Conceived and designed the experiments: NI ME KS. Performed the experiments: NI KS. Analyzed the data: NI. Contributed reagents/materials/analysis tools: MN ME. Wrote the first draft of the manuscript: NI. Contributed to the writing of the manuscript: MI HIso SI TSatoh MN TM HImano ES KK TSobue ST MN ME KS.
The authors have declared that no competing interests exist.
Using a combination of published data and modeling, Nayu Ikeda and colleagues identify tobacco smoking and high blood pressure as major risk factors for death from noncommunicable diseases among adults in Japan.
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.
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.
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.
Worldwide, a small number of modifiable risk factors are responsible for many premature or preventable deaths. For example, having high blood pressure (hypertension) increases a person's risk of developing life-threatening heart problems and stroke (cardiovascular disease). Similarly, having a high blood sugar level increases the risk of developing diabetes, a chronic (long-term) disease that can lead to cardiovascular problems and kidney failure, and half of all long-term tobacco smokers in Western populations will die prematurely from diseases related to smoking, such as lung cancer. Importantly, the five major risk factors for death globally—high blood pressure, tobacco use, high blood sugar, physical inactivity, and overweight and obesity—are all modifiable. That is, lifestyle changes and dietary changes such as exercising more, reducing salt intake, and increasing fruit and vegetable intake can reduce an individual's exposure to these risk factors and one's chances of premature death. Moreover, public health programs designed to reduce a population's exposure to modifiable risk factors should reduce preventable deaths in that population.
In 2000, the Japanese government initiated Health Japan 21, a ten-year national health promotion campaign designed to prevent premature death from non-communicable (noninfectious) diseases and injuries. This campaign set 59 goals to monitor and improve risk factor management in the Japanese population, which has one of the longest life expectancies at birth in the world (the life expectancy of a person born in Japan in 2009 was 83.1 years). Because the campaign's final evaluation revealed deterioration or no improvement on some of these goals, the Japanese government recently released new guidelines that stress the importance of simultaneously controlling multiple risk factors for chronic diseases. However, although several studies have quantified the impacts on life expectancy and cause-specific death of individual modifiable risk factors in Japan, the effects of multiple risk factors have not been assessed. In this study, the researchers use a “comparative risk assessment” framework to estimate the effects of 16 risk factors on cause-specific deaths and life expectancy in Japan. Comparative risk assessment estimates the number of deaths that would be prevented if current distributions of risk factor exposures were changed to hypothetical optimal distributions.
The researchers obtained data on exposure to the selected risk factors from the 2007 Japanese National Health and Nutrition Survey and from epidemiological studies, and information on the number of deaths in 2007 from different diseases from official records. They used published studies to estimate how much each factor increases the risk of death from each disease and then used a mathematical formula to estimate the effects of the risk factors on the number of deaths in Japan and on life expectancy at age 40. In 2007, tobacco smoking and high blood pressure accounted for 129,000 and 104,000 deaths, respectively, in Japan. Physical inactivity accounted for 52,000 deaths, high blood glucose and high dietary salt intake accounted for 34,000 deaths each, and alcohol use for 31,000 deaths. Life expectancy at age 40 in 2007 would have been extended by 1.4 years for both sexes, the researchers estimate, if exposure to multiple cardiovascular risk factors had been reduced to calculated optimal distributions, or by 0.7 years if these risk factors had been reduced to the distributions defined by national guidelines and goals.
These findings identify tobacco smoking and high blood pressure as the major risk factors for death from non-communicable diseases among adults in Japan, a result consistent with previous findings from the US. They also indicate that simultaneous control of multiple risk factors has great potential for producing health gains among the Japanese population. Although the researchers focused on estimating the effect of these risk factors on mortality and did not include illness and disability in this study, these findings nevertheless identify two areas of public health policy that need to be strengthened to improve health, reduce death rates, and increase life expectancy among the Japanese population. First, they highlight the need to reduce tobacco smoking, particularly among men. Second and most importantly, these findings emphasize the need to improve ongoing programs designed to help people manage multiple cardiovascular risk factors, including high blood pressure.
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Controlling risk factors for non-communicable diseases and external causes is essential for the improvement of adult health. Chronic diseases and injuries are the leading causes of global mortality, accounting for 63% and 9%, respectively, of 57 million deaths in 2008
The population of Japan has the longest life expectancy at birth in the world. Life expectancy at birth for Japanese women was 54.0 y in 1947 and rapidly increased until 1986, at which point, at 81.0 y, it became the longest in the world for the first time; female life expectancy at birth also reached its highest ever worldwide figure, 86.4 y, in Japan in 2009
With the aim of increasing the nation's health through the prevention of premature deaths from lifestyle-related diseases, the Japanese government initiated a 10-y national health promotion campaign called Health Japan 21 in 2000
In the present study, we therefore aimed to provide the most comprehensive and comparative assessment of preventable risk factors for mortality from non-communicable diseases and injuries in the Japanese adult population. We employed a comparative risk assessment strategy to quantify contributions of health risks to disease outcomes
We estimated the number of deaths that would have been saved in 2007 if multiple risk factors had been controlled at their optimal levels as determined by a theoretical-minimum-risk exposure distribution. To quantify and compare the mortality attributable to excess health risks, we used comparative risk assessment methods that have been described in detail elsewhere
We then multiplied the number of cause-specific deaths by population-attributable fractions to estimate mortality from diseases (causes of death) associated with each risk factor. The number of deaths attributable to a single risk factor was summed across different causes to obtain the total number of deaths attributable to that risk factor. The number of deaths from a single cause, however, could not be added across risk factors, because they may be causally related and we did not account for such relationships in the estimation of population-attributable fractions of individual risk factors.
