This investigation offers population-based data on the epidemiology of hypertension in older Dai adults in rural China. The rate of HBP among the Dai people aged 50 years or older was 43.2%. The subtype-specific prevalence of hypertension was 16.5% for SDH, 24.2% for ISH and 2.5% for IDH. Among all the hypertension patients, 37.9% were SDH, 56.8% were ISH and 5.8% were IDH. ISH was the most common kind of high blood pressure in rural elderly people, followed by SDH. In comparison with the age group of 50–59 years, Dai people in the age groups of 60–69 years and 70+ years were prone to a higher risk of ISH (OR > 1.0). However, along with the increase in age, SDH and IDH prevalence did not indicate an increasing trend (P>0.05). Among Dai people aged over 50 years, the SBP value tended to increase, and the DBP value tended to decrease, which led to a widening of the pulse pressure. The rigidity of large arteries (including the aorta) appeared to increase with age. The SBP value appeared to increase with age, which caused an increased incidence of ISH in elderly people. SBP is one of the most important cardiovascular risks and reflects diffuse atherosclerotic processes. If SBP declines by 10 mmHg, major cardiovascular disease events will decline by 20%, heart failure will decline by 18%, coronary heart disease will decline by 17%, stroke will decline by 17% and all-cause mortality will decline by 13% . From 1979 to 2015, the Chinese government had carried out a one-child policy to curb China’s population growth, which has led to changes in the demographic structure and ageing population in China. In accordance with the United Nations, an ageing society is one in which more than 7% of the total population is over 65 years old. According to the 2010 census of the Chinese population, 13.31% of the total population is aged 60 years, and 14.98% of the rural population is aged over 60 years. It is estimated that a quarter of the population will be 60 years or older by 2030 in China. Because of the increasing ageing population in China, the prevalence of hypertension, particularly ISH, is anticipated to increase significantly, which means that the ISH burden is rapidly rising. Therefore, ISH remains an important public health concern in China.
Compared to people with a normal weight, the prevalence of HBP, SDH, ISH and IDH among Dai people with obesity showed increasing trends (p<0.05). The prevalence of HBP, SDH, ISH and IDH among Dai people with obesity was 52.8%, 25.5%, 22.2% and 5.2%, respectively. Both SBP and DBP values increase with increasing BMI. The Dai people are mainly involved with agriculture. During busy seasons, their diet usually consists of a large amount of meat, which is high in saturated fat and cholesterol. The farmers think that high-fat dairy foods give them strength. Most Dai people do not have the awareness of the benefits of regular exercise. Most of them remain sedentary in their leisure time. Therefore, the guidance of maintaining a healthy diet and regular exercise is important in helping Dai people control their weight and prevent hypertension. Dai people should take part in accumulated moderate-intensity aerobic physical exercise ≥150 minutes /week . At the same time, they should keep healthy diets abundant in dark green vegetables, fresh fruits, whole grains (instead of refined grains), and low-fat and low-sodium dairy options .
Dai people who drank or smoked had a higher prevalence of HBP, SDH, ISH and IDH (P = 0.000) compared with those who did not drink or smoke. Wine culture is an important part of the national etiquette. Dai people are particularly good at brewing liquor. Dai people like to drink in large bowls in their daily life, during festivals, and for social reasons or entertainment. The drinking rate for Dai males over 50 years old is 45.6%. Through health education, it is best to reduce the frequency and amount of each drink as well as to abstain from alcohol altogether. In addition, the smoking rate among Dai people over 50 years old is 26.3% (50.1% for males and 13.4% for females). According to the Chinese Adult Tobacco Survey in 2015, the smoking rate of people over 15 years old was 27.7% (52.1% for males and 2.7% for females). The smoking rate of elderly Dai women is obviously higher than that of the whole country. Dai people think that it is normal for women to smoke, and some women have the habit of chewing tobacco as well. The high smoking rate is related to Dai people’s cultural customs and insufficient awareness of the hazards of smoking. Smoking is an important independent risk factor for hypertension and premature death . Tobacco dependence is a chronic disease. Healthcare professionals should provide some ways (including behavioural interventions and medicine) to help people quit smoking . In addition, it is important to reduce second-hand smoke exposure of non-smokers through health campaigns.
