Trends in Energy Imbalance Gap and Body Weight Status in the Japanese Adult Population: A System Dynamics Approach.

BACKGROUND: The double burden of malnutrition is a growing public health problem in Japan. We estimated the dynamics of the energy imbalance gap (EIG) (average daily difference between energy intake and expenditure) to explain trends in the prevalence of underweight, overweight, and obese Japanese adults. METHODS: We used individual-level data on body height and weight from the National Health and Nutrition Surveys from 1975 to 2015. We calibrated a validated system dynamics model to estimate the EIG for Japanese adults aged 20 to 74 years by survey year, sex, and weight status classified by the body mass index (BMI). RESULTS: The overall EIG for men increased from 2.3 kcal/day in 1975 to 4.7 kcal/day in 1987 and then decreased to 2.3 kcal/day in 2015. The overall EIG for women consistently decreased from 4.3 kcal/day in 1975 to -0.5 kcal/day in 2015. By BMI class, the EIG for men with a BMI of <30 kg/m2 began to decrease around 1990, indicating a deceleration in the prevalence of overweight and obese men. The EIG consistently decreased for women with a BMI of <25 kg/m2 and reached negative values from the late 2000s to early 2010s, indicating a gradual decrease in the prevalence of overweight and obese women. CONCLUSIONS: The dynamics of the EIG were different across sex and weight groups. Public health interventions should target a further decrease in the EIG for normal-weight, overweight, and obese men and a stop in the decreasing trends of the EIG in underweight and normal-weight women.

[Use of simulation models in health economic evaluation studies of dietary salt-reduction policies for cardiovascular disease prevention].

Objectives　Social security costs related to the healthcare and long-term care of patients with cardiovascular diseases is a national burden that is expected to grow as Japan's population ages. Nutritional policies for improving the nation's diet could prevent cardiovascular diseases, but scientific evidence on their costs and outcomes is limited. This study gives an overview of health economic evaluation studies on population-wide dietary salt-reduction policies that have been instituted for the purposes of cardiovascular disease prevention. Thus, this study provides background information for the development of evaluation methods that can be utilized in Japan for analyzing the effects of nutritional policies on public health and social security cost containment.Methods　We extracted representative health economic simulation models that are used for predicting the effects of cardiovascular disease-related interventions: Cardiovascular Disease Policy Model, IMPACT Coronary Heart Disease Policy and Prevention Model, US IMPACT Food Policy Model, Assessing Cost-Effectiveness (ACE) approach to priority-setting, and Prevention Impacts Simulation Model (PRISM). Next, we collected original articles on studies that used these models for assessing the costs and effects of national population-wide dietary salt-reduction policies. We then outlined the background, structure, and applied studies associated with each model.Results　The five models utilized Markov cohort simulation, microsimulation, proportional multistate life tables, and system dynamics to predict the effect of dietary salt-reduction policies on blood pressure reduction and cardiovascular disease prevention. The models were applied to countries such as Australia, England, and the United States to simulate long-term (10 years to lifetime) costs and effects. These applied studies examined policies that included health promotion campaigns, sodium labels on the front of food packages, and mandatory or voluntary reformulation by the food industry to reduce the salt content of processed foods.Conclusion　Health economic simulation modeling is actively being used to evaluate scientific evidence on the costs and outcomes of national dietary salt-reduction policies. Similarly, leveraging simulation modeling techniques could facilitate the evaluation and planning of dietary salt-reduction policies and other nutritional policies in Japan.

First incidence and associated factors of overweight and obesity from preschool to primary school: longitudinal analysis of a national cohort in Japan.

