Overview of the Burden and Challenges of Hypertension in Asia-Pacific

Hypertension is a major public health issue in Asia. With increasing life expectancy and changes in lifestyle and diet, the prevalence of hypertension is steadily rising, particularly in urban areas.¹ This is especially true in certain parts of Asia due to rapid economic development and urbanisation, which has led to an increasingly ageing population and an epidemic of obesity.^2,3 The increasing burden of hypertension in Asia is of great concern, given that it is a major risk factor for ischaemic heart disease, stroke and chronic kidney disease (CKD).⁴ Although its prevalence is not as high as in Western countries, the total number of patients in Asia is considerably larger.³ From 1990 to 2019, the prevalence of hypertension has increased by up to 40% in certain parts of Asia.⁵ Despite this, there is a relative paucity of research on hypertension in Asia compared with the West.⁵ Thus, there remain several crucial problems in the treatment of hypertension, such as lack of public awareness, low treatment rates and blood pressure (BP) control rates, especially in developing Asian countries.³ There is a need for more epidemiological data particularly with regard to resistant hypertension, patient adherence and burden of complications, as well as a need to take a closer look at the specific measures taken and the challenges faced by different countries.^3,6 The aim of this study was to perform a narrative review of the epidemiology of hypertension in the Asia-Pacific region, current measures taken by individual countries to tackle hypertension, and challenges in providing optimum care for the disease. Another aim was to identify the gaps that are shared by countries, as well as novel to each of them, to guide the direction for future research.

Methods

A writing committee was formed consisting of cardiologists and other physicians from across the Asia-Pacific region. Participating countries including Australia, Bangladesh, Cambodia, Hong Kong, India, Indonesia, Japan, Malaysia, Mongolia, the Philippines, Singapore, South Korea, Sri Lanka, Taiwan, Thailand and Vietnam contributed to the writing of this review. A search for relevant articles was performed for the period November 2012–November 2022 on six electronic databases: Medline, PubMed, Embase, Scopus, Web of Science and Google Scholar to look for related articles (Supplementary Table 1). Studies were excluded if they included only minority ethnic groups or specific education levels, occupation, or other socioeconomic groups.

In addition, the search was supplemented by articles provided by representative cardiologists from each country that participated in this review, with the help of electronic databases specific to each country (e.g.. Koreamed). Given that there were no representatives available at the time of writing for Brunei, Myanmar, Laos, Nepal and New Zealand, only epidemiological data were obtained for those countries. Key studies are summarised in the Supplementary Material.

The data extracted were then qualitatively synthesised and discussed under major subheadings. Under each subheading, key studies are summarised in Supplementary Tables 2–4. The five subheadings are: epidemiology; hospitalisation and financial impact; medication prescription; national guidelines, advocacy and measures; and barriers and challenges in managing hypertension.

Results and Discussion

Epidemiology

On review of the literature, all participating countries had formal data on the prevalence of hypertension in the form of government surveys (Figure 1 and Supplementary Table 2).^7–10 However, global mean BP stayed constant from 1990 to 2019, owing to a decrease in prevalence in high-income countries and the WHO European Region that was balanced by an increased prevalence of hypertension in low and middle-income countries.^11,12

The overall prevalence of hypertension in the Asia-Pacific region ranged between 10.6% and 48.3%. High-income countries (as per the World Bank definition), such as Japan and Singapore, had a considerably higher prevalence of hypertension (48.3% and 35.5%, respectively), possibly due to a greater degree of urbanisation and a growing elderly population.^8,9 However, the relationship between socioeconomic status (SES) and hypertension prevalence remains complex. For example, in Malaysia and Australia, a lower SES is typically associated with higher rates of hypertension, whereas in Hong Kong and Indonesia the inverse was shown to be true.¹³ Although not entirely clear, the latter may be due to frequent screening of hypertension in higher SES populations.¹⁴

Hypertension was usually more prevalent in men than in women, except for both the Philippines and Sri Lanka, where prevalence between genders was identical, and Indonesia, where there was a higher prevalence of hypertension in women.^15–17 This is consistent with previously reported observation and theorised to be due to divergent roles in the immune system, differences in renin–angiotensin–aldosterone systems, alongside differences in other environmental factors between sexes.¹⁸

There were also other factors leading to heterogeneity in hypertension prevalence between, and within, participating countries. Unsurprisingly, the prevalence of hypertension increases with age, often peaking in age groups older than 70 years.^8–10,16 Globally, 62.0% of hypertension-related mortality occurs in those aged 70 years and over. However, mortality linked to hypertension in low- and middle-income countries can reach up to 42.0% in patients aged below 70 years.¹¹

