Decrease in the relative heterogeneity of health with age: A cross-national comparison

Sex differences in the relative heterogeneity of frailty in relation to age, frailty, health protection, and five-year mortality

BACKGROUND

Previous studies have suggested that the relative heterogeneity of frailty declines with increases in age and the level of the frailty index (FI). In this study, we investigated the sex difference in the relative heterogeneity of frailty and its response to health-protective factors, in a Chinese community sample.

METHODS

Data used for this secondary analysis were obtained from the Beijing Longitudinal Study of Aging that involved 3257 community-dwelling Chinese people aged 55 years and older at baseline. An FI was constructed for each indicial using 35 variables assessing health-related problems. A protection index (PI) consisting of 27 variables assessing lifestyle and social engagement was also built. The relative heterogeneity of frailty, as measured by the coefficient of variation (CV) of the FI, was calculated as the ratio of the standard deviation to the mean FI for different age, FI, and PI groups, and for the five-year survival status.

RESULTS

The CV decreased with the increase in age (F = 20.60, P = .006) and the FI (F = 57.59, P = .001), consistent in both sexes. In each age group, the CV was higher in men than in women (t = 3.25, P = .018). A great level of protection was associated with a significantly reduced mortality, and an increased CV (t = 2.91, P = .027).

CONCLUSIONS

Our data demonstrate that a gender difference exists in the relative heterogeneity of frailty, which is negatively related to age and frailty as well as positively associated with health protection and the five-year survival.

Androgen effects on skeletal muscle: implications for the development and management of frailty

Androgens have potent anabolic effects on skeletal muscle and decline with age in parallel to losses in muscle mass and strength. This loss of muscle mass and function, known as sarcopenia, is the central event in development of frailty, the vulnerable health status that presages adverse outcomes and rapid functional decline in older adults. The potential role of falling androgen levels in the development of frailty and their utility as function promoting therapies in older men has therefore attracted considerable attention. This review summarizes current concepts and definitions in muscle ageing, sarcopenia and frailty, and evaluates recent developments in the study of androgens and frailty. Current evidence from observational and interventional studies strongly supports an effect of androgens on muscle mass in ageing men, but effects on muscle strength and particularly physical function have been less clear. Androgen treatment has been generally well–tolerated in studies of older men, but concerns remain over higher dose treatments and use in populations with high cardiovascular risk. The first trials of selective androgen receptor modulators (SARMs) suggest similar effects on muscle mass and function to traditional androgen therapies in older adults. Important future directions include the use of these agents in combination with exercise training to promote functional ability across different populations of older adults, as well as more focus on the relationships between concurrent changes in hormone levels, body composition and physical function in observational studies.

What age trajectories of cumulative deficits and medical costs tell us about individual aging and mortality risk: Findings from the NLTCS-Medicare data

An important feature of aging-related deterioration in human health is the decline in organisms' resistance to stresses, which contributes to an increase in morbidity and mortality risks. In human longitudinal studies of aging, such a decline is not measured directly, so indirect methods of statistical modeling have to be used for evaluating this characteristic. Since medical interventions reflect severity of occurring health disorders, data from Medicare service use files can be used for such modeling. In this paper, we use the National Long Term Care Survey (NLTCS) data merged with the Medicare service use files to investigate dynamics of stress resistance in the U.S. elderly. We constructed individual indices of cumulative deficits and medical costs and investigated their separate and joint effects on dynamics of mortality risks using the quadratic hazard model (QHM). We found that males show a faster decline in stress resistance with age than females.

How should we grade frailty in nursing home patients?

OBJECTIVES

To compare 3 methods of describing the frailty of older adults in nursing homes.

DESIGN

Secondary analysis of a prospective cohort study.

SETTING

Canadian long-term care institutions.

PARTICIPANTS

Institutionalized older adults in the second clinical examination cohort of the Canadian Study of Health and Aging (CSHA-2; n = 728).

MEASURES

Frailty was measured using the Cardiovascular Health Survey definition (Frail-CHS); the CSHA- Clinical Frailty Scale (CSHA-CFS) and a frailty index (FI).

RESULTS

The sample was very elderly (87.7 +/- 6.7 years), disabled (83%), and showed a high level of mobility impairment (83%). Each frailty measure correlated moderately well with each other (0.61-0.71) and with a disability measure (-0.45 to -0.53) but only weakly with age (0.13-0.19). By each measure, frailty was significantly associated (P < .01) with an increased risk of mortality, disability and cognitive decline. In a model that included both the frailty-CHS definition and the Frailty Index only the latter was associated with a higher risk of mortality (P < .01 for FI, P = .18 for Frail-CHS) and decline in the 3MS (P < .01 for FI, P = .20 for the Frail-CHS definition). Both measures were significantly associated with new onset disability (P < .01). Similar results were found when both the CSHA-CFS and Frailty Index were included in the models. Random combinations of 15 variables used to make up alternate 5-item Frail-CHS definitions showed that any stratification based on 5 variables allowed tertiles of risk to be discriminated.

