Utilisation of national community-based blood pressure monitoring service among adult Chinese and its association with hypertension treatment and blood pressure control—a mediation analysis

Hypertension is one of the major non-communicable diseases (NCDs) in the world that defined as one’s systolic blood pressure (SBP) above 140 mmHg or diastolic blood pressure (DBP) above 90 mmHg without taking any antihypertensive medicine. Hypertension is associated with higher risks of cardiovascular diseases (CVD) accounting for 17 million deaths in 2013 worldwide [1]. Additionally, It results in other NCDs such as diabetes and chronic kidney diseases. The prevalence of hypertension has been rising in decades in both developed and developing countries [2‐7]. In 2010, it was estimated that 31.1% of the world’s adults had hypertension; 28.5% in high-income countries and 31.5% in low-and-middle-income countries [8]. In China, hypertension prevalence is rising as the population grows older. According to a recent study, the prevalence of hypertension among people in the age group of 35–75 is 44.7, 92.6% of whom were above 45 years old [9].

Blood pressure of hypertensive persons is controlled if BP < 140-90 mmHg with or without medication. The major hypertension treatment is to take antihypertensive medicine. As the main cause of uncontrolled BP, hypertension is lack of treatment in most countries. Burden of the hypertension management was severe in many countries including China. A study across four Middle Eastern countries (Iran, Occupied Palestinian Territory, Saudi Arabia, and the United Arab Emirates) presented that 47% of persons with hypertension were treated and only 19% had controlled BP [10]. The study in South Asia showed hypertension treatment was 31.9% and BP of 12.9% was under control. In India, among all persons with hypertension, only 30.1% were known or on treatment, among whom nearly 61% had controlled BP [11]. In Nepal, only 29% of hypertensive persons were receiving treatment, and 8.2% had controlled BP [12]. The burden of hypertension treatment and BP control was even heavier in Africa. In Zambia, only 18.0% had any antihypertensive drug prescribed [13]. In Tanzania, nearly all patients (95.3%) had uncontrolled BP [14]. The condition is better in developed countries. Results of the German Health Examination Survey showed among persons aware of their hypertensive status 37.9% were BP uncontrolled. Among that 33.4% were untreated [15]. In China, hypertension treatment rates were reported under 50%, and BP control rates were lower than 20% [16‐18]. In general, when the rate of hypertension treatment is higher, the rate of BP control is higher, too.

In addition to inadequate medication treatment, uncontrolled hypertension is also attributed to unhealthy lifestyle behaviours including smoking, drinking and lack of exercise. In a study identified latent classes of hypertensive persons’ lifestyle risk factors including physical activity, smoking habits, and blood pressure control, about 85% of hypertensive persons were categorized in an intermediate to high-risk class of lifestyle [19]. In China, compared with all hypertensive persons, lower prevalence of smoking (25% vs 28%) and alcohol intake (28% vs 32%) was found among BP controlled persons while prevalence of adequate physical activity was higher (32% vs 25%). But all of them were higher among persons who were being treated (44% vs 28, 49% vs 32, 57% vs 25%) [20‐23]. A population survey in Japan stated that prevalence of current smoking and physical activity was 10 and 38.1%, and average alcohol intake was 67.4 g/week among treated hypertensive persons. It was close to the prevalence of total hypertensive population [24]. The condition of unhealthy lifestyles among hypertensive persons seems to be better in the developed country.

Conventionally, hypertensive persons are encouraged to control the symptom by long-term BP monitoring, medication use as well as establishing healthy lifestyle behaviours [25]. Interventions of community-based hypertension treatment have been proved to be effective in BP control. A study in Cameroon showed that BP control was better in those who were adherent to medication (47.5% versus 8.2%) [26]. A significant BP decrease was found after hypertension treatment management of a self-funded group in a resource-poor community in rural Honduras [27]. Improved behaviours are also key to achieve better BP control. Smoking has been reported as one of the most common predictors of uncontrolled blood pressure among hypertensive persons [21]. A study in Uganda indicated that significantly decreased odds of raised blood pressure were associated with moderate-to-vigorous physical activity [28]. Community-oriented hypertension management including treatment components and health promotion was proved to be a feasible way to achieved improvement in medication treatment, behaviours and reduction in BP and CVD risk [29]. However, the standards of community-based intervention were various in these study and the subjects were limited to certain communities. A design concerned of the mechanism of major interventions to a large population is absence. Evaluation of national intervention programs remains a challenge due to the difficulty of linking the program attendance and outcome at the population level.