Ethnicity was also an important factor in determining disease prevalence. For example, in Malaysia, Bumiputera Sarawak adults had the highest rate of hypertension (46.8%), almost double that of Malaysian Chinese adults (28.0%).¹⁹ In Australia, Aboriginal and Torres Strait Islander adults were also 50.0% more likely to die from circulatory diseases than non-indigenous Australians.²⁰ Similarly, countries such as Singapore and Sri Lanka reported varying rates of hypertension (28–37.5%) between different ethnicities.^10,16 Differences are often multi-factorial, involving a complex interplay between genetic predisposition and environmental factors including disease awareness among racial groups.²¹

Although the majority of participating countries had available data on overall prevalence of hypertension (often with further stratification by age, gender, ethnicity and SES), there remain gaps in reported rates of undiagnosed, untreated (i.e. hypertension that is officially diagnosed but untreated) and uncontrolled hypertension (i.e. hypertension that is treated suboptimally). Among countries with such data, there exists a great variation between countries in rates of undiagnosed (33–52.4%), untreated (10.6–61.4%) and uncontrolled hypertension (17–80%).^{8–10,15,19,22–25}

Part of the issue may be in the concordance of the definitions of undiagnosed, untreated and uncontrolled hypertension between these countries. Nevertheless, such disparity remains as an interesting observation. For example, in Mongolia, despite having a relatively low overall prevalence of hypertension (23.6%), the rates of untreated (53.2%) and uncontrolled hypertension (76%) were very high.²⁶ Even in high-income countries such as Singapore and South Korea, the rates of uncontrolled hypertension were 52% and 64.3%, respectively.^9,27 This is a crucial observation, because it may potentially guide changes in policy, possibly prompting shifts in resources and efforts: shifting the focus from improving initial diagnosis of the disease, to optimisation of treatment in those respective countries. Globally, treatment coverage varies by WHO region and country income level, where the highest coverage is seen in the Americas. Higher coverage, unsurprisingly, was seen in higher-income countries (i.e. 58.0% of adults with hypertension receiving treatment) versus low-income countries (28.0%).¹¹

Hospitalisation and Financial Impact

Data regarding hospitalisations linked to hypertension (Table 1) were generally quite sparse across the region. Where available, data regarding hospitalisations were mainly related to complications of hypertension (e.g. admissions for cerebrovascular disease, coronary artery disease [CAD], kidney disease and other end-organ damage). Furthermore, data on hospitalisation were largely heterogeneous and not standardised between participating countries, making statistical comparison challenging. Hospitalisation rates were reported in various manners including as a fraction of all hospitalisations, fraction of cardiovascular diseases or incidence (instead of prevalence) of hospitalisation. Nevertheless, we report simple observations based on existing literature.

In Australia, hospitalisation directly related to hypertension only (and not complications) remains a small proportion (2.4%) of total hospitalisations.²⁰ In other countries such as Singapore and Japan, patients with hypertension have a less than 1% chance of hospitalisation per year.^28,29 In Mongolia and Australia, hypertension comprised 35% and 46% of hospitalisations due to cardiovascular disease, respectively.^20,30 When considering hospitalisation of conditions and complications linked to hypertension, rates of hospitalisation related to CAD, CKD and cerebrovascular accidents were consistently reported as being very high in most countries (Supplementary Table 3).

There is a lack of data on which medical subspecialty (i.e. cardiology, endocrinology, nephrology or primary care) and what tier of care (i.e. primary or secondary) primarily manages hypertension. Therefore, we report the anecdotal experiences of each country’s representatives. In most countries, hypertension is primarily managed by primary care, while in Japan and Taiwan, hospital-based internal medicine physicians primarily manage hypertension.^31–33 In the Philippines and Malaysia, hypertension care is often shared between both primary care and internal medicine physicians.^34,35 At times, hypertension care is managed by the cardiologist, especially if there are established cardiovascular complications or comorbidities. It is also common for most ailments, including hypertension, to be managed by non-healthcare professionals in the region. For example, in the Philippines, 21% of the population surveyed have consulted non-physicians. Hence, they are continually exposed to inappropriate management as well as traditional beliefs and practices, including herbal medicines.³⁵

A key concern related to the burden of hypertension is its financial implications for countries worldwide. In our report, data on financial implications related to the disease were derived either from data on insurance reimbursement or as part of the Gross Domestic Product (GDP) report of a country. We note that most of the financial data reported highlight either the cost of hypertension-linked hospitalisation and/or medication prescription for hypertension.

