Hypertension High Among Rural Chinese Adults

Rural populations in the world suffer from problems of access to care, education, and income disparities. Hypertension is now becoming another major risk associated with rural life.

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 -  almost 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 is accelerating.

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.

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 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.

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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 western counties.

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.



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