A new method for correcting under-estimation of disabled life expectancy and an application to the Chinese oldest-old

Impact of diabetes on longevity and disability-free life expectancy among older South African adults: A prospective longitudinal analysis

AIMS

We seek to understand the coexisting effects of population aging and a rising burden of diabetes on healthy longevity in South Africa.

METHODS

We used longitudinal data from the 2015 and 2018 waves of the "Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa" (HAALSI) study to explore life expectancy (LE) and disability-free life expectancy (DFLE) of adults aged 45 and older with and without diabetes in rural South Africa. We estimated LE and DFLE by diabetes status using Markov-based microsimulation.

RESULTS

We find a clear gradient in remaining LE and DFLE based on diabetes status. At age 45, a man without diabetes could expect to live 7.4 [95% CI 3.4 - 11.7] more years than a man with diabetes, and a woman without diabetes could expect to live 3.9 [95% CI: 0.8 - 6.9] more years than a woman with diabetes. Individuals with diabetes lived proportionately more years subject to disability than individuals without diabetes.

CONCLUSIONS

We find large and important decrements in disability-free aging for people with diabetes in South Africa. This finding should motivate efforts to strengthen prevention and treatment efforts for diabetes and its complications for older adults in this setting.

Life Course Socioeconomic Status and Healthy Longevity in China

In 2020, China's population aged 60 or older exceeded 264 million, representing 25% of the global population in that age-group. Older adults in China experienced periods of dramatic political and social unrest in early life, as well as economic transformations leading to drastic improvements in living standards during adulthood and older age. However, the implications of life course socioeconomic status (SES) trajectories for healthy longevity in later life have not been systematically studied in China. We utilize data from the China Health and Retirement Longitudinal Study (CHARLS) to comprehensively investigate how early-life conditions and adult SES combine to influence healthy longevity in later life. We find that both childhood and adulthood SES are associated with late-life health. The largest disparities in life expectancy (LE) and disability-free LE are found between those with persistently low SES throughout life and those with consistently high SES. At age 45, the gap in total LE between the most advantaged and least advantaged groups is six years for men and five years for women. Despite China's major policy changes prioritizing equity in income and health care in recent decades, our findings suggest that dramatic health inequalities among older adults remain. Our findings extend the literature on the effect of socioeconomic patterns across the life course on gradients in later-life health and highlight continuing disparities in healthy longevity among older adults in China.

Smoking cessation in late life is associated with increased risk of all-cause mortality amongst oldest old people: a community-based prospective cohort study

OBJECTIVE

we aimed to investigate the association of smoking cessation with risk of all-cause mortality amongst oldest old people (aged ≥ 80 years).

DESIGN

this was a prospective cohort study.

SETTING

the Chinese Longitudinal Healthy Longevity Survey, implemented in 23 provinces of China.

PARTICIPANTS

a total of 28,643 community-dwelling oldest old people (mean age, 92.9 ± 7.5 years) were included.

METHODS

in this community-based cohort study, Cox proportional hazards models were used to examine the association of smoking cessation with risk of all-cause mortality.

RESULTS

during 136,585 person-years of follow-up from baseline to 1 September 2014, compared with never smokers, hazard ratios and 95% confidence intervals for all-cause mortality were 1.06 (1.02-1.10) for current smokers, 1.23 (1.09-1.39) for transient quitters (≤1 consecutive years since smoking cessation), 1.22 (1.12-1.32) for recent quitters (2-6 consecutive years since smoking cessation) and 1.11 (1.02-1.22) for long-term quitters (>6 consecutive years since smoking cessation). Cox models with penalised splines revealed an increased risk of all-cause mortality after smoking cessation; the highest mortality risk was observed within 2-4 years after smoking cessation and the risk gradually decreased with duration of smoking cessation. We further conducted subgroup analyses and sensitivity analyses to reduce the impact of reverse causation.

CONCLUSIONS

smoking is harmful to health in all populations. Our study findings indicated smoking cessation in late life to be associated with increased risk of all-cause mortality amongst oldest old people who have smoked for a long time.

Disability-Free Life Expectancy among People Over 60 Years Old by Sex, Urban and Rural Areas in Jiangxi Province, China

OBJECTIVE

To estimate and compare age trends and the disability-free life expectancy (DFLE) of the population over 60 years old in 2018 in Jiangxi Province, China, by sex and urban-rural areas.

METHODS

The model life table was employed to estimate the age-specific mortality rate by sex and urban-rural areas, based on the Summary of Health Statistics of Jiangxi Province in 2018 and the Sixth National Health Service survey of Jiangxi Province. DFLE and its ratio to life expectancy (LE) were obtained by the Sullivan method.

