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Beschreibung

Enables readers to understand practical solutions to reduce oral disease and improve oral health in a growing aging population

Oral Health for an Ageing Population offers global evidence and practical solutions to enable dental clinicians and policymakers implement effective policies and practices compatible with local needs and resources. The text clearly interprets evidence into knowledge, knowledge into policy, and policy into practice in the context of dental and general health care provision, offering international perspectives and specific examples of implemented global policies.

Specific sample topics covered in Oral Health for an Ageing Population include:

  • Burden of global aging and how to achieve oral health among the elderly (including detailed recommendations for integrated clinical and community initiatives)
  • Sustainable development goals, common risk factor approach, life course approach, non-communicable diseases, and frailty prevention
  • Implementing effective health policy at the international and national level and improving attitudes and awareness among the general public regarding oral health
  • Learning from the experience of Japan, the UK, and other countries, plus recommendations for future research, policy, and practice

Written by a leading expert in dental geriatrics, Oral Health for an Ageing Population is based on decades of experience dealing with oral health and general health issues arising in an aging society. It provides extensive reviews of the relevant empirical evidence and practical implementation proposals for dentists, dental hygienists, other healthcare professionals, and policymakers.

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Veröffentlichungsjahr: 2024

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Oral Health for an Ageing Population

Evidence, Policy, Practice and Evaluation

Kakuhiro Fukai

Fukai Institute of Health Science

3‐86 Hikonari Misato‐shi

Saitama

Japan, 341‐0003

This edition first published 2025© 2025 John Wiley & Sons Ltd

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Library of Congress Cataloging‐in‐Publication DataNames: Fukai, Kakuhiro, author.Title: Oral health for an ageing population : evidence, policy, practice and evaluation / Kakuhiro Fukai.Description: Hoboken, NJ : Wiley‐Blackwell, 2025. | Includes bibliographical references and index.Identifiers: LCCN 2024031449 (print) | LCCN 2024031450 (ebook) | ISBN 9781119541264 (paperback) | ISBN 9781119541295 (adobe pdf) | ISBN 9781119541271 (epub)Subjects: MESH: Oral Health | Aged | Health PolicyClassification: LCC RK55.A3 (print) | LCC RK55.A3 (ebook) | NLM WU 113 | DDC 617.6/010846–dc23/eng/20240801LC record available at https://lccn.loc.gov/2024031449LC ebook record available at https://lccn.loc.gov/2024031450

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Preface

Over the past decade, it has become clearer and clearer to me that more attention and research is needed globally at the intersection of population ageing and oral health, and indeed, awareness of the importance of this issue is now higher than ever. At both the national and international level, oral health throughout the life course is now seen as a fundamental and essential component of socioeconomic development. In 2015, I helped organize the 2015 World Congress on Oral Health and Ageing, which was held jointly by the Japan Dental Association and the World Health Organization in Tokyo, Japan, where the “Tokyo Declaration on Dental Care and Oral Health for Healthy Longevity” was issued. I then began serving as chair of the World Dental Federation’s (FDI) Oral Health for an Ageing Population (OHAP) task team, a role that has continued to this day. It was at the 2017 FDI World Congress in Madrid, Spain that the idea for this book was hatched.

The purpose of the OHAP task team was to build on the success of the 2015 Tokyo Declaration, engaging in further discussions and collaboration with colleagues around the world to put the goals of the declaration into practice. Phase I of the project concluded in 2020 and Phase II began in 2021, leading to the development and provision of education and policy recommendations to dental associations, government officials and dental professionals in Europe, North America and South America. Phase III started in 2024, with the goal of promoting the implementation of oral health campaigns and projects in all regions of the world, regardless of development level. I have also personally visited a number of Asian countries, as part of Japanese government assistance efforts, to discuss the topic of “Dental and Oral Health Care in Ageing Societies” with government officials and dental professionals, and to make recommendations based on Japan’s experiences. Furthermore, I have visited Nepal for two weeks nearly every year for the past three decades as part of an NGO to implement community health programs for schools, mothers and children, and older persons, and to conduct community health worker training. Throughout all of these activities and roles, I have noticed that population ageing and oral health have become more and more important as economies develop and population ageing progresses. Even in low‐ and middle‐income countries, there is a growing understanding that they will soon face the same ageing‐related public health challenges that high‐income countries are facing now.

In 2019, at the UN High‐Level Meeting (HLM), it was determined that oral health would be included in the definition of Universal Health Coverage (UHC), which had already been established as one of the common global Sustainable Development Goals (SDGs). In a further sign of global attention on oral health issues, the 2021 WHO General Assembly adopted a resolution on oral health for the first time in 17 years.

