control trial among grade five students in 28 primary schools and their families in Changzhi, China. It achieved a significant effect in lowering systolic blood pressure (SBP) in all family adults by 2.3 mmHg and in elderlies (aged > = 60 years) by 9.5 mmHg. The aim of this study was to assess the cost-effectiveness of this salt reduction program.

Methods

Costs of the intervention were assessed using an ingredients approach to identify resource use. A trial-based incremental cost-effectiveness ratio (ICER) was estimated based on the observed effectiveness in lowering SBP. A Markov model was used to estimate the long-term cost-effectiveness of the intervention, and then based on population data, extrapolated to a scenario where the program is scaled up nationwide. Findings were presented in terms of an incremental cost per quality-adjusted life year (QALY). The perspective was that of the health sector.

Results

The intervention cost Int$19.04 per family and yielded an ICER of Int$2.74 (90% CI: 1.17–12.30) per mmHg reduction of SBP in all participants (combining children and adult participants together) compared with control group. If scaled up nationwide for 10 years and assumed deterioration in treatment effect of 50% over this period, it would reach 165 million families and estimated to avert 42,720 acute myocardial infarction deaths and 107,512 stroke deaths in China. This would represent a gain of 635,816 QALYs over 10-year time frame, translating into Int$1,358 per QALY gained.

Conclusion

Based on WHO-CHOICE criteria, our analysis demonstrated that the proposed salt reduction strategy is highly cost-effective, and if scaled up nationwide, the benefits could be substantial.

Trial registration

ClinicalTrials.gov NCT01821144

Cardiovascular Diseases in India: Current Epidemiology and Future Directions

Cardiovascular diseases (CVDs) have now become the leading cause of mortality in India. A quarter of all mortality is attributable to CVD. Ischemic heart disease and stroke are the predominant causes and are responsible for >80% of CVD deaths. The Global Burden of Disease study estimate of age-standardized CVD death rate of 272 per 100 000 population in India is higher than the global average of 235 per 100 000 population. Some aspects of the CVD epidemic in India are particular causes of concern, including its accelerated buildup, the early age of disease onset in the population, and the high case fatality rate. In India, the epidemiological transition from predominantly infectious disease conditions to noncommunicable diseases has occurred over a rather brief period of time. Premature mortality in terms of years of life lost because of CVD in India increased by 59%, from 23.2 million (1990) to 37 million (2010). Despite wide heterogeneity in the prevalence of cardiovascular risk factors across different regions, CVD has emerged as the leading cause of death in all parts of India, including poorer states and rural areas. The progression of the epidemic is characterized by the reversal of socioeconomic gradients; tobacco use and low fruit and vegetable intake have become more prevalent among those from lower socioeconomic backgrounds. In addition, individuals from lower socioeconomic backgrounds frequently do not receive optimal therapy, leading to poorer outcomes. Countering the epidemic requires the development of strategies such as the formulation and effective implementation of evidence-based policy, reinforcement of health systems, and emphasis on prevention, early detection, and treatment with the use of both conventional and innovative techniques. Several ongoing community-based studies are testing these strategies.

The Association of Knowledge and Behaviours Related to Salt with 24-h Urinary Salt Excretion in a Population from North and South India

Consumer knowledge is understood to play a role in managing risk factors associated with cardiovascular disease and may be influenced by level of education. The association between population knowledge, behaviours and actual salt consumption was explored overall, and for more-educated compared to less-educated individuals. A cross-sectional survey was done in an age-and sex-stratified random sample of 1395 participants from urban and rural areas of North and South India. A single 24-h urine sample, participants' physical measurements and questionnaire data were collected. The mean age of participants was 40 years, 47% were women and mean 24-h urinary salt excretion was 9.27 (8.87-9.69) g/day. Many participants reported favourable knowledge and behaviours to minimise risks related to salt. Several of these behaviours were associated with reduced salt intake-less use of salt while cooking, avoidance of snacks, namkeens, and avoidance of pickles (all p < 0.003). Mean salt intake was comparable in more-educated (9.21, 8.55-9.87 g/day) versus less-educated (9.34, 8.57-10.12 g/day) individuals (p = 0.82). There was no substantively different pattern of knowledge and behaviours between more-versus less-educated groups and no clear evidence that level of education influenced salt intake. Several consumer behaviours related to use of salt during food preparation and consumption of salty products were related to actual salt consumption and therefore appear to offer an opportunity for intervention. These would be a reasonable focus for a government-led education campaign targeting salt.

Control of Blood Pressure and Risk Attenuation: Post Trial Follow-Up of Randomized Groups

Background

Evidence on long term effectiveness of public health strategies for lowering blood pressure (BP) is scarce. In the Control of Blood Pressure and Risk Attenuation (COBRA) Trial, a 2 x 2 factorial, cluster randomized controlled trial, the combined home health education (HHE) and trained general practitioner (GP) intervention delivered over 2 years was more effective than no intervention (usual care) in lowering systolic BP among adults with hypertension in urban Pakistan. However, it was not clear whether the effect would be sustained after the cessation of intervention. We conducted 7 years follow-up inclusive of 5 years of post intervention period of COBRA trial participants to assess the effectiveness of the interventions on BP during extended follow-up.

