Jennifer C. Cornman

Trends in Late-Life Activity Limitations in the United States: An Update From Five National Surveys

This article updates trends from five national U.S. surveys to determine whether the prevalence of activity limitations among the older population continued to decline in the first decade of the twenty-first century. Findings across studies suggest that personal care and domestic activity limitations may have continued to decline for those ages 85 and older from 2000 to 2008, but generally were flat since 2000 for those ages 65–84. Modest increases were observed for the 55- to 64-year-old group approaching late life, although prevalence remained low for this age group. Inclusion of the institutional population is important for assessing trends among those ages 85 and older in particular.

Chronic conditions and the decline in late-life disability

Using data from the 1997–2004 National Health Interview Survey (NHIS), we examine the role of chronic conditions in recent declines in late-life disability prevalence. Building upon prior studies, we decompose disability declines into changes in the prevalence of chronic conditions and in the risk of disability given a condition. In doing so, we extend Kitigawa’s (1955) classical decomposition technique to take advantage of the annual data points in the NHIS. Then we use respondents’ reports of conditions causing their disability to repartition these traditional decomposition components. We find a general pattern of increasing prevalence of chronic conditions accompanied by declines in the percentage reporting disability among those with a given condition. We also find declines in heart and circulatory conditions, vision impairments, and possibly arthritis and increases in obesity as reported causes of disability. Based on decomposition analyses, we conclude that heart and circulatory conditions as well as vision limitations played a major role in recent declines in late-life disability prevalence and that arthritis may also be a contributing factor. We discuss these findings in light of improvements in treatments and changes in the environments of older adults.

Declines in late-life disability: The role of early- and mid-life factors

Investigations into the reasons for declines in late-life disability have largely focused on the role of contemporaneous factors. Adopting a life-course perspective as a backdrop, in this paper we ask whether there also has been a role for selected early- and mid-life factors in the decline, and if so whether these factors have been operating through changes in the risks of disability onset or recovery. Drawing on five waves from 1995 to 2004 of the U.S. Health and Retirement Study, we found for the 75 years and older population in the United States that the prevalence of difficulty with activities of daily living (ADL) declined from 30.2% in 1995 to 26.0% in 2004, whereas the trend in difficulty with instrumental activities of daily living (IADL) was flat. Onset of ADL limitations also was reduced during this period while recovery increased. Changes in the educational composition of the older population were linked to declines in the prevalence of ADL limitations, but there were also modest contributions of changes in mothers education, self-rated childhood health, and lifetime occupation. Declines in late-life vision impairments and increases in wealth also contributed substantially to the downward trend, and had chronic conditions not increased, it would have been even larger. Reductions in the onset of ADL limitations were partly driven by changes in educational attainment of respondents and their mothers and, in late-life, better vision and wealth. In contrast, the recovery trend was not accounted for by changes in early- or mid-life factors. We conclude that early- and mid-life factors have contributed along with late-life factors to U.S. late-life disability trends mainly through their influence on the onset of, rather than recovery from, limitations.

Social Ties and Perceived Support: Two Dimensions of Social Relationships and Health Among the Elderly in Taiwan

Objectives: Assess the effects of social relationships on physical and mental health among the elderly in Taiwan. Methods: Using 4 waves of a survey of the elderly, we examine the relationship between social ties and perceived support and four health outcomes—mortality, functional status, self-assessed health, and depression. Results:Perceived support and social ties are related to health, but many of the apparent effects are attenuated in the presence of controls for prior health. However, positive perceptions about support are protective of mental (but not physical) health. Discussion: If baseline health is ignored, estimates of the effects of social relationships on health at a given stage of life are likely to be inflated by reverse causality or by effects occurring prior to baseline. Inclusion of controls for initial health reveals that, in general, the relationship between social support and health at the older ages in Taiwan is relatively modest.

