Active Life Expectancy

Background

Summary measures of population health, such as ALE, answer whether overall life expectancy is increasing faster or slower than life expectancy spent in good health. This question led to the development of a new family of indicators, namely health expectancies. The general model of health transition proposed by the World Health Organization (WHO) in 1984 distinguished overall life expectancy, disability-free life expectancy, and morbidity-free life expectancy (Figure 1). Its strength lies in its ability to assess the likelihood of different health scenarios expressed as interrelationships among these three measures: a pandemic of chronic diseases and disabilities, a compression of morbidity, and contradictory evolutions that include the scenario of dynamic equilibrium.

Research on such measures, combining mortality and morbidity data at the population level, dates back to the 1960s. The first method of calculation was proposed by H. F. Sullivan in 1971. Soon research took two directions. One, following the work of Sullivan, [Page 3]gave priority to data availability and calculation simplicity. The other, following the work of J. W. Bush and his collaborators, focused on several methodological refinements, including the multistate approach and weighting combinations. Health expectancies have been increasingly used in industrialized countries to assess the evolution of the populations' health status, in particular that of older people. Being independent of the size of populations and of their age structure, health expectancies allow direct comparisons of the different groups that make up populations (e.g., sexes, socioprofessional categories, regions). Since 1989, an international research network, REVES (Réseau Espérance de Vie en Santé [Network on Health Expectancy]), has coordinated research on summary measures, the need for which has been voiced by a number of international agencies such as WHO and the Organization for Economic Cooperation and Development (OECD). Indeed, in the final communiqué of its 1997 summit in Denver, Colorado, the Group of 8 (G8) encouraged collaborative biomedical and behavioral research to improve ALE and reduce disability.

Figure 1 General Model of Health Transition

Note: e0** and e60** are the numbers of years of autonomous life expected at birth and at 60 years of age, respectively. M50** is the age to which 50% of females could expect to survive without loss of autonomy.

Source: World Health Organization. The uses of epidemiology in the study of the elderly: Report of a WHO Scientific Group on the Epidemiology of Aging. Geneva: WHO (Technical Report Series 706), 1984. Reprinted with permission.

The health expectancy approach has now been extended to incorporate the modern concepts of the disablement process: chronic morbidity, functional limitation, activity restriction, and physical dependency, with progressively more attention being devoted to mental health expectancy.

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