1.2 Healthy Life Expectancy（HALE）

1.2.1 Definition of HALE

The increasing number of older people，higher expectations of “good health” within society，and policy interest in the potential for reducing public expenditures have led to international interest in the enhancement and measurement of the QOL of elderly people. In 1998，the Institute of Medicine’s Committee on Summary Measures of Population Health[33] concluded that “mortality measures，although important，provide decision makers incomplete and insensitive information about overall population health. Summary measures of population health need to recognize the physical and psychological illnesses and disabilities that cause much individual suffering and limit social and economic advances within and across nations.” Accordingly，the “healthy life expectancy（HALE）” measure，which is also called “health-adjusted life expectancy”，is used to summarize this notion.

Sanders[34] first elaborated on the concept of HALE in 1964，but it was not until the early 1970s that Sullivan[35] proposed a simple method for estimating life expectancy as a function of disability. HALE as proposed by the WHO in 2000 refers to “the length of life lived in full health”，which summarizes mortality and non-fatal outcomes in a single measure of average population health[36]. HALE as a natural extension of life expectancy combines quantity and quality of life into a single measure，and divides the remaining number of years into good or bad health. Thus，HALE addressed whether or not longer life is accompanied by the compression or expansion of morbidity.

1.2.2 Measures of HALE

HALE is derived from Sullivan’s method，which accounts for both mortality and morbidity in a single index within a representative sample in time[37]. The values are based on age-specific death rates for a particular calendar period together with comparable health state prevalence by age. Total lifetime can be divided into healthy periods and periods of health impairment[38].

The WHO[39] defined health as a state of complete physical，mental，and social well-being，not merely the absence of disease or infirmity. As many dimensions of health exist，many HALEs also exist. Thus，HALE can be measured in several ways，including life expectancy in good self-rated health（SRH），free of disability，free of a specific disease，or free of LTC. Such single measures of overall population health provide a useful adjunct to measures of health gaps，such as disability，morbidity，and SRH，which are often disaggregated by disease and injury[40]. The previous studies on HALE indicators that are related to this book were researched and are described below.

Disability

Early work on HALE focused on disability-free life expectancy（DFLE）. Combining disability and mortality，if the calculated HALE increases at a slower rate than life expectancy，a pandemic of disabilities might be expected；if HALE increases at a similar rate，there would be no change；and if the increase is larger，compression of disability would be confirmed. Measures of disability are important because they provide an appraisal of the burden caused by suboptimal health by considering other factors（e.g. underlying disease，and psychological and social factors）.

To understand and evaluate disability，it is important to have an understanding of the progression of disability，ending with a loss of functioning. In 1980，the “International Classification of Impairments，Disabilities，and Handicaps（ICIDH）” was published by the WHO. Disability was defined as follows：“in the context of health experience，a disability is any restriction or lack（resulting from an impairment）of ability to perform an activity in the manner or within the range considered normal for a human being.”[41] Then，this model has been revised into the “International Classification of Functioning，Activities and Participation（ICF）”[42]，which focuses on components of health as human functioning instead of disabilities as consequences of disease in a universal system. The ICF places the notions of ‘health’ and ‘disability’ in a new light—it acknowledges that every human being can experience a decrement in health and thereby experience some degree of disability. Disability is not something that only happens to a minority of humanity. Furthermore，personal and environmental factors as contextual factors are an essential component of the classification and interact with all three dimensions of health；thus，changes in the social and ecological environments can alter health conditions（Figure 1.6）.

Figure 1.6 ICF model

Source：WHO，2001[43].

Most current studies of disability among the elderly focus on the abilities to carry out ADL，which include daily activities in the home，at work，and at leisure. Most measures include two phenomena：Basic Activity of Daily Living（BADL）developed by Katz and his colleagues in 1963[44]，and Instrumental Activities of Daily Living（IADL）developed by Lawton and Brody in 1969[45]. BADL includes basic daily tasks that need to be performed by all people regardless of gender，culture，housing conditions，housing environment，and leisure time interest[46]，such as bathing，dressing，using the toilet，and eating. IADL includes more complex，outgoing activities that are essential for living an independent life in society[47]. In addition to these two measures，disability can also be accessed through mobility performance，objective measures that evaluate standardized tasks，such as standing in balance，walking distance，climbing stairs，and chair stand tests，among others by means of counting repetitions or timing the task. ADL is associated with dependence，so ADL levels have been found to be significant predictors of all-cause mortality，the levels of care at which people should receive institutionalization，and increase，use of hospital services[48][49][50].