We conducted all analyses separately by sex, using Stata version 11 (StataCorp). We restricted analyses to individuals aged 30 y and over, because the number of deaths from non-communicable diseases is small for younger ages. However, we included those aged 20 to 29 y when estimating deaths from external causes attributable to alcohol use, because the burden was assumed to be substantial in this age group.
We obtained data on the number of cause-specific deaths in 2007 from vital records
We included 16 risk factors in this analysis (
Risk Factor | Disease Outcomes |
High blood glucose | IHD, stroke, diabetes mellitus |
High LDL cholesterol | IHD, ischemic stroke |
High blood pressure | IHD, stroke, hypertensive diseases, other cardiovascular diseases |
Overweight/obesity | IHD; ischemic stroke; hypertensive disease; postmenopausal breast, colon, corpus uteri, kidney, and pancreatic cancers; diabetes mellitus |
Alcohol use | IHD; ischemic stroke; hemorrhagic stroke; hypertensive diseases; cardiac arrhythmias; cancers of breast, colorectal, esophagus, mouth, liver, larynx, pharynx, and selected other sites |
Tobacco smoking | IHD; stroke; aortic aneurysms and dissection; diabetes mellitus; lung, esophagus, mouth, pharynx, stomach, liver, pancreas, cervix, bladder, kidney, and other urinary cancers; leukemia; chronic obstructive pulmonary disease; lower respiratory tract infections; asthma; tuberculosis |
Physical inactivity | IHD, ischemic stroke, breast and colon cancers, diabetes mellitus |
High dietary trans fatty acids | IHD |
Low dietary polyunsaturated fatty acids | IHD |
High dietary salt | IHD, stroke, hypertensive disease, other cardiovascular diseasesa, stomach cancer |
Low intake of fruit and vegetables | IHD; ischemic stroke; colorectal, esophagus, lung, mouth, pharynx, and stomach cancers |
Hepatitis B virus | Liver cancer |
Hepatitis C virus | Liver cancer |
|
Stomach cancer |
Human papillomavirus | Cervix uteri cancer |
HTLV-1 | Adult T-cell lymphoma/leukemia |
This category includes rheumatic heart disease, endocarditis, cardiomyopathy, aortic aneurysms, peripheral vascular disorders, and other ill-defined cardiovascular diseases.
This category includes
IHD, ischemic heart disease.
Risk Factor, Exposure Metric, Data Source |
Optimal | Guidelines/National Goals |
|
||
Fasting plasma glucose (mmol/l) | 4.9 (0.3) | 5.6 (0.3) |
|
||
LDL cholesterol (mmol/l) | 2.0 (0.4) | 3.1 (0.7) |
|
||
Systolic blood pressure (mm Hg) | 115 (6) | 130 (7) |
|
||
Body mass index (kg/m2) | 21 (1) | 22 (1) |
|
||
Current alcohol consumption volumes and patterns | No alcohol use |
|
Alcohol-related road traffic accidents, national road accident data, 2004 |
No alcohol use | |
|
||
Smoking impact ratio, vital statistics 2007 data |
No smoking | |
|
||
Intensity of physical activity | Highly active | |
|
||
Percent of total calories from dietary trans fatty acids | 0.5 (0.05) | |
|
||
Percent of total calories from dietary polyunsaturated fatty acids | 10 (1) | |
|
||
Dietary sodium adjusted for total calories (g/d) | 0.5 (0.05) | 10 (1) |
|
||
Dietary fruit and vegetable intake adjusted for total calories (g/d) | 600 (50) | 350 (29) |
|
||
Seropositivity for hepatitis B surface antigen, blood donors' cohort, 1991–1993 |
No infection | |
|
||
Seropositivity for antibody to hepatitis C, blood donors' cohort, 1991–1993 |
No infection | |
|
||
Seropositivity for anti– |
No infection |
Values are means, with standard deviations in parentheses.
We obtained exposure data from the 2007 National Health and Nutrition Survey
The optimal category for liver cancer and suicide was “occasional drinkers” because previous studies used it as the reference category for estimation of relative risks.
