Epidemiology of hypertension in China and Japan

Journal of Human Hypertension (2000) 14, 765–769
 2000 Macmillan Publishers Ltd All rights reserved 0950-9240/00 $15.00
www.nature.com/jhh
REVIEW ARTICLE
Epidemiology of hypertension in China
and Japan
H Ueshima1, X-H Zhang2 and SR Choudhury1
1
Department of Health Science, Shiga University of Medical Science, Seta Tsukinow-cho, Otsu, Shiga
520–2192, Japan; 2Institute for International Health, The University of Sydney, Royal North Shore
Hospital, PO Box 1225, Crows Nest, Sydney, NSW 1585, Australia
Hypertension is a major risk factor for cardiovascular
disease in Chinese and Japanese with a low to moderate
serum cholesterol level. The prevalence of hypertension
is diverse in Chinese populations with different geographic region, lifestyles and cultures. The same diversity was observed in Japan in the past, but recently the
regional difference has become smaller. The large
decline in stroke mortality in Japan was followed by a
reduction in the prevalence of hypertension and the lowering level of blood pressure. This is partly explained by
various community-based hypertension control programmes. Chinese populations are now showing similar
patterns as those observed in Japan. These populations
still have high proportions of undetected hypertensives
and untreated patients in China. In both Chinese and
Japanese, high salt consumption is one of the most
important risk factors for hypertension. In addition to
this, the increase in body weight, smoking and alcohol
consumption in Chinese people seems to be the major
factors for the increasing trends in hypertension. Control of hypertension and lowering blood pressure in the
population level should be the important strategies for
the prevention of cardiovascular disease in Chinese
and Japanese.
Journal of Human Hypertension (2000) 14, 765–769
Keywords: China; Japan; blood pressure; epidemiology
Introduction
Hypertension is a major cardiovascular disease risk
factor which has a major impact on cardiovascular
morbidity and mortality in low cholesterol populations such as the Chinese and the Japanese.1–3
Japan had one of the highest stroke mortality rates
three decades ago, the level then was nearly equivalent to the level prevailing in China at the present
time.4 Over the last decades, research, prevention
and treatment of hypertension has been a priority in
Japan and China. In China, the prevalence of hypertension has increased over the last decade, mortality
from stroke has increased in the younger population, and death from ischaemic heart disease has
substantially increased in all age groups.5 In Japan,
the population mean blood pressure reached its
peak in the mid 1960s, then started to decline steadily along with a decline in the prevalence of hypertension and cardiovascular mortality.6 Various studies have clearly shown the strong association of high
blood pressure with cardiovascular mortality in
China and Japan. Recently, the Eastern Stroke and
Coronary Heart Disease Collaboration Project with
cohort studies in the Chinese and Japanese populations, showed that every 5 mm Hg of diastolic
blood pressure increase associated with 46%
Correspondence: Dr Hirotsugu Ueshima, Department of Health
Science, Shiga University of Medical Science, Seta, Tsukinowcho, Otsu, Shiga 520-2192, Japan
Received and accepted 9 April 2000
increase of stroke risk and 27% increase of coronary
heart disease (CHD).7 Even a 2-mm Hg difference in
systolic (SBP) or diastolic (DBP) blood pressure in
population level would make a substantial difference in the incidence of stroke and CHD among
populations in China.8 Hypertensive patients had
more than five times greater stroke risk than normotensives in a Chinese population.9 Large-scale antihypertensive trials in China demonstrated that a
moderate decrease of blood pressure, even in mild
hypertensive patients, would effectively reduce
stroke risk.10–12 Cohort studies in Japan also identified hypertension or high blood pressure as an
important risk factor for cardiovascular disease.2,3,13–15
In this paper the current epidemiology of hypertension in China and Japan, which are in different
stages of economic development, are presented.
Prevalence of hypertension
Hypertension, or high blood pressure, is not only an
important determinant of other cardiovascular diseases, it is also a common health problem in China.
