Predicting the risk of mobility difficulty in older women with screening nomograms: the Women's Health and Aging Study II

Monitoring mobility in older adults using a Global Positioning System (GPS) smartwatch and accelerometer: A validation study

There is growing interest in identifying valid and reliable methods for detecting early mobility limitations in aging populations. A multi-sensor approach that combines accelerometry with Global Positioning System (GPS) devices could provide valuable insights into late-life mobility decline; however, this innovative approach requires more investigation. We conducted a series of two experiments with 25 older participants (66.2±8.5 years) to determine the validity of a GPS enabled smartwatch (TicWatch S2 and Pro 3 Ultra GPS) and separate accelerometer (ActiGraph wGT3X-BT) to collect movement, navigation and body posture data relevant to mobility. In experiment 1, participants wore the TicWatchS2 and ActiGraph simultaneously on the wrist for 3 days. In experiment 2, participants wore the TicWatch Pro 2 Ultra GPS on the wrist and ActiGraph on the thigh for 3 days. In both experiments participants also carried a Qstarz data logger for trips outside the home. The TicWatch Pro 3 Ultra GPS performed better than the S2 model and was similar to the Qstarz in all tested trip-related measures, and it was able to estimate both passive and active trip modes. Both models showed similar results to the gold standard Qstarz in life-space-related measures. The TicWatch S2 demonstrated good to excellent overall agreement with the ActiGraph algorithms for the time spent in sedentary and non-sedentary activities, with 84% and 87% agreement rates, respectively. Under controlled conditions, the TicWatch Pro 3 Ultra GPS consistently measured step count in line with the participants' self-reported data, with a bias of 0.4 steps. The thigh-worn ActiGraph algorithm accurately classified sitting and lying postures (97%) and standing postures (90%). Our multi-sensor approach to monitoring mobility has the potential to capture both accelerometer-derived movement data and trip/life-space data only available through GPS. In this study, we found that the TicWatch models were valid devices for capturing GPS and raw accelerometer data, making them useful tools for assessing real-life mobility in older adults.

Defining and Measuring Preclinical Mobility Limitation: An Expert Consensus Exercise Informed by a Scoping Review

BACKGROUND

Early change in function in older adults has been termed preclinical disability (PCD). PCD has been understudied compared to other stages of disability because it is unlikely to receive comparative priority in clinical settings. It has major implications for prevention and population health as it may be the optimal time to intervene to prevent further decline. A standardized approach to research in PCD, including a common definition and measurement approaches, is needed to advance this work.

METHODS

The process to establish how PCD should be defined and measured was undertaken in 2 stages: (1) a scoping review of the literature, which was used to inform (2) a web-enabled consensus meeting with content experts.

RESULTS

The scoping review and the consensus meeting support the use of the term preclinical mobility limitation (PCML) and that it should be measured using both patient-reported and performance-based measures. It was agreed that the definition of PCML should include modification of frequency and/or method of task completion, without overt disability, and that requisite mobility tasks include walking (distance and speed), stairs, and transfers.

CONCLUSIONS

Currently, there are few standardized assessments that can identify PCML. PCML is the term that most clearly describes the stage where people experience a change in routine mobility tasks, without a perception of disability. Further evaluation into the reliability, validity, and responsiveness of outcome measures is needed to advance research on PCML.

Development and validation of a prediction model for self-reported mobility decline in community-dwelling older adults

OBJECTIVES

The aim of this study is to develop and validate two models to predict 2-year risk of self-reported mobility decline among community-dwelling older adults.

STUDY DESIGN AND SETTING

We used data from a prospective cohort study of people aged 65 years and over in England. Mobility status was assessed using the EQ-5D-5L mobility question. The models were based on the outcome: Model 1, any mobility decline at 2 years; Model 2, new onset of persistent mobility problems over 2 years. Least absolute shrinkage and selection operator logistic regression was used to select predictors. Model performance was assessed using C-statistics, calibration plot, Brier scores, and decision curve analyses. Models were internally validated using bootstrapping.

RESULTS

Over 18% of participants who could walk reported mobility decline at year 2 (Model 1), and 7.1% with no mobility problems at baseline, reported new onset of mobility problems after 2 years (Model 2). Thirteen and 6 out of 31 variables were selected as predictors in Models 1 and 2, respectively. Models 1 and 2 had a C-statistic of 0.740 and 0.765 (optimism < 0.013), and Brier score = 0.136 and 0.069, respectively.

CONCLUSION

Two prediction models for mobility decline were developed and internally validated. They are based on self-reported variables and could serve as simple assessments in primary care after external validation.

Relationship between physical activity level and balance in middle-aged and older women

Abstract Introduction: Physical exercise may improve motor skills, such as static standing balance. However, the association between physical activity level based on activities of daily living and static balance is unknown. Objective: To assess the association between the physical activity level and static balance in middle-aged and older women. Methods: This cross-sectional study involved 589 community-dwelling women. Static balance was assessed using the single-leg stance test (SLST) with eyes open and closed. Physical activity level was assessed using the International Physical Activity Questionnaire Short Form and classified as high, moderate, or low. Kruskal-Wallis test compared balance performance between participants with different physical activity levels. Multiple quantile regression analyses assessed the association between variables adjusted for age, family income, educational level, body mass index, comorbidities, and parity. Results: Participants with low physical activity level showed worse SLST performance with eyes open and closed than participants with high physical activity level in the bivariate analysis. However, physical activity level and SLST performance were not associated in the analysis adjusted for covariates. Conclusion: Our results suggested that only being active in daily living activities is not associated with better standing balance in middle-aged and older women. Specific physical exercise programs should be implemented to improve balance in this population.

Gait speed and 6-minute walking distance are useful for identifying difficulties in activities of daily living in patients with cardiovascular disease

BACKGROUND

Difficulty in activities of daily living (ADL) is common in patients with cardiovascular disease (CVD) and is associated with mortality.

OBJECTIVES

The relationship between gait speed/6-minute walking distance (6MWD) and difficulties in ADL in patients with CVD was explored.

METHODS

The study population consisted of 447 patients with CVD for whom data on gait speed, 6MWD, and difficulty in ADL during outpatient rehabilitation were available. Relationships of gait speed/6MWD and difficulty in ADL were examined using propensity-adjusted logistic regression analysis.

RESULTS

Both gait speed and 6MWD were significantly related to difficulty in ADL, and the areas under the curves were large. The cutoff values ranged from 0.93 to 1.30 m/s for gait speed and 370 to 500 m for 6MWD, from basic ADL to vigorous activities.

CONCLUSIONS

Both gait speed and 6MWD were used for the estimation of difficulty in ADL in patients with CVD. Gait speed can be measured easily and therefore could be incorporated in busy clinical practice to identify patients at risk for functional decline.

Risk Factors for Mobility Decline in Community-Dwelling Older Adults: A Systematic Literature Review

Mobility is essential to maintaining independence for older adults. This systematic review aimed to summarize evidence about self-reported risk factors for self-reported mobility decline; and to provide an overview of published prognostic models for self-reported mobility decline among community-dwelling older adults. Databases were searched from inception to June 2, 2020. Studies were screened by two independent reviewers who extracted data and assessed study quality. Sixty-one studies (45,187 participants) were included, providing information on 107 risk factors. High-quality evidence and moderate/large effect sizes for the association with mobility decline were found for older age beyond 75 years, the presence of widespread pain, and mobility modifications. Moderate-high quality evidence and small effect sizes were found for a further 21 factors. Three model development studies demonstrated acceptable model performance, limited by high risk of bias. These findings should be considered in intervention development, and in developing a prediction instrument for practical application.

