The effect of prior disability history on subsequent functional transitions

Comorbidities, healthcare use, and contact with healthcare transition services in older veterans after incarceration

BACKGROUND

The Health Care for Reentry Veterans (HCRV) program was established to support community reintegration for veterans after incarceration. Yet, it is unclear how those with and without HCRV contact differ. We sought to evaluate differences in medical and psychiatric conditions and healthcare utilization among mid-to late-life reentry veterans who did and did not receive HCRV outreach.

METHODS

Study participants were veterans aged ≥50 years who qualified for Medicare fee-for-service, had experienced incarceration for ≥1 year, and were released from incarceration between October 1, 2006, and September 30, 2018 (N = 9733). Using VA and Medicare claims data, we compared prevalence of medical and psychiatric diagnoses, and use of emergency, inpatient, and outpatient medical and mental health services up to 12 months after release between those with and without HCRV contact.

RESULTS

Veterans with HCRV contact (35.5%) had significantly higher rates of psychiatric conditions and medical conditions related to substance use (e.g., liver disease) compared to veterans without HCRV contact. Average time between release and first healthcare service use was significantly lower for HCRV veterans (36.5 ± SD 59.5 days) versus non-HCRV veterans (58.9 ± SD 77.5 days) and HCRV veterans were more likely to utilize the emergency department, inpatient and outpatient mental health services, and inpatient medical services.

CONCLUSION

HCRV reaches older reentry veterans with a large burden of mental health and substance use disorders. However, levels of multimorbidity were high among all older reentry veterans, pointing to a need to develop specialized geriatric models of care for this reentry population.

Cohort Profile: The Precipitating Events Project (PEP Study)

The Precipitating Events Project (PEP Study) is an ongoing longitudinal study of 754 nondisabled community-living persons age 70 years or older who were members of a large health plan in greater New Haven, Connecticut, USA. The study was established to rigorously evaluate the epidemiology of disability in older persons and to elucidate the role of intervening illnesses and injuries on the disabling process. Of the eligible members, 75.2% agreed to participate and were enrolled between March 1998 and October 1999. Participants have completed comprehensive home-based assessments at 18-month intervals and have been interviewed monthly over the phone with a completion rate of 99%. Detailed participant-level data on health care utilization are obtained annually through linkages with Medicare claims. Through June 2019, 702 (93.1%) participants have died after a median of 109 months, while 43 (5.7%) have dropped out of the study after a median of 27 months. Death certificates are available for all decedents. To date, 117 original reports have been published using data from the PEP Study, including many focusing on other high priority areas such as end of life, frailty, depressive symptoms, aging stereotypes, pain, sleep, and methodologic research. The PEP Study welcomes proposals to access data for meritorious analyses from qualified investigators.

A Longitudinal Study Examining the Change in Functional Independence Over Time in Elderly Individuals With a Functioning Kidney Transplant

Background:

Functional disability is defined as the need for assistance with self-care tasks.

Objective:

To document changes in functional status over time among older prevalent renal transplant recipients.

Design:

Single center, prospective, follow-up study.

Setting:

Single center, tertiary care transplant center.

Patients:

Patients, with a functioning kidney transplant, aged 65 years or older who underwent assessment of functional status approximately 12 months previously.

Measurements:

Validated tools used included Barthel Index, the Lawton-Brody Scale of Instrumental Activities of Daily Living, the Timed Up and Go test, the Veterans Specific Activity Questionnaire, the Mini-Cog, and dynamometer handgrip strength.

Methods:

Outpatient assessment by a trained observer.

Results:

Of the 82 patients previously studied, 64 (78%) patients participated in the follow-up study (mean age 70.5 ± 4.4 years, 58% male, 55% diabetic). Among those completing functional status measures, 32 (50%) had functional disability at baseline. Over the 1-year period, 11 (17%) of these patients experienced progressive functional decline, 6 (9%) exhibited no change, and 15 (23%) had functional recovery. Eleven patients (17%) initially independent, developed new-onset disability. One of the strongest predictors of progressive functional decline was having 1 or more falls in the previous year.

Limitations:

Assessments were performed only on 2 occasions separated by approximately 1 year.

Conclusions:

Fluctuations in disability states are common among older adults living with renal transplants. Episodes of functional disability may place individuals at higher risk of persistent and/or progressive disability.