Sex, Risk Factor | Age | ||||||||||||||
30–44 y | 45–59 y | 60–69 y | 70–79 y | ≥80 y | |||||||||||
|
Mean | SE |
|
Mean | SE |
|
Mean | SE |
|
Mean | SE |
|
Mean | SE | |
|
|||||||||||||||
Fasting plasma glucose (mmol/l) | 300 | 5.4 | 0.1 | 374 | 5.7 | 0.0 | 411 | 6.0 | 0.1 | 339 | 5.9 | 0.0 | 107 | 5.9 | 0.1 |
LDL cholesterol (mmol/l) | 300 | 3.3 | 0.0 | 375 | 3.4 | 0.0 | 413 | 3.1 | 0.0 | 340 | 3.0 | 0.0 | 108 | 2.9 | 0.1 |
Systolic blood pressure (mm Hg) | 312 | 124.2 | 0.8 | 394 | 133.9 | 0.9 | 427 | 140.9 | 0.9 | 359 | 142.2 | 1.0 | 116 | 144.1 | 1.8 |
Body mass index (kg/m2) | 673 | 23.9 | 0.1 | 777 | 23.8 | 0.1 | 620 | 23.8 | 0.1 | 470 | 23.6 | 0.2 | 155 | 22.6 | 0.3 |
Dietary TFA (% of total calories) | 806 | 0.3 | 0.0 | 858 | 0.3 | 0.0 | 664 | 0.2 | 0.0 | 517 | 0.2 | 0.0 | 179 | 0.3 | 0.0 |
Dietary PUFA (% of total calories) | 806 | 5.7 | 0.1 | 858 | 5.6 | 0.1 | 664 | 5.3 | 0.1 | 517 | 5.1 | 0.1 | 179 | 5.0 | 0.1 |
Dietary SFA (% of total calories) | 806 | 6.8 | 0.1 | 858 | 6.2 | 0.1 | 664 | 5.7 | 0.1 | 517 | 5.6 | 0.1 | 179 | 5.9 | 0.2 |
Dietary salt intake (g/d) | 806 | 11.4 | 0.2 | 858 | 12.3 | 0.2 | 664 | 12.6 | 0.2 | 517 | 12.2 | 0.2 | 179 | 10.9 | 0.3 |
Fruit and vegetable intake (g/d) | 804 | 288.6 | 6.0 | 856 | 342.5 | 6.6 | 663 | 432.3 | 8.8 | 515 | 446.8 | 9.6 | 178 | 463.5 | 15.9 |
Never or former drinkers (%) |
850 | 26.6 | 1.5 | 950 | 25.9 | 1.4 | 699 | 28.9 | 1.7 | 525 | 40.8 | 2.1 | 184 | 55.4 | 3.7 |
Alcohol-related accidents/four-wheel vehicle road traffic accidents, 2004 (%) |
1.7 | 1.7 | 1.7 | 1.7 | 1.7 | ||||||||||
Have intense physical activity (%) | 808 | 34.8 | 1.7 | 869 | 34.5 | 1.6 | 667 | 28.8 | 1.8 | 518 | 42.1 | 2.2 | 179 | 21.8 | 3.1 |
Never or former smokers (%) | 850 | 45.2 | 1.7 | 946 | 53.6 | 1.6 | 698 | 65.9 | 1.8 | 524 | 78.6 | 1.8 | 184 | 82.1 | 2.8 |
Smoking impact ratio | 0.0 | 0.6 | 0.5 | 0.5 | 0.7 | ||||||||||
Hepatitis B virus (%) |
0.9 | 0.9 | 0.9 | 0.6 | 0.6 | ||||||||||
Hepatitis C virus (%) |
0.6 | 1.6 | 2.6 | 7.9 | 7.9 | ||||||||||
23.6 | 47.4 | 66.1 | 73.4 | 72.6 | |||||||||||
|
|||||||||||||||
Fasting plasma glucose (mmol/l) | 563 | 5.3 | 0.0 | 620 | 5.7 | 0.0 | 523 | 5.9 | 0.0 | 408 | 5.9 | 0.0 | 154 | 5.9 | 0.1 |
LDL cholesterol (mmol/l) | 565 | 2.9 | 0.0 | 622 | 3.4 | 0.0 | 523 | 3.5 | 0.0 | 410 | 3.3 | 0.0 | 154 | 3.2 | 0.1 |
Systolic blood pressure (mm Hg) | 527 | 112.4 | 0.6 | 652 | 128.1 | 0.8 | 560 | 135.8 | 0.8 | 433 | 138.9 | 0.8 | 170 | 143.2 | 1.4 |
Body mass index (kg/m2) | 874 | 21.4 | 0.1 | 905 | 22.7 | 0.1 | 723 | 23.3 | 0.1 | 534 | 23.1 | 0.2 | 248 | 22.4 | 0.3 |
Dietary TFA (% of total calories) | 955 | 0.4 | 0.0 | 957 | 0.3 | 0.0 | 762 | 0.3 | 0.0 | 561 | 0.3 | 0.0 | 285 | 0.2 | 0.0 |
Dietary PUFA (% of total calories) | 955 | 5.9 | 0.1 | 957 | 6.0 | 0.1 | 762 | 5.6 | 0.1 | 561 | 5.3 | 0.1 | 285 | 5.3 | 0.1 |
Dietary SFA (% of total calories) | 955 | 7.8 | 0.1 | 957 | 7.0 | 0.1 | 762 | 6.2 | 0.1 | 561 | 5.9 | 0.1 | 285 | 5.7 | 0.2 |
Dietary salt intake (g/d) | 955 | 9.6 | 0.1 | 957 | 10.7 | 0.1 | 762 | 10.9 | 0.2 | 561 | 10.6 | 0.2 | 285 | 10.0 | 0.2 |
Fruit and vegetable intake (g/d) | 951 | 346.0 | 6.1 | 957 | 460.2 | 7.6 | 761 | 541.3 | 9.0 | 561 | 522.8 | 9.7 | 284 | 490.3 | 13.2 |
Never or former drinkers (%) |
1,014 | 54.9 | 1.6 | 1,047 | 61.1 | 1.5 | 795 | 75.5 | 1.5 | 579 | 83.4 | 1.5 | 310 | 88.7 | 1.8 |
Alcohol-related accidents/four-wheel vehicle road traffic accidents, 2004 (%) |
1.7 | 1.7 | 1.7 | 1.7 | 1.7 | ||||||||||
Have intense physical activity (%) | 958 | 36.3 | 1.6 | 959 | 40.9 | 1.6 | 765 | 39.0 | 1.8 | 562 | 45.4 | 2.1 | 286 | 21.3 | 2.4 |
Never or former smokers (%) | 1,014 | 81.8 | 1.2 | 1,047 | 87.1 | 1.0 | 794 | 92.1 | 1.0 | 579 | 96.5 | 0.8 | 310 | 95.5 | 1.2 |
Smoking impact ratio | 0.0 | 0.1 | 0.2 | 0.2 | 0.2 | ||||||||||
Hepatitis B virus (%) |
0.5 | 0.5 | 0.5 | 0.6 | 0.6 | ||||||||||
Hepatitis C virus (%) |
0.4 | 1.6 | 3.5 | 7.0 | 7.0 | ||||||||||
23.6 | 47.4 | 66.1 | 73.4 | 72.6 |
Sample size in the National Health and Nutrition Survey in 2007.
