Trends in Healthy Life Expectancy in Japan: 1986 - 2004

Article excerpt

Abstract

This article examines the increasing life expectancy of Japanese men and women in relation to their health from 1986 to 2004. We computed healthy life expectancy for seven available time-points using the prevalence-based Sullivan method. The results showed that, for both sexes and at all ages, the gains in life expectancy prior to 1995 were mostly in years of good self-rated health, while the gains thereafter were in years of poor self-rated health. The exception was for women at age 85, among whom there was an almost continuous increase in the number of years in poor health. The proportion of life spent in different health states suggested evidence of morbidity compression until 1995, followed by an expansion of morbidity.

1. Introduction

In almost all parts of the world, improvements in health and sanitation conditions, better living standards, higher educational attainments, and advancements in medical technologies are enabling people to live longer. In this regard, Japan leads the world. Life expectancy at birth in 2007 stood at 79.19 for Japanese men and 85.99 years for Japanese women (Ministry of Health, Labour and Welfare 2008a). According to recent statistics, 21.8% of the Japanese population is aged 65 and over, making the nation the oldest in the world (Ministry of Health, Labour and Welfare 2008b). As people live longer, several key health-related quality-of-life questions arise: Are these longer lives lived in good or in poor health? How many years and what proportion of the lifespan are lived in good versus poor health? And what are the changes and trends over time at the population level?

To answer these questions, we use the concept of health expectancy. As an extension of the concept of life expectancy, health expectancy is a summary measure of population health that takes into account both current mortality and morbidity levels of a population, and partitions years of life lived at a particular age into healthy and unhealthy years. This extension shifts the focus from quantity of life to quality of life. In recent years, the value of longer but less healthy lives has been questioned. Research has shown that increases in the total expected years of life are not necessarily accompanied by increases in the expected years of, or proportion of, disability-free life (Crimmins, Saito, and Ingegneri 1989, 1997; Crimmins, Hayward, and Saito 1994). As countries progress through the later stages of the epidemiological transition and chronic illnesses become more prevalent, it is no longer sufficient to rely on mortality indicators alone.

Since the 1980s, three main theoretical hypotheses about the relationship between increasing life expectancy and expected life-time in good health have been discussed. The first hypothesis is that a longer life involves greater suffering, as there are more years of life spent in ill health and with disabilities. The sick and frail are kept alive, but with expanding morbidity (Kramer 1980; Gruenberg 1977). Changes in life expectancy with a decrease in the proportion of healthy life years can be evidence of an expansion of morbidity. The second hypothesis is that there are longer periods of life in good health, i.e., that there is a delay in the onset and progression of illness with a compression of morbidity (Fries 1980, 1989). An increase in life expectancy accompanied by an increase in the proportion of life spent healthy can be regarded as evidence of a compression of morbidity. The last hypothesis is that there is a dynamic equilibrium between health and years of life. There could be more disability, but it is light and moderate, with a dynamic equilibrium maintained (Manton 1982).

Health expectancy can be measured by a variety of different health dimensions. This results in more specific terms used for health expectancies. For instance, if global self-rated health is measured, it is often called healthy life expectancy. In this paper, we used self-rated health to compute health expectancy. …