BACKGROUND/OBJECTIVES: To assess longitudinal changes in the first incidence of overweight and obesity and associated factors from preschool to primary school age in Japan. SUBJECTS/METHODS: We obtained individual-level data from the "Longitudinal Survey of Newborns in the 21st Century" on children born in Japan in 2001. This analysis included 15,427 children (7951 boys and 7476 girls) with complete anthropometric data reported annually from age 42 months to 12 years. We followed the criteria of the International Obesity Task Force to define overweight and obesity. We assessed annual and cumulative incidence proportions and estimated odds ratios for the first incidence at preschool age (42-66 months) and primary school age (7-12 years), using multivariable logistic regression. RESULTS: The annual incidence of overweight and obesity combined was 3.8% at age 54 months (3.5% in boys, 4.2% in girls), and 1.2% at age 12 years (1.6% in boys, 0.7% in girls). The cumulative incidence was 19.7% at age 12 years (21.9% in boys, 17.3% in girls). Odds ratios (95% confidence intervals) of incidence for girls compared with boys were 1.28 (1.12-1.46) at preschool age and 0.62 (0.55-0.68) at primary school age. Other associated factors at preschool age included birth month, birthweight, gestational length, region and municipality of residence, living with grandparents, and behavioral factors (bedtime hours, television viewing time, and skipping breakfast). These associations persisted at primary school age except birthweight and gestational length and associated factors covered maternal education, living without siblings, and school travel mode. CONCLUSIONS: The first incidence decreases from preschool to primary school age and follows different age trajectories for boys and girls in a high-income population with low levels of childhood overweight and obesity. Policy-makers should consider such age-based changes in incidence and associated factors to target appropriate groups for primary prevention.

[Key variable combinations for identifying non-participants in the Japan National Health and Nutrition Survey through record linkage with the Comprehensive Survey of Living Conditions].

Objectives　The identification of non-participants in the Japan National Health and Nutrition Survey (NHNS) requires record linkage with its master sample from the Comprehensive Survey of Living Conditions (CSLC). In principle, we can merge individual records between the two surveys by using key identifiers including household ID, but false matches and nonmatches can occur. We examined combinations of key variables for improving record linkage to identify nonparticipants in the NHNS.Methods　We used individual-level data from the NHNS and the CSLC from 1988 to 2015 (except 2012). We extracted from CSLC data individuals in participating unit blocks in the NHNS to merge records between the two surveys. We used four combinations of key variables: prefecture ID, census enumeration district ID, unit block ID, household ID, and household member ID (A); household member ID in A was replaced with sex and birth year and month or age (B); sex and birth year and month or age were added to A (C); two-stage linkage of B and C (D). We classified a sample of individuals into matched participants, unmatched NHNS participants, and unmatched CSLC participants (a proxy for nonparticipants). We compared the percentages of matched NHNS participants and unmatched CSLC participants across the four combinations of key variables.Results　We obtained a sample of 455,854 participants from the CSLC and 335,010 from the NHNS. The percentage of matched NHNS participants was highest in A (the upper 90%), followed by D (the lower 90%), B (the lower 90%), and C (the 80%). Compared to C, the percentage of matched NHNS participants was higher by 8-14 percentage points in A and 5-10 percentage points in B. Compared to B, it was higher by 0.1-0.4 percentage points in D. The percentage of unmatched CSLC participants was highest in C, followed by B, D, and A. The percentage of unmatched CSLC participants increased in D from the 20% level in the late 1980s to around 30% in the 1990s and stayed between the 30% level and the lower 40% level in the 2000s.Conclusion　The highest percentage of accurate matches of NHNS participants was obtained by considering changes in household member ID and incorrect entries on sex and birth year/month and age, and same-sex multiple births. However, there are limitations in handling unmatched participants due to changes in household ID or other reasons. It is therefore necessary to consider the possibility of false nonmatches included in unmatched CSLC participants in regarding them as non-participants in the NHNS.

Effects of behavioral counseling on cardiometabolic biomarkers: A longitudinal analysis of the Japanese national database.

In Japan, health insurers are obliged to conduct Specific Health Checkup (SHC) for middle-aged and elderly persons. High-risk persons are referred to Specific Health Guidance (SHG) to receive behavioral counseling based on individual action plans including targets for modification of daily energy balance through diet and physical activity. Using individual-level observational data, we examined the effects of diet and physical activity counseling on cardiometabolic biomarkers across the country. Subjects were 363,440 high-risk persons aged 40-64 who participated in intensive support in SHG for ≥3 months between April 2008 and March 2012. We considered participants as receiving counseling on diet alone, physical activity alone, combined, or neither if they had targets for diet only, physical activity only, both, or neither, respectively. Biomarkers included body mass index, waist circumference, systolic and diastolic blood pressure, high-density lipoprotein cholesterol, and hemoglobin A1c. Under the difference-in-differences approach, we used multivariable linear regression on repeated measures of biomarkers at SHCs before and after SHG and estimated the effects of each counseling type as an interaction with time of SHC. Compared with neither counseling, diet and physical activity counseling, alone or combined, were significantly associated with additional improvements in biomarkers after SHG, for example, body mass index (men: 0.03-0.06 kg/m2, women: 0.10-0.15 kg/m2) and waist circumference (men: 0.16-0.29 cm, women: 0.43-0.47 cm) in both sexes and high-density lipoprotein cholesterol in men (0.13-0.29 mg/dL). Modest improvements in biomarkers were associated with diet and physical activity counseling, although effect sizes were small.