Diseases

The term “disease” broadly refers to any condition that impairs normal function，and is therefore associated with dysfunction of normal homeostasis. HALE is an estimate of the number of healthy years free from the burden of disease，which is the impact of a health problem in an area measured by financial cost，mortality，morbidity，or other pertinent indicators. Several measures are used to quantify the burden imposed by disease on people. The first measure is years of potential life lost（YPLL），which estimates the number of years that a person’s life was shortened due to disease. However，the measure does not account for how disabled a person is before dying，and treats a person who dies suddenly and a person who died at the same age after decades of illness as equivalent. Another measure is the disability-adjusted life year（DALY），which considers the part of the years lost to being sick. Unlike YPLL，DALY reflects the burden imposed on people who are very sick but who live a normal lifespan. According to the Global Burden of Diseases Study 2010（GBD）[51] report，infectious diseases，maternal and childhood illness，and malnutrition now cause fewer deaths and less illness than they did 20 years ago. As a result，fewer children die each year，but more young and middle-aged adults are dying and suffering from disease and injury，as non-communicable diseases，such as cancer and heart disease，become the dominant causes of death and disability worldwide[52].

It had thus been well documented that a number of chronic diseases are observed more frequently in disabled elderly adults than in those who are not disabled. However，not all diseases cause disability，and some diseases cause more disability than others. Diseases with large effects on functional ability include stroke and other neurological disease，heart disease，respiratory disease，high body mass index，diabetes，depression，dementia，and musculoskeletal disease[53]. Although different medical conditions impose functional problems that are specific to each disease，musculoskeletal disease is a chronic disease that affects two dimensions of functional limitations and disability：mobility and ADL. The presence of more than one chronic disease in an individual—or comorbidity—has been reported to be related to the presence of disability and to that person’s future risk of disability. For example，the number of chronic diseases in a disability-free group at baseline is directly associated with the risk of losing mobility over four years[54]. Furthermore，after four years，the risk of becoming disabled is 4-fold higher for a person with chronic diseases than for a person with no chronic diseases[55]. In some instances，a disease may increase the risk of subsequent functional disability in itself，but it may also increase the risk of subsequent functional decline when a new condition develops[56]. Schroll et al.[57] observed a step-wise increase in disability with an increasing number of chronic conditions.

Long-term Care/Support

The rapid aging of society is leading to a rapid increase in the numbers of disabled individuals who need LTC or support. In most countries，care predominantly remains a family task that is primarily performed by women. However，the increasing proportion of women in the labor market and the declining ratio between those needing care and those who are potential caregivers are raising questions about the family’s ability to care for the elderly who need LTC or support for their daily activities[58]. While all developed countries provide LTC services，only a few of them have implemented LTC systems based on legislation and entitlement principles，such as Germany and Japan.

A recent study calculated HALE using the disability prevalence based on LTC insurance data in select developed countries[59]. Average life expectancy can be qualitatively divided into lifetime spent in good health and lifetime spent in LTC（average care duration）. The results not only described the evaluation of HALE，but also the effects of disease prevention programs or health promotion programs.

As an example，in Japan，LTC insurance was introduced for elderly individuals requiring nursing care，and certified people are classified into one of six care levels according to the severity of their disability and care needs. As municipal governments manage LTC insurance，data are routinely available at the municipal as well as the prefectural level，and are used as a source of disability prevalence data[60]. Seko et al.[61] calculated the expected years of life with care needs by age group and prefecture in Japan during 2005-2009，showing that the expected years of life with care needs at age 65 years increased from 1.43 years in 2005 to 1.62 years in 2009 for men，and from 2.99 to 3.44 years for women. As a proportion of total life expectancy，these values showed an increase from 7.9% to 8.6% in men and from 12.9% to 14.4% in women. In addition，the expected years with care needs did not increase in people age 65-69 years and 70-74 years，but markedly increased among individuals≥85 years old. These results indicated that the duration of senior life with disabilities increased in the Japanese population，particularly for the oldest-old people.

Self-rated Health

HALE is commonly used in attempts to assess how many years people lived in good health over the lifespan based on the global SRH scale. SRH as a subjective measure refers to the way that individuals feel about their own health，rating it from “very poor” to “very good.” This assessment tool was introduced in the United States in the late 1950s，and has become a convenient means through which health information can be collected. However，this particular health measure has both strengths and weaknesses[62].

In terms of strength，SRH is a good fundamental indicator of overall health status，and is almost always measured in large population health surveys. SRH can reflect aspects of health incorporating physical，mental，and social health，and can even predict mortality. Furthermore，an extensive body of literature reflecting a variety of settings and cultures has consistently demonstrated that SRH is a strong and independent predictor of subsequent illness，as well as both all-cause and specific mortality[63][64][65]. For example，respondents reported their health to be poor or very poor on average had increased risk of mortality than those reported having good health. This association was independent of age，blood pressure，and a range of chronic diseases[66]. Hence，SRH can provide valuable insights into the potential demand for health services and LTC needs of the elderly in an aging society.