Disability Experience and Measurement

Top themes of international research on disability in the past three decades are discussed: disability dynamics, buffers and barriers for disability, disability trends, and disability among very old persons. Each theme is highlighted by research examples. Turning to measurement, I discuss traditional measures of disability, new longer and shorter ones, and composites like disability-free life expectancy, noting their merits. Contemporary models of disability are presented, ranging from visual images to formal theories. The article ends on how scientists can facilitate movement of disability science into health care practice and policy.

Reducing the Shared Burden of Chronic Conditions among Persons Aging with Disability and Older Adults in the United States through Bridging Aging and Disability

Persons aging with long-term disabilities such as spinal cord injury or multiple sclerosis and older adults share similar chronic conditions in mid and later life in the United States. The rising general interest and more prevalent federal requirements for use of evidence-based practices (EBP) in health promotion and chronic condition interventions highlight the gap between demand and the availability of EBPs for persons aging with disability in particular. Addressing this gap will require focused efforts that will benefit substantially by bridging the fields of aging and disability/rehabilitation to develop new EBPs, translate existing EBPs across populations, and borrow best practices across fields where there are few current EBPs. Understanding distinctions between disability-related secondary conditions and age-related chronic conditions is a first step in identifying shared conditions that are important to address for both mid-life and older adults with disabilities. This review articulates these distinctions, describes shared conditions, and discusses the current lack of EBPs for both populations. It also provides recommendations for bridging activities in the United States by researchers, professionals, and consumer advocates. We argue that these can more efficiently move research and practice than if activities were undertaken separately in each field (aging and disability/rehabilitation).

Cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people: Results of a cluster randomized trial

Objective

To evaluate the cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people in comparison with usual care.

Methods

We conducted cost-effectiveness and cost-utility analyses alongside a cluster randomized trial with one-year follow-up. Participants were aged ≥ 70 years and at increased risk of functional decline. Participants in the intervention group (n = 1209) received a comprehensive geriatric assessment and individually tailored multifactorial interventions coordinated by a community-care registered nurse with multiple follow-up visits. The control group (n = 1074) received usual care. Costs were assessed from a healthcare perspective. Outcome measures included disability (modified Katz-Activities of Daily Living (ADL) index score), and quality-adjusted life-years (QALYs). Statistical uncertainty surrounding Incremental Cost-Effectiveness Ratios (ICERs) was estimated using bootstrapped bivariate regression models while adjusting for confounders.

Results

There were no statistically significant differences in Katz-ADL index score and QALYs between the two groups. Total mean costs were significantly higher in the intervention group (EUR 6518 (SE 472) compared with usual care (EUR 5214 (SE 338); adjusted mean difference €1457 (95% CI: 572; 2537). Cost-effectiveness acceptability curves showed that the maximum probability of the intervention being cost-effective was 0.14 at a willingness to pay (WTP) of EUR 50,000 per one point improvement on the Katz-ADL index score and 0.04 at a WTP of EUR 50,000 per QALY gained.

Conclusion

The current intervention was not cost-effective compared to usual care to prevent or postpone new disabilities over a one-year period. Based on these findings, implementation of the evaluated multifactorial nurse-led care model is not to be recommended.

Aging With Disability for Midlife and Older Adults

This analysis brings “aging with disability” into middle and older ages. We study U.S. adults ages 51+ and ages 65+ with persistent disability (physical, household management, personal care; physical limitations, instrumental activities of daily living [IADLs], activities of daily living [ADLs]), using Health and Retirement Study data. Two complementary approaches are used to identify persons with persistent disability, one based directly on observed data and the other on latent classes. Both approaches show that persistent disability is more common for persons ages 65+ than ages 51+ and more common for physical limitations than IADLs and ADLs. People with persistent disability have social and health disadvantages compared to people with other longitudinal experiences. The analysis integrates two research avenues, aging with disability and disability trajectories. It gives empirical heft to government efforts to make aging with disability an age-free (all ages) rather than age-targeted (children and youths) perspective.

Reversible States of Physical and/or Cognitive Dysfunction: A 9-Year Longitudinal Study

OBJECTIVES

To determine 1) age-adjusted transition probabilities to worsening physical/cognitive function states, reversal to normal cognition/physical function, or maintenance of normal state; 2) whether these transitions are modulated by sex, BMI, education, hypertension (HTN), health status, or APOE4; 3) whether worsening gait speed preceded cognition change, or vice versa.

