Hypertension among Mongolian adults in China: A cross‐sectional study of prevalence, awareness, treatment, control, and related factors

Abstract The objectives of the study were to comprehend the prevalence of hypertension (HTN) and prehypertension (PHT), awareness, treatment, and control of HTN and its distribution in urban, agricultural, pastoral, and semi‐agricultural/semi‐pastoral areas, and to explore the related factors of HTN among Mongolian adults in China. From August 2018 to August 2020, a multi‐stage stratified cluster random sampling method was conducted to investigate the prevalence of HTN among Mongolian adults aged ≥18 years living in China (n = 2558). Inclusion criteria for HTN were systolic blood pressure ≥ 140 mm Hg and/or diastolic blood pressure ≥ 90 mm Hg and/or had hypertensive history and/or taking antihypertensive drugs for HTN. The prevalence rates of HTN and PHT were 44.77% and 32.03%, respectively. The prevalence rates of PHT in urban, agricultural, pastoral, and semi‐agricultural/semi‐pastoral areas were 34.93%, 34.73%, 26.03%, and 33.44%, respectively, and the prevalence rates of HTN were 35.97%, 40.15%, 49.68%, and 48.07%, respectively. The awareness, treatment and control rates of HTN were 66.48%, 58.93%, and 16.48%, respectively. In this survey, the overweight, obesity, and central obesity rates were 34.30%, 30.67%, and 58.08%, respectively. Compared with Chinese adults ≥18 years, the prevalence rate of HTN among Mongolian adults in China aged ≥ 18 years was relatively high; the prevalence rate of PHT and HTN awareness, treatment, and control rates were similar. The prevalence of HTN and the rates of obesity and central obesity were higher in pastoral regions than in the other three types of regions, and the rate of overweight was highest in agricultural regions.


INTRODUCTION
Hypertension (HTN) is a serious challenge all over the world because of the condition's high prevalence in adults and the consequent risk of stroke and cardiovascular disease. 1 The prevalence of HTN changes with the level of progress of the economy, society, and civilization.
According to a systematic analysis, the global age-standardized prevalence of HTN in 2010 was 31.1%, about three-quarters of people with HTN live in middle-or low-income countries, and the awareness, treatment, and control rates of HTN were lower in middle-and low-income countries than in high-income countries. 2 HTN places a great burden not only on individuals but also on society as a whole. Uncontrolled high blood pressure is reported to lead to premature death and increases heart disease, stroke, kidney failure, blindness, and other complications. 3 High blood pressure is a risk factor for heart disease, 4 and there is growing evidence that HTN seems to be associated with common non-cardiovascular diseases, including dementia, cancer, oral health diseases, and osteoporosis. 5 In 2017, 2.54 million people died of HTN-related diseases in China, and 95.7% of these deaths were caused by cardiovascular diseases. 6 With the continuous reform and opening up seen in China, the country is gradually overcoming poverty, with the population's lives reaching a comfortable level. However, the incidence of non-infectious chronic diseases is on the rise. According to the results of the Chinese HTN Survey, conducted from 2012 to 2015, the crude prevalence rates of HTN and prehypertension (PHT) among Chinese adults aged ≥ 18 years were 27.9% and 39.1%, respectively. 7 The prevalence of HTN had increased from 25.2% in 2012 to 27.9% in 2015. 3 PHT is also known as an independent risk factor for HTN and cardiovascular disease. 8 However, in 2015, the awareness, treatment, and control rates of HTN among Chinese adults were 51.5%, 46.1%, and 16.9%, 7 respectively; these numbers were higher than those in previous years, but there was still room for improvement.
HTN is affected by many factors. Some surveys have revealed large differences in the relationship between genetic factors and HTN for people of different races. 9,10,11 Some studies have shown that Mongolian residents of China have a relatively high prevalence of HTN.

Survey participants
The flowchart of the study is shown in Figure 1.  On the basis of the mode of production, the participants' regions of residence were categorized as urban, agricultural, pastoral, or semiagricultural/semi-pastoral areas. 20

Statistical analysis
EpiData 3.1 database software was used to record data from the questionnaires. This error comparison software was used for logical error correction during the input process. At the same time, double-person input was used to identify and correct errors to ensure the accuracy of the data entry.
Continuous variables are described as means ± standard deviations, and Student's t-test or ANOVA was used for between-group comparisons. Categorical variables are described as percentages, and the chisquare test was used for comparisons between groups. The Mantel-Haenszel chi-square test was used to test trends of linear change.
Logistic regression was used for the multivariate analysis. SAS software, Version 9.4 (SAS Institute Inc., Cary, NC, USA) was used to conduct descriptive statistical tests to examine differences between groups. Differences were considered statistically significant when the p value was < .05.

Participants characteristics
In total, 2558 people were included in the survey. Participants with missing data on blood pressure and those of non-Mongolian ethnic-

Awareness, treatment, and control of HTN
The results on the awareness, treatment, and control of HTN are shown in

Prevalence of HTN and PHT, overweight, obesity, and central obesity in urban, agricultural, pastoral, and part-farming/part-pastoral regions
In urban, agricultural, pastoral, and part-farming/part-pastoral regions,  (Figures 2-4). The awareness and treatment rates were higher in pastoral regions than in the other three types of regions (p < .05), and the control rate was higher in agricultural regions than in the other three types of regions (p < .05).