In Australia, hospital admissions (accounting for AU$4.52 billion) contributed to the bulk of healthcare expenditure incurred by hypertension, followed by medication prescriptions at AU$1.68 billion.³⁶ In Malaysia, the cost of hospitalisation directly related to hypertensive disease in 2017 was RM 84,353,923 (~US$1.9 million).³⁷ In the Philippines, PhilHealth insurance reimbursed US$56 million for 444,628 hospitalisations for hypertension-related diagnoses incurred by 360,016 patients during a 3.5-year period, of which 42% of admissions were for essential or secondary hypertension, 19% for hypertensive heart or renal disease, and 39% for other consequences of untreated hypertension.³⁵ In Japan, South Korea and Indonesia, medical costs for hypertensive diseases were ¥1,790.7 billion (i.e. US$13.5 billion), ₩2,850 billion (i.e. US$2.2 billion) and US$2.0 billion, respectively.^38–40

The cost of treatment at a patient level was largely variable as well as between participating countries. Nugent et al. estimated that hypertension treatment would cost about US$13 (Tk 1,070) per patient per annum in Bangladesh.⁴¹ In Malaysia, the hypertension-related total direct costs per annum attributable to pre-hypertensive, stage 1 and stage 2 hypertensive patients were calculated to be RM 194.40, RM 209.16 and RM 326.64 respectively (approx. US$44, US$47 and US$74, respectively).³⁷ In high-income countries such as Singapore, the cost of intervention delivery of a multi-component intervention consisting of physicians trained in risk-based treatment, subsidised medications, nurse-delivered motivational conversation and telephone follow-ups was SG$231 (US$170 per annum).⁴²

An indirect financial implication of hypertension and hypertension-related diseases includes the loss of productivity. In Australia, hypertension is estimated to result in a loss of over 600,000 productivity-adjusted life years, equating to AU$137.2 billion in lost GDP over the working lifetime.³⁶ In Indonesia, direct costs of hypertension in 2020 was roughly US$78 million which is lower compared to the estimated US$115 million in indirect costs.⁴⁰ In Malaysia, the value of productivity potentially lost due to absenteeism from work due to hypertension was estimated at up to ten times the direct costs.³⁷

Medication Prescription

Commonly prescribed anti-hypertensives in the region include calcium channel blockers (CCBs), angiotensin-converting enzyme inhibitors, angiotensin receptor blockers (ARBs), β-blockers and diuretics as per national and international guidelines.⁴³ Some, such as ARBs and CCBs, remain popular first-line agents in most countries. β-Blockers were generally less commonly prescribed by most participating countries, but in the Philippines they remain popular (36% of total anti-hypertensives prescribed).¹⁵

In high-income countries such as Singapore, South Korea and Taiwan, most patients were on dual, rather than monotherapy, with only a small proportion of patients receiving triple or more therapies.^27,44 In fact, in Taiwan, up to 60% of treated hypertensive subjects need two or more drugs to achieve adequate hypertension control.⁴⁵ Conversely, in the Philippines and Sri Lanka, monotherapy has been the mainstay of treatment, with more than 80% and 46.7% being on monotherapy, respectively.^15,46 The rate of fixed-dose combination pills, or single-pill combination (SPC) medications, was largely unreported in most countries, despite the majority of national guidelines recommending their use locally. In Hong Kong, SPC formulation medication is not available in public hospital pharmacies but can be purchased with doctor prescriptions at local pharmacies through self-purchasing. In Singapore, SPC medication has been shown to be effective as part of a management strategy for patients with hypertension, but it is not subsidised at the primary care level.²⁹ We suspect that this may indeed be a common scenario faced by the majority of countries in the region.

High rates of untreated and uncontrolled hypertension in the region largely stem from having a significant proportion of patients with hypertension who remain unaware of or unconcerned about their diagnosis. In low-income countries, the rate of unaware patients is as high as 69.0%, whereas in high-income countries, the rate of unaware patients ranged between 33.0% and 49.0% (Supplementary Table 4). Populations at greater risk of not being aware of their diagnosis of hypertension include those originating from rural areas, younger patients, men and less educated patients. Recognition of these factors may aid in developing targeted health campaigns in the regions where knowledge is poorest. Even among those aware of their diagnosis, a significant proportion were non-adherent to medications prescribed or continued to have poorly controlled hypertension. In certain parts of Malaysia, despite adequate knowledge of hypertension, rates of optimum hypertension control remained low.⁴⁷ Similarly, as seen in Australia, despite knowing that hypertension is a reversible vascular factor, there is significant trepidation in commencement of anti-hypertensive agents due to perceived side-effects.⁴⁸