DESIGN

Analysis of 9-year prospective cohort data from the New Mexico Aging Process Study.

SETTING

Healthy independent-living adults.

PARTICIPANTS

60+ years of age (n= 598).

MEASUREMENTS

Gait speed, cognitive function (3MSE score), APOE4, HTN, BMI, education, health status.

RESULTS

Over 9 years, 2129 one-year transitions were observed. 32.6% stayed in the same state, while gait speed and cognitive function (3MSE scores) improved for 38% and 43% of participants per year, respectively. Transitions to improved function decreased with age (P< 0.001), APOE4 status (P=0.02), BMI (P=0.009), and health status (P=0.009). Transitions to worse function were significantly increased for the same factors (all P<0.05). Times to lower gait speed and cognitive function did not precede each other (P=0.91).

CONCLUSIONS

Transitions in gait speed and cognition were mutable with substantial likelihood of transition to improvement in physical and cognitive function even in oldest-old, which may have clinical implications for treatment interventions.

Effects of Nurse-Led Multifactorial Care to Prevent Disability in Community-Living Older People: Cluster Randomized Trial

BACKGROUND

To evaluate the effects of nurse-led multifactorial care to prevent disability in community-living older people.

METHODS

In a cluster randomized trail, 11 practices (n = 1,209 participants) were randomized to the intervention group, and 13 practices (n = 1,074 participants) were randomized to the control group. Participants aged ≥ 70 years were at increased risk of functional decline based on a score ≥ 2 points on the Identification of Seniors at Risk- Primary Care, ISAR-PC. Participants in the intervention group received a systematic comprehensive geriatric assessment, and individually tailored multifactorial interventions coordinated by a trained community-care registered nurse (CCRN) with multiple follow-up home visits. The primary outcome was the participant's disability as measured by the modified Katz activities of daily living (ADL) index score (range 0-15) at one year follow-up. Secondary outcomes were health-related quality of life, hospitalization, and mortality.

RESULTS

At baseline, the median age was 82.7 years (IQR 77.0-87.1), the median modified Katz-ADL index score was 2 (IQR 1-5) points in the intervention group and 3 (IQR 1-5) points in the control group. The follow-up rate was 76.8% (n = 1753) after one year and was similar in both trial groups. The adjusted intervention effect on disability was -0.07 (95% confidence interval -0.22 to 0.07; p = 0.33). No intervention effects were found for the secondary outcomes.

CONCLUSIONS

We found no evidence that a one-year individualized multifactorial intervention program with nurse-led care coordination was better than the current primary care in community-living older people at increased risk of functional decline in The Netherlands.

TRIAL REGISTRATION

Netherlands Trial Register NTR2653.

Consequences of interaction of functional, somatic, mental and social problems in community-dwelling older people

This study explores the combination of four common health problems in older people and whether problems on four domains result in an additional effect on indicators of poor health. For this purpose, a total of 2681 participants (32% male, mean age 82 years) of the Integrated Systematic Care for Older People (ISCOPE) study were screened on the presence of health problems on four domains (functional, somatic, mental, social) with the postal ISCOPE questionnaire. Extensive interview data on health indicators were obtained at baseline and at 12-months follow-up, including disability (Groningen Activities Restriction Scale, GARS), cognitive function (Mini-Mental State Examination, MMSE), depressive symptoms (Geriatric Depression Scale-15, GDS), loneliness (loneliness scale of De Jong Gierveld), and health-related quality of life (EQ-5D). General practitioner (GP) contact time (min/year) was estimated via GP electronic medical records. Of the study population, 9% had no health problems according to the screening, 8% had problems on one domain, 27% on two, 38% on three and 18% on four domains. At baseline, the number of health domains with problems was associated with poorer scores on the GARS, the MMSE, the GDS-15, the loneliness scale, the EQ-5D and with more GP contact time (p <0.001). Problems on all four domains had an additional negative effect on these health indicators (all p_interaction <0.001). At follow-up, an increased number of domains with problems was associated with an increased decline in health indicators (all p<0.001) and with an additional negative effect on GP contact time of the presence of problems on all four domains (p_interaction <0.001). We conclude that combinations of functional, somatic, mental and social problems are associated with poor health indicators in community-dwelling older people. Since problems on four domains have an additional effect on health, individuals with combined functional, somatic, mental and social problems could benefit from integrated care.