A major weakness of SRH is its subjective nature. SRH is assessed broadly and subjectively by the respondents themselves，rather than by physician diagnoses or other more objective indicators of health，such as chronic conditions，functional limitations，and disability. Consequently，SRH reports could be prone to the effects of exogenous factors，such as gender，race，and income level，as well as changes in attitudes and expectations toward health over time[67][68]. In brief，SRH allows for at least some measure of comparison across very diverse settings，because the results can be divided into categories representing poor health and good health. Thus，SRH provides a good starting point for comparisons of HALE across settings.

Using SRH，studies conducted in some developed countries showed inconsistent HALE results：upward trends for both men and women were observed in Finland[69] from 1978-1986，Great Britain[70] from 1980-1996，and Austria[71] from 1978-1998；a downward trend was observed in Germany[72] from 1986-1995，while in the Netherlands[73]，from 1983-2000，an upward trend was observed for men，while a downward or stable trend occurred for women. In Japan，Young et al.[74] examined the increasing life expectancy of Japanese men and women in relation to their SRH from 1986-2004. The results showed that the gains in life expectancy in both genders and at all ages primarily occurred in years of good SRH prior to 1995，while the gains in years of poor SRH occurred from 1995-2004. The exception was for women at age 85 years，among whom an almost continuous increase in the number of years living in poor health was observed. The proportion of life spent in different health states suggested evidence of morbidity compression until 1995，followed by an expansion of morbidity.

1.2.3 Review of HALE in the World

HALE has been extensively used to compare health between countries and to reflect many social，economic，and environmental influences，as well as other demographic variables. The Global Burden Diseases Study 2010 was the largest systematic effort conducted to measure the global distribution and causes of a wide array of major diseases，injuries，and health risk factors. The HALE for 187 countries from 1990-2010 and the comprehensive comparisons defined by gender，age，and socioeconomic groups are described below[75].

Gender

In 2010，HALE at birth was 59.0 years（range，57.3-60.6 years）for men and approximately 63.2 years（range，61.4-65.0 years）for women（Table 1.2）. Although male life expectancy at birth increased from 1990-2010 by 4.7 years and female life expectancy at birth increased by 5.1 years，the HALE at birth increased by only 4.2 years and 4.5 years，respectively，suggesting that the world’s population loses more years of healthy life to disability today than it did 20 years ago. Although HALE，like life expectancy，remains higher in women，women continue to lose more years to disability than men，and overall the gap between genders in both life expectancy and HALE continues to widen.

Age

In 2010，global HALE at age 60 years was approximately 14.4 years（range，13.6-15.2 years）for men and 17.0 years（range，16.1-17.9 years）for women，and had increased 1.4 years for men and 1.7 years for women since 1990（Table 1.2）. However，as mentioned before，HALE at birth had increased 4.2 years for men and 4.5 years for women since 1990，suggesting that the importance of the gap between the genders in HALE diminishes with age.

Table 1.2 Global HALE by gender and age in 1990 and 2010

Socioeconomic Group

Across countries，male HALE at birth in 2010 ranged from 27.8 years（range，17.2-36.5 years）in Haiti to 70.6 years（range，68.6-72.2 years）in Japan；female HALE at birth in 2010 ranged from 37.1 years（range，26.8-43.8 years）in Haiti to 75.5 years（range，73.3-77.3years）in Japan. Male HALE at birth in 2010 was below 50 years for 29 countries，compared to only 18 countries for female HALE. In 2010，38 countries had a male HALE at the birth of≥65 years，compared to 86 countries for female HALE. The gap increases appreciably between genders when socioeconomic groups are considered，an observation that further highlights health inequities，particularly for women，in whom no disparities are observed when life expectancy is considered alone[76]. People in more developed countries not only live longer，but they also spend a significantly smaller proportion of their life with disability and morbidity. Calculation of HALE suggests that health disparities are greater between social groups than between genders.

1.2.4 The Significance of Studying HALE in the Elderly

Globally，the increase in numbers and proportions of old and very old people has increased the concerns and worries of both the aging individuals themselves and health care planners. Individuals worry about declining intellectual abilities and physical health，while the changing demographic patterns are also coupled with worries that society may have to struggle with the aging process to deal with difficult issues such as the financial burden of providing for old age，and increasing demands on social and medical care in case of disability. These combined points of views of the individual and the society constitute the primary reason why an important goal of gerontological research，geriatric medicine，and public health is to increase HALE，which refers to the length of life lived in full health，considering disability，disease，LTC，and SRH.

Japan leads the world in the rapid pace of aging and highest HALE；thus，evaluation of HALE in Japan may provide evidence of trends of morbidity compression or expansion across all ages for both genders by calculating the proportion of life lived in different health status. Additionally，evaluation of HALE will be important for projecting the needs of health care in an aging population and evaluating the effects of interventions and policy changes on both the length and quality of life.