This survey covered about 0.5% all Tibetans from seven different high-altitudes in Ngawa and the results were representative. It showed the prevalence rate of hypertension was 24.6%, which was similar to previous survey results in Tibet (23–56%)[16–18], in Sichuan province(25.2%), and in nationally (23.2%) [6, 21, 22].
In our study, the awareness, treatment and control rate were 32.3%, 21.7% and 6.2% respectively, which were lower than in Guo’s report (36.1%, 12.4%, and 30.5% ). Compared with the 2015 Sichuan rural survey, the awareness rate of hypertension in Tibetan has increased (32.3% vs 24.6%), but the treatment rate (21.7% vs 24.7%) and the control rate (6.2% vs 14.7%)need to be further improved.
Multivariate attributive analysis showed residents at high altitude had high risk of hypertension. Perhaps main reason is their special lifestyle in this area. Firstly, at high altitudes, food resources are limited and food diversity is insufficient. Secondly, people in Ngawa like to eat traditional salty yak butter milk tea, highland barley wine and Yak meat, which are specialties of the plateau area . Finally, air-dried bacon is a common way to entertain guests in the area due to the alpine climate and traditional customs. People have unique diet that prioritizes meat, alcohol, and salt-rich food, which all increase the risk of hypertension.
We speculated that the low rate of awareness and treatment was due to their difficulty in obtaining medical examinations and health care knowledge at high altitudes. Although the level of government's health care in the region had improved in recent years, access to medical resources for the inhabitants of the Plateau is still insufficient. Hypertension remains a major public health problem in this special population. More methods and information communication technology could improve blood pressure control in Ngawa[26, 27].
There are significant differences in hypertension awareness and treatment rates in different age groups. The prevalence of hypertension in people over 60 years of age group was as high as 52.9% (Table 2). But the awareness and treatment rates was only 25.8% and 18% in this group. About 89% patients did not effectively control their blood pressure. Elderly patients may pay less attention to their health due to their lower education level and less medical knowledge, which leads to lower awareness and treatment rates. Another noteworthy is that nearly one-third of subjects in the 40–59 age groups had hypertension, and they were more likely to be taking anti-hypertensive medications than the older and younger groups, but the control rate (7.9%) was not satisfied. They are the backbone of society and the family, busy with work, neglecting to pay attention to their own health, which was also the reason for the lower awareness and treatment rate. Therefore, the level of health care in these areas needs to be further improved. But these patients would be benefited from appropriate therapy at most, and if treated, would have more control over their blood pressure .
It was disagreed with the results from other studies [28, 29], this study showed that female hypertension patients had lower effective awareness and treatment rate of BP than their male counterparts. We hypothesized that women in this group had low social status owing to their traditional customs. As a loyal housewife, women might not paying enough attention to their health, which may cause to low awareness and treatment rates in women patients. Further research is needed to confirm this hypothesis.
Although subjects with a family history of hypertension had 3.86-fold higher risk of developing hypertension (Fig. 4), fortunately, their awareness and treatment rate were higher. Maybe the high prevalence of the disease in their families helps them to better understand hypertension and prompts them to be more proactive in treating it. This trend was also mentioned in the Lebanon population in 2018.
In our study, obesity and overweight were associated with high prevalence of hypertension and subsequent awareness. Unfortunately, a larger proportion of patients remain uncontrolled. Other studies have received the same results as well[10, 20]. In our study, although subjects with a bachelor’s degree or higher education had higher awareness rate, they did poor job of treating and controlling their blood pressure. This was also mentioned in the Jackson Heart Study . The lower awareness rate was associated with lower education level and lower treatment rate was related to lack of medical care at high-altitudes. Low adherence may also reduce the control rate. Early detection and regular treatment guidelines were necessary to reduce low adherence in this area.
This study has some limitations. First, it was a cross sectional study, so it is limited in determining the direction of the association, as the exposure and the outcome are simultaneously assessed. Prospective studies are required for further investigation of these findings. Second, some of the selected residents, especially Tibetans over 70 years of age, were reluctant to go to the clinic for a check-up and fill out the questionnaire, which might lead to selection bias and cover up the actual survey data. Further epidemiological studies are needed to obtain more comprehensive information and data in order to develop appropriate prevention strategies and controls.