[Identification of seniors at risk--primary care: a validated questionnaire predicting functional decline]

OBJECTIVES

To modify and validate in primary healthcare the Identification of Seniors At Risk (ISAR) screening questionnaire to identify older persons at increased risk of functional decline and to compare this strategy with risk stratification by age alone.

STUDY DESIGN AND SETTING

Prospective development (n=790) and validation cohorts (n=2,573) of community-dwelling persons aged ≥70 years. Functional decline at 12 months was defined as an increase of at least one point on the modified Katz-activities of daily living index score compared with baseline or death.

RESULTS

Three items were independently associated with functional decline: age (odds ratio [OR] 1.06 per year; 95% confidence interval [CI] 1.02, 1.10) dependence in instrumental activities of daily living (OR: 2.17; 95% CI: 1.46, 3.22), and impaired memory (OR: 2.22; 95% CI: 1.41, 3.51). The area under the receiver operating characteristics curve (AUC) range of the ISAR-primary care model was 0.67-0.70 and 40.6% was identified at increased risk. Validation yielded an AUC range of 0.63-0.64. Age≥75 years alone yielded an AUC range of 0.56-0.57 and identified 65.0% at increased risk in the validation cohort.

CONCLUSION

Although the ISAR-Primary Care (ISAR-PC) has moderate predictive value, application of the ISAR-PC is more efficient than selection based on age alone in identifying persons at increased risk of functional decline. This paper is a translated and adjusted version based on a publication in Journal of Clinical Epidemiology, 67 (2014) 1121-1130.

A simple validated questionnaire predicted functional decline in community-dwelling older persons: prospective cohort studies

OBJECTIVES

To modify and validate in primary health care the Identification of Seniors At Risk (ISAR) screening questionnaire to identify older persons at increased risk of functional decline and to compare this strategy with risk stratification by age alone.

STUDY DESIGN AND SETTING

Prospective development (n = 790) and validation cohorts (n = 2,573) of community-dwelling persons aged ≥70 years. Functional decline at 12 months was defined as an increase of at least one point on the modified Katz-activities of daily living index score compared with baseline or death.

RESULTS

Three items were independently associated with functional decline: age (odds ratio [OR]: 1.06 per year; 95% confidence interval [CI]: 1.02, 1.10), dependence in instrumental activities of daily living (OR: 2.17; 95% CI: 1.46, 3.22), and impaired memory (OR: 2.22; 95% CI: 1.41, 3.51). The area under the receiver operating characteristics curve (AUC) range of the ISAR-primary care model was 0.67-0.70, and 40.6% was identified at increased risk. Validation yielded an AUC range of 0.63-0.64. Age ≥75 years alone yielded an AUC range of 0.56-0.57 and identified 55.4% at increased risk in the development cohort.

CONCLUSION

Although the ISAR-Primary Care (ISAR-PC) has moderate predictive value, application of the ISAR-PC is more efficient than selection based on age alone in identifying persons at increased risk of functional decline.

Disentangling the disabling process: insights from the precipitating events project

Among older persons, disability in activities of daily living is common and highly morbid. The Precipitating Events Project (PEP Study), an ongoing longitudinal study of 754 initially nondisabled, community-living persons, aged 70 or older, was designed to further elucidate the epidemiology of disability, with the goal of informing the development of effective interventions to maintain and restore independent function. Over the past 16 years, participants have completed comprehensive, home-based assessments at 18-month intervals and have been interviewed monthly to reassess their functional status and ascertain intervening events, other health care utilization, and deaths. Findings from the PEP Study have demonstrated that the disabling process for many older persons is characterized by multiple and possibly interrelated disability episodes, even over relatively short periods of time, and that disability often results when an intervening event is superimposed upon a vulnerable host. Given the frequency of assessments, long duration of follow-up, and recent linkage to Medicare data, the PEP Study will continue to be an outstanding platform for disability research in older persons. In addition, as the number of decedents accrues, the PEP Study will increasingly become a valuable resource for investigating symptoms, function, and health care utilization at the end of life.