For those aged 20–29 y, the mean (standard error) was 40.4 (2.7) in men (
Reported for the total age group of both sexes combined.
PUFA, polyunsaturated fatty acids; SE, standard error; SFA, saturated fatty acids; TFA, trans fatty acids.
We used self-reports to quantify exposures to physical inactivity and alcohol use, while we used measured data for other risk factors. In the physical examination for the 2007 NHNS, a blood test was intended to be conducted more than 4 h after a meal, although a number of blood samples were actually drawn less than 4 h after a meal. Because fasting plasma glucose was the unit for relative risk for high blood glucose adopted in the present study, we applied the following conversion equation proposed by the Committee of the Japan Diabetes Society
In the NHNS, health care professionals measured the blood pressure of seated persons in their right upper arm after 5 min of rest, using a Riva-Rocci mercury manometer. For a trend analysis of cardiovascular mortality attributable to high blood pressure, which is described below, we used the National Nutrition Surveys for 1980–2002 and the NHNS for 2003–2007. These surveys took only one blood pressure measurement per individual until starting to collect two measurements per individual in the 2000 survey. We therefore used a single measurement for the surveys in 1980–1999 and the second measurement for the 2000–2007 surveys. We excluded pregnant or breastfeeding women from the analysis of blood pressure.
For dietary risk exposure variables, dieticians visited households to distribute questionnaires and explain the survey method for diet and lifestyle. Household representatives weighed and recorded the quantity of each food item consumed for one day (excluding holidays). Dieticians visited households again during the survey period to check and correct completed questionnaires. We estimated intakes of dietary trans fatty acids using conversion factors of food items provided by the Cabinet of Japan Food Safety Committee
We used a smoking impact ratio as a more reliable indicator of accumulated exposure to tobacco smoking than the prevalence of current smokers. The smoking impact ratio was defined as total lung cancer mortality in excess of never-smokers in a study population relative to the excess lung cancer mortality among current smokers in a reference population
We obtained data on the prevalence of infections with hepatitis B and C viruses and the bacterium
In order to measure exposure levels of alcohol use related to deaths from road traffic injuries, we employed a proportion of alcohol-impaired driving, which was defined as driving with breath alcohol concentrations above 0 mg/l, to the total number of cases of road traffic accidents involving four-wheeled vehicles and motorcycles in 2004 (1.7%). We obtained this figure from a past study on alcohol concentrations in the breath of drivers, which used a national dataset prepared by the Japan Institute for Traffic Accident Research and Data Analysis
As an alternative distribution of risk exposures, we used an optimal distribution in which harmful effects of each risk factor on morbidity and mortality would be minimized in a population (i.e., a theoretical-minimum-risk exposure distribution). With the exception of infections, we obtained information on theoretical-minimum-risk exposure distributions from a previous study in the United States (
In the analysis of gains in life expectancy and probabilities of death, we also investigated alternative counterfactual distributions of risk exposures that followed recommendations of clinical guidelines and goals of Health Japan 21. This analysis enabled quantification of potential health gains that would be more realistic than theoretical minimums. We included risk factors in this part of our analysis only if specific control targets were available from these sources and units of measurement corresponded to those of relative risks (
The relationship between dietary salt intake and cardiovascular mortality was based on a convincing effect of high dietary salt on systolic blood pressure that was estimated from a meta-analysis of dietary trials (
We translated mortality changes into gains in life expectancy at 40 y of age to understand the potential impact of the management of risk factors on longevity. We constructed life tables using observed age-specific mortality rates and mortality that would be expected if risk factor exposures were controlled at alternative levels. We took the differences between these values as showing life expectancy gains that would occur when shifting from an actual risk factor exposure to a counterfactual. We also calculated effects on probabilities of dying between the ages of 15 and 60 y (45q15) and between 60 and 75 y (15q60).
We estimated joint effects of multiple risk factors on excess mortality from cardiovascular diseases and the additional life expectancy at age 40 y that would be achieved under counterfactual distributions. Risk factors included in this part of the analysis were high body mass index, high blood pressure, and high concentrations of blood glucose and low density lipoprotein (LDL) cholesterol. We took account of high dietary sodium intake to compensate for its indirect effect through elevated blood pressure, using the steps described above. We also adopted a 50% reduction of the excess risk of high body mass index on cardiovascular deaths to incorporate a mediation of its associations through other risk factors
To examine contributions of the management of modifiable risk factors to the improvement of life expectancy over time, we estimated the number of deaths from cancers attributable to tobacco smoking and deaths from stroke associated with high blood pressure from 1980 to 2007. We employed the algorithm described above to obtain consistent mortality data throughout this period, from which we used total lung cancer mortality in each year to calculate smoking impact ratios over time. For the analysis of high blood pressure and stroke, we excluded people over 80 y of age because the sample size was insufficient. We also incorporated the above-mentioned mediated effects of dietary sodium intake through raised blood pressure at the individual level.
