Prevalence and control of hypertension among a Community of Elderly Population in Changning District of shanghai: a cross-sectional study

Globally, cardiovascular disease (CVD) became the leading cause of mortality in 2013 and was responsible for nearly one-third of all deaths [1]. In the meantime, hypertension, which is considered to be the most crucial risk factor for CVD, has caused half of cardiovascular mortality and morbidity and led to 9.4 million deaths per year [2]. Additionally, approximately 40% of adults who were 25 and above were diagnosed with hypertension around the world [2]. Hypertension also places a severe burden on China’s population.

According to the baseline survey from the nationwide China Health and Retirement Longitudinal Study (CHARLS), hypertension had a higher under-diagnosis rate among middle-aged and elderly Chinese [3]. The prevalence of hypertension among study respondents over 75 years was 58.0% for men and 62.1% for women [3]. Although hypertension has been considered a treatable condition, life-long intake of medication is required to control a patient’s blood pressure. In many regions of the world, especially in low and middle-income countries such as China, hypertension control remains a major health threat [4‐6].

Population aging presents a tremendous challenge for China’s hypertension control. The United Nations estimated that individuals aged ≥60 constituted 16.2% of the total Chinese population in 2017, and they predicted the percentage would increase to 35.1% by 2050 [7]. As a large metropolitan city in China, the ageing population in Shanghai is increasingly serious, especially in central districts. Elderly people are at a higher risk of non-communicable diseases, hypertension and raised blood pressure (BP) [8]. In Shanghai, the prevalence of hypertension was 41.9% among individuals who were 34–74 years of age in the community population [9], and the prevalence was 59.4% among those aged ≥60 years [10]. Therefore, urgent action, optimal treatment approaches and proper public health strategies are needed to prevent and manage hypertension in the elderly population.

Despite the high prevalence of hypertension in China, there is a lack of updated epidemiological evidence for BP control among the elderly population, especially in cities suffering population ageing like Shanghai. Previous studies may also have defective small sample sizes, a failure to investigate the susceptible population, or an inability to examine hypertension controls [5, 11‐15].

This cross-sectional study was conducted to look into the current situation of hypertension burden in elderly Chinese residents. The study was designed to investigate the BP distribution and treatment effect among both prevalent cases and new cases with abnormal BP. The study’s objectives included the following: first, to investigate the prevalence of hypertension among the community population of individuals who are 65 years and older in the Changning District, Shanghai. Second, to evaluate the effect of blood pressure control among elderly hypertension patients. Third, to explore the risk factors associated with suboptimal BP control.

To the best of our knowledge, this study was one of the largest studies in China seeking to discover the prevalence and control hypertension among the elderly population. Overall, 38.3% (44,978/117,500) in the base population in Changning district were enrolled. This study provided new evidence signifying the current burden of hypertension and the critical situation for uncontrolled hypertension among the elderly population in central Shanghai, which is city in China with the largest number of elderly individuals. Furthermore, because the studied population was composed of a younger population compared to the base population, the disease burden might be underestimated.

This study showed that approximately 60% of the elderly residents in Changning had hypertension, and this crude prevalence of hypertension increased substantially with age. Meanwhile, the prevalence was higher in elderly females than males, which was a factor that was not observed in previous studies [11]. Hypertension prevalence in the present study was comparable to reports of previous surveys in China [11, 18]. Nonetheless, the prevalence found in this study was slightly lower than the study results from some high-income countries such as the United States [19]. A similar issue was also recognized in hypertension control. According to this study, only one-third of the hypertension patients aged 65 years and older had taken hypertensive medication to provide BP control. The proportion of treatment was much lower compared to other studies in China [10, 20], which might be because Chinese studies usually took the hypertension patients under a specific NCD control program as the denominators when reporting treatment coverage, whereas the denominator for this study was all hypertension patients regardless of their participation in a hypertension management program. The treatment coverage is unsatisfactory compared to high- and upper middle-income countries [11]. Although the proportion of controlled hypertension (43.4%) in this study was relatively higher compared to other developing countries [11], the control effect of hypertension was still unsatisfactory compared to many developed regions, such as Europe and the United States [21, 22]. Therefore, treatment management for elderly hypertension patients would be a tremendous challenge to the Shanghai health authority and health system.