Disability transitions in the oldest old in the general population. The Leiden 85-plus study

Transitions between disability states in older people occur frequently. This study investigated predictors of disability transitions in the oldest old and was performed in the Leiden 85-plus study, a population-based prospective cohort study among 597 participants aged 85 years. At baseline (age 85 years), data on sociodemographic characteristics and chronic diseases were obtained. Disabilities in basic activities of daily living (BADL) and instrumental activities of daily living (IADL) were measured annually for 5 years with the Groningen Activities Restriction Scale (GARS). Mortality data were obtained. A statistical multi-state model was used to assess the risks of transitions between no disabilities, IADL disability, BADL disability, and death. At baseline, 299 participants (50.0 %) were disabled in IADL only, and 155 participants (26.0 %) were disabled in both BADL and IADL. During 5-year follow-up, 374 participants (62.6 %) made >1 transition between disability states, mostly deterioration in disability. Males had a lower risk of deterioration [hazard ratio (HR), 0.75 (95 % CI, 0.58-0.96)] compared to females. No gender differences were observed for improvement [HR, 0.64 (95 % CI, 0.37-1.11)]. Participants with depressive symptoms were less likely to improve [HR, 0.50 (95 % CI, 0.28-0.87)]. Participants with depressive symptoms [HR, 1.46 (95 % CI, 1.12-1.91)], >1 chronic disease [HR, 1.60 (95 % CI, 1.27-2.01)], and with cognitive impairment [HR, 1.60 (95 % CI, 1.20-2.13)] had the highest risk of deteriorating. Disability is a dynamic process in the oldest old. Deterioration is more common than improvement. Older men are less likely to deteriorate than women. The presence of depressive symptoms, chronic disease, and cognitive impairment predicts deterioration.

Using group-based latent class transition models to analyze chronic disability data from the National Long-Term Care Survey 1984-2004

Latent class transition models track how individuals move among latent classes through time, traditionally assuming a complete set of observations for each individual. In this paper, we develop group-based latent class transition models that allow for staggered entry and exit, common in surveys with rolling enrollment designs. Such models are conceptually similar to, but structurally distinct from, pattern mixture models of the missing data literature. We employ group-based latent class transition modeling to conduct an in-depth data analysis of recent trends in chronic disability among the U.S. elderly population. Using activities of daily living data from the National Long-Term Care Survey (NLTCS), 1982-2004, we estimate model parameters using the expectation-maximization algorithm, implemented in SAS PROC IML. Our findings indicate that declines in chronic disability prevalence, observed in the 1980s and 1990s, did not continue in the early 2000s as previous NLTCS cross-sectional analyses have indicated.

Physical activity increases gains in and prevents loss of physical function: results from the lifestyle interventions and independence for elders pilot study

BACKGROUND

Physical activity (PA) appears to have a positive effect on physical function, however, studies have not examined multiple indices of physical function jointly nor have they conceptualized physical functioning as a state rather than a trait.

METHODS

About 424 men and women aged 70-89 were randomly assigned to complete a PA or a successful aging (SA) education program. Balance, gait speed, chair stand performance, grip strength, and time to complete the 400-m walk were assessed at baseline and at 6 and 12 months. Using hidden Markov model, empiric states of physical functioning were derived based on these performance measures of balance, strength, and mobility. Rates of gain and loss in physical function were compared between PA and SA.

RESULTS

Eight states of disability were identified and condensed into four clinically relevant states. State 1 represented mild disability with physical functioning, states 2 and 3 were considered intermediate states of disability, and state 4 severe disability. About 30.1% of all participants changed states at 6 months, 24.1% at 12 months, and 11.0% at both time points. The PA group was more likely to regain or sustain functioning and less likely to lose functioning when compared with SA. For example, PA participants were 20% more likely than the SA participants to remain in state 1.

CONCLUSION

PA appears to have a favorable effect on the dynamics of physical functioning in older adults.

First Steps towards Evidence-Based Preventive Home Visits: Experiences Gathered in a Swedish Municipality

The purpose of preventive home visits is to promote overall health and wellbeing in old age. The aim of this paper was to describe the process of the development of evidence-based preventive home visits, targeting independent community-living older persons. The evidence base was generated from published studies and practical experiences. The results demonstrate that preventive home visits should be directed to persons 80 years old and older and involve various professional competences. The visits should be personalized, lead to concrete interventions, and be followed up. The health areas assessed should derive from a broad perspective and include social, psychological, and medical aspects. Core components in the protocol developed in this study captured physical, medical, psychosocial, and environmental aspects. Results of a pilot study showed that the protocol validly identified health risks among older people with different levels of ADL dependence.