Working to Increase Stability through Exercise (WISE): Study protocol for a pragmatic randomized controlled trial of a coached exercise program to reduce serious fall-related injuries

Approximately one-third of older adults fall each year and fall-related injuries are a leading cause of death and disability among this rapidly expanding age group. Despite the availability of bisphosphonates to reduce fractures, concerns over side effects have dramatically reduced use, suggesting that other treatment options are needed. Though many smaller studies have shown that physical activity programs can reduce falls, no study has been adequately powered to detect a reduction in fall-related injuries. We present the design of a three-year randomized controlled clinical trial of 1130 adults age 65 and older with a past history of fragility fractures (e.g., vertebral, fall-related). The main aim is to determine the impact of a community-based multicomponent (strength, balance, aerobic) physical activity program led by trained volunteers (or delivered via DVD) and accompanied by coaching and oversight, by telephone and in-person, by a fitness professional. The main outcome measure is serious fall-related injuries. Secondary outcomes include health care utilization, bone and muscle mass, loneliness, health-related quality of life and mood. The study represents the first large clinical trial of a comprehensive physical activity program to reduce secondary injuries among patients with a history of fragility fracture.

INTERSECTING SELF-REPORTED MOBILITY AND GAIT SPEED TO CREATEA MULTI-DIMENSIONAL MEASURE OF AMBULATION: THE "AMBULATION SPEED-ENDURANCE" (ASE) TYPOLOGY

BACKGROUND

Assessing mobility through readily available and affordable protocols may help advance public health by providing early detection and implementing intervention therapies aimed at mitigating the progression from physiological vitality to disability at older ages. Until now, little attention has been given to how self-reported mobility (SRM) and gait speed can be combined in a categorization scheme.

OBJECTIVES

The specific aim of this report is to introduce the Ambulation Speed-Endurance (ASE) Typology to the literature-a classification system that intersects SRM and gait speed to create a multi-dimensional measure of ambulation.

DESIGN

Cross-sectional.

SETTING

Community-dwelling older adults in the United States.

PARTICIPANTS

Evidence is provided from the National Health and Aging Trends Study (NHATS) that community-dwelling older adults (n=5,403) may be found in each of the ASE Typologies. The discussion is complimented by investigating the cross-sectional predictors of a "Discrepancy Score" (measure of gap between speed and endurance) amongst those with gait speeds < 0.99 m/sec (n=4,521).

RESULTS

Multivariable linear regression results indicate level of severity in speed-endurance discrepancy is higher amongst: non-Latino-Blacks (β=0.48); Latinos (β=0.42); older ages; and lower educated. Models also show that severity in speed-endurance discrepancy is lower amongst: females (β=-0.38); those with higher body mass index; with more chronic health conditions; and poorer self-rated health.

CONCLUSION

Research should continue to investigate how to optimize SRM.

Association of Transcobalamin II (TCN2) and Transcobalamin II-Receptor (TCblR) Genetic Variations With Cobalamin Deficiency Parameters in Elderly Women

Cobalamin (vitamin B12) deficiency is a subtle progressive clinical disorder, affecting nearly 1 in 5 individuals > 60 years old. This deficiency is produced by age-related decreases in nutrient absorption, medications that interfere with vitamin B12 absorption, and other comorbidities. Clinical heterogeneity confounds symptom detection for elderly adults, as deficiency sequelae range from mild fatigue and weakness to debilitating megaloblastic anemia and permanent neuropathic injury. A better understanding of genetic factors that contribute to cobalamin deficiency in the elderly would allow for targeted nursing care and preventive interventions. We tested for associations of common variants in genes involved in cobalamin transport and homeostasis with metabolic indicators of cobalamin deficiency (homocysteine and methylmalonic acid) as well as hematologic, neurologic, and functional performance features of cobalamin deficiency in 789 participants of the Women’s Health and Aging Studies. Although not significant when corrected for multiple testing, eight single nucleotide polymorphisms (SNPs) in two genes, transcobalamin II ( TCN2) and the transcobalamin II-receptor ( TCblR), were found to influence several clinical traits of cobalamin deficiency. The three most significant findings were the identified associations involving missense coding SNPs, namely, TCblR G220R (rs2336573) with serum cobalamin, TCN2 S348F (rs9621049) with homocysteine, and TCN2 P259R (rs1801198) with red blood cell mean corpuscular volume. These SNPs may modify the phenotype in older adults who are more likely to develop symptoms of vitamin B12 malabsorption.

Trunk sway during walking among older adults: norms and correlation with gait velocity

The aim of this study was to establish quantitative norms for trunk sway during walking for older male and female ambulatory adults at different age groups (65-70, 71-75, 76-80, ≥81). We also assessed the relationship between dynamic trunk sway and gait velocity in older individuals with clinically normal or abnormal gaits. Trunk sway in medio-lateral (roll) and antero-posterior (pitch) planes was measured using a body-mounted gyroscope (SwayStar) during walking on a 4.5 m long instrumented walkway. Of the 284 older adults (mean age 76.8, 54.6% women) in this sample, the mean ± SD value of roll and pitch angles were 6.0 ± 2.0° and 6.7 ± 2.2° respectively. Older women showed significantly greater trunk sway in both roll and pitch angles than older men (p<0.01). In both men and women, there was no significant association of roll angle with age although gait velocity decreased with increasing age. The relationship between roll angle and gait velocity was U-shaped for the overall sample. Among the subgroup with clinically normal gait, increased roll angle was associated with increased gait velocity (p<0.001). However, there was no significant relationship between roll angle and gait velocity among the subgroup with abnormal gait. Therefore, the relationship between medio-lateral trunk sway and gait velocity differs depending on whether gait is clinically normal. We conclude that trunk sway during walking should be interpreted with consideration of both gait velocity and presence of gait abnormality in older adults.

A multidimensional assessment of physical performance for older Japanese people with community-based long-term care needs

BACKGROUND AND AIMS

A multidimensional assessment representing overall lower- and upper-extremity performance is necessary to identify functional decline among older adults. The aim of this study was to develop and validate a physical performance scale (PPS) using both cross-sectional and observational approaches in older adults with and without community-based long-term care (LTC) needs in Japan.

METHODS

A total of 416 community-living adults aged 75 years and over. The 7 items of the PPS include a range of physiological challenges, such as assessment of upper-extremity strength, lower-extremity strength, balance, and walking ability. Concurrent validity [correlating the PPS with self-reported functional status in activities of daily living (ADLs), instrumental ADLs, and Physical Function subscale of the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36PF)] and discriminative validity were assessed. Sensitivity to changes was evaluated with a 12-week exercise program.

RESULTS

Total PPS score was significantly correlated with self-reported functional status such as ADLs, instrumental ADLs (IADLs), and SF-36PF (r = 0.53-0.62) and demonstrated no floor effect and minimal ceiling effect (8.7 %). The total PPS score showed large areas under the curve (AUC = 0.89; 95 % confidence interval, 0.86-0.92) with regard to discrimination between individuals with and without LTC needs. In observational analysis, total PPS score demonstrated small meaningful change in high-risk individuals requiring care (effect size 0.34).

CONCLUSIONS

The PPS may be a useful tool for identifying functional status decline and improvement in older adults requiring community-based LTC.

