Introduction

Non-communicable diseases (NCDs) are the main cause of death and disability globally and in Brazil. According to the Global Burden of Disease studies, in 2017, 11 million deaths and 255 million Disability Adjusted Years (DALYs) were attributable to dietary risk factors worldwide. A high intake of sodium is considered the primary diet-related risk factor (being responsible for 3 million deaths and 70 million DALYs), because of its strong association with NCDs, such as cardiovascular diseases (ischemic heart disease, stroke, and hypertension) [1].

Cardiovascular diseases are one of the leading causes of global mortality and morbidity, and they also represent a major economic burden on health care systems in terms of the direct (e.g., medical consultations, hospitalizations, rehabilitation services, and drugs) and indirect (e.g., losses of productivity due to premature mortality and short- or long-term disability) costs associated with mortality and morbidity.

The costs of CVDs, as NCDs, are likely to continue to grow due to inadequate diets, an increase in obesity and the aging of societies, so it is very important to address the burden of these diseases in terms of mortality, morbidity and the costs to health systems and society. In addition, economic studies can provide evidence to support CVD prevention programs, which are very cost-effective measures, compared to the costs associated with treating CVD-related conditions [2].

In recent decades, the development of many health and economic modelling methodologies, involving both macro and microsimulations and static and dynamic analysis has improved and supported policy decisions by analyzing the potential impact and cost-effectiveness of health interventions. Most models focused on ex ante policy estimations and scenario comparisons for obesity and NCDs and often incorporated economic analysis in traditional mortality and morbidity outcomes [3][4][5][6]. Choosing an epidemiological model for health and economic evaluation depends on factors, such as the data availability, timeframe for results, programming and computer capacity, but most models are based on common principles, such as the use of relative risks, drawn from the literature, to establish causal frameworks that link changes in risk factors with health and cost outcomes [7].

For example, the health scenario static model for NCD risk factors, called PRIME (Preventable Risk Integrated ModEl), was developed by the University of Oxford and adapted methodologies similar to those used by the Global Burden of Disease Project. The model compares deaths from NCDs using a baseline and counterfactual scenarios and changing risk factors, such as diet, physical activity, alcohol consumption and smoking [8]. PRIME has been used for the evaluation of several policy scenarios in the United Kingdom, other European countries and Canada [9] and is a very comprehensive and user-friendly methodology for comparing policy options and estimating the impact of risk factor changes in terms of counterfactual scenarios.

Economic studies have highlighted the burden of NCDs, especially CVDs, on countries and health systems. In most low and middle income countries, the annual cost of CVD care is many times the total health expenditure per capita [5]. In Mexico, the burden of cardiovascular diseases comprises approximately 4% of the total national healthcare expenditure and approximately 46% of the health system cost [10]. In the United States, cost estimates of CVD episodes are at least twice as high as the cost of some conditions in the European Union [11].

In Brazil, the first national salt/sodium consumption based on spot urinary sodium excretion was released in 2019, despite data collection was conducted in 2013. The average salt consumption was estimated in 9.34g/day among adults (9.63g for men and 9.08g for women) and 97.6% of the adults consumed over the WHO recommendation of 5g/day [12]. The main dietary sources of sodium, according to national food acquisition surveys, are salt added to foods and industrialized products, as well as foods consumed within and out of the household [13]. As a result, 22.8% of the Brazilian adult population are hypertensive (25.8% of men and 20.0% of women) [14].

Consequently, salt/sodium reduction and hypertension prevention and control require multiple strategies, from health education and nutritional counseling to food reformulation, along with the secondary prevention and treatment of hypertension and CVD. The comparative impact of these conditions on health and costs is still unknown [15].

According to the 2013 Brazilian National Health Survey, chronic diseases increased hospitalizations and compromised normal activities among adults. Non-communicable diseases were also associated with more medical consultations and a greater use of the health services [16].

In Brazil, most of the population depends on the National Health System (SUS) for health care, which is publicly funded and universal, from primary health care to hospital treatment. Despite the high cost of CVD, there are few Brazilian studies that have estimated the federal government expenditures on the mortality and economic burden of these diseases and their major risk factor, excessive sodium consumption [17]. Nevertheless, cost-of-illness methodologies have been successfully used to estimate the costs associated with obesity and chronic kidney disease [18][19].