Old age, being overweight and obesity are traditional risk factors for uncontrolled hypertension [20]. In the meantime, the results of the present study provided additional support for that evidence. A recent study on elderly Chinese individuals aged 80 years or older estimated a hypertension prevalence of 75.3%, while 45.5% of hypertension was treated, and only 18.1% of hypertensive participants were controlled [15]. It is revealed that the importance of hypertension prevention and management for China’s elderly population would increase sharply with ageing. In the meantime, obesity also provides predictive information on atherosclerotic CVDs [23]. Previous studies indicated that abdominal obesity and visceral obesity were associated with increased hypertension prevalence among elderly population [15, 24]. Therefore, non-hypertensive elders can prevent hypertension through lifestyle modification and the reinforcement of daily exercise. These methods are also beneficial for the optimal control of BP among elderly patients. As indicated in other reports [25], elderly patients with less education showed less efficient hypertension control. Education is an important tool that leads to a higher socioeconomic status and healthier lifestyle habits, which could both strengthen and improve levels of awareness, treatment and control of hypertension. It has been shown that lack of knowledge hinders medication adherence, especially for an elderly population [26]. Results from multivariate analysis also indicated that the BP control among males was slightly better than BP control among females, although the difference was not statistically significant. Some studies conducted in other countries, such as Japan, Poland and the United States, reported higher hypertension prevalence and worse BP control among elderly females than elderly males [27‐29]. Further population-based studies are still needed to confirm whether an association exists between sex and BP control among the elderly population. On the other hand, more attention should be given to the effects of BP control among female patients because high blood pressure has a greater impact on cardiovascular risk in females than in males, and females after menopause are especially vulnerable [30, 31].

Previous studies suggested that a balanced diet plays an important role in hypertension prevention and control [32, 33]. Based on the present study, a dietary pattern with high consumption of meat was associated with uncontrolled hypertension. However, a null association between vegetable consumption and BP was observed, which was consistent with several other observational studies [34, 35]. The Dietary Approaches to Stop Hypertension (DASH) intervention study has shown that a diet rich in fruits, vegetables, and low-fat dairy products as well as low saturated fat can substantially lower both SBP and DBP [36]. Hypertension patients who drank regularly were less likely to have their BP under control. A Korean study discovered the adverse effects of drinking was significant for uncontrolled BP both at nighttime and over 24 h [37]. In fact, heavy drinking itself can be associated with resistant hypertension [38]. In addition, a previous meta-analysis showed that high salt intake was highly prevalent in low- and middle-income countries, and excessive use of salt had a greater impact on hypertension burden in urban regions than rural regions [39]. However, a significant relationship between salt intake and BP control was not observed in this study, which likely occurred due to the generally light cooking style in Shanghai.

Optimal BP control in elderly hypertension patients with comorbidities was achieved with less difficulty than in patients without comorbidities. Similar results were found in the Oslo Health Study 2000–2001 that showed the presence of diabetes or CVD was independently associated with better BP control [40]. In comorbidity situations, diabetes and cardio-cerebral vascular diseases can be aggravated by high or uncontrolled BP. Thus, patients with comorbid conditions are more likely to have frequent hospitalizations and adverse treatment outcomes. Therefore, BP control should be considered the priority for patients with comorbidities, especially for elderly patients. Indeed, there was a null association between antihypertensive treatment and BP control because only one-third of hypertension patients were treated with antihypertensive medication. However, an appropriate combination of antihypertensive medication treatment is still crucial for optimal BP control in both central regions and suburban or rural regions that have patients with less education and limited qualified medical resources [20].

Nevertheless, this study has limitations. First, it is a secondary analysis of cross-sectional data, so this study could not establish a cause-effect relationship between postulated factors and uncontrolled BP. Second, the study is missing some information, such as the exact date of diagnosis, duration of treatment, and social-economic status, such as family income level, that might be associated with hypertension control. Third, participants in this study received the health check-up on a volunteer basis and they might have younger ages and healthier physical conditions than the actual base population [16]. As a result, generalization of these findings from this study to other elderly populations in China should be handled with caution.

Among elderly residents (aged 65 and above) in central Shanghai, China, the prevalence of hypertension was high, yet the control of hypertension was unsatisfactory. Hypertension control is an essential precondition for reducing the impact, complications and deaths from cardiovascular diseases. This study yielded important information to improve our understanding of the hypertension burden. The study also contributed to clarifying the factors that have hindered hypertension control in this elderly population. Development of strategies that improve the management and control of hypertension among urban elderly residents, especially among hypertension patients without other NCDs are needed to respond to the urgent needs for disease control and comorbidity prevention.