We conducted statistical simulation to deal with the uncertainty that was introduced by using sample estimates for risk exposures and relative risks
Under the theoretically minimum counterfactuals listed in
Sex, Risk Factor | Total | Cardiovascular | Cancer | Diabetes Mellitus | Respiratory | Other NCD | Injuries | |||||||
|
||||||||||||||
High blood glucose | 34.1 | (26.4, 43.1) | 27.2 | (19.5, 36.2) | 6.9 | |||||||||
High LDL cholesterol | 23.9 | (16.7, 31.2) | 23.9 | (16.7, 31.2) | ||||||||||
High blood pressure | 103.9 | (86.0, 119.1) | 103.9 | (86.0, 119.1) | ||||||||||
High body mass index | 19.0 | (16.1, 21.9) | 13.8 | (11.1, 16.4) | 4.1 | (3.4, 4.9) | 1.1 | (0.8, 1.3) | ||||||
Alcohol use | 30.6 | (27.5, 34.7) | −2.0 | (−4.0, 0.0) | 18.2 | (16.2, 20.8) | −0.1 | (−0.1, −0.1) | 11.6 | (10.6, 12.7) | 2.9 | (1.9, 4.6) | ||
Tobacco smoking | 128.9 | (115.5, 153.6) | 33.4 | (25.4, 48.8) | 77.4 | (72.3, 83.9) | 18.1 | (12.6, 26.4) | ||||||
Physical inactivity | 52.2 | (46.7, 57.7) | 42.2 | (36.6, 47.6) | 9.3 | (8.5, 10.0) | 0.7 | (0.6, 0.9) | ||||||
High TFA intake | 0.0 | (0.0, 0.0) | 0.0 | (0.0, 0.0) | ||||||||||
Low PUFA intake | 21.2 | (8.1, 38.7) | 21.2 | (8.1, 38.7) | ||||||||||
High dietary sodium intake | 34.0 | (27.3, 39.4) | 19.0 | (16.1, 22.3) | 14.9 | (8.8, 19.6) | ||||||||
Low fruit and vegetable intake | 8.9 | (6.7, 10.8) | 5.1 | (3.3, 6.7) | 3.8 | (2.5, 4.9) | ||||||||
Hepatitis B virus | 11.6 | (9.8, 13.5) | 11.6 | (9.8, 13.5) | ||||||||||
Hepatitis C virus | 23.0 | (21.3, 24.5) | 23.0 | (21.3, 24.5) | ||||||||||
|
30.6 | (27.2, 33.5) | 30.6 | (27.2, 33.5) | ||||||||||
Human papillomavirus | 2.6 | 2.6 | ||||||||||||
HTLV-1 | 1.1 | 1.1 | ||||||||||||
Joint risk |
157.0 | (144.0, 173.4) | 157.0 | (144.0, 173.4) | ||||||||||
|
||||||||||||||
High blood glucose | 17.2 | (12.7, 22.2) | 14.3 | (9.8, 19.3) | 2.9 | |||||||||
High LDL cholesterol | 12.2 | (8.1, 15.9) | 12.2 | (8.1, 15.9) | ||||||||||
High blood pressure | 50.1 | (39.9, 58.5) | 50.1 | (39.9, 58.5) | ||||||||||
High body mass index | 12.1 | (10.0, 14.3) | 9.6 | (7.6, 11.6) | 2.0 | (1.6, 2.6) | 0.5 | (0.4, 0.7) | ||||||
Alcohol use | 25.8 | (22.6, 29.5) | −1.7 | (−3.7, 0.2) | 15.9 | (13.7, 18.2) | −0.1 | (−0.1, −0.1) | 9.0 | (8.2, 9.7) | 2.8 | (1.7, 4.4) | ||
Tobacco smoking | 94.9 | (87.7, 103.4) | 19.3 | (15.4, 24.5) | 66.5 | (61.8, 71.2) | 9.1 | (6.8, 10.9) | ||||||
Physical inactivity | 25.9 | (22.8, 29.4) | 21.0 | (18.1, 24.4) | 4.6 | (4.0, 5.1) | 0.3 | (0.3, 0.4) | ||||||
High TFA intake | 0.0 | (0.0, 0.0) | 0.0 | (0.0, 0.0) | ||||||||||
Low PUFA intake | 12.0 | (5.3, 29.3) | 12.0 | (5.3, 29.3) | ||||||||||
High dietary sodium intake | 18.4 | (13.0, 22.7) | 8.8 | (7.3, 10.2) | 9.7 | (4.4, 13.7) | ||||||||
Low fruit and vegetable intake | 7.6 | (5.5, 9.5) | 4.3 | (2.5, 5.9) | 3.3 | (2.1, 4.4) | ||||||||
Hepatitis B virus | 8.0 | (6.6, 9.6) | 8.0 | (6.6, 9.6) | ||||||||||
Hepatitis C virus | 14.8 | (13.4, 16.1) | 14.8 | (13.4, 16.1) | ||||||||||
|
20.0 | (17.0, 22.4) | 20.0 | (17.0, 22.4) | ||||||||||
HTLV-1 | 0.6 | 0.6 | ||||||||||||
Joint risk |
78.5 | (70.8, 87.8) | 78.5 | (70.8, 87.8) | ||||||||||
|
||||||||||||||
High blood glucose | 16.9 | (11.6, 23.3) | 12.9 | (7.6, 19.3) | 4.0 | |||||||||
High LDL cholesterol | 11.7 | (6.5, 18.0) | 11.7 | (6.5, 18.0) | ||||||||||
High blood pressure | 53.9 | (40.0, 66.9) | 53.9 | (40.0, 66.9) | ||||||||||
High body mass index | 6.8 | (5.0, 8.9) | 4.2 | (2.5, 5.9) | 2.1 | (1.6, 2.6) | 0.5 | (0.3, 0.8) | ||||||
Alcohol use | 4.8 | (3.8, 6.3) | −0.3 | (−0.5, −0.1) | 2.3 | (1.7, 3.3) | −0.0 | (−0.1, −0.0) | 2.6 | (2.1, 3.4) | 0.2 | (0.1, 0.3) | ||
Tobacco smoking | 34.0 | (22.9, 56.5) | 14.1 | (7.3, 28.2) | 10.9 | (8.3, 15.7) | 9.0 | (4.0, 17.4) | ||||||
Physical inactivity | 26.3 | (21.6, 30.9) | 21.2 | (16.5, 25.9) | 4.7 | (4.2, 5.2) | 0.4 | (0.3, 0.5) | ||||||
High TFA intake | 0.0 | (0.0, 0.0) | 0.0 | (0.0, 0.0) | ||||||||||
Low PUFA intake | 9.3 | (4.0, 16.1) | 9.3 | (4.0, 16.1) | ||||||||||