Prevalence of diabetes treatment effect modifiers: the external validity of trials to older adults

BACKGROUND AND AIMS

Potential treatment effect modifiers (TEMs) are specific diseases or conditions with a well-described mechanism for treatment effect modification. The prevalence of TEMs in older adults with type 2 diabetes mellitus (DM) is unknown. Objectives were to 1) determine the prevalence of pre-specified potential TEMs; 2) demonstrate the potential impact of TEMs in the older adult population using a simulated trial; 3) identify TEM combinations associated with number of hospitalizations to test construct validity.

METHODS

Data are from the nationally-representative United States National Health and Examination Survey, 1999-2004: 8646 Civilian, non-institutionalized adults aged 45-64 or 65+ years, including 1443 with DM. TEMs were anemia, congestive heart failure, liver inflammation, polypharmacy, renal insufficiency, cognitive impairment, dizziness, frequent mental distress, mobility difficulty, and visual impairment. A trial was simulated to examine prevalence of potential TEM impact. The cross-sectional association between TEM patterns and number of hospitalizations was estimated to assess construct validity.

RESULTS

The prevalence of TEMs was substantial such that 19.0% (95% CI 14.8-23.2) of middle-aged adults and 38.0% (95% CI 33.4-42.5) of older adults had any two. A simulated trial with modest levels of interaction suggested the prevalence of TEMs could nullify treatment benefit in 3.9-27.2% of older adults with DM. Compared to having DM alone, hospitalization rate was increased by several combinations of TEMs with substantial prevalence.

CONCLUSIONS

We provide national benchmarks that can be used to evaluate TEM prevalence reported by clinical trials of DM, and correspondingly their external validity to older adults.

The effect of changes in lower limb pain on the rate of progression of locomotor disability in middle and old age: evidence from the NorStOP cohort with 6-year follow-up

Locomotor disability (LMD) is common at older ages, and can lead to other significant disability and mortality. Prevalent pain has been shown to be associated with LMD. This article aimed to assess the association between changes in lower limb pain status (ascertained from a manikin) and changes in the level of self-reported LMD in a sample of UK adults age ≥ 50years, over a 6-year period (data collected at 3-year intervals). There was an average increase in the level of LMD over 6 years. Reports of an onset of lower limb pain were associated with a relative increase in LMD, independently of sociodemographic factors and the onset of selected comorbid diseases. A dose-response relationship was observed between the onset of multiple lower limb joint involvement and more frequent or intense pain and larger increases in LMD. Becoming free from lower limb pain was associated with a relative decrease in LMD, but did not return LMD scores to the level of those who had remained pain-free throughout. This is consistent with a cumulative effect on LMD of recurrent episodes of pain. Lower limb pain may be a key target for prevention and rehabilitation to reduce years lived with disability in later life.

Education predicts incidence of preclinical mobility disability in initially high-functioning older women. The Women's Health and Aging Study II

BACKGROUND

To examine the impact of educational attainment on the incidence of preclinical mobility disability (PCD).

METHODS

The Women's Health and Aging II Study is a prospective observational cohort study of 436 initially high-functioning community-dwelling women aged 70-79 years at baseline in Baltimore, Maryland. We measured the association of highest attained education level with preclinical mobility disability (PCD) over an 11-year period. PCD is defined as self-reported modification in any of four tasks without reporting difficulty in those tasks. The tasks were walking ½ mile, climbing up steps, doing heavy housework, and getting in/out of bed or chair.

RESULTS

Participants with less than 9 years of education were more likely to acquire incident PCD (hazard ratio: 3.1, 95% confidence interval = 1.2-7.7) than their counterparts with more education after adjusting for income, marital status, number of diseases, and high self-efficacy.

CONCLUSIONS

Lower education level is an independent predictor of incident preclinical mobility disability. This association has important implications for primary and secondary prevention and can be easily assessed in clinical encounters.

Physical and mental health-related correlates of physical function in community dwelling older adults: a cross sectional study

BACKGROUND

Physical function is the ability to perform both basic and instrumental activities of daily living, and the ability of older adults to reside in the community depends to a large extent on their level of physical function. Multiple physical and health-related variables may differentially affect physical function, but they have not been well characterized. The purpose of this investigation was to identify and examine physical and mental health-related correlates of physical function in a sample of community-dwelling older adults.

METHODS

Nine hundred and four community dwelling older men (n = 263) and women (n = 641) with a mean (95% Confidence Interval) age of 76.6 (76.1, 77.1) years underwent tests of physical function (Timed Up and Go; TUG), Body Mass Index (BMI) was calculated from measured height and weight, and data were collected on self-reported health quality of life (SF-36), falls during the past 6 months, number of medications per day, depression (Geriatric Depression Scale; GDS), social support, and sociodemographic variables.

RESULTS

Subjects completed the TUG in 8.7 (8.2, 9.2) seconds and expended 6,976 (6,669, 7,284) Kcal.wk-1 in physical activity. The older persons had a mean BMI of 27. 6 (27.2, 28.0), 62% took 3 or more medications per day, and 14.4% had fallen one or more times over the last 6 months. Mean scores on the Mental Component Summary (MCS) was 50.6 (50.2, 51,0) and the Physical Component Summary (PCS) was 41.3 (40.8, 41.8).Multiple sequential regression analysis showed that, after adjustment for TUG floor surface correlates of physical function included age, sex, education, physical activity (weekly energy expenditure), general health, bodily pain, number of medications taken per day, depression and Body Mass Index. Further, there is a dose response relationship such that greater degree of physical function impairment is associated with poorer scores on physical health-related variables.

CONCLUSIONS

Physical function in community-dwelling older adults is associated with several physical and mental health-related factors. Further study examining the nature of the relationships between these variables is needed.

Association of dynamic joint power with functional limitations in older adults with symptomatic knee osteoarthritis

OBJECTIVES

To determine which lower-limb joint moments and powers characterize the level of gait performance of older adults with symptomatic knee osteoarthritis (OA).

DESIGN

Cross-sectional observational study.

SETTING

University motion analysis laboratory.

PARTICIPANTS

Community-dwelling adults (N=60; 27 men, 33 women; age 50-79y) with symptomatic knee OA.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Physical function was measured using the long-distance corridor walk, the Short Physical Performance Battery, and the Late Life Function and Disability Instrument (LLFDI Function). Joint moments and power were estimated using an inverse dynamics solution after 3-dimensional computerized motion analysis.

RESULTS

Subjects aged 64.2+/-7.4 years were recruited. Ranges (mean +/- SD) for the 400-m walk time and the LLFDI Advanced Lower-Limb Function score were 215.3 to 536.8 (304.1+/-62.3) seconds and 31.5 to 100 (57.0+/-14.9) points, respectively. In women, hip abductor moment (loading response), hip abductor power (midstance), eccentric hamstring moment (terminal stance), and power (terminal swing) accounted for 41%, 31%, 14%, and 48% of the variance in the 400-m walk time, respectively (model R(2)=.61, P<.003). In men, plantar flexor and hip flexor power (preswing) accounted for 19% and 24% of the variance in the 400-m walk time, respectively (model R(2)=.32, P=.025).

CONCLUSIONS

There is evidence that men and women with higher mobility function tend to rely more on an ankle strategy rather than a hip strategy for gait. In higher functioning men, higher knee extensor and flexor strength may contribute to an ankle strategy, whereas hip abductor weakness may bias women with lower mobility function to minimize loading across the knee via use of a hip strategy. These parameters may serve as foci for rehabilitation interventions aimed at reducing mobility limitations.

Normative values for the unipedal stance test with eyes open and closed

PURPOSE

Limited normative data are available for the unipedal stance test (UPST), making it difficult for clinicians to use it confidently to detect subtle balance impairments. The purpose of this study was to generate normative values for repeated trials of the UPST with eyes opened and eyes closed across age groups and gender.