Ageing has already been progressing rapidly in high‐income nations, and it will soon begin to affect low‐ and middle‐income nations as well. Meanwhile, the global burden of oral disease remains heavy, and health inequality remains an urgent global issue. The need for new, creative, and economically efficient solutions for achieving healthy longevity is therefore universal, but the health care system of each country and community must be uniquely tailored to its own circumstances. Evidence is accumulating that oral health plays an important role in general health, but this knowledge has not been effectively translated into policy and practice on a global scale. As researchers, health professionals, and policymakers in each country strive to move forward in this process, the lessons Japan has learned as a frontrunner in the field of public policy for an ageing society can provide insight and inspiration for other countries.

Japan was one of the first countries to implement a UHC system, and the system has been functioning successfully for more than 60 years. Japan was also the first country to be confronted with the challenges of a super‐ageing society. For these reasons, Japan is currently engaged in an intensive process of making its healthcare system even more efficient, economical and prevention‐oriented, with an eye to creating an ageing‐friendly society. To achieve this, we are also trying to achieve more efficient and effective communication and collaboration among healthcare professionals in different fields.

There are many other examples of how countries around the world are dealing with these issues, with varying degrees of success. In the end, each country will need to find locally relevant and sustainable solutions to the problem of UHC. But in order to do so, we need to learn from each other’s successes and failures, and above all we need to have access to the most current and applicable evidence.

The processes of assessing national and regional oral healthcare policies and sharing outcomes globally, addressing issues at both the global and national level, and identifying solutions for the future can only proceed efficiently if it is based on collaboration between professionals in all related fields and around the world. This book is, therefore, intended to help raise the awareness of not only dental clinicians but also a wide array of health professionals and policymakers regarding oral health for an ageing population. It will provide them with the evidence as well as the practical solutions they need to implement effective policies and practices. But perhaps even more important than current policymakers and practitioners, my sincere hope is that the information in this book will be taught in healthcare and health policy‐related courses at the graduate and even undergraduate level. The people who will change the world 30 years from now (when people age 60 and over will account for 40% of the world’s population) must begin, as early as possible in their education, to develop a vision for the type of evidence‐based health policy that will lead to achieving healthy longevity globally. Evidence, public health policy, healthcare practices, and evaluation of the effectiveness of those practices are often studied as separate subjects and in abstract ways, but this book attempts to present them as elements of a connected and unified cycle that takes place in real‐world situations in each country, where limited resources require hard choices.

Population ageing is by no means unique to high‐income countries; it is an unavoidable fact for all humans that the risk of disease and disability increases with age. However, establishing and funding systems to maintain the health of older persons, including preventing oral diseases and oral function decline, is no easy task. It requires long‐term, sustained effort and investment to resolve the significant and unique challenges faced by each country, which often include the financial burden, lack of an existing healthcare system on which to build, and lack of trained professionals. No matter the current political or economic situation, however, every nation should begin taking practical and strategic steps to provide access to oral health care services for all residents. Oral health must be seen as a basic human right for people of all ages, including older persons. After all, everyone has the right to speak, eat and laugh.

The process of researching and writing this book took longer than expected due to the COVID‐19 pandemic, an unprecedented global public health crisis which began in January 2020. During this pandemic, older people were identified as a vulnerable population at higher risk of contracting the disease due to both ageing itself and the underlying respiratory and cardiovascular diseases that are associated with ageing. Indeed, elderly people experienced severe illness and death due to COVID‐19 at a much higher rate than the general population during this period. On the other hand, recent research has reported that the maintenance of healthy oral status, including the prevention of periodontal disease, is associated with reduced severity of COVID‐19 symptoms. The accumulation of oral health throughout the life course is reflected in the oral health and general health of older people. Provision of sufficient oral health services for the elderly population will also be key to dealing with future unexpected health crises similar to COVID‐19.

The six chapters in this publication discuss the policy, practice and evaluation of oral health for an ageing population. This section provides a summary of each chapter.

Chapter 1. Global ageing and health

The unavoidable reality of population ageing is affecting our society on a global scale. Biological ageing makes older adults susceptible to disease and leads to a decline in the bodily functions needed for daily living. Dental and oral health are essential for the lifelong maintenance of quality of life (QOL), and research has also shown that they contribute to the maintenance and improvement of general health. As a matter of basic human rights, the goal of every society should be to provide high‐quality dental care and oral health services to all residents and at all stages of life, especially for its most vulnerable populations, such as older adults and those with disabilities.