RESULTS

In 2018, the DFLE among people over 60 is 17.157 years for men and is 19.055 years for women, accounting for 89.7% and 86.5% of their LE respectively. The DFLE/LE of men is higher than that of women at all ages. LE and DFLE are higher for the population in urban areas than in rural areas. For women, DFLE/LE is higher in urban areas than in rural areas (except at ages 75 and 80). Urban men have a higher DFLE/LE than rural men (except at age 85). The difference in DFLE between men and women over 60 years is 1.898 years, of which 2.260 years are attributable to the mortality rate, and 0.362 years are due to the disability-free prevalence. In addition, the difference in DFLE between urban-rural elderly over 60 years old is mostly attributed to the mortality rate by gender (male: 0.902/1.637; female: 0.893/1.454), but the impact of the disability-free rate cannot be ignored either (male: 0.735/1.637; female: 0.561/1.454).

CONCLUSIONS

The increase in DFLE is accompanied by the increase in LE, but with increased age, DFLE/LE gradually decreases. With advancing age, the effect of disability on elderly people becomes more severe. The government administration must implement some preventive actions to improve health awareness and the life quality of the elderly. Rural elderly; rural women in particular, need to be paid more attention and acquire more health care.

Are China's oldest-old living longer with less disability? A longitudinal modeling analysis of birth cohorts born 10 years apart

BACKGROUND

China has transitioned from being one of the fastest-growing populations to among the most rapidly aging countries worldwide. In particular, the population of oldest-old individuals, those aged 80+, is projected to quadruple by 2050. The oldest-old represent a uniquely important group-they have high demand for personal assistance and the highest healthcare costs of any age group. Understanding trends in disability and longevity among the oldest-old-that is, whether successive generations are living longer and with less disability-is of great importance for policy and planning purposes.

METHODS

We utilized data from successive birth cohorts (n = 20,520) of the Chinese oldest-old born 10 years apart (the earlier cohort was interviewed in 1998 and the later cohort in 2008). Disability was defined as needing personal assistance in performing one or more of five essential activities (bathing, transferring, dressing, eating, and toileting) or being incontinent. Participants were followed for age-specific disability transitions and mortality (in 2000 and 2002 for the earlier cohort and 2011 and 2014 for the later cohort), which were then used to generate microsimulation-based multistate life tables to estimate partial life expectancy (LE) and disability-free LE (DFLE), stratified by sex and age groups (octogenarians, nonagenarians, and centenarians). We additionally explored sociodemographic heterogeneity in LE and DFLE by urban/rural residence and educational attainment.

RESULTS

More recently born Chinese octogenarians (born 1919-1928) had a longer partial LE between ages 80 and 89 than octogenarians born 1909-1918, and octogenarian women experienced an increase in partial DFLE of 0.32 years (P = 0.004) across the two birth cohorts. Although no increases in partial LE were observed among nonagenarians or centenarians, partial DFLE increased across birth cohorts, with a gain of 0.41 years (P < 0.001) among nonagenarians and 0.07 years (P = 0.050) among centenarians. Subgroup analyses revealed that gains in partial LE and DFLE primarily occurred among the urban resident population.

CONCLUSIONS

Successive generations of China's oldest-old are living with less disability as a whole, and LE is expanding among octogenarians. However, we found a widening urban-rural disparity in longevity and disability, highlighting the need to improve policies to alleviate health inequality throughout the population.

Incorporating biomarkers into the study of socio-economic status and health among older adults in China

The social gradient in health - that individuals with lower SES have worse health than those with higher SES- is welldocumented using self-reports of health in more developed countries. Less is known about the relationship between SES and health biomarkers among older adults residing in less developed countries. We use data from the ChineseLongitudinal Healthy Longevity Survey (CLHLS) longevity areas sub-sample to examine the social gradient in healthamong rural young-old and oldest-old adults (N=2,121). Our health indicators include individual biomarkers, metabolic syndrome, and self-reports of health. We found a largely positive relationship between SES and health. SES was more consistently associated with individual biomarkers among the oldest-old than the young-old, providing evidence for cumulative disadvantage. We discuss the implications of our findings for older adults who have lived through different social, economic, and health regimes.

Trajectories of ADL Disability Among Community-Dwelling Frail Older Persons

This study examines how activity of daily living (ADL) disability of community-living frail elders changes in a two-year period and how the pattern of change varies between those who subsequently died or were institutionalized and those who continued to live in the community. Multiple waves of data from a cohort of older participants ( N = 3,161) in Michigan’s Medicaid Waiver Program were analyzed using the hierarchical linear modeling (HLM) approach. The results suggest that changes in ADL disability were nonlinear and the pattern of change varied by their subsequent status. Participants who subsequently died or were institutionalized exhibited a steep increase in ADL disability during the last few months before the events, whereas continued community residents were relatively stable in ADL disability during the two-year study period. Within each group, substantial individual variation in ADL disability trajectories exists. Implications of the findings to research and practice are discussed.