METHODS

This prospective, mixed-model design was set in a tertiary care medical center. Healthy subjects (n= 549), 18 years or older, performed the UPST with eyes open and closed. Mean and best of 3 UPST times for males and females of 6 age groups (18-39, 40-49, 50-59, 60-69, 70-79, and 80+) were documented and inter-rater reliability was tested.

RESULTS

There was a significant age dependent decrease in UPST time during both conditions. Inter-rater reliability for the best of 3 trials was determined to be excellent with an intra-class correlation coefficient of 0.994 (95% confidence interval 0.989-0.996) for eyes open and 0.998 (95% confidence interval 0.996-0.999) for eyes closed.

CONCLUSIONS

This study adds to the understanding of typical performance on the UPST. Performance is age-specific and not related to gender. Clinicians now have more extensive normative values to which individuals can be compared.

Validation of lower extremity performance tests for determining the mobility limitation levels in community-dwelling older women

BACKGROUND AND AIMS

Assessment of mobility status among community-dwelling older people is important for preventing further deterioration of mobility and identifying changes in mobility as early as possible. We attempted to identify the optimal cut-off values for eight lower extremity performance (LEP) tests in community-dwelling older women with mobility limitation (ML) levels.

METHODS

The ML levels of 433 community-dwelling older women, mean age 73.2 years (SD 5.7, range 65-93) were classified according to selfreports. ML levels were identified by face-to-face interviews and according to self-reported difficulty in walking one-quarter of a mile or climbing 10 steps without resting. The LEP tests comprised one-legged stance, tandem stance, functional reach, tandem walk, alternate step, five chair sit-to-stands, timed up-and-go (TUG) and usual gait speed. Receiver-operating characteristic curves were obtained for all scales to assess optimal cut-off values.

RESULTS

The optimal cut-off value of 6.52 (s) for the TUG test was shown by the highest sensitivity (74%) and specificity (71%) in the discrimination of no ML from moderate ML, whereas the optimal cut-off value of 1.05 (m/s) in the usual gait speed test showed the highest sensitivity (73%) and specificity (67%) in the discrimination of moderate ML from severe ML.

CONCLUSIONS

Among community-dwelling older women, TUG and usual gait speed had the highest sensitivity and specificity in discriminating ML levels.

Derivation and testing of an interval-level score for measuring locomotor disability in epidemiological studies of middle and old age

PURPOSE

Locomotor disability is prevalent in middle and old age and although interval-level measurement instruments have been developed that relate to locomotor disability, there is currently no brief, interval-level score developed specifically to measure the severity of locomotor disability in the general population. We aimed to create such a score from five items of the SF-36 Physical Functioning subscale (PF-10): three walking- and two stair-climbing-related, and assess the scoring mechanism's measurement properties.

METHODS

Data were collected from postal surveys of adults aged 50 years and over. The walking and stair-climbing items were formed into two super-items to remove response dependency. The Rasch measurement model was used to form an interval-level score and fit to this model was assessed. The scoring mechanism was applied to three external data sets and fit to the Rasch model was assessed. Repeatability, construct validity, and responsiveness of the new interval scale were examined.

RESULTS

Overall, the fit of the super-items to the Rasch model was good, with little evidence of misfit. Our analyses broadly support the generalisability, repeatability, construct validity, and responsiveness of this new interval-level score.

CONCLUSIONS

An interval-level score for locomotor disability was created from five items of the PF-10 completed in a general population of adults aged 50 years and over. Further work is needed to assess the generalisability of this Rasch score to other populations and to determine a clinically meaningful change score.

Self-assessed health status, walking speed and mortality in older Mexican-Americans

BACKGROUND

Self-assessed health status (SAHS) and physical performance measures (in particular, walking speed) are strong predictors of health-related events. Nevertheless, the possible interaction between them in predicting major outcomes has not been clearly explored.

OBJECTIVE

The aim of the study is to evaluate the predictive and additive value for mortality of a SAHS measure and a walking speed test.

METHODS

Data are from 2,139 Mexican-Americans aged >or=65 years enrolled in the Hispanic Established Populations for Epidemiologic Studies of the Elderly, and followed for 5.8 years. At the baseline visit, participants were asked to answer to the question 'How is your health in general?' presented as a four-level Likert item (i.e., poor, fair, good, excellent). They were also asked to 'walk down and back as fast as it felt safe and comfortable' along an 8-ft track. Cox proportional hazard models, receiver operating characteristic (ROC) curve, and specificity/sensitivity analyses were performed to evaluate the predictive value of SAHS and walking speed for mortality.

RESULTS

The mean age of the sample was 72.1 years. Participants reporting 'poor' SAHS were more likely to die compared to those with 'excellent' SAHS, even after adjustment for potential confounders (HR 1.52, 95% CI 1.10-2.10). Similar results were obtained for participants with slow walking speed (<0.29 m/s; HR 1.68, 95% CI 1.27-2.24; reference group: walking speed >or=0.81 m/s). A statistically significant, but weak, correlation between SAHS and walking speed was observed (Pearson's r=0.069, p=0.001). No significant differences in areas under curves from ROC analyses were reported for the prediction of mortality when the SAHS and walking speed were tested (alone or in combination). Both tests presented high specificity (>or=80%) for the prediction of mortality.

CONCLUSION

SAHS and walking speed are not only significant and independent predictors of mortality in older Mexican-Americans, but also present a similar predictive value. The additive prognostic value of the two measures is limited.

At the tipping point: predicting severe mobility difficulty in vulnerable older women

OBJECTIVES

To identify clinical measures that aid detection of impending severe mobility difficulty in older women.

DESIGN

Cross-sectional and longitudinal cohort study.

SETTING

Urban community in Baltimore, Maryland.

PARTICIPANTS

One thousand two community-dwelling, moderate to severely disabled women aged 65 and older in the Women's Health and Aging Study I.

MEASUREMENTS

Self-report and performance measures representing six domains necessary for mobility: central and peripheral nervous systems, muscles, bones and joints, perception, and energy. Severe mobility difficulty was defined as usual gait of 0.5 m/s or less, any reported difficulty walking across a small room, or dependence on a walking aid during a 4-m walking test.

RESULTS

Four hundred sixty-seven out of 984 (47%) had severe mobility difficulty at baseline, and 104/474 (22%) developed it within 12 months. Baseline mobility difficulty was correlated with poor vision, knee pain, feelings of helplessness, inability to stand with feet side by side for 10 seconds, difficulty keeping balance while dressing or walking, inability to rise from a chair five times, and cognitive impairment. Of these, knee pain (odds ratio (OR)=1.74, 95% confidence interval (CI)=1.05-2.89), helplessness (OR=1.87, 95% CI=1.10-3.24), poor vision (OR=2.03, 95% CI=1.06-3.89), inability to rise from a chair five times (OR=2.50, 95% CI=1.15-5.41), and cognitive impairment (OR=4.75, 95% CI=1.67-13.48) predicted incident severe mobility difficulty within 12 months, independent of age.

CONCLUSION

Five simple measures may aid identification of disabled older women at high risk of severe mobility difficulty. Further studies should determine generalizability to men and higher-functioning individuals.

Allostatic load and frailty in the women's health and aging studies

BACKGROUND

Frailty involves decrements in many physiologic systems, is prevalent in older ages, and is characterized by increased vulnerability to disability and mortality. It is yet unclear how this geriatric syndrome relates to a preclinical cumulative marker of multisystem dysregulation. The purpose of this study was to evaluate whether allostatic load (AL) was associated with the geriatric syndrome of frailty in older community-dwelling women.