Life expectancy trends from 1950 to the end of the 21st century reveal an expected narrowing of the gap between the region with the lowest life expectancy (Africa) and the regions with the highest life expectancy (North America, Europe, Oceania). This gap will narrow from 30 years to about 10 years during this period. It is also clear that all regions of the world will have achieved a life expectancy of over 80 years by the end of this century.

However, in order to realize healthy longevity in our society, we need to work toward the following four objectives: 1) to increase life expectancy and prevent early death, 2) to prevent people from requiring long‐term care, 3) to slow the decline in daily living functions that accompanies ageing, and 4) to promote healthy behaviour from the early years of adulthood based on the life course approach.

Chapter 2. Achieving oral health among older adults: Community and clinical approaches

Oral diseases have a higher prevalence than systemic diseases. The oral health of older people is particularly affected by tooth loss, which results from the accumulation of dental caries and worsening periodontal disease throughout one’s life. Even when not accompanied by tooth loss, dental caries and periodontal disease themselves are also significant health risks that negatively affect the quality of life of older people. In addition, age‐related decline in the muscle strength of the tongue, orbicularis oculus, and the masticatory and swallowing muscles, together with reduced saliva, leads to a gradual decline in oral function. Prevention of such oral function decline is important in its own right, and it is also important for the prevention of frailty and for preventing and reducing dependence on long‐term care, because undernutrition is associated with frailty in the elderly. The risk of oral diseases continues throughout all life stages, so dental professionals are likely to care for patients frequently, regularly, and over a long period of time. This means that dental professionals are uniquely positioned to notice small, gradual changes in the physical and mental condition, including the oral function, of older patients.

Assessment of oral health status in older people requires community‐wide screening in addition to full dental examinations at dental clinics. If examinations at dental clinics are the only approach utilized, it is difficult to catch the beginning stages of reduced oral function in healthy people and take appropriate community and individual measures.

In order to prevent NCDs and frailty, which are highly associated with oral health, there is a need for communities and dental institutions to collaborate to implement public health programmes which include assessment and screening and are based on the principle of inter‐professional cooperation and driven by national policy.

This chapter, therefore, focuses on the importance of cooperation between local communities and dental institutions within the larger national healthcare system, which itself must be built around a stable medical insurance system and long‐term care insurance system.

In addition, cognitive function decline has become a major health challenge for ageing societies, so it is essential to consider how dental treatment and dental health guidance can be adapted specifically for people with dementia. This chapter therefore describes how dental treatment can be integrated into national dementia policies, with a particular focus on the emerging role of dental care in preventing cognitive decline.

Chapter 3. The link between systemic health and oral health

The maintenance of dental and oral health over a lifetime, as well as efforts to prevent tooth loss and to retain and/or recover oral function, contributes to the prevention and control of non‐communicable diseases (NCDs), which cause death or result in conditions requiring long‐term care. Dental and oral health maintenance also help to slow the senescence (ageing) process and promote healthy and independent longevity by improving diet and social function. To what extent does the scientific evidence accumulated thus far support these claims? This chapter represents a wide‐ranging, comprehensive review of the evidence regarding the effects of dental care and oral health on the various factors that damage health. This review leads us to a greater recognition, understanding, and visualization of the relationship between oral health and whole‐body health. The unambiguous conclusion is that we must reform our health care systems based on that recognition. This evidence can also be used as the basis for discussing, planning and implementing future research programs and agendas.

Chapter 4. Universal health coverage and effective health policy: Lessons from Japan

Barriers to oral health services, including dental care for older people, need to be removed in order to make these vital services accessible to all. This is in line with the philosophy of Universal Health Care (UHC), which is also reflected in the Sustainable Development Goals (SDGs), that everyone should have access to basic health services. Oral health is a key indicator of overall health in older age. Better integration of oral health care into the general health care system is required.

This chapter explains the definition and philosophy of UHC as well as how UHC achievement is assessed based on each country’s circumstances and resources.

In addition, Japan is a country where dental care has been covered under the public health insurance system since 1961, and programmes for the prevention of decline in oral function are positioned within the long‐term care insurance system. In addition, there is a publicly‐financed system of dental health check‐ups throughout infancy, childhood, adulthood and old age. Another unique aspect of Japan’s approach is that measures to prevent dental diseases and oral function decline are included in national health policies such as those targeting frailty, dementia, and NCDs. For these reasons, in this chapter Japan is presented as an example of how to position dental health and dental care within an advanced, effective, stable UHC system.