Results of the third National Blood Pressure Survey,
carried out in 1991, show that in a study population
of about 900 000 people aged 15 years and more the
prevalence of hypertension (SBP/DBP ⭓140/90
mm Hg or under antihypertensive treatment) was
11%. This suggests that there may be more than 100
million people with an undesirable level of blood
pressure in China at this time.16 In Japan, the
National Survey of Cardiovascular Disease conduc-
Epidemiology of hypertension in China and Japan
H Ueshima et al
766
ted in 1990 showed that age-adjusted prevalence of
hypertension (SBP/DBP ⭓160/95 or under antihypertensive treatment) in adults aged 30 years or
more was 27.9% in men and 24.6% in women.17,18 If
borderline hypertension is also included (SBP/DBP
⭓140/90 mm Hg or under antihypertensive
treatment), then the prevalence increases to an average of 47% for both men and women. However, in
this 1990 survey, blood pressure was measured only
once during mass screening, and age adjustment was
done using the standard Japanese population of
1985. Since the study methodologies were different,
we could not compare the rates between these two
countries. In Japan, 12% of the population was over
65 years or older in 1990 and for this reason the
prevalence of hypertension is very high.19 Given the
large population in China and rapid aging in the
Japanese population, it is clearly evident that hypertension is and will be a major public health problem
in this part of the world in the coming years.
The level of blood pressure and the prevalence of
hypertension increased with age. The sharp increase
occurred from 35 to 40 years of age in China and
around 40–50 years in Japan. In most areas, the ageadjusted mean level of blood pressure and the prevalence of hypertension was higher in men than in
women. Differences in blood pressure changed with
age according to gender. In China, it was higher in
men under 40 years old, remained similar between
both sexes from 40 to 50 years old, and reversed
after 50 years old.16,17 However, the differences by
gender for the prevalence of hypertension and other
cardiovascular diseases was much narrower in
China than in any other countries.20–22 In Japan also,
blood pressure correlating to gender differences was
almost similar to that of China, but in women aged
70 years or more hypertension prevalence was
higher than for men in the same age group.23
Lower levels of blood pressure and prevalence of
hypertension in rural compared to urban areas were
observed in both men and women, and in all age
groups from two national blood pressure surveys
and many other studies in China.24 This could be
due to a high fat diet as well as higher rates of obesity, heavy alcohol drinking and sedentary lifestyle
in urban areas. An urban-rural difference in the
prevalence of hypertension was also noted in
Japanese populations,25 however prevalence of
hypertension was higher in rural areas. Previous
studies in Japan showed geographical differences in
the prevalence of hypertension. Higher rates were
observed in the primarily rural northern part of
Japan and lower rates in the western part, but recent
national cardiovascular surveys do not show much
geographical variation in the prevalence of hypertension.17 One of the reasons for high blood pressure
in rural Japan was due to a high salt intake in
rural areas.26
There was a remarkable difference in the level of
blood pressure and the prevalence of hypertension
among geographic regions in China. Generally
speaking, the prevalence of hypertension was higher
in the north than in the south, particularly in the
Qingzang plateau region around the Tibetan and
northeast areas. This can be partly explained by a
Journal of Human Hypertension
higher rate of salt intake, and lower rates of intake of
fresh fruits and vegetables, higher body mass index,
smoking prevalence and alcohol drinking, as well as
colder weather in the north than in the south.24,27–29
There are more than 50 ethnic minorities constituting about 8% of the total population in China.