Age, gender and disability predict future disability in older people: the Rotterdam Study

BACKGROUND

To develop a prediction model that predicts disability in community-dwelling older people. Insight in the predictors of disability is needed to target preventive strategies for people at increased risk.

METHODS

Data were obtained from the Rotterdam Study, including subjects of 55 years and over. Subjects who had complete data for sociodemographic factors, life style variables, health conditions, disability status at baseline and complete data for disability at follow-up were included in the analysis. Disability was expressed as a Disability Index (DI) measured with the Health Assessment Questionnaire.We used a multivariable polytomous logistic regression to derive a basic prediction model and an extended prediction model. Finally we developed readily applicable score charts for the calculation of outcome probabilities.

RESULTS

Of the 5027 subjects included, 49% had no disability, 18% had mild disability, 16% had severe disability and 18% had deceased at follow-up after six years. The strongest predictors were age and prior disability. The contribution of other predictors was relatively small. The discriminative ability of the basic model was high; the extended model did not enhance predictive ability.

CONCLUSION

As prior disability status predicts future disability status, interventive strategies should be aimed at preventing disability in the first place.

Transitions in frailty status in older adults in relation to mobility: a multistate modeling approach employing a deficit count

OBJECTIVES

To investigate how changes in frailty status and mortality risk relate to baseline frailty state, mobility performance, age, and sex.

DESIGN

Cohort study.

SETTING

The Yale Precipitating Events Project, New Haven, Connecticut.

PARTICIPANTS

Seven hundred fifty-four community-dwelling people aged 70 and older at baseline followed up at 18, 36, and 54 months.

MEASUREMENTS

Frailty status, assessed at 18-month intervals, was defined using a frailty index (FI) as the number of deficits in 36 health variables. Mobility was defined as time in seconds on the rapid gait test, in which participants walked back and forth over a 20-foot course as quickly as possible. Multistate transition probabilities were calculated with baseline frailty, mobility, age, and sex estimated using Poisson and logistic regressions in survivors and those who died, respectively.

RESULTS

In multivariable analyses, baseline frailty status and age were significantly associated with changes in frailty status and risk of death, whereas mobility was significantly associated with the frailty but not with mortality. At all values of the FI, participants with better mobility were more likely than those with poor mobility to remain stable or to improve. For example, at 54 months, 20.6% (95% confidence interval (CI)=16-25.2) of participants with poor mobility had the same or fewer deficits, compared with 32.4% (95% CI=27.9-36.9) of those with better mobility.

CONCLUSION

A multistate transition model effectively measured the probability of change in frailty status and risk of death. Mobility, age, and baseline frailty were significant factors in frailty state transitions.

Relation of late-life social activity with incident disability among community-dwelling older adults

BACKGROUND

We tested the hypothesis that a higher level of social activity was associated with decreased risk of incident disability in older adults.

METHODS

Data came from older adults in the Rush Memory and Aging Project, an ongoing longitudinal cohort study of aging. Analyses were restricted to persons without clinical dementia and reporting no need for help performing any task in the particular functional domain assessed. Participants were followed for an average of 5.1 years (SD = 2.5). Social activity, based on 6 items (visiting friends or relatives; going to restaurants, sporting events, or playing games; group meetings; church/religious services; day or overnight trips; unpaid community/volunteer work), was assessed at baseline. Disability in basic activities of daily living, mobility disability, and instrumental activities of daily living was assessed annually. Proportional hazard models adjusted for age, sex, and education were used to examine the association between social activity and incident disability. Fully adjusted models included terms for depression, vascular diseases and risk factors, body mass index, social networks, and self-reported physical activity.

RESULTS

In fully adjusted models, among 954 persons without baseline disability, the risk of developing disability in activities of daily living decreased by 43% (hazard ratio = 0.57, 95% confidence interval = 0.46, 0.71) for each additional unit of social activity. Social activity was also associated with decreased risk of developing mobility disability (hazard ratio = 0.69, 95% confidence interval = 0.54, 0.88) and disability in instrumental activities of daily living (hazard ratio = 0.71, 95% confidence interval = 0.55, 0.93).