Methods

A total of 1341 individuals 40 years or older with hypertension (systolic BP 140 mm Hg or greater, diastolic BP 90 mm Hg or greater, or already receiving treatment) were followed by trained research staff masked to randomization status. BP was measured thrice with a calibrated automated device (Omron HEM-737 IntelliSense) in the sitting position after 5 minutes of rest. BP measurements were repeated after two weeks. Generalized estimating equations (GEE) were used to analyze the primary outcome of change in systolic BP from baseline to 7- year follow-up. The multivariable model was adjusted for clustering, age at baseline, sex, baseline systolic and diastolic BP, and presence of diabetes.

Findings

After 7 years of follow-up, systolic BP levels among those randomised to combined HHE plus trained GP intervention were significantly lower (2.1 [4.1–0.1] mm Hg) compared to those randomised to usual care, (P = 0.04). Participants receiving the combined intervention compared to usual care had a greater reduction in LDL-cholesterol (2.7 [4.8 to 0.6] mg/dl.

Conclusions

The benefit in systolic BP reduction observed in the original cohort assigned to the combined intervention was attenuated but still evident at 7- year follow-up. These findings highlight the potential for scaling-up simple strategies for cardiovascular risk reduction in low- and middle- income countries.

Trial Registration

ClinicalTrials.gov NCT00327574

Palm oil taxes and cardiovascular disease mortality in India: economic-epidemiologic model

OBJECTIVE

To examine the potential effect of a tax on palm oil on hyperlipidemia and on mortality due to cardiovascular disease in India.

DESIGN

Economic-epidemiologic model.

MODELING METHODS

A microsimulation model of mortality due to myocardial infarction and stroke among Indian populations was constructed, incorporating nationally representative data on systolic blood pressure, total cholesterol, tobacco smoking, diabetes, and cardiovascular event history, and stratified by age, sex, and urban/rural residence. Household expenditure data were used to estimate the change in consumption of palm oil following changes in oil price and the potential substitution of alternative oils that might occur after imposition of a tax. A 20% excise tax on palm oil purchases was simulated over the period 2014-23.

MAIN OUTCOME MEASURES

The model was used to project future mortality due to myocardial infarction and stroke, as well as the potential effect of a tax on food insecurity, accounting for the effect of increased food prices.

RESULTS

A 20% tax on palm oil purchases would be expected to avert approximately 363,000 (95% confidence interval 247,000 to 479,000) deaths from myocardial infarctions and strokes over the period 2014-23 in India (1.3% reduction in cardiovascular deaths) if people do not substitute other oils for reduced palm oil consumption. Given estimates of substitution of palm oil with other oils following a 20% price increase for palm oil, the beneficial effects of increased polyunsaturated fat consumption would be expected to enhance the projected reduction in deaths to as much as 421,000 (256,000 to 586,000). The tax would be expected to benefit men more than women and urban populations more than rural populations, given differential consumption and cardiovascular risk. In a scenario incorporating the effect of taxation on overall food expenditures, the tax may increase food insecurity by <1%, resulting in 16,000 (95% confidence interval 12,000 to 22,000) deaths.

CONCLUSIONS

Curtailing palm oil intake through taxation may modestly reduce hyperlipidemia and cardiovascular mortality, but with potential distributional consequences differentially benefiting male and urban populations, as well as affecting food security.

Social epidemiology of hypertension in middle-income countries: determinants of prevalence, diagnosis, treatment, and control in the WHO SAGE study

Large-scale hypertension screening campaigns have been recommended for middle-income countries. We sought to identify sociodemographic predictors of hypertension prevalence, diagnosis, treatment, and control among middle-income countries. We analyzed data from 47 443 adults in all 6 middle-income countries (China, Ghana, India, Mexico, Russia, and South Africa) sampled in nationally representative household assessments from 2007 to 2010 as part of the World Health Organization Study on Global Aging and Adult Health. We estimated regression models accounting for age, sex, urban/rural location, nutrition, and obesity, as well as hypothesized covariates of healthcare access, such as income and insurance. Hypertension prevalence varied from 23% (India) to 52% (Russia), with between 30% (Russia) and 83% (Ghana) of hypertensives undiagnosed before the survey and between 35% (Russia) and 87% (Ghana) untreated. Although the risk of hypertension significantly increased with age (odds ratio, 4.6; 95% confidence interval, 3.0-7.1; among aged, 60-79 versus <40 years), the risk of being undiagnosed or untreated fell significantly with age. Obesity was a significant correlate to hypertension (odds ratio, 3.7; 95% confidence interval, 2.1-6.8 for obese versus normal weight), and was prevalent even among the lowest income quintile (13% obesity). Insurance status and income also emerged as significant correlates to diagnosis and treatment probability, respectively. More than 90% of hypertension cases were uncontrolled, with men having 3 times the odds as women of being uncontrolled. Overall, the social epidemiology of hypertension in middle-income countries seems to be correlated to increasing obesity prevalence, and hypertension control rates are particularly low for adult men across distinct cultures.