The ethnic diversity in the level of blood pressure
has been noted in many studies since 1970. A higher
prevalence of hypertension (⭓20%) has been
observed in some Tibetan, Korean and Mongolian
people living in the northern part of China, compared to lower prevalence in the Yi (3%) and Li
(6%) people living in the southern part of the country. Different ethnic populations living in the same
area had different blood pressure levels, while the
same ethnic populations living in different areas had
even larger differences in blood pressure levels. For
example, prevalence of hypertension among Tibetan
people in Lhasa was 17%, while the same ethnic
people in southern part of Qinghai province was
only 1.3%.24 It seems that living conditions and lifestyle are more major determinants for blood pressure level.30
Rates of awareness, treatment and
control
Rates of awareness, treatment and control for hypertension were low in China. According to the 1991
National Blood Pressure Survey, only 36% of all
hypertensives (⭓140/90 mm Hg and under antihypertensive treatment) aware of having high blood
pressure in the urban population, and 14% in the
rural population. The percentage of all hypertensives under treatment was 17% in the urban and 5%
in the rural population. Among all hypertensives,
only 4.1% in the urban and 1.2% in the rural area
had their blood pressure controlled. These low rates
are attributed to minimal health education and lack
of health care facilities in rural areas compared to
urban areas.27 In Japan, according to the 1990
National Cardiovascular Survey, awareness rate was
44% among hypertensives (⭓140/90 mm Hg and
under antihypertensive treatment).17 However, the
non-treatment rate among hypertensives in the elderly age group was 35%. For the middle-aged population this increased to 60%.31 It is a great public
health challenge to decrease the non-treatment rate
of diagnosed hypertension in Japan, especially in
the younger population.
Major risk factors of hypertension
Apart from those unmodifiable risk factors such as
age, sex, family history, and ethnic and geographic
regions, the major modifiable determinants for the
level of blood pressure in the Chinese population
were lifestyle (cultural and habitual) and living conditions (available and affordable food and medical
care and supplies).32 A Chinese diet with lower saturated fat, which contributes to lower blood cholesterol and lower rates of coronary heart disease, has
been recognised in many population studies.33–35
However, high sodium, low potassium, low animal
protein, low fresh vegetable and fruit intake in
Epidemiology of hypertension in China and Japan
H Ueshima et al
Chinese population, especially in the northern part
of China due to the cold climate, poor production
and economic situation, were major contributors to
the high level of blood pressure and high risk of
stroke.36–39 A strikingly similar situation prevailed
in Japan before the 1960s, when there was high dietary salt intake and low animal protein and fat intake,
with strenuous labour-intensive work and poor
housing conditions.40 All these factors may have
contributed to the high blood pressure levels,
especially SBP level, in that period in the Japanese
population. The INTERSALT study also suggested
that a higher SBP level in Japanese than in US white
population may be attributable to a higher sodium
intake for men and women and to a higher alcohol
intake for men in Japan.41 A restricted salt intake
trial in the Tianjin population showed that blood
pressure decreased substantially in both the hypertensive group and the normotensive group with a
low sodium and high potassium diet.42 Heavy alcohol drinking is also a risk factor for hypertension.43–45
A randomised controlled trial in Japan showed that
moderation of alcohol in mild hypertensives
reduces blood pressure.46
Body mass index, as a combined result from total
calorie intake, physical activity and genetic factors,
played an important role in determining the level of
blood pressure individually and between populations in China and Japan.8,16,18,47 Even though the
prevalence of being overweight and obese in these
countries was not high compared to the western
population, it is foreseen to become a serious problem soon due to over-nutrition and reduced physical
activity both during working and leisure time as a
consequence of economic transition in China. In
Japan, also, body mass index is increasing in men
and women, except in young women.18
Time trends of hypertension
Precisely estimating the time trends of hypertension
is quite difficult due to differences in methodology
and definition of hypertension in the two national
blood pressure surveys and many local studies carried out in China. Generally speaking, it is estimated
that the prevalence of hypertension increased about
20%, mainly in mild hypertension, from 1980 to
1991.24,47,48 During the last decade, most of the
above-mentioned risk factors increased in the Chinese population. For example, body mass index
increased by 0.5–2.1 units.