CONCLUSIONS

Social activity is associated with a decreased risk of incident disability in activities of daily living, mobility, and instrumental activities of daily living, among community-dwelling older adults.

Treatment of death in the analysis of longitudinal studies of gerontological outcomes

BACKGROUND

Longitudinal studies in gerontology are characterized by termination of measurement from death. Death is related to many important gerontological outcomes, such as functional disability, and may, over time, change the composition of an older study population. For these reasons, treating death as noninformative censoring of a longitudinal outcome may result in biased estimates of regression coefficients related to that outcome.

METHODS

In a longitudinal study of community-living older persons, we analytically and graphically illustrate the dependence between death and functional disability. Relative to survivors, decedents display a rapid decline of functional ability in the months preceding death. Death's strong relationship with functional disability demonstrates that death is not independent of this outcome and, hence, leads to informative censoring. We also demonstrate the "healthy survivor effect" that results from death's selection effect, with respect to functional disability, on the longitudinal makeup of an older study population.

RESULTS

We briefly survey commonly used approaches for longitudinal modeling of gerontological outcomes, with special emphasis on their treatment of death. Most common methods treat death as noninformative censoring. However, joint modeling methods are described that take into account any dependency between death and a longitudinal outcome.

CONCLUSIONS

In longitudinal studies of older persons, death is often related to gerontological outcomes and, therefore, cannot be safely assumed to represent noninformative censoring. Such analyzes must account for the dependence between outcomes and death as well as the changing nature of the cohort.

Transitions in the functional status of disabled community-living older adults over a 3-year follow-up period

The purpose of this study was to investigate transitions over time in the functional status of disabled community-living elderly. The study explored clinical and socio-demographic predictors of functional status decline. Data from the SIPA 3-year longitudinal study were analyzed (n=1164). Three categories of functional status were defined: no important disability, significant IADL disability and significant ADL disability. At baseline, results show that the prevalence rates were 26.9%, 58.6% and 14.5% for the three categories of functional status. After 12 months, about 50-60% of participants had remained in the same status, while some 10-15% of those with baseline significant disability had improved. The patterns of transitions between 12 and 36 months of follow-up were slightly different. The results indicated more deterioration (13-38%) and less improvement (6-9%). After controlling for baseline functional status, the best predictors for functional decline at 36 months were prior disability, functional limitations, cognitive impairment and comorbidity burden. We found that older adults' functional status may decline or improve even if the participants are disabled. Disabled conditions play a crucial role in the development of future disability and preventive actions need to be implemented.

Longitudinal association between depressive symptoms and disability burden among older persons

BACKGROUND

Although depressive symptoms in older persons are common, their association with disability burden is not well understood. The authors evaluated the association between level of depressive symptoms and severity of subsequent disability over time and determined whether this relationship differed by sex.

METHODS

Participants included 754 community-living persons aged 70 years or older who underwent monthly assessments of disability in four essential activities of daily living for up to 117 months. Disability was categorized each month as none, mild, and severe. Depressive symptoms, assessed every 18 months, were categorized as low (referent group), moderate, and high. Multinomial logit models invoking Generalized Estimating Equation were used to calculate odds ratios and 95% confidence intervals.

RESULTS

Moderate (odds ratio = 1.30; 95% confidence interval: 1.18-1.43) and high (odds ratio = 1.68; 95% confidence interval: 1.50-1.88) depressive symptoms were associated with mild disability, whereas only high depressive symptoms were associated with severe disability (odds ratio = 2.05; 95% confidence interval: 1.76-2.39). Depressive symptoms were associated with disability burden in both men and women, with modest differences by sex; men had an increased likelihood of experiencing severe disability at both moderate and high levels of depressive symptoms, whereas only high depressive symptoms were associated with severe disability in women.

CONCLUSIONS

Levels of depressive symptoms below the threshold for subsyndromal depression are associated with increased disability burden in older persons. Identifying and treating varying levels of depressive symptoms in older persons may ultimately help to reduce the burden of disability in this population.

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.