Considering the scarcity of data on the economic burden of dietary risk factors, such as sodium consumption, on cardiovascular disease, the present study aims to estimate the burden of cardiovascular diseases attributable to excessive sodium consumption, with hypertension as the intermediate outcome, in terms of the deaths and costs to the Brazilian publicly funded health system in 2017. The findings of this study should contribute to the improvement of the management of health system expenditures in developing countries, including Brazil.

Materials and methods

Study setting

This study provides, first, a health impact evaluation, which models the effect of sodium reduction on mortality associated with blood pressure and CVD, followed by a cost-of-illness analysis [14], from the perspective of the Brazilian National Health System (Sistema Único de Saúde, SUS), in 2017. All input variables and data sources are summarized in Table 1.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 1. Summary of the key model inputs and sources for health and economic modeling.

https://doi.org/10.1371/journal.pone.0235514.t001

The 1988 Brazilian Constitution states health as a citizen’s right and a duty of the state, and it established the foundations for the Unified Health System (SUS) and its main principles of universality, integrality, and social participation [27]. SUS is responsible for approximately 75% of medical care in Brazil and for health promotion, health surveillance, vector control, health education, and primary, specialist outpatient, and hospital level health care [18].

Brazil’s Information System on Mortality (Sistema de Informações de Mortalidade, SIM) is a comprehensive, population-based system, with high-quality information on mortality by cause, sex, education, age-group and location. Regarding the costs of disease treatment to the national health system, all costs associated with secondary health care are registered by public and private hospitals in the SUS Outpatient Information System (Sistema de Informação Ambulatorial, SIA/SUS) and the Hospital Information System (Sistema de Informação Hospitalar, SIH/SUS).

The costs of anti-hypertension drugs provided by the Farmacia Popular Program were obtained from the National Department of Pharmaceutical Care. The “Farmácia Popular do Brasil” Program (PFPB) was established through a public owned pharmacy network, and was subsequently expanded through partnerships with the retail private pharmacies, especially providing medications for hypertension, diabetes and asthma [28].

The most recent nationally representative salt consumption data was assessed from spot urine collected in 2013, as part of the Brazilian National Health Survey (NHS), a household survey with a representative sample of the Brazilian adult population. The estimated salt intake was described according to gender (male and female), age group (18 to 29; 30 to 44; 45 to 59; and 60 or older), among other disaggregations. We have assumed that salt intake remained constant from 2013 to 2017, considering that, in the previous decade, despite changes in dietary salt sources, the estimates of total salt intake was unchanged [13].

The present study ran a non-communicable disease scenario macro-simulation models to estimate the potential impact of modifications in dietary salt intakes on mortality and costs from cardiovascular diseases (CVD). A detailed presentation of the data sources and the methods used is available as Supplementary Materials.

Cardiovascular disease is considered, in this study, to comprise coronary heart disease, stroke, hypertensive disease, heart failure, aortic aneurysm, pulmonary embolism and rheumatic heart disease (International Codes of Disease (ICDs): I20–25, I60–69, I10–15, I50, I71, I26 and I05–09, respectively).

Results

Deaths attributable to excessive sodium consumption

In 2017, 49% of the Brazilian population was 30 years of age or older (95 million people), and according to the National Mortality Information System [21], 734,437 people in the country died from preventable diseases. Among these, 312,163 died from cardiovascular disease.

Table 2 lists the estimated number of deaths that may be averted or delayed if Brazilian men and women aged 30 years of more reduced their salt consumption to 5 g per day (2 g of sodium/day), as recommended by the WHO, the differences in salt consumption by men and women according to their age-groups.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 2. Estimated number of deaths attributed to excessive sodium consumption in Brazil, 2017.

https://doi.org/10.1371/journal.pone.0235514.t002

Considering the excessive salt consumption by Brazilians, premature deaths (<75 years) represented 53% of the deaths that may have been prevented through sodium reduction. Coronary heart disease (CHD), stroke and hypertensive disease accounted for 90% of these deaths. It is estimated that 6.4% of all preventable deaths and 15.0% of CVD deaths could be averted or delayed by consuming less salt, considering the average salt consumption at 9.34g/day.