In Japan, data from the National Nutrition Survey,
carried out annually since 1956, provide the opportunity to examine the time trend of blood pressure
and other cardiovascular disease risk factors. The
age-specific mean SBP level for men and women
increased from 1956 to the mid 1960s in each age
group.49,50 After that there was a steady declining
trend in almost all age groups. The mean blood
pressure declined about 9.1 mm Hg and 14.6 mm Hg
in men in their 50s and 60s from 1965 to 1990
(Figure 1). Prevalence of systolic hypertension (SBP
⭓180 mm Hg) in the elderly also dropped markedly
from 1965 to 1990, for example from 21% to 4.2%
in the 50-year-old group, and from 11% to 3.3% in
the 60-year-old group. Similarly, diastolic hypertension (DBP ⭓100 mm Hg) also declined.28 This
decline in blood pressure was largely attributed to
the organised efforts of various community-based
hypertension control programmes in the 1960s to
prevent the epidemic of stroke at that time. The
basic strategies for hypertension control included
systematic blood pressure screening for detection of
hypertensives, referral of high risk individuals,
health education for patients, advice on healthy diet
by trained personnel, and increasing community
awareness of blood pressure control by reducing salt
intake. After successful results of community-based
hypertension control programme, the national
government started supporting blood pressure
screening in every prefecture after 1973. In 1982, a
national Act was implemented by which every
municipal government was required to conduct
767
Figure 1 Trend in systolic blood pressure for men by age group in Japan, 1956–1995.
Journal of Human Hypertension
Epidemiology of hypertension in China and Japan
H Ueshima et al
768
health screening and education for those aged 40
years or over to prevent cardiovascular diseases.50
With all these efforts the rate of treatment of hypertension markedly increased.50 Salt intake decreased
steadily from 1972.51 During the last decades a 2.4gm reduction in salt consumption per capita per day
was observed.6 These efforts at the community and
national level brought about a caused lower rate of
hypertension prevalence in Japan. The stroke and
coronary heart disease mortality also declined in
parallel with the decline of mean blood pressure.6,50
Hypertension in China and Japan is a major public
health problem but has different dimensions. With
the increasing prevalence of hypertension and
related factors, and low awareness, treatment and
control rates in hypertensives, the burden of stroke
and ischaemic heart disease in the Chinese population will increase unless health care education and
an intensive intervention programme are undertaken now in the general population in China.
Although tremendous successes have been achieved
in reducing population mean blood pressure and
cardiovascular mortality, with rapid aging of the
population, the number of patients with high blood
pressure will increase substantially. Controlling
hypertension by screening and treatment is a formidable task given the present high rate of non-treatment. Large-scale population intervention studies
are on-going in Japan to reduce the blood pressure
in the intervention population by modifying lifestyle such as low sodium and high potassium diet,
moderation of alcohol consumption and exercise
along with smoking cessation. The result of this
study will help to formulate a policy of intervention
in the population for overall reduction of cardiovascular disease in Japan and in China. Diet is also
an important contributing factor to population blood
pressure. The INTERSALT study established salt
intake as an important contributor to blood pressure.41 INTERMAP is an international epidemiological study carried out in the USA, UK, China, and
Japan with the aim of identifying dietary factors
related to blood pressure. Results of this study will
be helpful in identifying dietary factors associated
with optimal blood pressure in different cultural settings and will be helpful in setting guidelines in
these countries.
Conclusion
To prevent an epidemic of cardiovascular disease in
China and to further reduce stroke with prevention
of a rise in ischaemic heart disease in Japan, hypertension control by screening, treatment and primary
prevention of risk factors will be an important task
for physicians, public health professionals and policy makers in this region.
References
1 WHO MONICA. WHO MONICA Project: risk factors.
Int J Epidemiol 1989; 18: S46–S64.
2 Ueshima H. Brief report on Follow-up Study of 1980
National Cardiovascular Survey (NIPPON DATA). J
Jpn Asso Cerebro-Cardiovasc Dis Cont (JACD) 1997;
31: 231–237 (in Japanese).
Journal of Human Hypertension
3 Ueshima H et al. Multivariate analysis of risk factors
for stroke: Eight-year follow-up study of farming villages in Akita, Japan. Prev Med 1980; 9: 722–740.
4 NIH International Activities. Report on International
Activities, Fiscal Year 1997, NHLBI, 1997.
5 PRC Ministry of Public Health. Chinese Health Statistics Annual Report. Beijing; 1986–1998.
6 Ueshima H. Changes in dietary habits, cardiovascular
risk factors and mortality in Japan. Acta Cardiol 1990;
45: 311–327.
7 Eastern Stroke and Coronary Heart Disease Collaborative Group. Blood pressure, cholesterol and stroke in
Eastern Asia. Lancet 1998; 352: 1801–1807.