Validation of New Measures of Disability and Functioning in the National Health and Aging Trends Study

BACKGROUND Measurement gaps continue to hamper fuller understanding of late-life disability trends and dynamics. This article reports findings that validate the self-reported components of the disability protocol to be used in the new National Health and Aging Trends Study. The protocol was designed to redress existing measures by attending to environmental aspects of disability, capturing a broader range of capacity to perform tasks and including participation restriction items. METHODS We undertook an in-person validation study to determine the reliability, validity, and initial measurement properties of the National Health and Aging Trends Study self-reported disability protocol (n = 326). A random subset (n = 111) was readministered the protocol within 2-4 weeks. The interview and reinterview included new self-reported measures of physical capacity, activity limitations, and participation restrictions, as well as established performance and cognitive tests. We calculated percent agreement and kappa between interviews for all self-reported items and summary measures. We also assessed the construct validity of summary measures through correlations with demographic characteristics, frailty, memory, and performance-based mobility and confirmed whether activity limitations and participation restrictions were distinct domains. RESULTS New items and derived summary measures demonstrate robustness over a short time period, with kappas for retained/recommended items in the .60-.80 range. The summary measures correlate as expected with age, sex, residential status, and established performance-based constructs. Two factors, representing activity limitations and participation restrictions, were confirmed. CONCLUSIONS The National Health and Aging Trends Study protocol preserves the ability to examine more traditional measures of functioning while offering new insights into how activities are performed and preserving key conceptual distinctions.

Sex differentials in biological risk factors for chronic disease: estimates from population-based surveys.

BACKGROUND In light of substantial sex differences in health outcomes, researchers need to focus on disentangling the underlying biological and social determinants. The objective of this study is to determine whether two populations that differ in many cultural and social dimensions--Taiwan and the United States--also vary with regard to sex differentials in biological markers of chronic disease. METHODS The analysis is based on three population-based surveys that include interviews, urine and blood specimens, and physical examinations: the Social Environment and Biomarkers of Aging Study (SEBAS) in Taiwan, the Wisconsin Longitudinal Survey (WLS), and the MacArthur studies of successful aging. The outcomes comprise six indicators of cardiovascular risk (total/high-density lipoprotein [HDL] cholesterol, HDL cholesterol, systolic and diastolic blood pressure, glycosylated hemoglobin, and waist/hip ratio) and four markers of sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis functioning (epinephrine, norepinephrine, cortisol, and dehydroepiandrosterone sulfate [DHEA-S]). RESULTS U.S. males have significantly higher risk than females for all indicators of cardiovascular risk except glycosylated hemoglobin (p < 0.05). Sex differences are less consistent and smaller in Taiwan. Indicators of SNS and HPA axis functioning reveal a significant female disadvantage in both countries. CONCLUSIONS The analysis identifies important sex differences between Taiwan and the United States in biomarkers of cardiovascular risk that are consistent with cause of death data and may emanate from cultural and social differences between the two societies. The similarity of sex differences in SNS and HPA axis functioning across studies may reflect either stable sex differences in biological aging of these axes or commonalities in the social construction of gender-based responses to life experiences.

Disability, participation, and subjective wellbeing among older couples

This paper investigates the link between disability and subjective wellbeing, using data from the 2009 Disability and Use of Time supplement to the Panel Study of Income Dynamics, the longest running national panel study in the United States. Disability is construed broadly to include both the presence of any physical, cognitive, or sensory impairment or activity limitation and also the severity of underlying impairments. Subjective wellbeing is measured using two distinct approaches: reports of life satisfaction and of moment-to-moment wellbeing-both positive and negative-on the previous day. The latter, collected through 24-h time diaries, also offers for the first time the ability to explore the role of participation in particular kinds of activities linking disability to subjective wellbeing. The analytic sample included married persons ages 60 and older and their spouses (n = 751 married individuals) who completed 1498 diaries. Several new findings emerged: no matter what the measure of wellbeing, older married adults with disability report worse subjective wellbeing than those without, and neither different demographic and socioeconomic profiles nor differences in participation fully account for these disparities. Influences of disability on global life satisfaction and episodic reports of happiness were relatively small and of comparable size. However, notably sizeable differences were identified in the cumulative number of pleasant minutes experienced yesterday by disability status - on the order of 71 fewer minutes on average for those with a disability of average severity. Differences appear to be more strongly linked to somatic symptoms of pain and feeling tired than to differential intensity of experiencing happiness, sadness, frustration, or worry. We also found limited support for the notion that participation partially mediates the relationship between disability and global, but not episodic, subjective wellbeing.

