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Introduction: "Frailty" has attracted attention for its promise of identifying vulnerable older adults, hence its potential use to better tailor geriatric health care. There remains substantial controversy, however, regarding its nature and ascertainment. Recent years have seen a proliferation of frailty assessment methods. We argue that the development of frailty assessments should be grounded in "validation"-the process of substantiating that a measurement accurately and precisely measures what it intends, identify unresolved measurement issues, and highlight measurement-related considerations for clinical practice.Methods: Principles for validating frailty measures are elucidated. We follow principles-articulated, for example, by Borsboom-in which a construct must be clearly defined and then analyses undertaken to substantiate that a measurement accurately and precisely measures what it intends. Key elements are content validity, criterion validity, and construct validity, with an emphasis on the latter.Results: We illustrate the principles for a physical frailty phenotype construct.Conclusions: Unresolved conceptual issues include the roles of intersecting concepts such as cognition, disease severity, and disability in frailty measurement, conceptualization of frailty as a state versus a continuum, and the potential need for dynamic measures and systems concepts in furthering understanding of frailty. Clinical considerations include needs to distinguish interventions designed to address frailty "symptoms" versus underlying physiology, improve "prefrailty" measures intended to screen individuals early in their frailty progression, address feasibility demands, and further visioning followed by rigorous efficacy research to address the landscape of potential uses of frailty assessment in clinical practice. [ABSTRACT FROM AUTHOR]

Objective To investigate the psychosocial etiology of physical frailty by examining the influence of chronic stress and perceived control. Method Using population-based samples of older adults from the Health and Retirement Study, this study employed structural equation modeling in cross-sectional (N = 5,250) and longitudinal (N = 2,013) samples to estimate the effects of chronic stress and socioeconomic status (SES) on baseline frailty and change in frailty status over 4 years and the extent to which perceived control mediates or moderates effects of chronic stress. Results Perceived control fully mediated effects of chronic stress and partially mediated effects of SES on both baseline frailty and change in frailty. Multigroup analyses revealed that the mediating role of perceived control was consistent across age, gender, and racial/ethnic subgroups. There was no evidence to support a moderating role of perceived control in the chronic stress and frailty relationship. Discussion Findings provide novel evidence for a mediating role of perceived control in pathways linking SES and chronic stress to frailty, further underscoring the importance of psychosocial constructs to the development and progression of frailty in older adults. [ABSTRACT FROM AUTHOR]

Background: Frailty assessment provides a means of identifying older adults most vulnerable to adverse outcomes. Attention to frailty in clinical practice is more likely with better understanding of its prevalence and associations with patient characteristics. We sought to provide national estimates of frailty in older people.Methods: A popular, validated frailty phenotype proposed by Fried and colleagues was applied to 7,439 participants in the 2011 baseline of the National Health and Aging Trends Study, a national longitudinal study of persons aged 65 and older. All measures drew on a 2-hour in-person interview. Weighted estimates of frailty prevalence were obtained.Results: Fifteen percent (95% CI: 14%, 16%) of the older non-nursing home population is frail, and 45% is prefrail (95% CI: 44%, 47%). Frailty is more prevalent at older ages, among women, racial and ethnic minorities, those in supportive residential settings, and persons of lower income. Independently of these characteristics, frailty prevalence varies substantially across geographic regions. Chronic disease and disability prevalence increase steeply with frailty. Among the frail, 42% were hospitalized in the previous year, compared to 22% of the prefrail and 11% of persons considered robust. Hip, back, and heart surgery in the last year were associated with frailty. Over half of frail persons had a fall in the previous year.Conclusions: Our findings support the importance of frailty in late-life health etiology and potential value of frailty as a marker of risk for adverse health outcomes and as a means of identifying opportunities for intervention in clinical practice and public health policy. [ABSTRACT FROM AUTHOR]

Objectives. Studies of late-life disablement typically address the role of advancing age as a factor in developing disability, and in some cases have pointed out the importance of time to death (TTD) in understanding changes in functioning. However, few studies have addressed both factors simultaneously, and none have dealt satisfactorily with the problem of missing data on TTD in panel studies. Methods. We fit latent-class trajectory models of disablement using data from the Health and Retirement Study. Among survivors (~20% of the sample), TTD is unknown, producing a missingdata problem. We use an auxiliary regression equation to impute TTD and employ multiple imputation techniques to obtain final parameter estimates and standard errors. Results. Our best-fitting model has 3 latent classes. In all 3 classes, the probability of having a disability increases with nearness to death; however, in only 2 of the 3 classes is age associated with disability. We find gender, race, and educational differences in class-membership probabilities. Discussion. The model reveals a complex pattern of age- and time-dependent heterogeneity in late-life disablement. The techniques developed here could be applied to other phenomena known to depend on TTD, such as cognitive change, weight loss, and health care spending. [ABSTRACT FROM AUTHOR]