Any national UHC system needs to take into account the financial burden and to make effective and efficient use of human resources in the health sector. Cross‐sector collaboration is therefore required, and it is effective to include oral health programmes in overall health policy rather than having an isolated policy that is specific to dental and oral health. As health systems differ in each country, it is advisable to build on and make use of the strengths of each system and for countries to share and learn from each other’s UHC initiatives. Access to essential oral health services throughout life is a fundamental human right that should be ensured in every region and in every country.

Chapter 5. Lessons from the United Kingdom, Europe, North America and Australia

One of the goals of Universal Health Coverage is to create a healthcare system to provide equal accessibility to affordable healthcare for all people. Barriers to healthcare accessibility directly cause deterioration of health, particularly for the elderly and other vulnerable groups. Ageing populations and slow economic growth are prompting most developed nations to reconsider their social security systems, particularly in the area of healthcare reform. Developed countries share some common challenges: how to provide all residents with equal access to a fair, sustainable healthcare system with limited financial resources.

This chapter reviews the medical health insurance systems of seven developed, Western nations: the UK, Sweden, Australia, Canada, France, German, and the US. The characteristics and challenges of these countries’ public health insurance systems are summarized based on research reports and government records from 1995 to 2019. Some of these countries have government‐funded or social insurance‐type systems, while others rely primarily on private insurance. In terms of dental insurance coverage, the developed countries covered in this chapter run the gamut, with some providing government‐funded dental insurance, some providing partial coverage, and some relying entirely on private insurance coverage. There is room for improvement in terms of providing dental care to a wider range of people without imposing undue financial burden.

Dental care is not covered or only partially covered in most of the developed nations discussed in this chapter, even though dental treatments often impose a heavy financial burden on patients. Public health insurance in the US only serves as the primary source of coverage for persons in limited age ranges and those who have certain socioeconomic characteristics. There is potential for improvement so that a wider range of people can receive higher‐quality public health care with reduced financial burden.

Chapter 6. Health policy in Asia: Overview and Vision

Population ageing is progressing throughout the world, and Asia is no exception. Over the next 30 years, ageing will accelerate rapidly in Asian countries. On the other hand, total fertility rate (TFR) has fallen in many Asian countries. This means that governments must take a two‐pronged policy approach, implementing both a social security system for the elderly and a childcare support system for young families at the same time. This poses an impossible financial burden on such governments.

This chapter represents a close examination of the health insurance systems of Asian countries, which have a large number of elderly people. The characteristics and challenges of the health insurance systems of ten Asian countries (China, India, Indonesia, South Korea, Malaysia, Philippines, Singapore, Thailand, Indonesia, and Vietnam) are summarized, with a specific focus on identifying the funding sources of the health insurance system in each country, based on research reports and government records from 2008 to 2018. It is necessary to develop country‐specific variations of UHC, and this can best be accomplished by sharing information and incorporating the most useful aspects of each country’s system.

UHC is one solution to this problem. However, there are a number of obstacles preventing many countries from achieving UHC. These include insufficient financial resources, shortage of medical and dental professionals as well as medication and facilities, and the tendency of the wealthy to enrol in private insurance plans. Therefore, it is necessary for each country to work toward achieving UHC in a way that fits with its own specific history and circumstances, while sharing information, advice and successful ideas with each other. This type of cooperation and information sharing can contribute to progress toward achieving UHC not only in Asian countries, but also globally.

I would like express my sincere gratitude to the editors at Wiley who have shepherded this project from beginning to end: Jessica Evans, Erica Judisch, Jayadivya Saiprasad, Tanya McMullin, Katherine King, Oliver Raj, Sreemol Manikandan, Adam Campbell, and Anitha Jasmine Stanley. Their support, assistance, prodding, and persistence was invaluable in bringing this project to fruition. I would also like to thank my research assistant, Sachiko Onai‐Hayakawa, for her tireless and reliable work on the figures, tables, and references. Finally, I would like to thank Jeffrey Huffman for his diligence and encouragement in editing this book over the past six years. Without his help, this book could not have been completed.

22nd September 2024

Kakuhiro Fukai

1Global ageing and health

CHAPTER MENU

1.1 Introduction

1.2 Changes in the world population and longevity

1.3 Causes of death and determinants of life expectancy

1.4 Ageing and decline in the functions of daily living

1.5 Average life expectancy (LE) and healthy life expectancy (HLE)

1.5.1 The gap between LE and HLE

1.5.2 Prolonging HLE

1.5.3 Measuring HLE around the world

Japanese indicators of HLE

European indicators of HLE

US indicators of HLE

WHO indicators of HLE

1.6 Strategy for healthy ageing: how to achieve healthy ageing?

1.7 Ageing society and social security

1.8 Oral health and ageing

1.8.1 Oral health in an ageing society

1.8.2 Oral health and HLE

1.9 Challenges of general health and oral health in an ageing society

1.10 Conclusion

References

1.1 Introduction

The unavoidable reality of population ageing is affecting our society on a global scale. Biological ageing makes older adults susceptible to disease and leads to a decline in the bodily functions needed for daily living. Dental and oral health are essential for the lifelong maintenance of quality of life (QOL), and research has also shown that they contribute to the maintenance and improvement of general health. As a matter of basic human rights, the goal of every society should be to provide high‐quality dental care and oral health services to all residents and at all stages of life, especially for its most vulnerable populations, such as older adults and those with disabilities.

