Elsevier

The Lancet

Volume 385, Issue 9967, 7–13 February 2015, Pages 563-575
The Lancet

Series
Health, functioning, and disability in older adults—present status and future implications

https://doi.org/10.1016/S0140-6736(14)61462-8Get rights and content

Summary

Ageing is a dynamic process, and trends in the health status of older adults aged at least 60 years vary over time because of several factors. We examined reported trends in morbidity and mortality in older adults during the past two decades to identify patterns of ageing across the world. We showed some evidence for compression of morbidity (ie, a reduced amount of time spent in worse health), in four types of studies: 1) of good quality based on assessment criteria scores; 2) those in which a disability-related or impairment-related measure of morbidity was used; 3) longitudinal studies; or 4) studies undertaken in the USA and other high-income countries. Many studies, however, reported contrasting evidence (ie, for an expansion of morbidity), but with different methods, these measures are not directly comparable. Expansion of morbidity was more common when trends in chronic disease prevalence were studied. Our secondary analysis of data from longitudinal ageing surveys presents similar results. However, patterns of limitations in functioning vary substantially between countries and within countries over time, with no discernible explanation. Data from low-income countries are very sparse, and efforts to obtain information about the health of older adults in less-developed regions of the world are urgently needed. We especially need studies that focus on refining measurements of health, functioning, and disability in older people, with a core set of domains of functioning, that investigate the effects of these evolving patterns on the health-care system and their economic implications.

Introduction

Demographic projections suggest that the populations of all countries are ageing, which will have wide-ranging effects on social, economical, and health systems. The world's population aged 60 years and older is set to rise from 841 million in 2013, to more than 2 billion by 2050, and exceed the number of children by 2047. By 2050, 21·1% of the world population will be 60 years or older, and 80% of this demographic group will live in low-income and middle-income countries, compared with about two-thirds at present. During the same period, global life expectancies are predicted to rise, reaching 83 years in high-income regions and 75 years in low-income and middle-income regions by 2045–50; when compared with life expectancy figures for 2010–15, the gap between life expectancies in more developed and less developed world regions is expected to narrow.1 The population aged 60 years and older in less-developed regions is projected to rise from 554 million in 2013 to nearly 1·6 billion by 2050, because the annual growth rate of this section of the population in these regions is almost three times that in more-developed regions of the world. This growth in the older population is taking place in parallel with increasing inequalities in income, disparities in access to health care and social-support systems, and widening health gaps as a result of complex patterns of disease burden and globalisation of health risks. In most developing countries, these issues are compounded by a lifetime of accumulated health risks associated with poverty and inadequate access to health care. The changing epidemiological profiles in low-income and middle-income countries are largely driven by a set of conditions, such as rapid urbanisation, and changing dietary habits and levels of physical activity, that are different from those that were prevailing when these shifts in profiles happened in the high-income countries. Older populations are showing an increase in the incidence and prevalence of chronic non-communicable diseases that occur before the onset of old age with a natural history that takes place in conditions of poverty—these have been referred to as post-transitional illnesses in pretransitional circumstances.

In view of these trends, there has been much speculation about the health that this ageing cohort will have, such as: will the years gained be productive and healthy, or will elderly people live longer lives in conditions of ill health? Three main hypotheses have been proposed to address this question.2 The compression of morbidity hypothesis posits a situation for which the age of onset of morbidity is delayed to a greater extent than life expectancy rises, thereby compressing morbidity into a short period at a late age.3 The expansion of morbidity hypothesis maintains the opposite, that increases in life expectancy are matched or exceeded by added periods of morbidity.4 Both compression and expansion of morbidity could happen in absolute or relative terms—ie, changes in the absolute number of years lived with disability—or in terms of healthy life expectancy as a proportion of total life expectancy.

Key messages

  • Populations are rapidly ageing worldwide with major implications for health systems. This situation is more prevalent in low-income and middle-income countries

  • A key question is whether older generations will be healthier than those who have preceded them. In other words, will we be adding life to years as populations age by ensuring maintained functioning and wellbeing?