High dietary sodium intake | 15.6 | (11.3, 19.2) | 10.3 | (7.7, 13.1) | 5.3 | (1.9, 7.5) | ||||||||
Low fruit and vegetable intake | 1.3 | (0.9, 1.7) | 0.8 | (0.4, 1.2) | 0.5 | (0.3, 0.6) | ||||||||
Hepatitis B virus | 3.6 | (2.8, 4.5) | 3.6 | (2.8, 4.5) | ||||||||||
Hepatitis C virus | 8.2 | (7.3, 9.0) | 8.2 | (7.3, 9.0) | ||||||||||
|
10.6 | (8.9, 12.0) | 10.6 | (8.9, 12.0) | ||||||||||
Human papillomavirus | 2.6 | 2.6 | ||||||||||||
HTLV-1 | 0.5 | 0.5 | ||||||||||||
Joint risk |
78.5 | (66.9, 91.1) | 78.5 | (66.9, 91.1) |
Values in parentheses indicate lower and upper bounds of 95% CI.
A combination of high blood glucose, high LDL cholesterol, high blood pressure (directly, and indirectly through high dietary salt intake), and high body mass index.
NCD, non-communicable disease; PUFA, polyunsaturated fatty acids, TFA, trans fatty acids.
High blood pressure was associated with 104,000 cardiovascular deaths (95% CI: 86,000–119,000) in 2007. This was the greatest risk factor for cardiovascular mortality of all risk factors included in this analysis, and the mortality burden was shared evenly between the sexes. A majority of deaths attributable to high blood pressure occurred among people aged 70 y and over (85,000 deaths) and were caused by stroke (47,000 deaths, 95% CI: 38,000–56,000) or ischemic heart disease (28,000 deaths, 95% CI: 15,000–39,000).
Although the numbers of attributable deaths for other physiological, lifestyle, dietary, and infectious factors were small when compared to those for tobacco smoking and high blood pressure, most of these other factors were associated with tens of thousands of deaths from non-communicable diseases and external causes. Physical inactivity was associated with 52,000 deaths (95% CI: 47,000–58,000), and 75% of them occurred among people aged 70 y and older. Ischemic heart disease was the major cause of mortality attributable to this risk factor (31,000 deaths, 95% CI: 28,000–35,000). High blood glucose was associated with 34,000 deaths (95% CI: 26,000–43,000), of which 75% occurred among people aged 70 y and over and 68% were caused by ischemic heart disease. High dietary salt intake was associated with 19,000 cardiovascular deaths (95% CI: 16,000–22,000), which were included in cardiovascular mortality attributable to high blood pressure, and there were 15,000 deaths from stomach cancer (95% CI: 9,000–20,000). Seventy-six percent of deaths attributable to this risk factor occurred among people aged 70 y and over.
Alcohol use was associated with 31,000 deaths (95% CI: 27,000–35,000) from non-communicable diseases and injuries, 84% of which occurred among men. A major cause of death attributable to this risk factor was liver cirrhosis (11,000 deaths, 95% CI: 10,000–12,000), followed by liver cancer (6,000 deaths, 95% CI: 4,000–8,000), esophagus cancer (5,000 deaths, 95% CI: 4,000–5,000), and colon cancer (4,000 deaths, 95% CI: 4,000–5,000). Alcohol use was associated with 3,000 (95% CI: 2,000–5,000) out of 83,000 deaths of people aged 20 y and over from external causes included in this study. Two thousand deaths were from suicide (95% CI: 1,000–4,000), and there were fewer than 1,000 deaths each attributable to falls, road traffic accidents, homicide, and other injuries. Most of the suicide deaths attributable to alcohol use occurred among men, particularly those aged 30 to 59 y (71%).
Infection with
High LDL cholesterol was associated with 24,000 cardiovascular deaths (95% CI: 17,000–31,000), largely from ischemic heart disease (23,000 deaths, 95% CI: 16,000–30,000). Low dietary intake of polyunsaturated fatty acids was associated with 21,000 deaths from ischemic heart disease (95% CI: 8,000–39,000), and 47% of these deaths occurred among people aged 80 y and over. High body mass index was associated with 19,000 deaths (95% CI: 16,000–22,000): 64% of these deaths occurred in men, and ischemic heart disease was the major cause (11,000 deaths, 95% CI: 8,000–13,000).