To ensure that dental care and oral health contribute to attaining healthy longevity, the accumulation of clear evidence must be prioritized, and action must be taken to secure and maintain the prominent role of dental care and oral health within an effective and efficient social security system and healthcare policy.

In that context, this chapter provides an overview of global ageing and global health, with special attention given to their relation to oral health.

1.2 Changes in the world population and longevity

The world population increased almost three‐fold from 2.57 billion in 1950 to 8 billion in 2022 and is projected to reach 8.5 billion in 2030, 9.7 billion in 2050 and 10.4 billion in 2100. The greater portion of this population will be living in low and middle‐income countries (LMICs; UN 2022) (Figure 1.1).

A historical survey of population ageing reveals that the average human life expectancy was about 40 years all the way up to the 18th century. As a result of decreases in infection‐related deaths, life expectancy rose to 50 years from the 18th to the 20th century and then rose dramatically to 80 years from the middle of the 20th century to the present day (UN 2022) (Figure 1.2).

Figure 1.2 shows the estimated trends of life expectancy at birth in different regions of the world from 1950 to the end of this century. The clearest pattern here is the narrowing of the gap between the region with the lowest life expectancy (Africa) and the regions with the highest life expectancy (North America, Europe, Oceania). This gap narrows from 30 years to about 10 years during this period. It is also clear from this graph that all regions of the world will have achieved a life expectancy of over 80 years by the end of this century (UN 2019).

The percentage of older adults increased from 7.7% in 1950 to 16.1% in 2010 in the high‐income countries and from 3.8% to 5.8% during the same time period in LMICs (UN 2022). Population ageing is occurring in all regions of the world and in countries at all income levels and is progressing at a faster rate in LMICs.

Figure 1.1 World population by major area, 1950–2100 (United Nations 2022).

Figure 1.2 Life expectancy at birth (both sexes combined) by region, 1950–2100 (years) (UN 2022).

Looking at the same phenomenon from a different perspective, Figure 1.3 shows the total older adult population in each region (UN 2019). The percentage of older adults aged 65 years and over is also on the increase in each region (UN 2019) (Figure 1.4). This provides a visual representation of the fact that most of the older adults in the world live in Asia, and that trend will continue to increase, with the African older adult population following in the second half of the century. From the standpoint of global public health, if the goal is to ensure that no one or no region is left behind, improvement of healthcare provisions in Asia and Africa will have an outsized effect. Confronting this problem will require the sharing of experience, wisdom and evidence on a more massive and global scale than we have seen before now. Another important challenge will be to improve and increase data collection systems, needs assessment research and the implementation of public health programmes and systems in Asia and Africa, along with the evaluation thereof (including cost‐effectiveness).

Living longer lives has long been a desire and goal of humans and human societies, and in the 20th century the world saw great increases in both population and longevity, largely due to scientific and medical advances, and the accompanying accumulation of knowledge, that have been achieved in each country. However, it is an unavoidable fact that ageing leads to a decline in the physical and mental functions needed for daily living, as well as increasing vulnerability to disease. For this reason, many challenges still need to be addressed in order to achieve a society in which all older people can live with dignity and security. Such challenges include the establishment and maintenance of a sustainable social security system characterized by comprehensive healthcare provision, a system of long‐term care provision, a solid financial resource basis for these services, and the continual accumulation of research.

Figure 1.3 Population (both sexes combined) by 5‐year age cohorts aged 65 years and over by region, 1950–2100 (thousands) (UN 2019).

Figure 1.4 Percentage of people aged 65 years and over (both sexes combined) by region, 1950–2100 (United Nations 2022).

Figure 1.5 Total fertility by major area, 1950–2100 (children per woman) (UN 2022).