Aside from pharmacological treatment, the making of healthier lifestyle choices remains a paramount factor in the successful management of hypertension. Unfortunately, lack of symptoms despite suboptimal care of hypertension may cause patients to underestimate their own illness, resulting in a reluctance to undergo treatment or make lifestyle changes. In Malaysia, hypertension awareness and education materials are generally limited, and what exists is poorly developed or ineffective, which may have contributed to suboptimal care.⁴⁹ There is also a clear gap between knowledge and action, whereby the mere knowledge of activities that can control BP does not necessarily lead to healthier lifestyle changes or adherence to medication. This is further compounded by the patient opting for non-evidence-based traditional or homeopathic remedies, especially in resource-limited communities.

While most countries reported on patient attitude and their perspective towards hypertension, far fewer had data exploring the perspectives of the healthcare workers. This is an important aspect because there could be a mismatch between the beliefs of the patients and the healthcare professionals, which could lead to disagreements regarding treatment and subsequent non-adherence. In Malaysia, a discrepancy between the perceptions of the treating doctors and their patients has been identified specifically surrounding BP targets for therapy, importance of lifestyle modifications, and responsibilities in managing hypertension.^19,50 Mismatch of information between healthcare providers may also exist. In Mongolia there were reported issues surrounding poor communication between healthcare workers.⁵¹ Identifying and rectifying these issues is essential to improve the management of hypertension and patient outcomes.

There is also evidence that patients in the region may require more than only pharmacological therapy to achieve optimal BP control. The HOPE-4 trial in Malaysia has shown that a package of interventions consisting of combination therapy, task-sharing with non-physician healthcare workers, technology and family support was more effective than usual care for hypertension.⁵² In Singapore, a similar study also showed that a multicomponent intervention was more effective than usual care.²⁹ More emphasis should be placed on a holistic and comprehensive management plan for hypertensive patients rather than medication only.

National Guidelines, Advocacy and Measures

All countries have a set of national guidelines on hypertension management (Table 2) and at least one society that advocates for hypertension care locally. For the diagnosis of hypertension, an office BP ≥140/90 mmHg was set in the guidelines of all participating countries. The target BP for the general population in most countries was <140/90 mmHg. In addition, most countries recommend lower BP targets of <130/80 mmHg in specific patient populations (e.g. younger, overweight patients, smokers, and patients with other cardiovascular risk factors, in individuals younger than 75 years or who have cerebrovascular disease [without bilateral carotid artery stenosis and cerebral main artery occlusion], CAD or CKD, diabetes or use of anti-thrombotic drugs). Overall, this is consistent with thresholds set by international guidelines.⁴³

Under the WHO Global Action Plan, one of the nine voluntary targets is the achievement of a 25% relative reduction in the prevalence of raised BP by 2025 relative to 2010 levels.⁵³ To achieve this goal, government policies play a crucial role. The most frequently used initiatives include raising awareness of hypertension, limiting salt intake, smoking cessation, promoting physical activity and effective health screening programs.

As part of Australia’s Biggest Blood Pressure Check Campaign, free BP assessments are provided, and BP check platforms conveniently located outside pharmacies and in shopping centres.⁵⁴ With most of the salt intake being in the form of added salt, low-sodium salt (with up to half the usual amount) and other strategies to reduce salt in processed foods holds promise. Several community-based collaborations are also in place with healthcare providers and insurance agencies among others, to improve uptake of hypertension awareness and management.

Other initiatives such as the Healthier SG initiative, Philippine Package of Essential non-communicable Disease Interventions (Phil PEN), and PROLANIS Chronic Disease Management Program consist of various packages of intervention measures: mobilising family physicians, regular health screenings, activating community partners and more, emphasising the importance of a multi-pronged approach.^55–57 Furthermore, in Singapore, health screenings and anti-hypertensive medications are often heavily subsidised by the government to keep them affordable.⁵⁸

There is a need for continuous training and education on cardiovascular risk stratification, to guide initiation of treatment, and to achieve BP targets in hypertension, in parallel with guidelines that are constantly being updated. Patient education and awareness campaigns are also essential to ensure that patients are well-informed about hypertension, the management of their condition and the importance of adhering to treatment plans.

Technology is also transforming the way healthcare is delivered. For example, telemedicine and remote monitoring technologies have made healthcare more accessible to people living in remote areas who would otherwise have limited access to healthcare services. In addition, electronic health records have made it easier for healthcare providers to access patient information and coordinate care between different providers. Moreover, countries are incorporating the use of artificial intelligence, big data and machine learning to develop more personalised treatment plans.