Purpose: A primary goal for aging policy is to optimize independence in later life. We estimate the cross-sectional association between physical and social challenge in the home environment and use of assistive devices (AD) for mobility in the home, controlling for lower extremity physical performance (short physical performance battery [SPPB]) and other factors. Design and Methods: Data are from the Women’s Health and Aging Study I, a prospective study of the factors related to physical disability in a sample of moderately to severely disabled older women. We describe these associations in the baseline sample overall and also within subsets who do and do not have both a baseline and a 3-year follow-up observation. Results: On average, physical challenge in the home environment is inversely associated with level of AD use (p < .05) in the overall sample, independent of SPPB, living alone, and other factors. We do not find a significant (p < .05) association between social challenge and the level of AD use in the overall sample. Findings by follow-up responder status were similar (with minor variability). Implications: Future cohorts who are better educated and more receptive to technology may confront challenges in the home environment that limit their ability to age in place. Our findings suggest that the physical challenges of the home are significantly related to AD use. Future analyses that explore the mechanisms of the home environment as a source of challenges to independent functioning could help in the design of future interventions for these cohorts as they age. [ABSTRACT FROM PUBLISHER]

Few studies have addressed changes in physical activity participation over time among the elderly. The authors hypothesized that there were distinct trajectories of physical activity level over time and identifiable predictors of such trajectories, as well as that the maintenance of regular physical activity, even below recommended levels, was associated with lower mortality risk. Using longitudinal data (1994–2009) from 433 initially high-functioning older women aged 70–79 years at baseline, a joint latent class and survival mixture model identified 4 activity trajectory classes: always active (16.6%), fast declining (19.2%), stable moderate (32.3%), and always sedentary (31.9%). Obesity, coronary artery disease, chronic obstructive pulmonary disease, depressive symptoms, low self-efficacy, mobility disability, and low energy were associated with sedentary behavior and/or a fast decline in activity. Women in the fast declining and always sedentary classes had hazard ratios for death of 2.34 (95% confidence interval: 1.20, 4.59) and 3.34 (95% confidence interval: 1.72, 6.47), respectively, compared with the always active class; no mortality difference was found between the stable moderate and always active groups (hazard ratio = 1.24, 95% confidence interval: 0.63, 2.47). Our findings suggest that physical activity does not have to be vigorous to be beneficial and that the gain may be the greatest among women who reported the lowest levels of activity. [ABSTRACT FROM PUBLISHER]

Background. Few studies focus on "preclinical" warning signs associated with mortality. In this article, we investigate associations between all-cause mortality and two clusters of biological risk factors: (i) standard clinical measures related to cardiovascular disease and metabolic function; and (ii) nonclinical measures pertaining to hypothalamic-pituitary-adrenal axis activity, sympathetic nervous system activity, and inflammatory response. Methods. Data come from the 2000 Social Environment and Biomarkers of Aging Stud,. a national sample of Taiwanese persons aged 54 years or older; 1497 persons were interviewed in their homes, and 1023 participated in a hospital examination. The analysis is based on 927 respondents with complete information. Logistic regression models describe the association between biomarkers and the 3-year probability of dying. Results. Although both groups of biomarkers are significantly associated with mortality, the model with neuroendocrine and immune biomarkers has better explanatory and discriminatory power than the one with clinical measures. The association between these nonclinical measures and mortality remains strong after adjustment for the clinical markers, suggesting that the physiological effects of the nonclinical biomarkers are broader than those captured by the cardiovascular and metabolic system measures included here. Conclusions. Nonclinical markers are likely to provide warning signs of deteriorating health and function beyond what can be learned from conventional markers. Our findings are consistent with those of recent studies that (i) demonstrate the importance of neuroendocrine and immune system markers for survival, and (ii) indicate that standard clinical variables are less predictive of mortality in older than in younger populations. [ABSTRACT FROM AUTHOR]

We investigate how biological markers of individual responses to stressful experiences are associated with profiles of physical and mental functioning in a national sample of middle-aged and elderly Taiwanese. Data come from a population-based sample of middle-aged and elderly Taiwanese in 2000. The data combine rich biological measures with self-reported information on physical and mental health. Grade of membership methods are used to summarize functional status, and multinomial logit models provide information on the association between biological measures and function. The analysis identifies significant associations between biomarkers of stressful experience and profiles of physical and mental functioning. The estimates reveal the potential importance for health of both low and high values of biological parameters. The findings point to directions for future research regarding development of aggregate measures of cumulative dysregulation across multiple physiological systems. [ABSTRACT FROM AUTHOR]

The authors comment on the connection between remaining lifetime and the trajectory of late-life disability. Few critics have argued that using time to death (TTD) as a predictor of disability confuses the direction of causality. They said the author's our approach to imputation of TTD among censored observations is not valid because TTD is not missing at random (MAR).