  • High-income countries show some evidence that a compression of morbidity (a reduction over time in the total lifetime days of disability) is taking place, as noted from trends of functioning and disability status. However, uncertainty remains about the health of future older generations in view of the different risk factor exposures in different cohorts and increases in the prevalence of chronic diseases

  • Low-income and middle-income countries currently have no reliable evidence of compression, and morbidity might even be expanding, driven by lifestyle risk factors and increasing prevalence of chronic diseases

  • In view of the shortage of data, robust evidence needs to be generated about these trends to ensure an appropriate response from health and social systems

Healthy life expectancy is a measure that combines mortality and morbidity information in one index, expressing the number of healthy years of life lost because of poor health, and incorporating a range of severities to quantify poor health, which are based on different weights being assigned to different severity levels of disability that have resulted from various disorders. Data from the Global Burden of Disease 2010 study5 show that from 1990 to 2010, as life expectancy rose healthy life expectancy increased more slowly, and little progress was made in the reduction of the non-fatal health effects of diseases. For example, during this period, men aged 50 years had a healthy life expectancy increase of 0·75 years for each year of increase in life expectancy. The corresponding rise in healthy life expectancy for women aged 50 years was 0·77 years. Although total life expectancy in Japanese women—currently the highest in the world with also some of the lowest disability levels in the world—increased by 3·9 years, healthy life expectancy increased only by 3·2 years during the same period.5

Evidence for the theory of equilibrium of morbidity lends support to a more multidimensional perspective, for which lessened progression and severity of morbidity are accompanied by rises in moderate or mild morbidity.6 Data suggest that although severe disability-free life expectancies might have decreased in some high-income countries during the past four decades, total disability-free life expectancy has stagnated.7 In fact, in older adults, morbidity might have expanded.8 Health interventions that are targeted at lethal diseases could lead to increased years spent with a disability, which suggests that dissemination and uptake of lifestyle change interventions that reduce risk across a range of chronic disorders are essential. The coexistence of many diseases in an individual could mean that when mortality due to one disorder is prevented, disability due to another might become increasingly important.

Although life expectancy is clearly rising, the patterns of increase have not been consistent, with variable surges and periods of stagnation.9 Whether gains in life expectancy will occur at a diminishing rate, or continue indefinitely, is under debate.6 Investigators of studies of morbidity trends have drawn conflicting conclusions, and the quality of studies themselves are subject to several design and contextual factors, including the definition of morbidity, period studied, and study population.9, 10 Several review studies from high-income country settings have reported a fall in disability during the past few decades,3, 11, 12 with concurrent increases in prevalence of chronic diseases;13, 14, 15, 16 however, these studies did not contain evidence from people aged 85 years and older.9

By contrast, in 2007, a review by the international Organisation for Economic Cooperation and Development (OECD) that used disparate data reported by countries, showed that although there is clear evidence of a reduction in disability in elderly people in five of the 12 countries studied, in other countries rates are increasing or stable. Although prevalence of most of these disorders and risk factors has increased, no clear judgment could be made about the link between chronic disorders and severe disabilities. The OECD investigation relied on a proxy operationalisation of severe disability— namely, one that was most clearly consistent with the available national, self-report, survey data, and was intuitively linked to long-term care needs. The study investigators concluded that “it would not seem prudent for policy makers to count on future reductions in the prevalence of severe disability in elderly people, but rather to expand national capacity in long-term care and programmes to prevent or postpone chronic conditions”.

The situation in low-income and middle-income countries is much less studied, with very few data available. Delineation of the path of health and morbidity in old age has important implications for public health and the economy in terms of aspects of medical spending,17 planning of social programmes,18 prediction of trends in the workforce,18 and the social patterning of poverty.19

We identified data for this Series paper, by searches of PubMed (Medline) and CABI Global Health Database on June 17, 2011. We used four classifications of search words, relating to older age; morbidity, activities of daily living, disability, impairment, length of hospital stay, chronic disease, and health status; life expectancy, and actuarial analysis; and trends. Only articles published in English between 1991 to present were included. Specifically, we aimed to answer these questions: have there been changes in the age of onset or severity of late-life morbidity, in relation to life expectancy? Which hypotheses of health and ageing trends have been supported by published work?

Second, we also undertook new analyses of publicly available crossnational datasets that contain harmonised items related to the health status of older adults during many periods. In these analyses we addressed several related questions—has the proportion of older adults with a disability remained stable, increased, or reduced over time? Is this change due to the effects of age or is it a cohort effect? What are the factors that affect these longitudinal trends? And how do these patterns compare across countries? We used data from all the years that are available for public use.

We focused our analysis on trends in functioning in older adults because the review by Prince and colleagues in this Series20 addresses the issue of trends in chronic diseases in far greater detail. An analysis of data from the Global Burden of Disease study5 shows that nearly a quarter of all disease burden globally is carried by those aged 60 years and older, and that the per person burden is higher in developing countries, driven mainly by cardiovascular and respiratory diseases, and sensory impairments.

Section snippets

Trends in morbidity

The major issues when trying to understand levels and trends in the health of older adults are the absence of a common definition of health and understanding its constructs, and the need for a subsequent measurement of health in a way that is similar over time and across populations.