Social measures also play an essential role in the management of hypertension. Social factors such as access to healthcare, social support and the living environment play a significant role in one’s ability to manage hypertension. Increasing physical accessibility to healthcare services through the construction of more hospitals and clinics is crucial, such as that being prioritised in Singapore and South Korea.^55,59,60

Affordability is equally important, which can often be achieved through various government subsidies. In Singapore, the Community Health Assist Scheme (CHAS) enables all Singapore citizens to receive subsidies for medical care at specified clinics.⁶¹ In more rural areas, mobile clinics can also be established to promote health screening and hypertension awareness.

In addition, social support networks can help patients manage their hypertension by providing emotional support, encouragement and accountability. In Singapore, ‘social prescriptions’ via partnership with various agencies are used to promote exercise and connect like-minded people to form a support network.⁵⁵ The use of technology via mobile phone apps is also an effective way to encourage patients to exercise regularly and stay healthy. Through gamification and rewards, users are encouraged to sign up for in-app challenges and health programs to earn ‘Healthpoints’ in a mobile phone app by the Health Promotion Board Singapore.⁶²

Barriers to and Challenges in the Management of Hypertension

Despite all of the policies implemented, hypertension rates in most countries continue to rise yearly. A list of the main challenges involved in managing hypertension is given in Table 3. One of the primary challenges is the lack of understanding and of awareness of hypertension, which, despite several policies in place, continues to be a significant problem in several countries. This could be due to a lack of implementation and follow-up on implemented policies and measures, especially in low- to middle-income countries. Both manpower issues as well as political factors, including changes in national government, affect the ability to implement long-lasting, large-scale national policies successfully.^49,63,64 The lack of effective implementation of public health initiatives may limit the effectiveness of these policies, and without detailed monitoring it is difficult to assess the effectiveness of these policies, resulting in resource wastage. There is often also an uneven distribution of healthcare resources across the country, with a relative lack of healthcare access in rural areas.^49,65 In high-income countries, the main challenge pertains to an ageing population, which invariably causes a rise in the rate of hypertension.^66–68

Several challenges also exist in the healthcare system of each country. With the rising epidemic of hypertension, a key challenge faced by numerous countries would be a shortage of physicians, especially in primary care to improve early detection of the disease. At worst, existing primary care physicians are often overwhelmed by the number of patients due to the continuous rise in the prevalence of hypertension. This is often exacerbated by the lack of an effective referral system (resulting in poor coordination between primary care and other tiers of care), as well as a lack of facilities in rural areas. There are also issues in the consult itself. Communication between healthcare professionals often remains brief, with a reported lack of personalised and meaningful interactions that are context and culturally specific, and there remains confusion on how much emphasis should be placed on lifestyle changes at various levels of care, and on whom the responsibility should fall.

A common problem in several countries, regardless of income level, involves medication adherence. Factors affecting adherence, however, are largely culturally dependent. In Bangladesh, patient adherence to treatment is directly linked to family support, where higher family support resulted in better adherence.⁶⁹ In addition, patient non-adherence is also associated with a lack of understanding that hypertension is a chronic disease. In developed countries, well-educated patients may refuse anti-hypertensives for fear of being burdened with medication indefinitely.^70,71 Interestingly, cultural differences in diet have provided a somewhat unique challenge. Cultural pressures to drink alcohol, as well as to consume the local diet, may hinder efforts to maintain a low sodium diet.^72–74 Traditional diets in Asian countries are also known to contain large amounts of salt and fat. In countries such as South Korea and Japan, packaged ramen is extremely popular but contains high levels of salt.^74,75 In Singapore, the same nationwide education program on hypertension had varying effects in terms of racial/ethnic disparities. Future interventions should be tailored towards targeted communities, keeping in mind age group, sociocultural differences, response cost and other challenges specific to disadvantaged groups.

Conclusion

Hypertension remains a silent threat in the Asia-Pacific region. It is clear that barriers exist at various levels, and ultimately resources need to be channelled into managing the disease more efficiently; and that the management of hypertension extends beyond that of medication prescription alone. The Asia-Pacific region faces a rising prevalence of hypertension along with its associated challenges. Although there are several measures already in place, much more could be done to curb the disease. Not only does our paper highlight some key similarities shared by countries in Asia-Pacific, it also identifies several unique challenges and barriers faced by individual nations with regard to the five major domains. Collaboration between stakeholders both within and between countries is crucial to effectively tackle these issues.

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