In addition, while Asia and Africa still have relatively high fertility (Figure 1.5) that can, if used effectively, be viewed as a ‘population bonus’ (promoting economic development), these two regions will, in the second half of the century, follow the population dynamics trend that the developed world is currently experiencing – namely a ‘population onus’ where a decreasing working‐age population must support an increasing ageing population. Therefore, as Asia and Africa begin developing their healthcare system, they must keep in mind the need for long‐term financial sustainability, the keys to which are community‐based, education‐oriented, prevention‐focused public health systems rather than after‐the‐fact medical and pharmacological treatment (UN 2022).

The world population is nearly 8 billion and rising, but the pace of increase is expected to slow over the next century, particularly in developed countries. As developing countries achieve greater economic development due to educational advancements and technological innovation, the rate of their population increase will slow down as well, eventually leading a more stable and sustainable global population.

1.3 Causes of death and determinants of life expectancy

Figure 1.6 shows the leading causes of death globally in 2020, and eight of the 10 leading causes of death are non‐communicable diseases (NCDs). While acute diseases such as infections and diarrhoeal diseases remain the top causes of death in low‐income countries, chronic diseases such as ischaemic heart disease, stroke and cancer are the main causes of death in high‐income countries [World Health Organization (WHO) 2020c].

Figure 1.6 Leading causes of death globally (WHO 2020d).

As a country’s economy improves, the mortality of pregnant women and newborns declines, but other challenges need to be overcome in order to continue extending life expectancy – in particular, the prevention of disease in the early years of adulthood (thereby reducing premature mortality) and the reduction of mortality in older adults. As a result, developing countries are facing the triple burden of acute infections, chronic diseases and newly emerging infections (Beard 2016) (Figure 1.7).

In Japan, for example, these diseases, such as cancer, heart disease, pneumonia and cerebrovascular disease, account for approximately 70% of all deaths [Ministry of Health Labour and Welfare (MHLW), Japan 2021a] (Figure 1.8). Theoretically, if these diseases can be successfully prevented (or at least become non‐fatal), we can expect an extension in the average life expectancy of 3–4 years in the case of cancer, approximately 1.5 years in the case of heart disease, and around 1 year in the case of pneumonia and cerebrovascular diseases (MHLW of Japan 2021b) (Figure 1.9). This same strategy applies to LMICs as well, which over the past 50 years have been experiencing their own steady shift from infectious diseases to NCDs (WHO 2011).

Figure 1.10 shows the survival curve of the Japanese population. The number of deaths peaks at age 85 in men and age 91 in women (MHLW of Japan 2020a). The average life expectancy is 81.6 years for men and 87.7 years for women, but what is not emphasized often enough is that the survival rate at that age is approximately 60% for both men and women (MHLW of Japan 2020b). The survival curve begins to decline from age 65, and then begins to decline more steeply from age 75. Therefore, people are most likely to die between ages 75 and 100. This also means that illness and dependence are at their peak within this age range. This means that, from the standpoint of healthcare provision, the period of life beyond the average life span should be the primary focus of attention and resource allocation.

Figure 1.7 Mortality at different ages for countries of low, middle, and high income, 2012.

Source: Beard, J.R. 2016/with permission of Elsevier.

Figure 1.8 Proportion of leading cause of death by sex and age in Japan, 2021.

Source: Ministry of Health, Labour and Welfare, Japan 2021, Vital Statics, 2021.

Figure 1.9 Estimated increase in life expectancy when specified causes of death are eliminated in Japan, 2020.

Source: Ministry of Health, Labour and Welfare, Japan 2021, Life table, 2021.

Figure 1.10 Survival curve of the Japanese population.

Source: Data from Ministry of Health, Labour and Welfare of Japan (2020a), Life table.

All humans experience a certain degree of unavoidable loss of functional ability as they age, especially beyond the age of 65. Although life expectancy of a country or region is affected by socioeconomic level, the gap between healthy life expectancy and actual life expectancy remains constant at around 9 years (OECD 2019 WHO 2020a).

This unavoidable decline in intrinsic functional ability is manifested in multimorbidity, which consists of organ function decline along with reduced muscle mass and strength. That in turn leads to frailty, declining immunological resistance to infectious disease, and accumulation of NCD risk caused by habitual lifetime behaviour as well as genetic factors. There is great individual variation in the rate of decline of functional ability.

However, regardless of this individual variation, there appears to be an ultimate life span limit for all humans at around 115–120 years (based on the most recent statistical estimations; Hekimi and Guarente 2003; Dong et al. 2016). Fries’s survival curves (Fries 1980) supported this conclusion, as do Japan’s current survival curves (MHLW of Japan 2020a) (Figure 1.10).

Figure 1.11 shows how the leading causes of death have changed over time in Japan. A clear disease shift can be seen after World War II, when infectious diseases were rapidly brought under control due to improvements in sanitation and nutrition, and NCDs such as cancer and heart disease began their steady rise along with economic development and ageing (MHLW of Japan 2020b).