METHODS

We examined the cross-sectional relationship between AL and a validated measure of frailty in the baseline examination of two complementary population-based cohort studies, the Women's Health and Aging studies (WHAS) I and II. This sample of 728 women had an age range of 70-79. We used ordinal logistic regression to estimate the relationship between AL and frailty controlling for covariates.

RESULTS

About 10% of women were frail and 46% were prefrail. AL ranged from 0 to 8 with 91% of participants scoring between 0 and 4. Regression models showed that a unit increase in the AL score was associated with increasing levels of frailty (OR = 1.16, 95% CI = 1.04-1.28) controlling for race, age, education, smoking status, and comorbidities.

CONCLUSION

This study suggests that frailty is associated with AL. The observed relationship provides some support for the hypothesis that accumulation of physiological dysregulation may be related to the loss of reserve characterized by frailty.

Evaluating disability over discrete periods of time

BACKGROUND

To advance the field of disability assessment, additional developmental work is needed. The objective of this study was to determine the potential value of participant recall when evaluating disability over discrete periods of time.

METHODS

We studied 491 residents of greater New Haven, Connecticut, who were 76 years old or older. Participants completed a comprehensive assessment that included several new questions on disability in four essential activities of daily living (bathing, dressing, transferring, and walking). Participants were also assessed for disability in the same activities during monthly telephone interviews before and after the comprehensive assessment. Chronic disability was defined as a new disability that was present for at least three consecutive months.

RESULTS

We found that up to half of the incident disability episodes, which would otherwise have been missed, can be ascertained if participants are asked to recall whether they have had disability "at any time" since the prior assessment; that these disability episodes, which are ascertained by participant recall, confer high risk for the subsequent development of chronic disability, with an adjusted hazard ratio of 2.5 (95% confidence interval, 1.1-5.8); and that participant recall for the absence of disability becomes increasingly inaccurate as the duration of the assessment interval increases, with 2.2%, 6.0%, 6.9%, and 9.1% of participants having inaccurate recall at 1, 3, 6, and 12 months, respectively.

CONCLUSIONS

Our results demonstrate both the promise and limitations of participant recall and suggest that additional strategies are needed to more completely and accurately ascertain the occurrence of disability among older persons.

Preclinical disability as a risk factor for falls in community-dwelling older adults

BACKGROUND

Falls are common and serious problems in older adults. The goal of this study was to examine whether preclinical disability predicts incident falls in a European population of community-dwelling older adults.

METHODS

Secondary data analysis was performed on a population-based longitudinal study of 1644 community-dwelling older adults living in London, U.K.; Hamburg, Germany; Solothurn, Switzerland. Data were collected at baseline and 1-year follow-up using a self-administered multidimensional health risk appraisal questionnaire, including validated questions on falls, mobility disability status (high function, preclinical disability, task difficulty), and demographic and health-related characteristics. Associations were evaluated using bivariate and multivariate logistic regression analyses.

RESULTS

Overall incidence of falls was 24%, and increased by worsening mobility disability status: high function (17%), preclinical disability (32%), task difficulty (40%), test-of-trend p <.003. In multivariate analysis adjusting for other fall risk factors, preclinical disability (odds ratio [OR] = 1.7, 95% confidence interval [CI], 1.1-2.5), task difficulty (OR = 1.7, 95% CI, 1.1-2.6) and history of falls (OR = 4.7, 95% CI, 3.5-6.3) were the strongest significant predictors of falls. In stratified multivariate analyses, preclinical disability equally predicted falls in participants with (OR = 1.7, 95% CI, 1.0-3.0) and without history of falls (OR = 1.8, 95% CI, 1.1-3.0).

CONCLUSIONS

This study provides longitudinal evidence that self-reported preclinical disability predicts incident falls at 1-year follow-up independent of other self-reported fall risk factors. Multidimensional geriatric assessment that includes preclinical disability may provide a unique early warning system as well as potential targets for intervention.

Subtypes of disability in older persons over the course of nearly 8 years

OBJECTIVES

To characterize distinct and clinically meaningful subtypes of disability, defined based on the number and duration of disability episodes, and to determine whether the incidence of these disability subtypes differ according to age, sex, or physical frailty.

DESIGN

Prospective cohort study.

SETTING

Greater New Haven, Connecticut.

PARTICIPANTS

Seven hundred fifty-four community-living residents aged 70 and older and initially nondisabled in four essential activities of daily living.

MEASUREMENTS

Disability was assessed during monthly telephone interviews for nearly 8 years; physical frailty was assessed during comprehensive home-based assessments at 18-month intervals. The incidence of five disability subtypes was determined within the context of the 18-month intervals in participants who were nondisabled at the start of the interval: transient, short-term, long-term, recurrent, and unstable.

RESULTS

Incident disability was observed in 29.8% of the 18-month intervals. The most common subtypes were transient disability (9.7% of all intervals), defined as a single disability episode lasting only 1 month, and long-term disability (6.9%), defined as one or more disability episodes, with at least one lasting 6 or more months. Approximately one-quarter (24.7%) of all participants had two or more intervals with an incident disability subtype. Although there were no sex differences in the incidence rates for any of the subtypes, differences in rates were observed for each subtype according to age and physical frailty, with only one exception, and were especially large for long-term disability.

CONCLUSION

The mechanisms underlying the different disability subtypes may differ. Additional research is warranted to evaluate the natural history, risk factors, and prognosis of the five disability subtypes.

Health-related fitness tests as predictors of difficulties in long-distance walking among high-functioning older adults

BACKGROUND AND AIMS

Health-related fitness (HRF) tests are valid predictors of self-reported mobility difficulties among high-functioning older adults. The aim of the present study was to identify optimal cut-off values for HRF tests predicting self-reported difficulties in walking 2 km (WD).

METHODS

Subjects were 55- to 69-year-old men and women who were free of WD at baseline. The HRF assessment in 1996 included seven test items, and postal questionnaires were used to assess occurrence of new WD in 2002. Analysis of covariance and receiver-operating characteristic analysis were used as statistical methods.

RESULTS

In a 1-km walk, the sensitivity and specificity at the optimal cut-off 10:15 (min:s) for men were 63% and 75%, and at the cut-off 10:47 for women 70% and 71%. In dynamic back extension, the sensitivity and specificity at the optimal cut-off 16.5 (repetitions) were 67% and 65% in men and 82% and 59% at cut-off 13.5 in women. Correspondingly, in backward walking, the sensitivity and specificity at the optimal cut-off 27.7 (seconds) were 65% and 69% in men and 74% and 61% at cutoff 35.0 in women.

CONCLUSIONS

The 1-km walk, dynamic back extension and backward walking tests had the best predictive value for WD. These tests, with identified cut-off values, can be used to screen individuals who are at increased risk of WD. Tests can also be used in physical activity counseling to target activity to those components of HRF that indicate poor fitness and are important for good walking ability.

Compensatory strategies used by older adults facing mobility disability

Preclinical disability in mobility tasks can be recognized by asking people without overt mobility disability whether they have changed the way, either the manner or the frequency, of doing a mobility task because of a health or physical condition. Like other compensatory strategies, preclinical mobility disability has a dual nature as both a risk marker associated with impairment or limitation and a mediating factor affecting the natural history of disability. The method of ascertaining preclinical disability through self-report has been shown to have construct validity, to be reliable, and to identify people at an elevated risk of developing overt mobility disability over 1 to 2 years. Many worthy research questions in this field remain to be addressed, especially regarding qualitative heterogeneity (doing more vs doing less) and interactions among compensatory strategies. Nonetheless, there is sufficient evidence to apply what is known about preclinical disability to screening in clinical settings. This area of research and practice constitutes an opportunity for physical medicine and rehabilitation and geriatric medicine to jointly make a large beneficial impact on population health through strategies to prevent disability because rapidly growing numbers of older adults will experience this early and potentially malleable stage.