Health Expectancies in Adults Aged 50 Years or Older in China

OBJECTIVE

The purpose of this study is to understand the functional health of older adults in China and to assess the potential for advancing healthy and active aging.

METHOD

Data of 13,739 older adults aged 50 years and older from the China Health and Retirement Longitudinal Study in 2011 were analyzed. Life expectancy in good perceived health, chronic-disease-free life expectancy, active life expectancy, and severe impairment-free life expectancy were calculated using Sullivan's method.

RESULTS

At age 50 years, older adults had a life expectancy in good perceived health of 7.0 and 6.7 years in men and women, respectively. They would remain chronic-disease-free for 8.4 and 8.6 years, without activity limitation for 23.6 and 26.0 years, and severe impairment-free for 21.4 and 24.2 years.

DISCUSSION

The world's largest aging population was spending a substantial proportion of remaining life years in suboptimal health and well-being, while remaining largely independent in basic self-care without severe impairments.

A Systematic Literature Review of Studies Analyzing Inequalities in Health Expectancy among the Older Population

Aim

To collect, organize and appraise evidence of socioeconomic and demographic inequalities in health and mortality among the older population using a summary measure of population health: Health Expectancy.

Methods

A systematic literature review was conducted. Literature published in English before November 2014 was searched via two possible sources: three electronic databases (Web of Science, Medline and Embase), and references in selected articles. The search was developed combining terms referring to outcome, exposure and participants, consisting in health expectancy, socioeconomic and demographic groups, and older population, respectively.

Results

Of 256 references identified, 90 met the inclusion criteria. Six references were added after searching reference lists of included articles. Thirty-three studies were focused only on gender-based inequalities; the remaining sixty-three considered gender along with other exposures. Findings were organized according to two leading perspectives: the type of inequalities considered and the health indicators chosen to measure health expectancy. Evidence of gender-based differentials and a socioeconomic gradient were found in all studies. A remarkable heterogeneity in the choice of health indicators used to compute health expectancy emerged as well as a non-uniform way of defining same health conditions.

Conclusions

Health expectancy is a useful and convenient measure to monitor and assess the quality of ageing and compare different groups and populations. This review showed a general agreement of results obtained in different studies with regard to the existence of inequalities associated with several factors, such as gender, education, behaviors, and race. However, the lack of a standardized definition of health expectancy limits its comparability across studies. The need of conceiving health expectancy as a comparable and repeatable measure was highlighted as fundamental to make it an informative instrument for policy makers.

Regional variations in and correlates of disability-free life expectancy among older adults in China

Background

Considerable socioeconomic and health inequalities have been reported in China. However, because of a lack of appropriate data, limited research has been conducted on variations in disability-free life expectancy (DFLE) among older adults. This study aimed to use the most up-to-date disability survey data to explore geographical variations in DFLE at age 60 in China and to identify the socioeconomic and health care factors that partially account for these variations.

Methods

This study used 2006 mortality data extrapolated from the 1990 and 2000 Census and disability data from a national disability survey conducted in 2006. Disability was performance based and was diagnosed by trained physicians. DFLE was calculated by region using the Sullivan method. Multiple linear regression models by gender were conducted to explore correlates of DFLE.

Results

DFLE at age 60 varied widely by region, from 11.2 to 20.8 years in 2006. Per capita gross domestic product, proportion of urban residents, and access to health care were the primary factors associated with geographical variations in DFLE.

Conclusion

The pattern of differences in DFLE by region mirrors the pattern of regional economic development in China. Countermeasures to decrease regional differences in DFLE include accelerating regional economic development and improving health care distribution.

Modeling transition rates using panel current-status data: how serious is the bias?

Studies of disability dynamics and active life expectancy often rely on transition rates or probabilities that are estimated using panel survey data in which respondents report on current health or functional status. If respondents are contacted at intervals of one or two years, then relatively short periods of disability or recovery between surveys may be missed. Much published research that uses such data assumes that there are no unrecorded transitions, applying event-history techniques to estimate transition rates. In recent years, a different approach based on embedded Markov chains has received growing use. We assessed the performance of both approaches, using as a criterion their ability to reproduce the parameters of a "true" model based on panel data collected at one-month intervals. Neither of the widely used approaches performs particularly well, and neither is uniformly superior to the other.