Utilisation of community-based BP monitoring service was defined as receiving free blood pressure examination at least 4 times annually in the study. In 2009, a national program, Essential Public Health Services (EPHS) was launched in China as part of the new Health Care System Reform [30]. Chronic disease screening and management were included as part of the public health services and provided to community-dwelling patients free of charge, with an aim to attain universal coverage with equitable basic health care. Grass-root health institutions of urban community centres and rural township hospitals are responsible for establishing a health record and for providing free health examinations including BP measurement once a season for every hypertensive person living in their catchment areas. The use of this service at least 4 times a year were defined as utilisation of community-based BP monitoring service. Through monitoring of BP condition, community or village doctors should give instructions on hypertension treatment and health-related life behaviours after checking symptoms [31]. Only a few studies have estimated utilisation of this service since national data on the frequency of community-based BP examinations is scarce. A study showed 8.1% of hypertension patients received the EPHS-covered service by 2013 based on free physical examination paid by the government and it brought about an increase of monitoring, treatment, and control of hypertension [32]. But the evidence is limited on the relationship between community-based BP monitoring with hypertension control. Mechanisms of mediation effect of hypertension treatment and healthy lifestyle behaviours were not considered. It is necessary to examine the utilisation of this service and to find how to improve effectiveness of this program.

It is believed that patients could achieve a better outcome of BP control if they follow health expertise advice on hypertension treatment and healthy lifestyles in terms of exercising properly [33], avoiding smoking and drinking [34]. Supported by previous study reports, our hypothesis is that community-based BP monitoring has a positive effect on hypertension control through medication treatment and healthy lifestyle establishment. (Fig. 1) Accordingly, this study aims to provide an overall estimate of national-level utilisation of community-based BP monitoring service among hypertensive persons and to explore its association with blood pressure control. Mediation analysis was designed to explore mechanisms of mediation effects of hypertension treatment and healthy lifestyles between them.

Table 1 shows among 2487 hypertensive persons, 69% of them were the elderly. The mean age was 64.2 (SE = 0.24) years old (ranged from 45 to 102). Only 32.1% of subjects had BP monitored by the community or village doctors. 28.0% of subjects were uneducated. 80.0% of them lived with a spouse or cohabitated. 52.8% of them were from rural areas and 54% had a job. 94% of them were insured. 77.9% of hypertensive persons seldom drank. One-fifth of them did not exercise. The prevalence of smoking was 22.8%. The rate of patients taking antihypertensive medicine were 88.1%. Hypertensive persons had their BP monitored in the community or village were more likely to be female, with less household income, with lower level education and from rural areas. It indicated the underuse of community service by richer, higher educated, and urban patients. The hypertension treatment rate was significantly higher in patients who had BP monitored by the community or village doctors.

Table 2 presented that 57.4% of subjects had controlled BP. The BP control rate was higher in subjects who had BP monitored and who were treated by hypertensive medication. We found no difference of lifestyles including drinking, smoking, and physical activity in BP control so they were excluded in the further mediation analysis.

The reach of the community-based BP monitoring service varied largely between different regions (from 16 to 69%), as well as the BP control rate (from 23 to 76%). Among 28 provinces of China, the percentage of BP monitoring patients was the largest in Qinghai and Gansu provinces in western China, while the smallest in Heilongjiang and Hunan province in the central and eastern China. The rate of BP control was the highest in the west of Xinjiang and Chongqing provinces and the lowest in the Fujian and Guizhou Province (Fig. 2).

A binary regression analysis was conducted to investigate factors affected the hypertension treatment. Null hypothesis was β_i = 0. The results were shown in Table 3. It indicated significant factors affected hypertension treatment. The hypertension treatment was significantly associated with community-based BP monitoring of hypertensive persons (β = 1.259, P < 0.01, OR = 3.52, CI = 2.467–5.030). Patients who were more likely to use antihypertensive medicine tended to be females, living with spouse or cohabitated and with diabetes.

A binary logistic regression was conducted to investigate factors affected BP control. As shown in Table 3, BP control was significantly associated with community-based BP monitoring (β = 0.220, P < 0.05, OR = 1.246, CI = 1.035–1.499). Subjects more likely to control their BP tended to be female and with higher level education (Table 4).

As community-based BP monitoring service utilisation significantly predicted both the dependent variable of hypertension control and the mediator variable of hypertension treatment but not healthy lifestyle behaviours, the mediation model was adjusted based on our original hypothesis in Fig. 3. A final logistic regression was conducted including the mediator variable of hypertension treatment. The results in Table 5 showed the mediation effect of hypertension treatment on BP control. Taking hypertension treatment into consideration, BP control was significantly associated with hypertension treatment, but the independent variable of BP monitoring was not statistically significant anymore (P = 0.816). It indicated the use of BP monitoring service had no direct effect on BP control. The effect of independent variable BP monitoring on dependent variable BP control was completely mediated by the intermediate variable of hypertension treatment. Hypertension treatment played a perfect mediation role between monitoring and hypertension control. The Sobel test was conducted to further confirm its mediation effect (t = 4.51, SE = 1.66, P < 0.001). The final mediation model of the independent variable (community-based BP monitoring service utilisation), the mediator variable (medication treatment) and the dependent variable (hypertension control) was shown in Fig. 4.

Based on a nationally representative data from CHARLS, this study explored the association between utilisation of community-based BP monitoring service and BP control among hypertensive adults aged above 45. The prevalence of community-based BP monitoring service use was 32% among hypertensive persons in 2015. It showed an improvement in EPHS utilisation of hypertensive persons compared with a previous estimate in China (vs 8.1% in 2013) [32]. Compared with subjects whose BP was not monitored, those who used the community-based BP monitoring service had a higher likelihood of hypertension treatment as well as BP control but not healthy lifestyle behaviours. Moreover, better BP control was achieved through treatment improved by community-based BP monitoring.