Secondary Data Analysis of National Surveys in Japan Toward Improving Population Health.

Secondary data analysis of national health surveys of the general population is a standard methodology for health metrics and evaluation; it is used to monitor trends in population health over time and benchmark the performance of health systems. In Japan, the government has established electronic databases of individual records from national surveys of the population's health. However, the number of publications based on these datasets is small considering the scale and coverage of the surveys. There appear to be two major obstacles to the secondary use of Japanese national health survey data: strict data access control under the Statistics Act and an inadequate interdisciplinary research environment for resolving methodological difficulties encountered when dealing with secondary data. The usefulness of secondary analysis of survey data is evident with examples from the author's previous studies based on vital records and the National Health and Nutrition Surveys, which showed that (i) tobacco smoking and high blood pressure are the major risk factors for adult mortality from non-communicable diseases in Japan; (ii) the decrease in mean blood pressure in Japan from the late 1980s to the early 2000s was partly attributable to the increased use of antihypertensive medication and reduced dietary salt intake; and (iii) progress in treatment coverage and control of high blood pressure is slower in Japan than in the United States and Britain. National health surveys in Japan are an invaluable asset, and findings from secondary analyses of these surveys would provide important suggestions for improving health in people around the world.

Association of Energy Intake With the Lack of in-Person Review of Household Dietary Records: Analysis of Japan National Health and Nutrition Surveys From 1997 to 2011.

BACKGROUND: National surveys have demonstrated a long-term decrease in mean energy intake in Japan, despite the absence of a decrease in the prevalence of overweight and obesity. We aimed to examine whether total energy intake of survey respondents is associated with completion of an in-person review of dietary records and whether it affects the trend in mean energy intake. METHODS: We pooled data from individuals aged 20-89 years from the National Nutrition Surveys of 1997-2002 and the National Health and Nutrition Surveys of 2003-2011. We conducted a linear mixed-effects regression to estimate the association between total energy intake and the lack of an in-person review of semi-weighed household dietary records with interviewers. As some respondents did not have their dietary data confirmed, we used regression coefficients to correct their total energy intake. RESULTS: Compared with respondents completing an in-person review, total energy intake was significantly inversely associated with respondents not completing a review across all sex and age groups (P < 0.001). After correction of total energy intake for those not completing a review, mean energy intake in each survey year significantly increased by 2.1%-3.9% in men and 1.3%-2.6% in women (P < 0.001), but the decreasing trend in mean energy intake was sustained. CONCLUSIONS: Total energy intake may be underestimated without an in-person review of dietary records. Further efforts to facilitate completion of a review may improve accuracy of these data. However, the increasing proportion of respondents missing an in-person review had little impact on the decreasing mean caloric intake.

Is adjustment for reporting heterogeneity necessary in sleep disorders? Results from the Japanese World Health Survey.