CONCLUSIONS

Frailty is a robust concept and however defined, elderly people who are frail have worse outcomes than those who are not frail. The 3 measures showed varying ability to express grades of frailty.

A comparison of two approaches to measuring frailty in elderly people

BACKGROUND

Many definitions of frailty exist, but few have been directly compared. We compared the relationship between a definition of frailty based on a specific phenotype with one based on an index of deficit accumulation.

METHODS

The data come from all 2305 people 70 years old and older who composed the clinical examination cohort of the second wave of the Canadian Study of Health and Aging. We tested convergent validity by correlating the measures with each other and with other health status measures, and analyzed cumulative index distributions in relation to phenotype. To test criterion validity, we evaluated survival (institutionalization and all-cause mortality) by frailty index (FI) score, stratified by the phenotypic definitions as "robust," "pre-frail," and "frail."

RESULTS

The measures correlated moderately well with each other (R=0.65) and with measures of function (phenotypic definition R=0.66; FI R=0.73) but less well with cognition (phenotypic definition R=-0.35; FI R=-0.58). The median FI scores increased from 0.12 for the robust to 0.30 for the pre-frail and 0.44 for the frail. Survival was also lower with increasing frailty, and institutionalization was more common, but within each phenotypic class, there were marked differences in outcomes based on the FI values-e.g., among robust people, the median 5-year survival for those with lower FI values was 85%, compared with 55% for those with higher FI values.

CONCLUSION

The phenotypic definition of frailty, which offers ready clinical operationalization, discriminates broad levels of risk. The FI requires additional clinical translation, but allows the risk of adverse outcomes to be defined more precisely.

Cumulative index of elderly disorders and its dynamic contribution to mortality and longevity

The composite index constructed from longitudinal survey data as the level of deficits accumulated by an individual (frailty index) captures important systemic aspects of deterioration in a human organism, and is an attractive candidate for studying determinants of aging and longevity. The objective of this paper was to investigate the ability of this index to characterize human aging, mortality, and longevity. We use 32 variables from the National Long Term Care Survey data characterizing health and daily activities deficits to construct the cumulative frailty index. We use the Cox's proportional hazard model to describe its contribution to mortality. The risk of death considered as the function of the frailty index has asymmetric U-shaped form. The asymmetric U-function of the absolute risk is getting steeper (narrower) with age. The asymmetric U-function describing the relative risk exhibits the opposite tendency with age. The narrowing of the absolute risk functions with age reflects the age-related decline in stress resistance. The widening of the relative risk function with age indicates an increase in the relative contribution of other, unobserved, risk factors (including senescence) to the risk of death. This suggests increasing the role of senescence per se in the increasing risk of death with age compared to the role of specific pathology.

Frailty in Relation to the Accumulation of Deficits

This review article summarizes how frailty can be considered in relation to deficit accumulation. Recalling that frailty is an age-associated, nonspecific vulnerability, we consider symptoms, signs, diseases, and disabilities as deficits, which are combined in a frailty index. An individual's frailty index score reflects the proportion of potential deficits present in that person, and indicates the likelihood that frailty is present. Although based on a simple count, the frailty index shows several interesting properties, including a characteristic rate of accumulation, a submaximal limit, and characteristic changes with age in its distribution. The frailty index, as a state variable, is able to quantitatively summarize vulnerability. Future studies include the application of network analyses and stochastic analytical techniques to the evaluation of the frailty index and the description of other state variables in relation to frailty.

Accelerated accumulation of health deficits as a characteristic of aging

Cross-sectional analyses show that an index of aging-associated health/well-being deficits, called the "frailty index", can characterize the aging process in humans. This study provides support for such characterization from a longitudinal analysis of the frailty index properties. The data are from the National Long Term Care Survey assessed longitudinally health and functioning of the U.S. elderly in the period 1982-1999. In cross-sectional analysis, the frailty index exhibits accelerated increase with age till oldest-old ages (95+), with possible deceleration thereafter. Longitudinal analysis confirms the accelerated accumulation of deficits in aging individuals. The time-dynamics of the frailty index is affected by two sex-sensitive processes: (i) selection of robust individuals, resulting in a decline of the mean frailty index with age and (ii) accumulation of deficits associated with physiological aging and its interaction with environment, which results in an accelerated increase of individual frailty index prior to death irrespective of chronological age. Current frailty index levels in individuals are more predictive of death than the index past values. Longitudinal analysis provides strong evidence that the cumulative index of health/well-being deficits can characterize aging-associated processes in humans and predict death better than chronological age during short-term periods.

