Changes And Forecasts Of Disability-free Life Expectancy Among The Older People In China

The declines in mortality and fertility rate lead to a rapid population aging.In response to an aging population,the World Health Organization put forward the strategic concept of "Healthy Aging" in the 1990s,pointing out that the increases of life expectancy did not necessarily mean the improvement of quality of life and healthy life expectancy should be emphasized.Healthy life expectancy combines the information of death and health,and has shown complex and varied patterns with the changes of life expectancy.As life expectancy increases,healthy life expectancy may increase faster or decline,or change in line with life expectancy.This may reflect real variations in healthy life expectancy across time and space,or it may be due to differences in study designs.The research results on the changes of healthy life expectancy of the elderly in China also showed various patterns,and no consensus has been reached.And the lack of understanding would make healthy life expectancy forecast in the future even more uncertain.Healthy China 2030 calls for a significant increase in healthy life expectancy,but does not come up with specific figures.There is an urgent need for in-depth research in the changes and forecasts of healthy life expectancy in China.Based on the data from Chinese Longitudinal Healthy Longevity Survey(CLHLS)conducted in 1998,2000,2002,2005,2008,2011,2014 and 2018,this study estimates the elderly’s disability-free life expectancy by using Sullivan method to investigate the change pattern of Chinese elderly’s disability-free life expectancy during 1998-2018.Lee-Carter model is used to stochastically forecast the Chinese elderly’s mortality and health rates in 2019-2038 and then Sullivan method is employed to estimate disabilityfree life expectancy.This study has the following findings:1.The disability-free life expectancy and its proportion to life expectancy of the elderly in China had increased with fluctuation.During 2002-2018,the disability-free life expectancy of the Chinese elderly aged 65 had changed in three stages.It increased in 2002-2008,declined in 2008-2011 and increased again in 2011-2018.The proportion of disability-free life expectancy to life expectancy had increased in 2002-2008,decreased in 2008-2014 and increased in 2014-2018.The disability-free life expectancy of males aged 65 had increased from 12.26 years to 13.76 years,and its proportion to life expectancy had increased from 91.65%to 93.10%.For females aged 65,the disability-free life expectancy had increased from 13.78 years to 16.13 years,and its proportion to life expectancy had increased from 88.37%to 90.12%.2.The changes of disability-free life expectancy was caused by the changes of mortality and disability-free rates.The disability-free life expectancy increases during 2002-2008 was due to the decline in mortality and the increase in disability-free rates.The decline of disability-free life expectancy in 2008-2011 was mainly caused by the decrease in disability-free rates which offset the effects of mortality reduction,while the decline in mortality and increase in disability-free rates in 2011-2018 led to the disability-free life expectancy increases.3.There were age and gender differences in Chinese elderly’s disability-free life expectancy.With age,the decline of the disability-free life expectancy slowed down,and its proportion to life expectancy showed accelerated decline.Females did not necessarily stay healthy,although they lived longer than males.Females’disability-free life expectancy was higher than males’,but its advantage gradually disappeared with age,and the disability-free life expectancy of females at older age was even lower than that of males.Males had an advantage in the proportion of disability-free life expectancy to life expectancy and it expanded with age.4.The results of stochastic projection indicate that the changes of disability-free life expectancy of Chinese older people would show great uncertainties during 20192038.The median prediction of disability-free life expectancy and its proportion to life expectancy would increase.In 2038,the disability-free life expectancy of males aged 65 would increase to 15.85 years,and its proportion would increase to 93.53%.For females aged 65,the disability-free life expectancy would increase to 18.09 years,and its proportion would increase to 91.43%.However,when the prediction error is considered,disability-free life expectancy and its proportion to life expectancy may decline in the future.And the 95%prediction interval would expand over time.During 2020-2038,95%prediction interval of disability-free life expectancy would increase from[13.43,15.62]to[12.83,20.08]for males aged 65,and would increase from[15.71,17.84]to[14.98,21.85]for females aged 65.And 95%prediction interval of its proportion would increase from[91.49%,94.23%]to[87.27%,99.45%]for males,and would increase from[88.37%,91.86%]to[83.53%,98.34%]for females.The upper prediction would show a faster increase in disability-free life expectancy and its proportion to life expectancy,while the lower predication would show a continuous and rapid downward trend in disability-free life expectancy and its proportion to life expectancy.The trend in disability life expectancy of the elderly will be highly uncertain in 2019-2038.The median prediction would show an increase in disability life expectancy of males and a decrease in disability life expectancy of females.When the prediction error is considered,the 95%prediction interval would continue to expand over time.The lower prediction would rapidly decline,while the upper prediction would steadily increase.During 2020-2038,95%prediction interval of disability life expectancy would increase from[0.96,1.25]to[0.11,1.87]for males aged 65,and would increase from[1.58,2.07]to[0.37,2.95]for females aged 65.This study is an in-depth research in the changes of disability-free life expectancy of Chinese older people during 1998-2018,which helps us understand the elderly’s quality of life.We predicted the Chinese elderly’s disability-free life expectancy in the future using stochastic forecasting model,scientifically measured the uncertainty of changes in death and health levels,and improved the scientific nature of the prediction results.We also confirmed the applicability of Lee-Carter model in forecasting Chinese older people’s disability-free life expectancy.The findings are of reference value for the realization of healthy aging and for the improvement and formulation of relevant policies on aging.