BACKGROUND: Anchoring vignettes are brief texts describing a hypothetical character who illustrates a certain fixed level of a trait under evaluation. This research uses vignettes to elucidate factors associated with sleep disorders in adult Japanese before and after adjustment for reporting heterogeneity in self-reports. This study also evaluates the need for adjusting for reporting heterogeneity in the management of sleep and energy related problems in Japan. METHODS: We investigated a dataset of 1002 respondents aged 18 years and over from the Japanese World Health Survey, which collected information through face-to-face interview from 2002 to 2003. The ordered probit model and the Compound Hierarchical Ordered Probit (CHOPIT) model, which incorporated anchoring vignettes, were employed to estimate and compare associations of sleep and energy with socio-demographic and life-style factors before and after adjustment for differences in response category cut-points for each individual. RESULTS: The prevalence of self-reported problems with sleep and energy was 53 %. Without correction of cut-point shifts, age, sex, and the number of comorbidities were significantly associated with a greater severity of sleep-related problems. After correction, age, the number of comorbidities, and regular exercise were significantly associated with a greater severity of sleep-related problems; sex was no longer a significant factor. Compared to the ordered probit model, the CHOPIT model provided two changes with a subtle difference in the magnitude of regression coefficients after correction for reporting heterogeneity. CONCLUSION: Sleep disorders are common in the general adult population of Japan. Correction for reporting heterogeneity using anchoring vignettes is not a necessary tool for proper management of sleep and energy related problems among Japanese adults. Older age, gender differences in communicating sleep-related problems, the presence of multiple morbidities, and regular exercise should be the focus of policies and clinical practice to improve sleep and energy management in Japan.

Inequalities in non-communicable diseases and effective responses.

In most countries, people who have a low socioeconomic status and those who live in poor or marginalised communities have a higher risk of dying from non-communicable diseases (NCDs) than do more advantaged groups and communities. Smoking rates, blood pressure, and several other NCD risk factors are often higher in groups with low socioeconomic status than in those with high socioeconomic status; the social gradient also depends on the country's stage of economic development, cultural factors, and social and health policies. Social inequalities in risk factors account for more than half of inequalities in major NCDs, especially for cardiovascular diseases and lung cancer. People in low-income countries and those with low socioeconomic status also have worse access to health care for timely diagnosis and treatment of NCDs than do those in high-income countries or those with higher socioeconomic status. Reduction of NCDs in disadvantaged groups is necessary to achieve substantial decreases in the total NCD burden, making them mutually reinforcing priorities. Effective actions to reduce NCD inequalities include equitable early childhood development programmes and education; removal of barriers to secure employment in disadvantaged groups; comprehensive strategies for tobacco and alcohol control and for dietary salt reduction that target low socioeconomic status groups; universal, financially and physically accessible, high-quality primary care for delivery of preventive interventions and for early detection and treatment of NCDs; and universal insurance and other mechanisms to remove financial barriers to health care.

Control of hypertension with medication: a comparative analysis of national surveys in 20 countries.

OBJECTIVE: To examine hypertension management across countries and over time using consistent and comparable methods. METHODS: A systematic search identified nationally representative health examination surveys from 20 countries containing data from 1980 to 2011 on blood pressure measurements, the diagnosis and treatment of hypertension and its control with antihypertensive drugs. For each country, the prevalence of hypertension (i.e. systolic blood pressure ≥ 140 mmHg or antihypertensive use) and the proportion of hypertensive individuals whose condition was diagnosed, treated or controlled with medications (i.e. systolic pressure < 140 mmHg) were estimated. FINDINGS: The age-standardized prevalence of hypertension varied between countries: for individuals aged 35 to 49 years, it ranged from around 12% in Bangladesh, Egypt and Thailand to around 30% in Armenia, Lesotho and Ukraine; for those aged 35 to 84 years, it ranged from 20% in Bangladesh to more than 40% in Germany, the Russian Federation and Turkey. The age-standardized percentage of hypertensive individuals whose condition was diagnosed, treated or controlled was highest in the United States of America: for those aged 35 to 49 years, it was 84%, 77% and 56%, respectively. Percentages were especially low in Albania, Armenia, the Islamic Republic of Iran and Turkey. Although recent trends in prevalence differed in England, Japan and the United States, treatment coverage and hypertension control improved over time, particularly in England. CONCLUSION: Globally the proportion of hypertensive individuals whose condition is treated or controlled with medication remains low. Greater efforts are needed to improve hypertension control, which would reduce the burden of noncommunicable diseases.

Trends and Characteristics of Brown Rice Consumption among Adults in Japan: An Analysis of the National Health and Nutrition Surveys, 2012-2019.

