Researchers led by Zhaoqing Sun of the
Department of Cardiology, First Affiliated Hospital, China Medical University, Shenyang, say the rise in hypertension may represent
the internalized stresses of adapting to a rapidly changing
economic and cultural landscape in China -
25% of the incidence over a 5-year period found in a
large population sample from a single rural region, the Liaoning province.
Cardiovascular disease, including both stroke and heart disease,
is now the leading cause of death among Chinese adults. Hypertension
is an important modifiable risk factor for cardiovascular disease
and total mortality in the Chinese population, the researchers said in their findings published in the Annals of Family Medicine.
Because more than one-half of the Chinese population lives in
rural regions, shifts in mortality that are due to cardiovascular
disease have enormous public health and economic consequences.
Studies published in the 1980s and 1990s suggested that the
prevalence and incidence of hypertension in rural China were
very low. During the past 2 decades, however, China in general,
and rural China in particular, has been undergoing rapid social
changes. Rural residents periodically commute to urban regions,
where they acquire urban and westernized lifestyles and dietary
habits. These changes are occurring all over China, but they
are particularly pronounced in the northeast and west, where
agricultural production is not high and growth of urban centers
More recent data suggest a rapid acceleration
in the number of cases of hypertension in rural China. Salt
consumption has been shown to be higher in northern than in
southern China, and activity levels in northeastern rural China,
where Liaoning Province is situated, decreased significantly
during the winter. These factors may also contribute to the
particularly high prevalence of hypertension in Liaoning Province.
In rural areas of China, 84% of consumed salt is added during
cooking or as a preservative of foods prepared in the fall for
consumption through the spring. The researchers questioned the
participants' addition of salt to daily meals, as well
as the amount of salt used in salted foods, and then calculated
the total salt consumed by the family per year divided by the
number of family members to get an estimate of the individual
salt intake per year.
Two western studies, one from Canada and
the Framingham study from the United States, found an annual
hypertension incidence of between 2.6 and 9.3.
The highest annual
incidence of 9.3% was for persons who had pre-hypertension in
the 1990s. Our study in rural Liaoning Province shows an annual
hypertension incidence of 11.4%, which is higher than that from
any of the other studies previously reported.
Obviously then in the last two decades, incidence
of hypertension has been accelerating among rural Chinese adults
and now even exceeds the incidence in urban Chinese and in most
The researchers noted - "Although our calculated method of salt intake was not precise,
results from our analysis also indicated that higher salt intake
contributed to the progression of hypertension. In our study,
the average salt intake is more than 15 g/d in rural China.
According to World Health Organization recommendations, sodium
chloride consumption should be less than 6 g/d for everyone,
especially for children and adults. Health promotion and education
about reducing salt intake should therefore be strengthened
in this specific region.
"The incidence of hypertension may vary in different ethnic groups. Our data highlighted that the incidence of
hypertension was higher in the Mongolian population than in
the Han population. Mongolian men and women had hazard ratios
of 1.089 and 1.159, respectively, for developing hypertension
compared with the Han population. Further exploration into the
genetic causes of incident hypertension for the rural Chinese
and Mongolian populations is needed.
"Our study reported that more than 80% of all cases of incident
hypertension were untreated. Surprisingly for us, the hypertension
control rate was less than 2%, which is similar to our previous
cross-sectional study findings.
"The Systolic Hypertension in
China Study (Syst-China) found that antihypertensive treatment
targeted to achieve systolic blood pressure reductions produced
a 38% reduction in stroke, which is more prevalent in China.
Given the high rates of stroke in China and the striking reductions
in cardiovascular events that result from treatment with antihypertensive
medication, the high incidence of untreated and uncontrolled
hypertension shown here highlights the critical need for enhanced
blood pressure monitoring, treatment, and control programs in
this rural region."
The researchers called for a public health strategy involving educational and environmental
interventions targeting village doctors and others
responsible for primary care in rural areas, as well as at the
rural population. Public health measures were successful in
China during the period between 1950 and 1980 in reducing the
incidence of infectious diseases and improving maternal and
infant survival. This approach needs to be applied now for chronic
diseases, such as hypertension, they stressed.