A comprehensive research project examining old age in China has shed new light on the social, behavioral, biological, and environmental risk factors that play an important role in healthy longevity.

Edward Tu Jow Ching, Associate Professor, Division of Social Science, at the Hong Kong University of Science and Technology said the purpose of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) was to collect data to determine how China can adequately face the challenges of aging to achieve the goals of healthy longevity. "This means not only surviving into old age, but also remaining healthy during advanced age," said the Professor.

The research work was conducted in waves during 2002 and 2005 and an additional survey was conducted in 2008. The first survey waves included 3,142 centenarians, 3,747 nonagenarians, 4,238 octogenarians, and 4,845 seniors aged 65-79. For the first time, researchers investigated the mortality trajectories of the oldest-old (ages 80-105) in a developing country. Among the findings, data revealed that receiving adequate medical service during sickness in childhood or never/rarely suffering from serious illness during childhood significantly reduces the risk of being impaired in activities of daily living (ADL), being cognitively impaired, and self-reporting poor health by 18 per cent to 33 per cent among the oldest-old of those surveyed.

"With the largest sample size among similar studies ever conducted in the world, through this project, we offer unparalleled and cost-effective opportunities for answering questions about healthy longevity," said Professor Tu. The results have been published in Chinese and English and the findings presented at academic workshops and conferences.

The research process was conducted with support from the Taiwan Academia Sinica and the China National Foundation for Social Sciences and funding from the Hong Kong Research Grants Council (RGC). To ensure that the survey covered a wide range of demographics, studies were conducted in 943 counties/cities, which were randomly selected. "We collected a unique and large sample of data from the oldest-old in China and used the data in multivariate logistic regression analyses," explained Professor Tu.

"We concluded from our analysis that policies that enhance childhood health care and children's socioeconomic well-being have large and long-lasting benefits even in the oldest of old age," said Professor Tu. He added, in another analysis, the research team looked at the correlation of the body mass index (BMI) in conjunction with healthy longevity. "We determined that those with the best health among the oldest-old had BMI between 25 to 29.9 and that those with higher BMI had better cognitive function," said the Professor.

To encourage the usage of the CLHLS multi-wave datasets, the research team has produced four longitudinal datasets, in addition to cross-sectional datasets, in various formats for researchers to use. So far, 230 registered users have accessed the datasets.

Professor Edward Tu Jow Ching
Division of Social Science
The Hong Kong University of Science and Technology
soejctu@ust.hk