Brown rice is a familiar whole grain in Japan. We examined national trends in brown rice consumption among Japanese adults aged ≥20 years old, using individual-level data from the National Health and Nutrition Surveys conducted between 2012 and 2019. We employed multivariable logistic regression to identify factors associated with brown rice consumption. The 95th percentile of daily brown rice intake remained at 0.0 g throughout the study period. The percentage of brown rice consumers increased from 1.8% (95% confidence interval: 1.6-2.1) in 2012 to 2.6% (95% confidence interval: 2.0-3.4) in 2019. Compared with individuals who consumed only white rice, brown rice consumers had significantly higher mean intake levels of macronutrients, legumes, vegetables, fruits, and nuts. Brown rice consumption was positively associated with certain sociodemographic characteristics (being female, older age, residing in a major city, living without very young children, and having higher education levels) and health behaviors (lower body mass index, engaging in regular exercise, and being a former or never smoker). Despite its potential nutritional benefits in balanced diets, only a small fraction of adults in Japan consume brown rice, indicating a need for further promotion, particularly among individuals with characteristics associated with brown rice consumption.

Determinants of reduced child stunting in Cambodia: analysis of pooled data from three demographic and health surveys.

OBJECTIVE: To assess how changes in socioeconomic and public health determinants may have contributed to the reduction in stunting prevalence seen among Cambodian children from 2000 to 2010. METHODS: A nationally representative sample of 10 366 children younger than 5 years was obtained from pooled data of cross-sectional surveys conducted in Cambodia in 2000, 2005, and 2010. The authors used a multivariate hierarchical logistic model to examine the association between the prevalence of childhood stunting over time and certain determinants. They estimated those changes in the prevalence of stunting in 2010 that could have been achieved through further improvements in public health indicators. FINDINGS: Child stunting was associated with the child's sex and age, type of birth, maternal height, maternal body mass index, previous birth intervals, number of household members, household wealth index score, access to improved sanitation facilities, presence of diarrhoea, parents' education, maternal tobacco use and mother's birth during the Khmer Rouge famine. The reduction in stunting prevalence during the past decade was attributable to improvements in household wealth, sanitation, parental education, birth spacing and maternal tobacco use. The prevalence of stunting would have been further reduced by scaling up the coverage of improved sanitation facilities, extending birth intervals, and eradicating maternal tobacco use. CONCLUSION: Child stunting in Cambodia has decreased owing to socioeconomic development and public health improvements. Effective policy interventions for sanitation, birth spacing and maternal tobacco use, as well as equitable economic growth and education, are the keys to further improvement in child nutrition.

Spatiotemporal variations in mean height of 17-year-old students born in 1957-2002 across 47 Japanese prefectures: Evidence from School Health Surveys.

This paper examines the secular trends and variations in mean height of 17-year-old students born in 1957-2002 across 47 prefectures in Japan. Mean height is consistently lower in southwest prefectures and greater in prefectures in the Greater Tokyo Area and from the south-central area to the north-western area facing Eurasia in the main island. Both the range and the coefficient of variation stay constant in the cohorts born during the 1970s or later, following rapid increases of mean height in the prefectures that initially have the lowest means. A comprehensive policy framework may be needed to address diverse factors affecting the physical growth of adolescents at the subnational level.

Economic effects of dietary salt reduction policies for cardiovascular disease prevention in Japan: a simulation study of hypothetical scenarios.

Objective: Reducing dietary salt intake is an essential population strategy for cardiovascular disease (CVD) prevention, but evidence on healthcare costs and outcomes is limited in Japan. We aimed to conduct a pilot economic evaluation under hypothetical scenarios of applying the salt reduction policies of England to Japan. Methods: We examined salt reduction policies in England: media health promotion campaigns, front-of-pack labeling, and voluntary and mandatory reformulation with best-case and worst-case policy cost scenarios. We assumed that these policies were conducted in Japan for 10 years from 2019. We used published data on epidemiology and healthcare expenditures in Japan and the costs and effects of salt reduction policies in England, and defined the benefits as a decrease in national medical expenditures on CVD. We developed a Markov cohort simulation model of the Japanese population. To estimate the annual net benefits of each policy over 10 years, we subtracted monitoring and policy costs from the benefits. We adopted a health sector perspective and a 2% discount rate. Results: The cumulative net benefit over 10 years was largest for mandatory reformulation (best case) at 2,015.1 million USD (with costs of USD 48.3 million and benefits of USD 2063.5 million), followed by voluntary reformulation (net benefit: USD 1,895.1 million, cost: USD 48.1 million, benefit: USD 1,943.2 million), mandatory reformulation (worst case, net benefit: USD 1,447.9 million, cost: USD 1,174.5 million, benefit: USD 2,622.3 million), labeling (net benefit: USD 159.5 million, cost: USD 91.6 million, benefit: USD 251.0 million), and a media campaign (net benefit: USD 140.5 million, cost: USD 110.5 million, benefit: USD 251.0 million). There was no change in the superiority or inferiority of policies when the uncertainty of model parameters was considered. Conclusion: Mandatory reformulation with the best-case cost scenario might be economically preferable to the other alternatives in Japan. In future research, domestic data on costs and effects of salt reduction policies should be incorporated for model refinement.