Trends in disability-free life expectancy among Chinese older adults

OBJECTIVE

This study evaluates trends in disability-free life expectancy (DFLE) of Chinese adults aged 60 and older.

METHODS

Based on two national disability surveys in 1987 and 2006 as well as mortality data from World Population Prospects, the Sullivan method was used to calculate DFLE.

RESULTS

DFLE increased from 13.0 to 13.9 years at age 60 and from 1.2 to 1.5 years at age 90 in 1987 and 2006, respectively. The proportion of DFLE increased after age 75. The proportion of DLE(x) with severe disability decreased while that of least disability increased. Onset of disability was delayed from 0.3 years to 4.7 years across disability types.

CONCLUSIONS

Trends in DFLE by age and severity of disability as well as the delayed onset of disability provide evidence for the compression of morbidity among the oldest old in China. But a similar trend was not found among the young-old.

On the Estimation of Disability-Free Life Expectancy: Sullivan' Method and Its Extension

A rapidly aging population, such as the United States today, is characterized by the increased prevalence of chronic impairment. Robust estimation of disability-free life expectancy (DFLE), or healthy life expectancy, is essential for examining whether additional years of life are spent in good health and whether life expectancy is increasing faster than the decline of disability rates. Over 30 years since its publication, Sullivan's method remains the most widely used method to estimate DFLE. Therefore, it is surprising to note that Sullivan did not provide any formal justification of his method. Debates in the literature have centered around the properties of Sullivan's method and have yielded conflicting results regarding the assumptions required for Sullivan's method. In this article we establish a statistical foundation of Sullivan's method. We prove that, under stationarity assumptions, Sullivan's estimator is unbiased and consistent. This resolves the debate in the literature, which has generally concluded that additional assumptions are necessary. We also show that the standard variance estimator is consistent and approximately unbiased. Finally, we demonstrate that Sullivan's method can be extended to estimate DFLE without stationarity assumptions. Such an extension is possible whenever a cohort life table and either consecutive cross-sectional disability surveys or a longitudinal survey are available. Our empirical analysis of the 1907 and 1912 U.S. birth cohorts suggests that while mortality rates remain approximately stationary, disability rates decline during this time period.

Improving knowledge about disability transitions by adding retrospective information to panel surveys. Population health metrics

Background

Panel data are often used to estimate key measures of public health, such as years lived with and without disability. Panel surveys commonly measure disability at intervals of one or two years, and occasionally more than two. It is likely that these intervals often include unreported changes in functional status. Unreported changes may bias estimates of disability transition probabilities, which are commonly used to estimate years lived with and without disability. Most surveys do not ask participants about periods with and without disability in the time since they last responded to the survey. We examined a way to improve the usefulness of panel surveys and our understanding of disability processes, by eliciting retrospective disability information.

Methods

Data were from the United States' National Long Term Care Survey. At each wave, this survey asks disabled respondents how long they have been disabled. We tested whether estimates of probabilities predicting changes in disability status can be improved by making use of this retrospective disability information. Methods included embedded Markov Chain analysis, microsimulation, and the Hausman specification test.

Results

Estimates based on data that include retrospective information are significantly different from those that use only the more limited information that is contemporaneous to the surveys. They are also more efficient. At age 65, all estimated probabilities for becoming disabled were higher when retrospective information was used, and all probabilities for remaining disabled were lower. Microsimulation revealed that using retrospective information increased the number of functional status transitions. For example, for women the mean number of transitions from nondisabled to disabled or dead was 52.7% greater when retrospective information was added to the analysis.

Conclusion

Our results suggest that the value of future panel studies for estimating transitions in disability could be notably enhanced by adding a small number of questions asking respondents for details about their disabilities–and lack of disabilities–in the period since a preceding survey wave. Information provided by such questions could substantially improve both the measurement of disability histories and estimates of disability processes.

Sociodemographic Effects on the Dynamics of Task-specific ADL Functioning at the Oldest-old Ages: The Case of China

Studies that systematically examine the dynamics of task-specific ADL functioning and its associates are very rare. Using the first three waves of the Chinese Longitudinal Healthy Longevity Survey, this study examines the dynamics of each of the six ADL tasks (bathing, dressing, toileting, indoor transferring, eating, and continence) and their sociodemographic correlates among the oldest-old by including the ADL information both at the follow-up wave for survivors and at the time prior to death for those who died during survey intervals. Effects of age, gender, urban/rural residence, ethnicity, education, primary lifetime occupation, primary source of daily expenses, living alone, and marital status are examined in both the absence and presence of other various confounders. Our results show that each sociodemographic factor still plays some limited role in the dynamics of ADL functioning across tasks.