8 Zhou BF et al. Ecological analysis of the association
between incidence and risk factors of coronary heart
disease and stroke in Chinese population. CVD Prev
1998; 1: 207–216.
9 He J, Klag MJ, Wu Z, Whelton PK. Stroke in the
People’s Republic of China. 2. Meta-analysis of hypertension and risk of stroke. Stroke 1995; 26: 2228–2232.
10 Lansheng Gong et al. Shanghai Trial of Nifedipine in
the Elderly (STONE). J Hypertens 1996; 14: 1237–
1245.
11 Lisheng Liu. Effect of hypertension control on stroke
incidence and fatality: report from Syst-China and
post-stroke antihypertensive treatment. J Hum Hypertens 1996; 10: S9–S11.
12 PAT Collaborating Group. Post-stroke antihypertensive treatment study. A preliminary result. Chin Med
J 1995; 108: 710–717.
13 Tanaka H et al. Risk factors for cerebral hemorrhage
and cerebral infarction in a Japanese rural community.
Stroke 1982; 13: 62–73.
14 Ueda K et al. Intracerebral hemorrhage in a Japanese
community, Hisayama: incidence, changing pattern
during long-term follow-up, and related factors. Stroke
1988; 19: 48–52.
15 Kodama K, Sasaki H, Shimizu Y. Trend of coronary
heart disease and its relationship to risk factors in
Japanese
population:
a
26-year
follow-up,
Hiroshima/Nagasaki study. Jpn Circ J 1990; 54: 414 –
421.
16 China 1991 Blood Pressure Screen Steering Committee. China National Blood Pressure Screen in 1991—
data book. Beijing, 1993.
17 The Ministry of Health and Welfare. A report of
National Survey on Circulatory Disorders 1990. Tokyo:
Cardiovascular Disease Research Foundation 1993 (in
Japanese, English abstract).
18 Liu L et al. Changes in body mass index and its
relationships to other cardiovascular risk factors
among Japanese population: Results from the 1980 and
1990 national cardiovascular surveys in Japan. J Epidemiol 1999; 9: 163–174.
19 Health and Welfare Statistics Association. Kokumin
Eisei no Doko, Kousei no Shihyo 1999, 46 (Suppl)
(in Japanese).
20 Zhang XH, Sasaki S, Kesteloot H. The sex ratio of mortality and its secular trends. Int J Epidemiol 1995; 24:
720–729.
21 WHO MONICA Project. Stroke incidence and mortality correlated to stroke risk factors in the WHO
MONICA Project, an ecological study of 18 populations. Stroke 1997; 28: 1367–1374.
22 Tunstall-Pedoe H et al. Contribution of trends in survival and coronary-event rates to changes in coronary
heart disease mortality: 10-year results from 37 WHO
MONICA Project populations. Lancet 1999; 353:
1547–1557.
23 Sakata K, Labarthe DR. Changes in cardiovascular dis-
Epidemiology of hypertension in China and Japan
H Ueshima et al
24
25
26
27
28
29
30
31
32
33
34
35
36
37
ease risk factors in three Japanese national surveys
1971–1990. J Epidemiol 1996; 6: 93–107.
Wu YK. Reports from Chinese National Hypertension
Survey in 1979–1980. Chinese Academy of Medical
Sciences: Beijing, 1982, pp 1–15.
Konishi M et al. Trends for coronary heart disease and
its risk factors in Japan. Epidemiologic and pathologic
studies. Jpn Circ J 1990; 54: 428– 435.
Sasaki N. High blood pressure and the salt intake of
the Japanese. Jpn Heart J 1962; 3: 313–316.
Tao S et al. Hypertension prevalence and status of
awareness, treatment and control in China. China Med
J 1995; 108: 483– 489.
Chen J et al. Diet, Life-style, and Mortality in China. A
Study of the Characteristics of 65 Chinese Counties.
Oxford University Press: Oxford, 1991.
Ge Keyou, Zai Fengying, Yan Huaichen. Dietary and
Nutritional Status of Chinese Population (1992
National Nutrition Survey). 1st edn. Peoples Medical
Publishing House: Beijing, 1995.