Adult mortality attributable to preventable risk factors for non-communicable diseases and injuries in Japan: a comparative risk assessment.

BACKGROUND: The population of Japan has achieved the longest life expectancy in the world. To further improve population health, consistent and comparative evidence on mortality attributable to preventable risk factors is necessary for setting priorities for health policies and programs. Although several past studies have quantified the impact of individual risk factors in Japan, to our knowledge no study has assessed and compared the effects of multiple modifiable risk factors for non-communicable diseases and injuries using a standard framework. We estimated the effects of 16 risk factors on cause-specific deaths and life expectancy in Japan. METHODS AND FINDINGS: We obtained data on risk factor exposures from the National Health and Nutrition Survey and epidemiological studies, data on the number of cause-specific deaths from vital records adjusted for ill-defined codes, and data on relative risks from epidemiological studies and meta-analyses. We applied a comparative risk assessment framework to estimate effects of excess risks on deaths and life expectancy at age 40 y. In 2007, tobacco smoking and high blood pressure accounted for 129,000 deaths (95% CI: 115,000-154,000) and 104,000 deaths (95% CI: 86,000-119,000), respectively, followed by physical inactivity (52,000 deaths, 95% CI: 47,000-58,000), high blood glucose (34,000 deaths, 95% CI: 26,000-43,000), high dietary salt intake (34,000 deaths, 95% CI: 27,000-39,000), and alcohol use (31,000 deaths, 95% CI: 28,000-35,000). In recent decades, cancer mortality attributable to tobacco smoking has increased in the elderly, while stroke mortality attributable to high blood pressure has declined. Life expectancy at age 40 y in 2007 would have been extended by 1.4 y for both sexes (men, 95% CI: 1.3-1.6; women, 95% CI: 1.2-1.7) if exposures to multiple cardiovascular risk factors had been reduced to their optimal levels as determined by a theoretical-minimum-risk exposure distribution. CONCLUSIONS: Tobacco smoking and high blood pressure are the two major risk factors for adult mortality from non-communicable diseases and injuries in Japan. There is a large potential population health gain if multiple risk factors are jointly controlled.

What has made the population of Japan healthy?

People in Japan have the longest life expectancy at birth in the world. Here, we compile the best available evidence about population health in Japan to investigate what has made the Japanese people healthy in the past 50 years. The Japanese population achieved longevity in a fairly short time through a rapid reduction in mortality rates for communicable diseases from the 1950s to the early 1960s, followed by a large reduction in stroke mortality rates. Japan had moderate mortality rates for non-communicable diseases, with the exception of stroke, in the 1950s. The improvement in population health continued after the mid-1960s through the implementation of primary and secondary preventive community public health measures for adult mortality from non-communicable diseases and an increased use of advanced medical technologies through the universal insurance scheme. Reduction in health inequalities with improved average population health was partly attributable to equal educational opportunities and financial access to care. With the achievement of success during the health transition since World War 2, Japan now needs to tackle major health challenges that are emanating from a rapidly ageing population, causes that are not amenable to health technologies, and the effects of increasing social disparities to sustain the improvement in population health.

Estimation of the Effect of Salt-Intake Reduction on Cardiovascular Mortality Decline between 1950 and 2017 in Japan: A Retrospective Simulation Study.