Health and social surveys rely heavily on self-reported measures. Self-reported health statistics have been traditionally measured in the older population with three main strategies. The first approach is to ask

Analyses of longitudinal studies

We have undertaken an analysis of several longitudinal studies of ageing and of cross-sectional analysis of a large dataset from the World Health Surveys as described in the appendix. Across all countries in the surveys, the proportion of respondents with ADL limitations shows a steady rise with age. However, this increase is substantial between the ages of 50 and 70 years in countries like Greece, Spain, and Italy, compared with countries such as the Netherlands, Sweden, and Switzerland where

Implications for the future and possible interventions

Our systematic examination of the scientific literature shows that support for morbidity pattern hypotheses varies mainly according to the type of health indicator. Disability-related or impairment-related measures of morbidity tend to support the theory of compression of morbidity, whereas chronic disease morbidity tends to support the expansion of morbidity hypothesis. Parker and Thorslund59 previously reported similar patterns in a review.

A simplified view of population-health change

Discussion

Our analysis of three large longitudinal surveys of older adults with a harmonised assessment of disability with regard to ADL and IADL limitations, shows varied patterns. Not all countries show consistent evidence for a compression of morbidity. Italy, Spain, and Greece seem to have much larger proportions of people who are disabled across all ages, irrespective of the measure used. However, difficulties with IADLs seem to become more apparent in elderly respondents across all countries.

References (73)

  • JF Fries

    Measuring and monitoring success in compressing morbidity

    Ann Intern Med

    (2003)
  • EM Gruenberg

    The failures of success

    Milbank Mem Fund Q Health Soc

    (1977)
  • KG Manton

    Changing concepts of morbidity and mortality in the elderly population

    Milbank Mem Fund Q Health Soc

    (1982)
  • RJ Perenboom et al.

    Trends in disability-free life expectancy

    Disabil Rehabil

    (2004)
  • EM Crimmins et al.

    Change in disability-free life expectancy for Americans 70-years-old and older

    Demography

    (2009)
  • EM Crimmins

    Trends in the health of the elderly

    Annu Rev Public Health

    (2004)
  • RF Schoeni et al.

    Persistent, consistent, widespread, and robust? Another look at recent trends in old-age disability

    J Gerontol B Psychol Sci Soc Sci

    (2001)
  • S Jacobzone

    Coping with aging: international challenges

    Health Aff (Millwood)

    (2000)
  • G Payne et al.

    Counting backward to health care's future: using time-to-death modeling to identify changes in end-of-life morbidity and the impact of aging on health care expenditures

    Milbank Q

    (2007)
  • EM Crimmins et al.

    Change in the Prevalence of Diseases among Older Americans: 1984-1994

    Demogr Res

    (2000)
  • VA Freedman et al.

    Contribution of chronic conditions to aggregate changes in old-age functioning

    Am J Public Health

    (2000)
  • VA Freedman et al.

    Chronic conditions and the decline in late-life disability

    Demography

    (2007)
  • DM Cutler

    Declining disability among the elderly

    Health Aff (Millwood)

    (2001)
  • EM Crimmins et al.

    Trends in health and ability to work among the older working-age population

    J Gerontol B Psychol Sci Soc Sci

    (1999)
  • M Prince et al.

    The burden of disease in older people; implications for health policy and practice

    Lancet

    (2014)
  • International classification of functioning, disability, and health

    (2006)
  • JA Salomon et al.

    Health state valuations in summary measures of population health

  • JA Salomon et al.

    Quantifying individual levels of health: definitions, concepts and measurement issues

  • Survey module for measuring health state

    (2012)
  • M Wilson et al.

    Improving measurement in health education and health behavior research using item response modeling: introducing item response modeling

    Health Educ Res

    (2006)
  • CJ Murray et al.

    Empirical evaluation of the anchoring vignette approach in health surveys

  • E Cambois et al.

    Trends in disability-free life expectancy at age 65 in France: consistent and diverging patterns according to the underlying disability measure

    Eur J Ageing

    (2008)
  • KG Manton et al.

    Cohort changes in active life expectancy in the U.S. elderly population: experience from the 1982-2004 National Long-Term Care Survey

    J Gerontol B Psychol Sci Soc Sci

    (2008)
  • JO Moe et al.

    Trends and variation in mild disability and functional limitations among older adults in Norway, 1986–2008

    Eur J Ageing

    (2011)
  • P Pinheiro et al.

    Calculation of health expectancies with administrative data for North Rhine-Westphalia, a Federal State of Germany, 1999-2005

    Popul Health Metr

    (2009)
  • J Sagardui-Villamor et al.

    Trends in disability and disability-free life expectancy among elderly people in Spain: 1986-1999

    J Gerontol A Biol Sci Med Sci

    (2005)
  • Cited by (635)

    View all citing articles on Scopus
    View full text