How do socioeconomic, behavioral, environmental, and biological factors influence the healthy longevity of human beings? There has been considerable research on the influence of these factors on mortality from birth to older age but remarkably little research on how these factors affect the likelihood that a person will survive and remain healthy to an oldest old age. To rephrase our opening question, why do some people die at 80 and others at 100? Why do some people survive to oldest old age with a high quality of life while other elders suffer from poor health? Little is known about this, and the little that is known has been learned in recent years (Finch, 1990; Jeune, 1995; Christensen and Vaupel, 1996).

It is important to gain an understanding of the determinants of healthy longevity because populations in most countries are aging. China's population, in particular, is aging at an extraordinarily rapid pace (Banister, 1990; Ogawa, 1988; Zeng and Vaupel; 1989, Zeng and George, 2000). If current rates of mortality improvement persist, then it will be as likely for a child born today to reach the age of 100 as it was for a child born eight decades ago to reach the age of 80. Even under current mortality regimes in developed countries, more than half of all newborn girls will reach age 80 and 2% age 100 (Vaupel and Gowan, 1986).

Most of the elderly persons under the age of 80 are relatively healthy, but the oldest old generally require assistance. The oldest old persons consume amounts of services, benefits, and transfers far out of proportion to their numbers. For example, about a quarter of Medicare payments to hospitals were for oldest old patients in 1988 in New York City (Suzman et al., 1992: 6). According to a German study published in 1996, 1.7%, 3.2%, 6.2%, 10.7%, and 26.3% of the elderly aged 65-69, 70-74, 75-79, 80-84 and 85+, respectively, require health care services on a regular basis (Schneekloth et al., 1996). Obviously, the oldest old are the population group most in need of assistance, and this is the most difficult and expensive part of the care-giving service work for the elderly. And yet very little is known about the oldest old in China and in almost all other developing countries. Population surveys of the elderly are rare in developing countries. Moreover, the proportional sampling design has resulted in insufficient sample sizes for the oldest old in the few elderly surveys that have been conducted. Almost all census tabulations in China and other developing countries grouped 85+, 80+, or even 65+ as one category, which suppresses the heterogeneous characteristics of the oldest old. It is therefore imperative for sound academic research and policy making to conduct survey studies in developing countries to fill in the data gap for the oldest old population.

China offers an unparalleled opportunity for studies of the age 80+ population of a developing country because its population is so large and the age reporting of Han Chinese and most other ethnic minority groups appears to be generally reliable (as discussed below). The Chinese population now totals over 1.25 billion. Despite very high mortality in the past, there are large numbers of elderly Chinese today, and the population is aging at a very rapid pace. There were 63 million people aged 65 and over in 1990, which was less than 6 percent of the total population; by the middle of the next century there will be 330 million, under the modest mortality assumption, or 400 million under the low mortality assumption. And there were 8 million Chinese aged 80 and over in 1990, but there will be 114 million (modest mortality) or nearly 160 million (low mortality) by mid-21st century (Zeng and Vaupel, 1989). Research on the large but extraordinarily selected population of Chinese oldest old may provide important insights into why some people survive to advanced old age in good health.

The objectives of our ongoing research project on the “determinants of healthy longevity in China” are threefold:

1. To fill in the data gap and gain a better understanding of demographic and socioeconomic conditions, as well as of the health status and care-giving needs of the oldest old population;
2. To shed new light on the determinants of healthy longevity and to discover social, behavioral, environmental and biological factors that may have an influence on the healthy longevity of human beings, as well as to answer questions such as why some people survive to very old age without much suffering while others suffer considerably; and
3. To provide a scientific base for sound policy making and implementation, so as to improve the system of care-giving services and, ultimately, the quality of life of the elderly.

The general design of our project is to conduct a national longitudinal survey with a sample size of more than 9,000 oldest old in three waves: 1998, 2000, and 2002. The survey includes both individual and community data. In addition, some case studies on families and areas that exhibit exceptional longevity will be conducted after the year 2000. This book presents a summarized description and discussion of the first wave of our survey, which was conducted in 1998, and initial findings on active life expectancy at oldest old ages. Following this introduction, we present an outline of the survey, including the sample design and an evaluation of the data quality, the weighting method and the age, sex and residence specific weights used to compute the overall average for the oldest old persons age 80+ and the averages of the age groups.

(Source:Edited by China Population and Development Research Center)