Years of Life Lost (YLL).

Premature deaths are also responsible for a large burden in terms of Years of Life Lost (YLL), which are part of the Disability Adjusted Life Years (DALY). All cardiovascular deaths attributable to excessive sodium consumption, in 2017, are estimated to have caused 575,172 YLL, most of which were from CHD, stroke and hypertensive disease, as shown in Table 3. The YLL of men are, in general, higher than those of women, which is likely due to their higher rates of premature death by CVD.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 3. Estimated Years of Life Lost (YLL) due to excessive sodium consumption in Brazil, 2017.

https://doi.org/10.1371/journal.pone.0235514.t003

Costs of cardiovascular disease attributable to excessive sodium consumption to the Brazilian Health System.

Tables 4 and 5 present the costs of cardiovascular diseases (CVD) to the Brazilian National Health System in 2017, considering hospitalizations and outpatient costs, respectively, which are estimated to be preventable by reducing sodium consumption to 2 g per day. Hospitalizations and outpatient costs due to cardiovascular diseases totaled US$590 million dollars in 2017, which corresponds to 1.88 billion Brazilian Reals, and 14.2% of these costs (US$84) could be prevented by reducing sodium consumption.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 4. Estimated cardiovascular disease hospitalization costs (US$ thousand) to the National Health System due to excessive sodium consumption in Brazil, 2017.

https://doi.org/10.1371/journal.pone.0235514.t004

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 5. Estimated cardiovascular disease outpatient costs to the National Health System due to excessive sodium consumption in Brazil, 2017.

https://doi.org/10.1371/journal.pone.0235514.t005

Hospitalization costs due to excessive sodium consumption were estimated at US$76.2 million, and 87% of these costs were attributed to coronary heart disease, stroke and heart failure (Table 4). The annual outpatient costs attributable to excessive sodium consumption were estimated at US$6.1 million (Table 5). As in the case of preventable deaths, over 93% of the costs of outpatient care are related to CHD, stroke and hypertensive diseases. For both hospitalizations and outpatient care, the costs associated with men were nearly higher than those associated with women, namely, 62% of the total hospitalization and 53% of the outpatient costs.

Medication for high blood pressure.

In Brazil, primary health care facilities freely distribute drugs for hypertension, diabetes and asthma, and these drugs are also subsidized in private pharmacies through the “Farmacia Popular” Program. In 2017, the Program spent US$450.5 million on anti-hypertensive drugs, and 24.7% of these costs are attributable to excessive sodium consumption among Brazilians.

In Table 6, the costs of medication for hypertension due to excessive sodium consumption reached US$109.8 million in 2017, and 56.5% of the costs were associated with women.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 6. Estimated costs of hypertension drugs (US$ thousand) to the National Health System attributed to excessive sodium consumption in Brazil, 2017.

https://doi.org/10.1371/journal.pone.0235514.t006

Productivity costs due to premature death by CVD.

In 2017, as shown in Table 7, productivity losses due to premature deaths attributable to excessive sodium consumption reached US$752.7 million. We found that 72.3% (US$544.6 million) of the productivity losses among men were due to a higher sodium consumption, combined with higher death rates by CVDs and the pension age (currently, in Brazil, the pension age is 60 years of age for women and 64 years for men).

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 7. Estimated productivity losses (US$ thousand) of premature CVD deaths due to excessive sodium consumption in Brazil, 2017.

https://doi.org/10.1371/journal.pone.0235514.t007

Productivity losses due to premature death increase with age and peak at 50 to 54 years among men and at 45 to 49 years among women. Over 62% of the productivity losses for both sexes were concentrated within the 30 to 50 years of age range, which represents a large burden to the economy, considering the impact on the labor force of the country.

Discussion

Excessive sodium consumption leads to high blood pressure, which increases the risk of cardiovascular diseases, such as coronary heart disease, stroke, heart failure, pulmonary embolism, aortic aneurysm, rheumatic heart disease, and hypertensive disease [26][25]. The populations of most countries around the world, including Latin America, consume much over 2 g [35][36][37] of sodium per day, and the health and economic impacts of interventions are very important considerations for policymakers.