Evaluation of a method for fitting a semi-Markov process model in the presence of left-censored spells using the Cardiovascular Health Study

We used a longitudinal data set covering 13 years from the Cardiovascular Health Study to evaluate the properties of a recently developed approach to deal with left censoring that fits a semi-Markov process (SMP) model by using an analog to the stochastic EM algorithm--the SMP-EM approach. It appears that the SMP-EM approach gives estimates of duration-dependent probabilities of health changes similar to those obtained by using SMP models that have the advantage of actual duration data. SMP-EM estimates of duration-dependent transition probabilities also appear more accurate and less variable than multi-state life table estimates.

Correlates of improvement in walking ability in older persons in the United States

OBJECTIVES

We analyzed factors associated with improvement in walking ability among respondents to the nationally representative Health and Retirement Study.

METHODS

We analyzed data from 6574 respondents aged 53 years or older who reported difficulty walking several blocks, 1 block, or across the room in 2000 or 2002. We examined associations between improvement (versus no change, deterioration, or death) and baseline health status, chronic conditions, baseline walking difficulty, demographic characteristics, socioeconomic status, and behavioral risk factors.

RESULTS

Among the 25% of the study population with baseline walking limitations, 29% experienced improved walking ability, 40% experienced no change in walking ability, and 31% experienced deteriorated walking ability or died. In a multivariate analysis, we found positive associations between walking improvement and more recent onset and more severe walking difficulty, being overweight, and engaging in vigorous physical activity. A history of diabetes, having any difficulty with activities of daily living, and being a current smoker were all negatively associated with improvement in walking ability. After we controlled for baseline health, improvement in walking ability was equally likely among racial and ethnic minorities and those with lower socioeconomic status.

CONCLUSIONS

Interventions to reduce smoking and to increase physical activity may help improve walking ability in older Americans.

Analyzing change in recovery patterns in the year after acute hospitalization

OBJECTIVE

To examine trajectories of recovery and change in patterns of personal care and instrumental functional activity performance to determine whether different assessment interval designs within a 12-month period yield different estimates of improvement and decline after acute hospitalization and inpatient rehabilitation.

DESIGN

Secondary analysis of a 12-month prospective cohort study.

SETTING

Transition to the community.

PARTICIPANTS

Adults (N=419) admitted to acute care and receiving inpatient rehabilitation for a neurologic, lower-extremity musculoskeletal, or medically complex condition.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Improvement, no change, and decline as measured by the personal care and instrumental scale of the Activity Measure for Post-Acute Care.

RESULTS

Assessment at the end of a single 12-month follow-up assessment interval showed that over 60% of the participants improved. In contrast, analysis of 2 fixed-length 6-month assessment intervals revealed an almost 40% decrease in the proportion who improved from 6 to 12 months. Fewer participants continued to improve in the time periods further from the acute hospitalization and the proportion of subjects who declined increased from 21.4% to 31.2% to 38.0% over the 3 consecutive assessment intervals (baseline to 1 mo, 1-6 mo, 6-12 mo). Only 58 (19.7%) participants continued on the same path of recovery from baseline to 12 months (9.8% improved over all 3 consecutive time periods, 3.1% made no change, 6.8% declined).

CONCLUSIONS

Examination of change over shorter compared with longer assessment intervals revealed considerable variability in the trajectories of recovery. Research is needed to determine the appropriate frequency and timing for measuring and monitoring function and recovery after an acute hospitalization.

Improvement and decline in health status from late middle age: Modeling age-related changes in deficit accumulation

In a prospective multi-panel cohort study, we investigated how, from late middle age, individuals' health status improves or declines. In the Canadian National Population Health Survey, transition probabilities between different health states were estimated for 4330 people (58.8% women) aged 55+ at baseline over 2-year intervals from 1994 to 2000. Health status was defined by a deficit count, using 33 health-related variables combined in a frailty index. For each time interval, the chance of accumulating deficits increased linearly with the number of deficits. Older survivors (aged 70-85) showed a slightly lower chance of stability or improvement (52%; 95% confidence interval 50-54%) compared with those in late middle age (56%; 54-58%). Changes in health states can be described with high accuracy (R2=0.92) by a modified Poisson distribution, using four parameters: the background odds of accumulating additional deficits, the chance of incurring more or fewer deficits, given the existing number, and the corresponding probabilities of dying. An age-invariant limit to deficit accumulation was observed at 22 deficits. From late middle age, transitions in health states occur with a regularity that is easily modeled. Improvements in health can occur at any age. At all ages, there is a limit to deficit accumulation.