If systolic blood pressure (directly, and indirectly through dietary salt intake), blood glucose, LDL cholesterol, and body mass index were controlled jointly to their optimal distributions, i.e., theoretical-minimum-risk exposure distributions, 157,000 cardiovascular deaths would have been prevented in 2007 (95% CI: 144,000–173,000). The mortality burden attributable to the combination of these risks was shared equally between the sexes, and a majority of the burden occurred among people aged 70 y and older.
Japanese life expectancy at age 40 y was 40.4 y for men and 46.8 y for women in 2007
(A) Life expectancy at age 40. (B) Probability of death between 15 and 60 y of age. (C) Probability of death between 60 and 75 y of age. Joint risk is a combination of high blood pressure (directly, or indirectly through high dietary salt intake), high blood glucose, high LDL cholesterol, and high body mass index. BMI, body mass index; CVD, cardiovascular disease; NCD, non-communicable diseases; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids; TFA, trans fatty acids.
For women, controlling systolic blood pressure and tobacco smoking to optimal counterfactuals would have extended life expectancy at age 40 y by 0.9 y (95% CI: 0.7–1.1) and 0.6 y (95% CI: 0.4–1.0), respectively. The impact of tobacco smoking on a probability of death in older women was estimated to be 8% (95% CI: 5–13), which was comparable to that of high blood pressure (7%, 95% CI: 6–8). A joint effect of cardiovascular risk factors on female life expectancy at age 40 y was estimated to be 1.4 y (95% CI: 1.2–1.7), with a decrease in probability of death of 8% (95% CI: 7–10) for younger adults and 11% (95% CI: 10–12) for older ages.
Risk Factor | e40 (Years) | 45q15 (Percent) | 15q60 (Percent) | |||
|
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High blood glucose | 0.1 | (0.0, 0.2) | −0.1 | (−1.0, −0.1) | −0.7 | (−1.2, −0.2) |
High LDL cholesterol | 0.0 | (0.0, 0.0) | −0.6 | (−1.3, −0.1) | 0.0 | (−0.1, 0.0) |
High blood pressure | 0.4 | (0.3, 0.5) | −1.2 | (−2.1, −0.3) | −3.0 | (−3.7, −2.3) |
High body mass index | 0.1 | (0.1, 0.2) | −1.8 | (−2.2, −1.4) | −1.6 | (−2.0, −1.2) |
High dietary salt intake | 0.0 | (0.0, 0.0) | −3.4 | (−0.2, 0.0) | −2.4 | (−0.5, −0.1) |
Low fruit and vegetable intake | 0.0 | (0.0, 0.0) | −0.5 | (−0.9, −0.3) | 0.0 | (0.0, 0.0) |
Joint risk |
0.7 | (0.6, 0.9) | −5.8 | (−8.4, −5.1) | −6.0 | (−7.4, −5.2) |
|
||||||
High blood glucose | 0.1 | (0.1, 0.2) | −0.2 | (−0.9, 0.0) | −0.7 | (−1.2, −0.2) |
High LDL cholesterol | 0.0 | (0.0, 0.0) | −0.4 | (−0.8, 0.0) | −0.4 | (−0.7, −0.3) |
High blood pressure | 0.4 | (0.3, 0.5) | 0.0 | (0.0, 0.0) | −2.8 | (−3.5, −2.1) |
High body mass index | 0.0 | (0.0, 0.1) | −0.1 | (−0.4, 0.0) | −1.1 | (−1.5, −0.8) |
High dietary salt intake | 0.0 | (0.0, 0.0) | −0.2 | (−0.3, −0.1) | −0.4 | (−0.5, −0.2) |
Low fruit and vegetable intake | 0.0 | (0.0, 0.0) | 0.0 | (−0.1, 0.0) | 0.0 | (0.0, 0.0) |
Joint risk |
0.7 | (0.6, 0.9) | −3.1 | (−2.6, −1.0) | −5.6 | (−6.6, −4.9) |
Values in parentheses indicate lower and upper bounds of 95% CI.
A combination of high blood glucose, high LDL cholesterol, high blood pressure (directly, and indirectly through high dietary salt intake), and high body mass index.
Data for (A) men and (B) women.
Data for (A) men and (B) women.
To our knowledge, this is the first study in Japan to assess and compare effects of a comprehensive list of modifiable risk factors on life expectancy and death from non-communicable diseases and injuries under the framework of comparative risk assessment. Our study indicates that major risks for adult mortality from these causes are tobacco smoking and high blood pressure, as well as a combination of multiple cardiovascular risks. We also demonstrate that, over the past 27 y, cancer mortality attributable to tobacco smoking has increased, especially in the older population, while stroke death associated with high blood pressure has decreased.