In Japan, a decrease in cardiovascular mortality has coincided with reduced population salt intake since the 1950s. The purpose of this study was to quantify the effect of reduced population salt intake on the long-term trends of cardiovascular mortality. Using government statistics and epidemiological study results in people of 20-69 years old from 1950 to 2017, including the National Health and Nutrition Survey, we developed a system dynamics model of age-specific cardiovascular mortality and salt intake. We estimated the period and cohort effects on mortality and calibrated the model for the historical mortality rate. We then simulated the counterfactual scenario of no decrease in salt intake to estimate the reduction in cardiovascular deaths associated with decreased mean salt intake. Compared with the base run and calibrated to the actual data, approximately 298,000 and 118,000 excess deaths were observed in men and women, respectively, assuming no change in salt intake over the entire period. The model suggests that the decline in salt intake since the 1950s has contributed to a non-negligible reduction in cardiovascular mortality.

Trends and Disparities in Adult Body Mass Index Across the 47 Prefectures of Japan, 1975-2018: A Bayesian Spatiotemporal Analysis of National Household Surveys.

Background: Among high-income countries, Japan has a low prevalence of obesity, but little is understood about subnational trends and variations in body mass index (BMI), largely owing to the lack of data from representative samples of prefectures. We aimed to examine long-term trends and distributions of adult BMI at the prefecture level in Japan from the late 1970s using a spatiotemporal model. Methods: We obtained cross-sectional data for 233,988 men and 261,086 women aged 20-79 years from the 44 annual National Health and Nutrition Surveys (NHNS) conducted during 1975-2018. We applied a Bayesian spatiotemporal model to estimate the annual time series of age-standardized and age-specific mean BMI by 20-year age group and sex for each of the 47 prefectures. We assessed socioeconomic inequalities in BMI across prefectures using the concentration index, according to population density. Results: In men, the age-standardized prefectural mean BMI ranged from 21.7 kg/m2 (95% credible interval, 21.6-21.9) to 23.1 kg/m2 (22.9-23.4) in 1975 and from 23.5 kg/m2 (23.3-23.7) to 24.8 kg/m2 (24.6-25.1) in 2018. In women, the age-standardized prefectural mean BMI ranged from 22.0 kg/m2 (21.9-22.2) to 23.4 kg/m2 (23.2-23.6) in 1975 and from 21.7 kg/m2 (21.6-22.0) to 23.5 kg/m2 (23.2-23.8) in 2018. Mean BMI was highest in the southernmost prefecture for most of the study period, followed by northeast prefectures. The increase in mean BMI was largest in southwest prefectures, which caught up with northeast prefectures over time. The concentration index was negative, indicating higher BMI in less-populated prefectures. Absolute values of the concentration index were greater in women than in men and increased over time. Conclusions: There were variations in adult mean BMI across prefectures, and geographic distributions changed over time. Further national and local efforts are needed to address the rising trend in mean BMI, particularly among men in rural prefectures, and socioeconomic inequalities among women. Bayesian hierarchical modeling is useful for reconstructing long-term spatiotemporal trends of mean BMI by integrating small-sized survey samples at the prefecture level in the NHNS.

Reduction of Cardiovascular Events and Related Healthcare Expenditures through Achieving Population-Level Targets of Dietary Salt Intake in Japan: A Simulation Model Based on the National Health and Nutrition Survey.

Reducing population dietary salt intake is expected to help prevent cardiovascular disease and thus constrain increasing national healthcare expenditures in Japan's super-aged society. We aimed to estimate the impact of achieving global and national salt-reduction targets (8, <6, and <5 grams/day) on cardiovascular events and national healthcare spending in Japan. Using published data including mean salt intake and systolic blood pressure from the 2019 National Health and Nutrition Survey, we developed a Markov model of a closed cohort of adults aged 40−79 years in 2019 (n = 66,955,000) transitioning among six health states based on the disease course of ischemic heart disease (IHD) and stroke. If mean salt intake were to remain at 2019 levels over 10 years, cumulative incident cases in the cohort would be approximately 2.0 million for IHD and 2.6 million for stroke, costing USD 61.6 billion for IHD and USD 104.6 billion for stroke. Compared with the status quo, reducing mean salt intake towards the targets over 10 years would avert 1−3% of IHD and stroke events and save up to 2% of related national healthcare costs. Attaining dietary salt-reduction goals among adults would yield moderate health economic benefits in Japan.