Frequency of going outdoors as a good predictors for incident disability of physical function as well as disability recovery in community-dwelling older adults in rural Japan

BACKGROUND

The clinico-epidemiologic relevance of the reduction in the frequency of going outdoors in older adults has not been well characterized. This study examined whether the frequency of going outdoors has predictive values for incident physical disability and recovery among community-dwelling elderly.

METHODS

One thousand, two hundred and sixty-seven persons aged 65+ years who lived in a rural community in Niigata, Japan, and participated in the baseline survey were assessed again 2 years later in terms of mobility, and instrumental and basic activities of daily living (IADL and BADL). We compared the incident disability and recovery at follow-up among three subgroups classified by the baseline frequency of going outdoors: once a day or more often, once per 2-3 days, and once a week or less often. Multivariate analyses tested associations between the frequency of going outdoors and functional transition, independent of potential confounders.

RESULTS

A lower frequency of going outdoors at baseline was associated with a greater incident disability, and a lower recovery at the two-year follow-up. Even after adjustment, the effects of going outdoors remained significant. Adjusted risks of incident mobility and IADL disabilities were significantly higher (odds ratio[OR]=4.02, 95% confidence interval [CI]: 1.77-9.14 and OR=2.65, 95% CI: 1.06-6.58), respectively, and recovery from mobility disability was significantly lower (OR=0.29, 95% CI: 0.08-0.99) for “once a week or less often” subgroup compared with “once a day or more often” subgroup.

CONCLUSION

The frequency of going outdoors is a good predictor for incident physical disability and recovery among community-living elderly. Public health nurses and clinicians should pay more attention how often their senior clients usually go outdoors.

Association between mild anemia and executive function impairment in community-dwelling older women: The Women's Health and Aging Study II

OBJECTIVES

To evaluate the relationship between mild anemia and executive function in community-dwelling older women.

DESIGN

Cross-sectional.

SETTING

Community-based.

PARTICIPANTS

High-functioning subjects participating in the baseline assessment of the Women's Health and Aging Study (WHAS) II, Baltimore, Maryland, 1994 to 1996. WHAS II eligibility criteria included aged 70 to 80, a Mini-Mental State Examination score of 24 or greater, and absence of advanced disability (difficulty in no more than 1 domain of physical function). Included in this study were 364 subjects with a hemoglobin concentration 10 g/dL or greater and known executive function status.

MEASUREMENTS

Trail Making Test (TMT) Parts B and A. Tertiles of time to complete each test were used to define best (bottom), intermediate, and worst (top) performance. Tertiles of the difference TMT-B minus TMT-A were calculated. Anemia defined as hemoglobin concentration less than 12 g/dL.

RESULTS

The percentage of subjects in the worst TMT-B, TMT-A, and TMT-B minus TMT-A performance tertile was highest for those with anemia. Prevalent anemia substantially increased the likelihood of performing worst (as opposed to best) on the TMT-B (odds ratio (OR) = 5.2, 95% confidence interval (CI) = 1.3-20.5), TMT-A (OR = 4.8, 95% CI = 1.5-15.6), and TMT-B minus TMT-A (OR = 4.2, 95% CI = 1.0-17.2), even after controlling for age, education, race, prevalent diseases, and relevant physiological and functional parameters.

CONCLUSION

This study provides preliminary evidence in support of the hypothesis that mild anemia might be an independent risk factor for executive function impairment in community-dwelling older adults. Whether such an association is causal or noncausal remains to be determined.

Transitions to mobility difficulty associated with lower extremity osteoarthritis in high functioning older women: longitudinal data from the Women's Health and Aging Study II

OBJECTIVE

To assess the impact of lower extremity osteoarthritis (OA) on transitions to mobility difficulty, and to assess the influence of pain, excess weight, and quadriceps strength on these transitions.

METHODS

We analyzed longitudinal data acquired from 199 participants in the Women's Health and Aging Study II (ages 70-79 years) who initially reported no lower extremity limitation (e.g., difficulty walking one-quarter mile) or difficulty in activities of daily living (ADL; e.g., transferring). Prevalent lower extremity OA was determined from validated algorithms encompassing multiple data sources. Markov transition models were created to analyze the first transition from no difficulty at baseline to lower extremity limitations, ADL difficulty, or both 18, 36, and 72 months later.

RESULTS

Compared with women without OA (n = 140), a higher proportion of women with lower extremity OA (n = 59) initially reported pain on most days and more severe pain while walking (P < 0.05). Women with OA were also heavier, with a higher proportion being obese or overweight (P < 0.001). Lower extremity OA, higher body mass index, and lower knee extensor strength independently increased the risk of transition to combined lower extremity and ADL difficulty first over 72 months.

CONCLUSION

Lower extremity OA increased the likelihood of developing difficulty in both lower extremity tasks and ADL over 72 months in a cohort of initially high functioning older women. Two modifiable factors, higher relative weight and lower knee extensor strength, substantially impacted these transitions, and therefore warrant increased attention in the management of lower extremity OA.

Epidemiology of gait disorders in community-residing older adults

OBJECTIVES

To study the epidemiology of gait disorders in community-residing older adults and their association with death and institutionalization.

DESIGN

Community-based cohort study.

SETTING

Bronx County and the research center at Albert Einstein College of Medicine.

PARTICIPANTS

The Einstein Aging study recruited 488 adults aged 70 to 99 between 1999 and 2001. At entry and during annual visits over 5 years, subjects received clinical evaluations to determine presence of neurological or nonneurological gait abnormalities.

MEASUREMENTS

Prevalence and incidence of gait disorders based on clinical evaluations and time to institutionalization and death.

RESULTS

Of 468 subjects (95.9%) with baseline gait evaluations, 168 had abnormal gaits: 70 neurological, 81 nonneurological, and 17 both. Prevalence of abnormal gait was 35.0% (95% confidence interval (CI) = 28.6-42.1). Incidence of abnormal gait was 168.6 per 1,000 person-years (95% CI = 117.4-242.0) and increased with age. Men had a higher incidence of neurological gait abnormalities, whereas women had a higher incidence of nonneurological gaits. Abnormal gaits were associated with greater risk of institutionalization and death (hazard ratio (HR) = 2.2, 95% CI =1.5-3.2). The risk was strongly related to severity of impairment; subjects with moderate to severe gait abnormalities (HR = 3.2, 95% CI = 1.9-5.2) were at higher risk than those with mild gait abnormalities (HR = 1.8, 95% CI = 1.0-2.8).

CONCLUSION

The incidence and prevalence of gait disorders are high in community-residing older adults and are associated with greater risk of institutionalization and death.

The Dynamic Nature of Mobility Disability in Older Persons

OBJECTIVES

To determine the rates of clinically meaningful transitions in mobility disability; evaluate how these transitions differ according to age, sex, and physical frailty; and depict the duration of the resulting episodes of mobility disability.

DESIGN

Prospective cohort study.

SETTING

General community in greater New Haven, Connecticut, from March 1998 to October 2004.