The leading single risk factors for adult mortality from non-communicable diseases and injuries in Japan, i.e., tobacco smoking, high blood pressure, physical inactivity, and high blood glucose concentrations, agree with those in the world and the US
Our estimate of the impact of tobacco smoking on male life expectancy at age 40 y (1.8 y) was smaller than those of past cohort studies in Japan. Previous studies showed that, according to smoking status at the time of the baseline survey, life expectancy for men aged 40 y in the total population was shorter than that of never-smokers by around 2.5 y
Our results suggest that the threat of tobacco smoking for mortality is enormous in men and has been increasing over time through the accumulation of exposure to this risk in the older population. A previous study showed that lifetime smoking prevalence was low for the generation born in the late 1930s who experienced the deprivation in the early postwar years, but rose thereafter until it peaked for the birth cohort of the 1950s
Our study suggests that a decrease in population blood pressure partly accounts for a reduced mortality from stroke at least since 1980, although the downward trend leveled off for elderly men in the early 1990s. Stroke mortality started decreasing in the late 1960s and has been the major contributor to the increase of life expectancy in Japan
Despite the decrease in stroke mortality attributable to high blood pressure, this is still the major risk factor for cardiovascular mortality in Japan. The management of high blood pressure is not adequate even under the practical standards of domestic clinical guidelines. In 2007, less than 60% of hypertensive patients took antihypertensive medication daily, and only 20% had their blood pressure controlled
Another key finding of our study is that a considerable number of deaths from cardiovascular diseases would be prevented through joint control of multiple risk factors in Japan. In addition to the traditional approach of focusing on single risk factors, health education and effective treatment based on absolute risk have great potential for improving primary and secondary prevention of cardiovascular mortality. Our results support current domestic efforts to target high-risk populations, such as cardiovascular risk stratification according to categories of multiple risks
Our study suggests that physical inactivity contributes to a substantial mortality from non-communicable diseases in Japan. Lack of exercise is common: in 2008, two-thirds of the Japanese adult population engaged in less than 30 min of moderate activity per week or less than 20 min of vigorous activity three times per week
Our results suggest that mortality from external causes, such as suicide and traffic accidents, associated with alcohol use is fairly small in Japan. For suicide, relative risks of alcohol use were insignificant, except for heavy drinking, in a large Japanese cohort study
One of distinctive characteristics of adult mortality in Japan is a large number of cancer deaths attributable to infectious agents, which is possibly common in East-Asian countries
Will the estimated improvements in population health outcomes be worth all the efforts required of the government, citizens, and health care workers involved in the modification of risk factors? The overall increases in life expectancy associated with improved risk factor exposures may appear small in comparison with observed improvements in Japanese longevity over previous decades. This is, however, consistent with a past study's finding showing that even complete elimination of deaths from major causes would not affect life expectancy as much as anticipated in the US, and an additional drop in mortality would have only a marginal effect in countries where the rapid increases of life expectancy have already ended
Our study was based on global efforts of various agencies to pool evidence on causality and consistency of relative risks. We also used Japanese population evidence from large-scale cohort studies if they confirmed established causality, although effects of excess risks should not vary across populations
Our analysis had several limitations that should be noted. First, we focused on impacts of risk factors on mortality relative to changes in life expectancy and did not account for morbidity and disability. It is important in future studies to integrate these nonfatal health outcomes and examine disability-adjusted life years under the framework of comparative risk assessment in Japan. This is particularly true because the prognosis of non-communicable diseases has been improving with enhanced access to care, advances in medical technologies, and the standardization of treatment. Second, we could not incorporate standard metabolic equivalents in the categorization of exposures to physical inactivity because of the lack of detailed data from the 2007 survey, but instead we adopted a broader classification based on only the intensity and duration of physical activity that was used in the Global Burden of Disease Study in 2000. Third, data on dietary sodium intake until 1995 were recorded at the household level, which might increase uncertainty concerning the estimated stroke mortality attributable to high blood pressure in the early years. Fourth, we employed LDL cholesterol as an exposure metric for high concentrations of serum cholesterol, because it is the major atherogenic lipoprotein and a primary target for prevention of coronary heart disease
To sustain the trend of longevity in Japan for the 21st century, additional efforts in a variety of fields are required for decreasing adult mortality from chronic diseases and injuries. A first step will be to powerfully promote effective programs for smoking cessation. Indeed, tobacco smoking is deeply rooted in Japanese society, and coordinating among interests of ministries and industries is hard. Health care professionals, including physicians, who are highly conscious of the harms of tobacco will play the primary role in treatment of smoking and creating an environment for implementation of stringent tobacco control policies. Moreover, it is urgent to establish a monitoring system for management of high blood pressure at the national level. Further investigation through national health surveys will help understand factors that contribute to the inadequate control of blood pressure in the Japanese population. Measuring the quality of the care that is actually delivered by interventions will be of paramount importance in the assessment of current policies and programs for the treatment of multiple cardiovascular risks including hypertension. These concerted actions in research, public health, clinical practice, and policymaking will be the key for maintaining good population health in the aging society.
Translation of the article into Japanese by the authors.
(DOCX)
Relative risks for the effects of physiological risk factors on non-communicable diseases.
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Relative risks for the effects of alcohol use on disease outcomes from meta-analyses.
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Relative risks for the effects of alcohol use on disease outcomes from Japanese studies.
(DOCX)
Relative risks for the effects of tobacco smoking on disease outcomes.
(DOCX)
Relative risks for the effects of physical inactivity on disease outcomes.
(DOCX)
Relative risks for the effects of dietary risk factors on disease outcomes.
(DOCX)
Relative risks for the effects of infections on disease outcomes.
(DOCX)
Population-attributable fractions of cause-specific mortality attributable to individual risk factors in men in 2007.
(DOCX)
Population-attributable fractions of cause-specific mortality attributable to individual risk factors in women in 2007.
(DOCX)
We thank Goodarz Danaei, Hideki Hashimoto, Rintaro Mori, Christopher JL Murray, and Akira Oshima for their helpful comments; Amarjargal Dagvadorji, Farshad Farzadfar, Jinghua Li, and Mengru Wang for their technical assistance; Kazue Kondo, Ruriko Sano, Yasuko Sato, and Setsuko Shibuya for their administrative support.
confidence interval
human T-lymphotropic virus type 1
low density lipoprotein
National Health and Nutrition Survey