Figure 1.11 Trends in death rates for leading causes of death in Japan (per 100 000 population).

Source: Vital Statistics, Statistics and Information Department, Minister’s Secretariat, Ministry of Health, Labour and Welfare of Japan. Note: the figures for 2020 are approximate.

The main causes of death (disease structure) have changed throughout history. People used to die of starvation, accidents, violence and war. As the world became more peaceful and industrialization proceeded, infectious diseases became the leading cause of death. Scientific and medical advancements, along with public health measures, succeeded in reducing the prevalence of infectious diseases, resulting in the current situation, where NCDs have become the top killer (WHO 2020).

However, as the COVID‐19 pandemic illustrated, a new infectious disease can cause a new global pandemic at any time. Low‐income countries must deal with a triple burden of continuing high infectious disease rates, increasing NCDs and containment of newly emerging infectious diseases.

In the 20th century, the leading causes of death were starkly different between developed (infectious diseases) and developing (NCDs) countries. That situation, however, is rapidly changing and NCDs are already dominating as the leading causes of death in developing countries as well (WHO 2020). For this reason, preventing the occurrence and spread of NCDs such as cardiovascular diseases, cancer and diabetes mellitus is an important health policy issue in both high‐income countries and LMICs.

1.4 Ageing and decline in the functions of daily living

Apart from diseases, other causes of death include ageing and accidents. When cells and organ tissue (which are groups of cells) and organs can no longer function, humans become incapable of maintaining their bodily functions as an individual organism, resulting in death. In fact, a review of the causes of individual deaths reveals that death occurs when any of the vital organs (those needed for maintaining life), such as the heart, brain, kidney and various blood vessels, can no longer function. Moreover, the process leading to death varies depending on which disease is causing that decline in organ function. For example, in the case of cerebrovascular disease, the time from becoming unable to carry out normal activities of daily living (ADLs) until the time of death is quite long (and accompanied by gradual decline). In the case of cancer, however, ADLs may be relatively normal until there is a sudden and swift decline just before death (Lynn 2001).

Ageing, therefore, is defined as a gradually progressive decline in physical functions. Ageing at the organ level can be attributed to damage to certain types of cells which have almost no ability to divide, such as brain cells, nerve cells and myocardial cells. In other cases, ageing occurs when cells stop dividing after completing approximately 50 cycles of sub‐division, a phenomenon seen in almost all organs other than the abovementioned ones (Hayflick and Moorehead 1961). Either way, all organs age as one gets older, and organ ageing manifests itself in the form of reduced function. This directly causes age‐related decline in muscle strength, nerve conduction velocity, lung capacity and resistance to disease, and this decline cannot be avoided in humans. For example, when evaluating age‐related change in grip strength in the Japanese population, a decrease of about 12 kg in men and about 6 kg in women was observed between late‐middle age and old age (MHLW of Japan 2021c) (Figure 1.12). Moreover, the percentage of essential organ function remaining at age 80 (at age 30 it is 100%) is 80% for nerve conduction velocity, less than 60% for lung capacity and renal plasma flow, and approximately 40% for maximal voluntary ventilation (Kagawa 1996). Despite this decline in organ function due to ageing, organs function together as a system, in a complementary and compensatory manner, in order to adequately support everyday living functions. However, as ageing progresses, a combination of physical and psychological symptoms and conditions, collectively referred to as geriatric syndrome, are commonly observed in older adults (Sasaki 2008).

Figure 1.12 Average grip strength of Japanese by age.

Source: Data from Ministry of Health, Labour and Welfare, 2021, Portal site of Statistics of Japan.

1.5 Average life expectancy (LE) and healthy life expectancy (HLE)

1.5.1 The gap between LE and HLE

The world’s average life expectancy as of 2012 was 68 years in men and 73 years in women, with a mean of 70 years for both sexes combined. In contrast to the average life expectancy of 60 years in men and 63 years in women in low‐income countries, the life expectancy in high‐income countries reaches 76 years and 82 years, respectively. The average life expectancy of both sexes combined is 62 years in low‐income countries, 66 years in low‐middle‐income countries, 74 years in high‐middle‐income countries and 79 years in high‐income countries, indicating that life expectancy extends with economic development. By contrast, the global average HLE is 63.3 years, and the average HLE by economic status is 53, 57, 66 and 70 years, respectively (WHO 2014, 2020c) (Figures 1.13 and 1.14). There is an approximately 8‐year difference between life expectancy and HLE, and this gap is consistent regardless of a country’s economic status.