Frailty and survival of rural and urban seniors: results from the Canadian Study of Health and Aging

BACKGROUND AND AIMS

Relatively little is known about how region of residence influences frailty of seniors. Frailty indexes can be used to investigate these effects. We constructed and validated a frailty index, to investigate the differences in health status between rural and urban seniors.

METHODS

We studied rural (n=949) and urban (n=7598) older adults in the Canadian Study of Health and Aging, of whom 22% died over 72 months. The frailty index was generated from 40 self-reported health deficits (symptoms, diseases, disabilities, unfavourable living conditions).

RESULTS

The average value of the frailty index increased exponentially with age in both groups (rural: r=0.94; urban: r=0.97, p<0.01) and was highly correlated with mortality (r=0.96 for rural, r=0.97 for urban, p<0.01). Up to age 80, there were few rural-urban differences in frailty. After age 80, the rural sample showed higher mortality than the urban sample. The hazard ratio for death for each increment in the frailty index was 1.38 (1.14-1.72) in rural participants vs 1.18 (1.11-1.26) in urban participants. Women lived longer than men at any index value.

CONCLUSIONS

Frailty index analysis readily summarizes health and mortality differences between very old rural and urban dwellers, which reflect differences in deficit accumulation, and in the impact of gender on survival. The frailty index provides efficient dimensionality reduction for studying group differences in the health of older adults.

Health decline, aging and mortality: how are they related?

The deterioration of human health with age is manifested in changes of thousands of physiological and biological variables. The contribution of some of such changes to the mortality risk may be small and cannot be reliably detected by existing statistical methods. A cumulative index of health/well-being disorders, which counts changes in observed variables on the way of losing health, may be an appropriate way to take the effects of such variables into account. In this paper we investigate regularities of the aging-related changes in human health/well-being/survival status described by such an index using the new version of the quadratic hazard model of human aging and mortality. We found that the shape and the location of the mortality risk, considered as a function of the introduced health-related index, changes with age reflecting the decline in stress resistance and the age-dependence of the "optimal" health/well-being status. Comparison of these results with findings from early studies using the Cox's-like model of risk function indicates that the results are likely to describe regularities of deterioration in human health during the aging process.

Accumulation of health disorders as a systemic measure of aging: Findings from the NLTCS data

BACKGROUND

An index of age-associated health/well-being disorders (deficits), called the "frailty index" (FI), appears to be a promising characteristic to capture dynamic variability in aging manifestations among age-peers. In this study we provide further support toward this view focusing on the analysis of the FI age patterns in the participants of the National Long Term Care Survey (NLTCS).

METHODS

The NLTCS assessed health and functioning of the U.S. elderly in 1982, 1984, 1989, 1994, and 1999. Detailed information for our sample was assessed from about 26,700 interviews. The individual FI is defined as a proportion of health deficits for a given person.

RESULTS

The FI in the NLTCS exhibits accelerated age patterns. The acceleration is larger for elderly who, at younger ages, had a lower FI (low FI group) than for those who showed a higher FI at younger ages (high FI group). Age-patterns for low and high FI groups tend to converge at advanced ages. The rate of deficit accumulation is sex-sensitive.

CONCLUSIONS

The accelerated FI age patterns suggest that FI can be considered as a systemic measure of aging process. Convergence of the (sex-specific) FI age patterns for low and high FI groups by extreme ages might reflect the limit of the FI-specific (or systemic) age as well as the limit of adaptation capacity in aging individuals.

Limits to deficit accumulation in elderly people

We evaluated limits to the accumulation of deficits (symptoms, diseases, disabilities) for 33,069 people aged 65+ years. We combined deficits in a frailty index (theoretical range 0-1) and found that the 99% limit varied little between samples, representing a frailty index value of about 0.65 +/- 0.05. This near-maximum shows no relationship with age. It is the same in community and institutional samples, even though the mean value is much higher in the latter. The data suggest a level of frailty beyond which, even in developed countries, further deficit accumulation is not sustainable.

Going from bad to worse: a stochastic model of transitions in deficit accumulation, in relation to mortality

As people age, they accumulate deficits. The more deficits they accumulate, the greater their vulnerability, which can be expressed as the probability to accumulate even more deficits, or to die. The probability of death is known to be exponentially related to the number of deficits. Using data from elderly (aged 65 + years) participants in the Canadian Study of Health and Aging (n = 9008), we investigated the relationship between the number of deficits and the change in the number of deficits over two successive 5 year intervals. We show that the probabilities of changes in the number of deficits, in relation to baseline, are well fitted (R(2) > 0.98) by a simple distribution, with two parameters. The model suggests a maximum to deficit accumulation, and illustrates no level of deficit accumulation at which there is a net gain in fitness. Age-related deficit accumulation is highly characteristic, and can be modeled as a stochastic process with readily interpretable parameters.