PARTICIPANTS

Seven hundred fifty-four community-living older persons, aged 70 and older, who were nondisabled (i.e., required no personal assistance) in four activities of daily living.

MEASUREMENTS

Mobility disability, defined as the inability to walk one quarter of a mile and to climb a flight of stairs, respectively without personal assistance, was assessed every month for up to 5 years.

RESULTS

For both mobility tasks, rates per 1,000 person-months were higher for transitions from no disability to intermittent disability (34.7 for walking one quarter of a mile and 17.4 for climbing a flight of stairs), intermittent to continuous disability (52.0 and 42.5), continuous to intermittent disability (35.4 and 31.5), and intermittent to no disability (68.6 and 85.4) than for other transitions. Older age, female sex, and physical frailty were associated with greater likelihood of transition to states of greater disability and lower likelihood of regaining independent mobility.

CONCLUSION

Mobility disability in older persons is a highly dynamic process, characterized by frequent transitions between states of independence and disability. Programs designed to enhance independent mobility should focus not only on the prevention of mobility disability but also on the restoration and maintenance of independent mobility in older persons who become disabled.

Inner city, middle-aged African Americans have excess frank and subclinical disability

BACKGROUND

Healthy People 2010 seeks to decrease or eliminate the health disparities experienced by disadvantaged minority groups.

METHODS

African American Health (AAH) is a population-based panel study of community-dwelling African Americans born between 1936 and 1950 from two strata. The first encompasses a poor, inner city area, and the second involves a suburban population with higher socioeconomic status. The authors recruited 998 participants (76% recruitment). Frank disability was assessed for 25 tasks and defined as inability or difficulty performing that task. Subclinical disability was assessed for 12 tasks and defined as no difficulty but a change in either manner or frequency of task performance. Frank disability prevalences were compared with national data for community-dwelling non-Hispanic white persons (NHW) and African American persons in the same age range.

RESULTS

Compared with the suburban sample, the inner city group had a higher prevalence of frank disability for all 25 tasks (p<.05 for 16) and subclinical disability for 11 of the 12 tasks (p<.05 for 5). Both strata had more frank disability compared with the national NHW population. The inner city area had higher frank disability proportions than did the national African American sample, whereas the suburban group had similar disability levels.

CONCLUSIONS

The AAH inner city group experiences more frank disability than other populations of African Americans and NHWs. The increased prevalence of subclinical disability in the inner city group compared with the suburban group suggests that the disparity in frank disability will continue. These findings indicate that African Americans living in poor inner city areas in particular need intensive and targeted clinical and public health efforts.

Incidence of loss of ability to walk 400 meters in a functionally limited older population

OBJECTIVES

To assess the incidence of and factors related to nondisabled but functionally limited older adults aged 75 to 85 years losing the ability to walk 400 m.

DESIGN

Observational study with average follow-up of 21 months.

SETTING

Community.

PARTICIPANTS

At baseline, 101 persons with objective signs of functional limitations and intact cognitive function agreed to participate in the study. Of these, 81 were able to walk 400 m at baseline, and 62 participated in the follow-up examination.

MEASUREMENTS

Mobility disability was defined as an inability to complete a 400-m walk test. At baseline, eligible participants (n=81) had the ability to walk 400 m, scored between 4 and 9 on the Short Physical Performance Battery (SPPB; range 0-12), and scored 18 or more on the Mini-Mental State Examination. Demographics, difficulty in daily activities, disease status, behavioral risk factors, and muscle strength were assessed at baseline and follow-up.

RESULTS

Of 62 persons at follow-up, 21 (33.9%) developed incident mobility disability. The strongest predictors of loss of mobility were the time to complete the 400-m walk at baseline (odds ratio (OR)=1.6 per 1-minute difference, 95% confidence interval (CI)=1.04-2.45), and decline in SPPB score over the follow-up (OR=1.4 per 1-point difference, 95% CI=1.01-1.92).

CONCLUSION

Older persons with functional limitations have a high rate of loss of ability to walk 400 m. The 400-m walk test is a highly relevant, discrete outcome that is an ideal target for testing preventive interventions in vulnerable older populations.

Measures of Physical Performance and Risk for Progressive and Catastrophic Disability: Results From the Women's Health and Aging Study

BACKGROUND

Physical performance measures can predict incident disability, but little research has assessed and compared how these measures predict progressive and rapid-onset (catastrophic) disability. The authors evaluated the ability of upper and lower extremity performance measures to predict progressive and catastrophic disability in activities of daily living (ADL), mobility, and upper extremity function.

METHODS

The incidence of progressive and catastrophic disability was assessed semiannually during a 3-year period in 884 women participating in the Women's Health and Aging Study I. Four-meter walking speed, balance, and chair stands tests were used to evaluate lower extremity function. The putting-on-blouse test, the Purdue pegboard test, and grip strength were used to assess upper extremity function. Summary performance scores (SPS) for the lower and upper extremities were calculated. Among participants in whom disability developed, those who reported no difficulty in the previous year were defined as cases of catastrophic disability, and those who previously reported little or some difficulty were considered to be cases of progressive disability. Cox proportional hazard regression analyses were used to evaluate the association of performance measures and time to incident disability. The predictive ability of performance measures was compared using receiver-operator characteristic curves.

RESULTS

All lower and upper extremity measures, with the exception of grip strength, significantly predicted the onset of progressive ADL disability, but only walking speed was significantly associated with the onset of catastrophic ADL disability. The chair stands test, walking speed, and the lower extremity SPS were significantly associated with the onset of both progressive and catastrophic mobility disability. Only lower extremity individual tests and SPS significantly predicted the onset of both progressive and catastrophic upper extremity disability. The receiver-operator characteristic curves for ADL and mobility disability showed that all performance measures evaluated had a greater predictive ability for progressive than for catastrophic incident disability. This finding was not consistent for upper extremity disability. The areas under the curve for walking speed and lower extremity SPS were very similar, ranging from 0.58 to 0.81 and from 0.57 to 0.85, and the predictive ability of these two measures was the greatest for all disability outcomes assessed.

CONCLUSION

Physical performance measures of lower extremity and, in particular, walking speed and lower extremity SPS are valuable tools to predict different forms of disability, especially those with a progressive onset.

Untangling the concepts of disability, frailty, and comorbidity: implications for improved targeting and care

Three terms are commonly used interchangeably to identify vulnerable older adults: comorbidity, or multiple chronic conditions, frailty, and disability. However, in geriatric medicine, there is a growing consensus that these are distinct clinical entities that are causally related. Each, individually, occurs frequently and has high import clinically. This article provides a narrative review of current understanding of the definitions and distinguishing characteristics of each of these conditions, including their clinical relevance and distinct prevention and therapeutic issues, and how they are related. Review of the current state of published knowledge is supplemented by targeted analyses in selected areas where no current published data exists. Overall, the goal of this article is to provide a basis for distinguishing between these three important clinical conditions in older adults and showing how use of separate, distinct definitions of each can improve our understanding of the problems affecting older patients and lead to development of improved strategies for diagnosis, care, research, and medical education in this area.

The burden and patterns of disability in activities of daily living among community-living older persons

BACKGROUND

The onset of disability in activities of daily living (ADLs) is considered a sentinel event in the life of an older person, but recent evidence suggests that newly disabled elders have high rates of recovery. We performed a longitudinal study to determine the burden and patterns of ADL disability among previously nondisabled, community-living older persons.

METHODS

We studied 754 community-living persons, aged 70 years or older, who were categorized into three groups according to their risk for disability (low, intermediate, high). Participants were interviewed each month for 2 years to determine the presence and severity of disability in four key ADLs: bathing, dressing, walking, or transferring.