Reliability and Validity of Self-Care and Mobility Accommodations Measures in the National Health and Aging Trends Study

PURPOSE OF THE STUDY Comprehensive measures of disability accommodations have been lacking in national health and aging studies. This article introduces measures of accommodations developed for the National Health and Aging Trends Study, evaluates their reliability, and explores the validity and reliability of hierarchical classification schemes derived from these measures. DESIGN AND METHODS We examined test-retest reliability for questions about assistive device use, doing activities less often, and getting help from another person with both percentage agreement and kappa (N = 111). Summary measures across activities and several hierarchical classification schemes (e.g., no accommodation, devices/activity reductions only, help) were developed. For the latter, we also evaluated validity by examining correlations with measures of capacity and demographic characteristics (N = 326). RESULTS Items about assistive device use and help in the last month were robust (most kappas 0.7-0.9). Activity reduction measures were moderately reliable (around 0.5) but still showed reasonable agreement. Reliabilities for summary measures were good for device use (0.78-0.89) and help (0.62-0.67) but lower, albeit acceptable, for activity reduction (0.53). Hierarchical classifications had acceptable reliability and levels demonstrated hierarchical properties. IMPLICATIONS National Health and Aging Trends Studys self-care and mobility accommodation measures offer ample reliability to study adaptation to limitations and can be used to construct a reliable and valid hierarchy.

Demographic and Socioeconomic Status Differences in Perceptions of Difficulty With Mobility in Late Life

OBJECTIVES This study assesses whether socioeconomic and demographic differences in reported mobility limitations are attributable to differential perceptions of mobility difficulty that result in the differential use of response categories. METHODS Data come from the Social Environment and Biomarkers of Aging Study and its parent study, the Taiwan Longitudinal Study of Aging. Ordered probit models with person-specific cut-points are used to test whether, after controlling for underlying mobility using objective performance measures, cut-points for reporting mobility limitations vary across groups defined by demographic and socioeconomic characteristics. RESULTS Age is the only characteristic that is consistently associated with the location of the cut-points for reporting mobility difficulty: At the same level of underlying mobility difficulty, older adults are more likely than younger adults are to report difficulty with all tasks except short walks. Other variables showed differences but only for one specific activity, for example, urban residents are more likely to report difficulty running than are rural residents with the same underlying level of mobility function. DISCUSSION For most mobility activities, there are no systematic differences in the perception of difficulty by individual characteristics. Thus, for older Taiwanese adults, differences in mobility limitations associated with socioeconomic status are more likely to reflect underlying differences in function than differences in how these groups report the same capacity. The usual loss of mobility with age, however, reflects both a decrease in capacity and a lowering of the threshold for reporting difficulty.

Socioeconomic Status and Biological Markers of Health An Examination of Adults in the United States and Taiwan

Objective: The study documents whether socioeconomic status (SES) differentials in biological risk are more widely observed and larger in the United States than Taiwan. Method: Data come from the Social Environment and Biomarkers of Aging Study in Taiwan and the Midlife in the United States study. We use regression analyses to test whether four summary measures of biological risk are significantly related to categorical measures of education, income, and subjective social status among four country–sex-specific subgroups. Results: Physiological dysregulation is significantly, negatively related to SES in both the United States and Taiwan, especially for males. The prevalence and magnitude of the relationships are similar in the two countries: 12 of 24 possible SES–biological summary score relationships are significant in the United States and 11 of 24 are significant in Taiwan. Discussion: Overall, SES differentials in biological risk do not appear to be more widely observed or larger in the United States than in Taiwan.