In Japan, HLE is defined as extending through the period of life in which there are no restrictions on the ADLs. Under Japan’s Long‐term Care Insurance System, this definition excludes those at Care Level 1 (requiring partial care due to a decline in the ability to perform basic self‐care tasks and other ADLs) or above. Japan’s HLE in 2019 was 72.7 years in men and 75.4 years in women, which is 8.7 years and 12.1 years lower, respectively, than the average life expectancy. Of the 36.21 million people aged 65 years and over, 4.71 million (13.0%) are at Care Level 1 or above (Cabinet Office, Japan 2022).

The diseases that most commonly lead to a condition requiring long‐term care are presented in Figure 1.15. Dementia is responsible 17.6% of the time, cerebrovascular diseases 16.1% of the time, fractures/falls 12.5% and articular disease 10.8% (Figure 1.13).

1.5.2 Prolonging HLE

Life expectancy increases in tandem with economic development. And to be sure, increasing life expectancy is the primary goal of public health policy. As seen in Figures 1.14 and 1.15 (WHO 2014, 2020a), from a population standpoint, increased life expectancy always means increased HLE. However, the gap between HLE and actual life expectancy remains remarkably constant at around 9 years, no matter the economic status of the country or the region of the world it is in. One of the goals of global public health, therefore, should be to ensure the provision of health and well‐being during these years. This can be accomplished with a two‐pronged approach that combines the provision of high‐quality, long‐term care and the establishment of age‐friendly communities where all people live together in mutual cooperation and older adults are valued and respected.

Figure 1.13 Life expectancy and healthy life expectancy by economic status.

Source: World Health Organization 2014 / with permission of World Health Organization.

Figure 1.14 The gap between life expectancy and healthy life expectancy.

Source: World Health Organization 2020c / with permission of World Health Organization.

Figure 1.15 Causes leading to a condition requiring long‐term care (Japan).

Source: Adapted from Ministry of Health, Labour and Welfare of Japan, 2019, Comprehensive survey of living conditions.

Figure 1.14 shows the gap between life expectancy and HLE by world region (WHO 2020). The current world average life expectancy is 72 years. By contrast, HLE is around 63 years. There is an approximately 9‐year difference between life expectancy and HLE, and this gap is fairly consistent regardless of a country’s economic status and healthcare system. Therefore, we need to take collective action to narrow this gap so that we can have not just a ‘longer life’ but a ‘longer, better life’.

1.5.3 Measuring HLE around the world

HLE is a generic term that is generally used for the average time people can be expected to live in a given state of health. There are three ways to measure HLE: ‘average period of time spent without limitation in daily activities’, ‘average period of time individuals consider themselves to be healthy’ and ‘average period of time spent independently engaging in daily activities’ (Hashimoto 2014).

However, various countries use their own methods of measuring this construct, so care must be taken when comparing HLE data among countries.

Japanese indicators of HLE

In Japan, the Health Japan 21 project established three indicators of HLE. The underlying concept and the method of measurement of these three indicators are described here. All three methods are calculated using Sullivan’s method.

The first, ‘average period of time spent without limitations on daily activities’, defines health as the absence of limitations on daily activities. It is measured by asking the following question: ‘Do you currently have any restrictions on your daily life due to health problems?’ A negative answer indicates a healthy state, and an affirmative answer indicates an unhealthy state. There is also a supplementary question asking about the presence or absence of restrictions for specific activities, although this is not used for calculating the indicator. The data generated from this supplementary question can be used to implement evidence‐based health promotion activities that are more effectively targeted, thus contributing to the prevention of serious diseases and the prevention of dependency on long‐term care.

The second indicator is ‘the average period of time individuals consider themselves to be healthy’. Here, the state of health is defined as being aware that you are healthy. It is measured by asking, ‘How is your current health?’ and providing five answer choices: ‘very good’, ‘good’ and ‘normal’ are taken as an indication that the respondent is healthy, while ‘not very good’ and ‘not good’ indicate an unhealthy state.

The third indicator is ‘average period of time spent independently engaged in daily activities’. This indicator defines a healthy state as a certain degree of independence in daily living activities. Those determined to be at levels 2–5 in terms of the degree of long‐term care required are considered to be unhealthy and thereby eligible for long‐term care insurance, while all others are considered to be in a state of health (independence). This indicator can also be called ‘average daily self‐reliance period’.

European indicators of HLE

Three methods of measuring HLE have been developed under the European Community Health Indicators Monitoring system. The underlying concept and the method of measurement of these three indicators are described here. All three methods are calculated using Sullivan’s method.