Of hypertensive participants, the awareness in our study was 25.0% (232/928) for HBP, 34.7% (123/354) for SDH, 20.0% (104/520) for ISH and 9.3% (5/54) for IDH, which was much lower than that reported in urban northwest China (42.9%) , Thailand (43.9%), the USA (69%), London (44%) and South Korea (60.1%). Perhaps the reasons were as follows. The Dai ethnic population in our study resided in rural southwest China. They often had a lower level of education and a lack of basic health knowledge. Few of them realized that they have hypertension because of no symptoms. Therefore, undiscovered hypertensive patients accounted for a significant proportion. Due to their lower income, many people were not willing to go to the hospital, which indicates that in the early phase, a large number of hypertensive patients were not found.
Of the participants with hypertension, 23.8% (221/928) had HBP, 26.8% (95/354) had SDH, 23.1% (120/520) had ISH and 11.1% (6/54) took antihypertensive medications. The rates of control were 6.9% for HBP, 7.9% for SDH, 6.3% for ISH and 5.6% for IDH. The rates of treatment and control of hypertension in the population aged over 18 years in 2012 in China were 41.1% and 13.8%, respectively. Dai people have lower rates of treatment and control. There are some reasons for this phenomenon. First, the hypertension awareness of those participants who were diagnosed with hypertension was very low. The examination of blood pressure is not still fully covered by current health insurance companies. Second, classic antihypertensive drugs are involved in calcium channel blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers and thiazide diuretics. Long-term antihypertensive drugs are better than short-term drugs. For economic reasons, Dai people prefer to choose short-term antihypertensive medicines, such as hydrochlorothiazide, captopril and captopril. When attempting to control SBP with antihypertensive medicine in older people with high blood pressure, physicians may worry about the underlying negative effects of exceeding a decline in DBP. Some doctors lack a comprehensive understanding of the significance of SBP control, which may decrease the effectiveness of hypertension treatment. Third, Xishuangbanna is a tropical rainforest climate with abundant animal and plant resources. Some Dai people prefer Chinese herbal medicine to treat hypertension. In addition, most of them do not have knowledge about keeping their blood pressures normal. When their blood pressure was found to be “normal”, they would stop antihypertensive therapy. Thus, the frequency and number of patient follow-ups decreased. Most patients did not make sufficient lifestyle changes.
Some limitations of this study need to be acknowledged. First, because we only visited the subject once, white-coat hypertension (when a patient sees a doctor, his/her blood pressure will elevate) and secondary hypertension were not eliminated from the hypertensive group. Second, our study conducted a population-based survey based on randomly selected samples. We could not determine whether there was a nonresponse selection bias. Data on smoking habits, alcohol drinking habits, salt intake and exercise routines were in accordance with self-report, and biological measurements or specific tests were not performed, which could lead to misclassification due to recall bias. Furthermore, due to the cross-sectional design of this study, we did not infer cause and effect.
In conclusion, hypertension prevalence is high among Dai people in rural China. Most of the hypertensive Dai people didn’t realize that they had hypertension. The prevalence of treatment and control was low. ISH was the most common kind of hypertension in the rural elderly population. Coupled with China’s ageing population, ISH remains to be a primary public health problem and a challenging issue for practising physicians in rural China. Older age, obesity, smoking, drinking and a history of hypertension are all risk factors for ISH. Public health strategies should regularly provide more information to both local physicians and the general population on how to prevent hypertension and encourage people to monitor and track their blood pressure and to follow the advice of medical experts. A combination of drugs and lifestyle modifications should be strongly recommended to reduce cardiovascular events.