RESULTS

Among the 690 nondecedents, the rates of any disability were 17.7%, 48.7%, and 65.2%, respectively, for the low-, intermediate-, and high-risk groups. Whereas only 6.9% of nondecedents in the low-risk group had more than 1 month of disability, 38.2% and 50.6% of nondecedents in the intermediate- and high-risk groups (i.e., physically frail), respectively, had multiple months and/or episodes of disability. The patterns of disability were quite diverse, with no single pattern representing the disability experience of more than half the decedents or nondecedents in any of the risk groups.

CONCLUSIONS

Disability among community-living older persons, particularly those who are physically frail, is a highly dynamic process with considerable diversity. Our results provide strong evidence to support an emerging paradigm of disability as a reversible, and often recurrent, event.

Predicting the Probability of Falls in Community-Residing Older Adults Using the 8-Foot Up-and-Go: A New Measure of Functional Mobility

The purpose of this study was to determine whether performance on the 8-ft up-and-go test (UG) could discriminate between older adult fallers (n = 71) and nonfallers (n = 63) and whether it would be as sensitive and specific a predictor of falls as the timed up-and-go test (TUG). Performance on the UG was significantly different between the recurrent faller and nonfaller groups (p < .01), as was performance on the TUG (p < .001). Older adults who required 8.5 s or longer to complete the UG were classified as fallers, with an overall prediction rate of 82%. The specificity of the test was 86% and the sensitivity was 78%. Conversely, the overall prediction rate for older adults who completed the TUG in 10 s or longer was 80%. The specificity of the TUG was 86% and the sensitivity was 71%.

Underestimation of disability in community-living older persons

OBJECTIVES

When ascertaining the occurrence of disability, long assessment intervals may be problematic because they do not account for the possibility of recovery or for deaths or losses to follow-up. Our objective was to compare the rates of disability obtained from single follow-up assessments with those obtained from monthly assessments for intervals up to 24 months.

DESIGN

Prospective cohort study.

SETTING

General community.

PARTICIPANTS

Seven hundred fifty-four nondisabled persons, aged 70 and older, categorized into three groups according to their risk for disability (low, intermediate, and high).

MEASUREMENTS

Participants were followed with monthly telephone interviews to determine the occurrence of disability in one or more of four key activities of daily living (ADLs).

RESULTS

For each risk group, the rates of disability obtained from monthly assessments of ADL function (cumulative disability) were considerably greater than those obtained from single follow-up assessments (prevalent disability). These differences in rates increased progressively as the length of the assessment interval increased. For example, the cumulative and prevalence rates of disability in participants in the intermediate risk group were 0.24 and 0.11 at 6 months, 0.36 and 0.20 at 12 months, 0.46 and 0.16 at 18 months, and 0.53 and 0.20 at 24 months, respectively. Although the overall rates were lower, the results for persistent disability, defined as a new disability that was present for at least 2 consecutive months, were similar. Although these differences in rates were attributable almost exclusively to recovery from disability in the first 6 months, they were due increasingly to deaths and losses to follow-up over the next 18 months, particularly in participants in the high-risk group.

CONCLUSIONS

The occurrence of disability is substantially underestimated by longitudinal studies with long assessment intervals. More frequent assessments of functional status could lead to an improved understanding of the course and overall burden of disability in community-living older persons.

Looking at the relationship between hemoglobin concentration and prevalent mobility difficulty in older women. Should the criteria currently used to define anemia in older people be reevaluated?

OBJECTIVES

The World Health Organization (WHO) and other currently used criteria for defining anemia in older women are mainly based on statistical distribution considerations. To explore their clinical appropriateness, we evaluated the relationship between hemoglobin (Hb) concentration, prevalent mobility difficulty, and the Summary Performance Score (SPS).

DESIGN

Cross-sectional study.

SETTING

Two population-based studies, the Women's Health and Aging Studies I and II, Baltimore, Maryland.

PARTICIPANTS

Six hundred thirty-three community-dwelling women aged 70 to 80 with Hb levels obtained within 90 days from baseline assessment.

MEASUREMENTS

Mobility difficulty (self-reported difficulty walking one-quarter of a mile or climbing 10 steps (primary outcome)). SPS, a performance-based summary measure of lower extremity function that combines the results of walking, chair stands, and balance tests (secondary outcome).

RESULTS

Mobility difficulty prevalence was not constant within the WHO "normal" Hb range (12.0-16.0 g/dL). For example, a Hb of 13.5 g/dL was associated with a significantly lower mobility difficulty prevalence than a Hb of 12.0 g/dL (OR=0.68, 95% CI=0.47-0.93), even after adjustment for chronic diseases and other relevant health indicators. A consistent trend of improvement in performance-based scores with increasing Hb categories less than 12.0 g/dL, 12.0 to 13.0g/dL, and 13.0-14.0 g/dL was observed.

CONCLUSION

Our findings raise two hypotheses: (1) Hb currently perceived as "mildly-low" and even "low-normal" might have an independent, adverse effect on mobility function, and (2) Hb of 12.0 g/dL might be a suboptimal criterion for defining anemia in older women. Formal testing of these hypotheses might prove relevant for anemia- and mobility disability-related clinical decision-making.

Self-reported preclinical disability identifies older women with early declines in performance and early disease

There appears to be a preclinical stage of physical disability which precedes onset of task difficulty (disability) in those who develop disability progressively as a result of chronic disease. Such a stage provides a basis for identifying older adults at risk of becoming disabled. This cross-sectional study evaluated whether a preclinical stage of physical function identified by self-report is associated with decrements in objective physical performance measures or increases in disease; that is, whether these measures, in those with preclinical disability, are intermediate between individuals who report no difficulty and no preclinical changes and those who report difficulty. The Women's Health and Aging Study II, an observational study of 436 women 70-80 years of age who were among the two-thirds least disabled living in the community. Participants were sampled from the HCFA Medicare eligibility lists and were determined eligible if they reported no difficulty, or difficulty in only one of four domains of physical function: mobility, upper extremity, IADL and ADL tasks. At the first follow-up (18 months after baseline), participants completed questionnaires on physical functioning for tasks in each of these domains, with possible answer options for each task: they had (1) difficulty (disabled); (2) no difficulty and no modification of task performance (High Function); or (3) no difficulty but reported modification and/or change in frequency of task performance (a self-report measure of preclinical disability predictive of incident difficulty). At the same visit, standardized, objective measures of function and disease were obtained, including measured walk; chair stands; strength: hip flexion, knee extension, ankle dorsiflexion, and grip; balance: function reach, single leg stand, tandem stand; joint exam: hip pain on passive motion and knee pain or tenderness; spirometry; ankle:arm blood pressure ratio; visual function: acuity, contrast sensitivity, stereopsis; and graded treadmill exercise test. Data were analyzed from the first follow-up examination. Physical performance decreased, and disease frequency increased, in association with decreasing self-reported mobility function (in walking one-half mile and climbing 10 steps), across three self-report categories: High Function, Preclinical Disability (Task Modification but No Difficulty) and Disability (Difficulty). These findings pertained for measures of walking speed, balance, strength, and knee and hip osteoarthritis. Self-reported level of function predicted differences in ranges as well as means for walking speed, balance and strength. These findings indicate a physiologic basis for self-reported function, including preclinical disability, specifically that different levels of disease severity, impairments and physical performance are concurrently associated with different categories of self-reported function. They also suggest new avenues for screening and intervention to prevent disability.