Zhao GS et al. Nutrition, metabolism, and hypertension. A comparative survey between dietary variables
and blood pressure among three nationalities. J Clin
Hypertens 1986; 2: 124 –131.
Ueshima H, Okayama A, Kita Y, Choudhury SR.
Current epidemiology of hypertension in Japan. Nippon Rinsho 1997; 55: 146–151 (in Japanese).
Xu X et al. Environmental and occupational determinants of blood pressure in rural communities in China.
Ann Epidemiol 1997; 7: 95–106.
PRC-USA Cardiovascular and cardiopulmonary Epidemiology Research Group. An epidemiological study
of cardiovascular and cardiopulmonary disease risk
factors in four populations in the People’s Republic of
China. Circulation 1991; 85: 1083–1096.
Kesteloot H et al. Serum lipids in the People’s Republic of China. Comparison of Western and Eastern populations. Arteriosclerosis 1985; 5: 427– 433.
Vartiainen E et al. Mortality, cardiovascular risk factors, and diet in China, Finland, and the United States.
Pub Health Rep 1991; 106: 41– 46.
Nara Y et al. Relationship between dietary factors and
blood pressure in China. The Sino-Japan CARDIAC
Cooperative Research Group. J Cardiovasc Pharmacol
1990; 16: S40–S42.
Tian HG et al. Associations between blood pressure
and dietary intake and urinary excretion of electrolytes
in a Chinese population. J Hypertens 1995; 13: 49–56.
38 Zhou BF et al. The relationship of dietary animal protein and electrolytes to blood pressure: a study on
three Chinese populations. Int J Epidemiol 1994; 23:
716–722.
39 Wu X, Wu Y, Zhou B. The incidence of hypertension
and associated factors in 10 population groups of
China. Chung-Hua i Hsueh Tsa Chih 1996; 76: 24 –29
(in Chinese).
40 Shimamoto T et al. Trends for coronary heart disease
and stroke and their risk factors in Japan. Circulation
1989; 79: 503–515.
41 INTERSALT Cooperative Research Group. INTERSALT:
an international study of electrolyte excretion and
blood pressure. Results for 24 hour urinary sodium
and potassium excretion. BMJ 1988; 297: 319–328.
42 Lai FR et al. A population study for high salt intake
and blood pressure and the result from intervention
trials. Chin Prev Med 1992; 26: 168–170.
43 Ueshima H et al. Alcohol Intake and hypertension
among urban and rural Japanese populations. J Chron
Dis 1984; 37: 585–592.
44 Ueshima H et al. Alcohol drinking and high blood
pressure: Data from a 1980 National Cardiovascular
Survey of Japan. J Clin Epidemiol 1992; 45: 667–673.
45 Choudhury SR et al. The associations between alcohol
drinking and dietary habits and blood pressure in
Japanese men. J Hypertens 1995; 13: 587–593.
46 Ueshima H et al. Effect of reduced alcohol consumption on blood pressure in untreated hypertensive men.
Hypertension 1993; 21: 248–252.
47 Wu ZS et al. Multiprovincial monitoring of the trends
and determinants in cardiovascular diseases (SinoMonica project)—Morbidity and mortality monitoring.
Chin J Cardiol 1997; 25: 6–11.
48 Wu X et al. Prevalence of hypertension and its trends
in Chinese populations. Int J Cardiol 1995; 52: 39– 44.
49 Ueshima H, Tatara K, Asakura S, Okamoto M. Declining trends in blood pressure level and the prevalence
of hypertension, and changes in related factors in
Japan, 1956–1980. J Chron Dis 1987; 40: 137–147.
50 Shimamoto T, Iso H, Iida M, Komachi Y. Epidemiology of cerebrovascular disease: stroke epidemic in
Japan. J Epidemiol 1996; 6: S43–S47.
51 Ueshima H, Tatara K, Asakura S. Declining mortality
from ischemic heart disease and changes in coronary
risk factors in Japan, 1956–1980. Am J Epidemiol 1987;
125: 62–72.
769
Journal of Human Hypertension