Multivariable risk assessment
Age ≥35 years, overweight, obesity, central obesity, male sex, dyslipidemia, and family history of HTN were risk factors for HTN (p < .05).  7 The HTN prevalence seen among Mongolians in F I G U R E 3 Awareness, treatment, and control rates of HTN in urban, agricultural, pastoral, and semiagricultural/semi-pastoral F I G U R E 4 Overweight, obesity, and central obesity rates in urban, agricultural, pastoral, and semiagricultural/semi-pastoral areas China was also higher than that found in some developed countries, including that found among US adults (29.1%) 23 and in Canada (19.5%), England (30%), 24 and Spain (42.6%). 25 The overall HTN prevalence for Mongolians in China was also higher than the prevalence reported for other ethnic minorities in China, such as Tibetans (36%) 26 and Uyghurs (15.73%). 27 In our study, the prevalence of HTN was observed to increase with age and BMI and to be higher for men than for women, which is in line with previous studies. 28 Existing studies have shown that HTN is associated with BMI, family history, waist-hip ratio, chronic disease history, and eating habits. 29 In the past 18 years, the prevalence of obesity in China has increased significantly. 30 High BMI is a risk factor for HTN, and previous studies have demonstrated a quantitative relationship between BMI and HTN. 31 Overweight affects the incidence of HTN. 32 Overweight and obesity are associated with a remarkable increase in the hazard of all-cause death in the world's population 33 and are also major risk factors for HTN. In the survey in ical support, and smoking cessation programs are needed. 6 We found that the prevalence of HTN was relatively high in urban, agricultural, pastoral, and part-farming/part-pastoral regions.
The overweight rate was higher in agricultural regions than in the other three types of regions, and the obesity and central obesity rates were highest in pastoral regions. Thus, the highest rates of overweight and obesity were found in agricultural and pastoral regions, respectively, and the highest prevalence rates of PHT and HTN were observed in urban and pastoral regions, respectively. However, the prevalence rates of PHT found in urban and rural regions were very close. Differences in HTN prevalence are affected by regional variation in topography, eating habits, living habits and genetic factors. Body composition differences have been observed between Chinese Mongolians and people of other nationalities in China, which is related to genetic and environmental factors. 42 Some studies have found that specific food group consumption patterns are significantly associated with HTN. 43 In the present study, exercise was a protective factor for HTN among Mongo- The rates of HTN awareness, treatment, and control in urban, agricultural, pastoral, and part-farming/part-pastoral regions in this study were similar to the national Chinese level but higher than those previously reported among Tibetans (45%, 30%, and 7%) 26 and Uyghurs (59.57%, 52.74%, and 21.29%) 27 in China. These differences are closely related to regional variation in economy and culture. Poor medical conditions, lack of health service personnel, and insufficient service ability and health education in remote areas all affect the control of HTN.
Our finding suggested that, among Mongolian people living in China, the rates of HTN treatment, awareness, and control were higher in pastoral than in the other three types of regions, indicating that the attention to pastoral regions has been gradually improved in recent years.

Limitations
This survey had several limitations. First, the study was completed in three consecutive years; however, all surveys were administered by the same team and in the same calendar month each year. Second, there were more middle-aged people in this sample than in the overall population; however, because we standardized the prevalence of HTN to a 2019 national sample, the representativeness of our finding is very strong. Third, because this research relied on a cross-sectional survey, the ability to infer causality is weak, and it was therefore difficult to explore the causal relationships between various factors and HTN.

CONCLUSIONS
In conclusions, compared with the national level, the results of this cross-sectional survey showed that the prevalence of HTN was higher among Mongolian adults aged ≥18 years in China; the rates of obesity, overweight and central obesity were relatively high; the prevalence of PHT, the awareness, treatment, and control rates of HTN were similar, but the overall rate was low. The prevalence of HTN and the rates of obesity and central obesity were higher in pastoral regions than in the other three types of regions, and the rates of overweight was highest in agricultural regions. This survey and previous research have demonstrated that HTN has become an important public health problem threatening the Mongolian people in China.

ACKNOWLEDGMENT
We thank all research staff for their collection of data and blood samples and all the study participants for their participation and contri-

CONFLICT OF INTEREST
All authors report no potential conflicts of interest in relation to this article.

AUTHOR CONTRIBUTIONS
Lingyan Zhao contributed to the conception and design of the work.
Peiyao Yu and Yuzhen Ning prepared the first draft of the manuscript.
Yumin Gao, Yanping Zhao, Lin Tie, Lijitu Wu, Lili Zhang, and Ru Zhang contributed to the collection of data for the work. Meng Cui, Hui Pang, Qian Wu, Zhidi Wang, and Le Chen contributed to data analysis and interpretation for the work. All authors critically revised the manuscript and gave the final approval.