This study uses an original macrosimulation approach to link sodium consumption with CVDs mediated by high blood pressure and shows the impact of sodium consumption on deaths and the costs to the health system and society in Brazil. The results confirm that Brazil follows the estimates, provided by the GBD 2017 study, of the burden of sodium consumption, as a major risk factor for death and disease. Excessive sodium consumption by Brazilians was estimated to be responsible for 6.4% of all preventable deaths and 15.0% of CVD deaths in 2017, which corresponds to 47,017 estimated deaths.

Excessive sodium consumption was also estimated to be responsible for US$76.2 million, in terms of the total hospitalization costs, and US$6.1 million in outpatient care costs to the Brazilian National Health System in 2017. Because outpatient costs do not account for primary health care, which covers over 70% of the population and is responsible for the first level of health care, especially to people with chronic diseases, the attributable costs of CVDs caused by excessive sodium consumption, presented here, are likely underestimated.

The costs of hypertension drugs corresponded to over US$450 million (60% of the costs of the publicly distributed and subsidized Farmacia Basica Program) in 2017, and almost one fourth of these costs could be averted by reducing sodium consumption to recommended levels (US$109.8 million). While the costs of hypertension drugs have increased, since the creation of the program in 2004, the free or subsidized supply of hypertension drugs has proved to be an effective secondary CVD prevention strategy. As a result, the expansion of access to medicines for the treatment of chronic diseases, such as hypertension, has resulted in an average annual reduction of 27.6% in hospitalizations and 8.0% in deaths by cardiovascular disease in Brazil [38].

Regarding age differences, the burden of excessive sodium consumption generally increases with age, although a significant number of attributable deaths and costs already arise in younger groups. This can be explained by the higher sodium consumption among adolescents and adults and by the higher relative risks associated with CVDs in younger age groups. In terms of gender differences, women tend to access health services more frequently and consume less sodium than men. As a result, the burden of sodium-related deaths is higher in men, while the health system and societal costs tend to be similar between women and men.

Health economics methodologies also allow estimations related to dietary risks and NCDs, such as sodium consumption, including the years of life lost, years of productive life lost and the burden of premature deaths by CVD, to be made. The indirect societal costs are not limited to these analyses and may include costs of premature retirements, presentism, absenteeism and other costs of diseases to families and communities.

Non-communicable diseases were estimated to have caused losses of up to 7.3% of the Brazilian Gross Domestic Product (2.2% in early retirement and 5.1% in absenteeism and presentism) in 2015 [39]. In the US, hypertension, coronary heart disease and stroke cause a productivity loss of 2.8% due to absenteeism and a 6.8% loss due to presentism per employee, per year [40].

Conclusions

This study conservatively estimates that yearly 47,017 deaths, over US$84 million (268 million Brazilian Reals) in costs to the Brazilian Health System and US$827 million in costs of premature deaths to the country’s economy could be prevented or avoided, if the population consumed an average of 2 g of sodium (5 g of salt) per day. The methodologies presented in this study may be used to estimate the potential impact of different health strategies on sodium reduction and select “best buy” interventions for policy-makers.

Our findings suggest that sodium reduction policies in Brazil must be strengthened in order to reduce the significant burden of excessive sodium consumption on the country. These policies might include health promotion, food regulation, nutritional counseling, prevention, surveillance and disease treatment, which must be prioritized according to their cost-effectiveness.

Further research using health and economic modeling approaches is needed, especially in developing countries, to monitor health expenditure and to aid in improving policy implementation and the allocation of public funds in order to reduce preventable deaths by cardiovascular diseases and other NCDs and their toll on health systems and society.

Supporting information

Acknowledgments

This investigation was performed as part of the IDRC (International Research Development Centre of Canada), project #108167, “Scaling Up and Evaluating Salt Reduction Policies and Programs in Latin American Countries,” and as part of the doctoral project of Eduardo A.F. Nilson. The authors are especially grateful to the NCD modelling teams from the University of Liverpool and the University of Oxford for sharing their knowledge and models and discussing their application.