Though improvement had been achieved over time, less than half of the hypertensive persons had their BP regularly examined by the community or village doctors. Percentage of hypertensive persons had their BP examined at least once annually was reported about 54–58% in 2011 and 51–65% in 2013 in China [32]. A similar finding was found in a community-based research in German that only 33.7% of hypertensive persons received at least twice BP examination in 2016 [35]. It indicated that the community-based service of hypertension management was underused. The prevalence of utilisation of hypertension monitoring service was still low.

This low reaching of community-based management may be due to several reasons. First, it is likely that many patients are unaware of this service in the community and consequently do not avail it [36]. Further implementation of this program should involve widespread public education to strengthen the residents’ consciousness of their health status and chronic disease management. Capability of community workforce should be further improved to gain residents’ trust. Second, the shortage in public health and primary care workforce may contribute to the lack of delivery in community-based services such as home visit BP examination and counselling [32]. Third, due to the relatively limited quality of care of grass-root health institutions, hypertensive persons who have multiple accesses to health care, for example, higher level hospitals in urban, may not choose to visit the community or village doctors.

On the other hand, utilisation of this service showed a development of hypertension management in grass-roots institutions, especially for the disadvantaged population [37]. Community-based hypertension monitoring was used more by patients with lower household income. The reason may be that it is free to have one’s BP examined by community or village doctors. The same result was found that more uneducated patients used this service. In spite of the underuse of BP monitoring, patients with higher educated level were more likely to control their BP. It is usually related to better health literacy for people who are educated [38]. It indicated that although community-based health management improved the health access for the disadvantaged population, its effectiveness could be further improved.

At the same time, this service has made a difference since an improvement of hypertension management was realized in less developed areas of China. In rural, patients used this service more than urban ones. Those patients from the western provinces where is the most underdeveloped area in China were mostly monitored and had controlled BP. It was possibly because of the local scarcity of multiple health facilities in these areas. It also takes longer to travel to higher level institutions from the rural [39]. It is no wonder that the community-based BP monitoring service has played a role in these regions. Nevertheless, as this service was not equally used, future studies should be focused on its geographic disparity.

Self or home monitoring of BP had been proved effective on increase hypertension treatment and BP control [40], whereas no national community-based monitoring program being evaluated yet for both economic and operative matters. This study presented that community-based BP monitoring once a season by health expertise had a significant impact on improving the rate of hypertension treatment, which was the key factor of hypertension control [41]. Having a usual source of care, optimizing adherence, and minimizing therapeutic inertia are associated with higher rates of BP control [42]. This EPHS covered programme made a difference in optimizing the prevention, recognition, and care of hypertension as a paradigm shift to population care and the use of strategies known to control BP. This finding indicates the broader international significance that with affordable funding of about 6 USD (40RMB) per capita, utilisation of free BP monitor provided by grass-roots’ expertise termly shall be a possible management tool to achieve better BP control at the population level. However, it is possible that people who are motivated to participate in monitoring are also motivated to manage their BP. If so causality may, in part, be attributed to their general motivation, rather than the intervention on its own. A future longitudinal study should be considered as it is probably impossible to ascertain this effect in this cross-sectional study.

Meanwhile, Studies had shown intervention program ran by grass-root institutions could effectively achieve higher BP control rate by improving not only medication use but also healthy lifestyle behaviours [43]. But a related study in the US presented regular access to primary care did not result in improved clinical outcomes because of its overall high prevalence of risk factors such as smoking and obesity [44]. The similar result was found in this study that the national utilisation of BP monitoring service in China was not related to health lifestyle behaviours such as alcohol intake, physical activity, and smoking. It is possible that community or village doctors paid more attention to patient’s medication use rather than on instructions on healthy lifestyle behaviours about drinking, smoking and physical activity. Also, compared with clinical intervention, it could take much longer and a harder time to encourage patients to achieve normal BP by establishing a healthy lifestyle. BP examination in 4 follow-up visits a year provided by national EPHS may not provide efficient education about healthy lifestyles. Further prospective studies should focus on healthy lifestyles establishment, as well as prescription patterns [45] and medication adherence [46, 47] of hypertensive persons receiving community-based management.

The use of BP monitoring service had no direct effect on BP control. Utilisation of national community-based BP monitoring service is positively associated with BP control through a full medication effect of hypertension treatment. This study emphasized that through improving antihypertensive medication use among hypertensive persons, the national community-based BP monitoring could be an effective way to achieve hypertension control. Termly BP monitoring by community-based health expertise among hypertensive persons, for instance, once a season, can be recommended to public health policymakers for BP control through instructions on medication treatment and health behaviours. It was suggested that awareness of EPHS service and primary health care workforce should be enhanced to increase utilisation of community-based BP management. Education about healthy lifestyle behaviours in EPHS should be bolstered in the future.