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1.  Adaptive Short Forms for Outpatient Rehabilitation Outcome Assessment 
Objective
To develop outpatient adaptive short forms (ASFs) for the Activity Measure for Post-Acute Care (AM-PAC) item bank for use in outpatient therapy settings.
Design
A convenience sample of 11,809 adults with spine, lower extremity, upper extremity and miscellaneous orthopedic impairments who received outpatient rehabilitation in one of 127 outpatient rehabilitation clinics in the US. We identified optimal items for use in developing outpatient ASFs based on the Basic Mobility and Daily Activities domains of the AM-PAC item bank. Patient scores were derived from the AM-PAC computerized adaptive testing (CAT) program. Items were selected for inclusion on the ASFs based on functional content, range of item coverage, measurement precision, item exposure rate, and data collection burden.
Results
Two outpatient ASFs were developed: 1) an 18-item Basic Mobility ASF and 2) a 15-item Daily Activities ASF, derived from the same item bank used to develop the AM-PAC-CAT. Both ASFs achieved acceptable psychometric properties.
Conclusions
In outpatient PAC settings where CAT outcome applications are currently not feasible, IRT-derived ASFs provide the efficient capability to monitor patients’ functional outcomes. The development of ASF functional outcome instruments linked by a common, calibrated item bank has the potential to create a bridge to outcome monitoring across PAC settings and can facilitate the eventual transformation from ASFs to CAT applications easier and more acceptable to the rehabilitation community.
doi:10.1097/PHM.0b013e318186b7ca
PMCID: PMC3947754  PMID: 18806511
Outcomes Assessment; Rehabilitation; Item Response Theory; Physical Functioning
2.  Psychometric properties of the Late-Life Function and Disability Instrument: a systematic review 
BMC Geriatrics  2014;14:12.
Background
The choice of measure for use as a primary outcome in geriatric research is contingent upon the construct of interest and evidence for its psychometric properties. The Late-Life Function and Disability Instrument (LLFDI) has been widely used to assess functional limitations and disability in studies with older adults. The primary aim of this systematic review was to evaluate the current available evidence for the psychometric properties of the LLFDI.
Methods
Published studies of any design reporting results based on administration of the original version of the LLFDI in community-dwelling older adults were identified after searches of 9 electronic databases. Data related to construct validity (convergent/divergent and known-groups validity), test-retest reliability and sensitivity to change were extracted. Effect sizes were calculated for within-group changes and summarized graphically.
Results
Seventy-one studies including 17,301 older adults met inclusion criteria. Data supporting the convergent/divergent and known-groups validity for both the Function and Disability components were extracted from 30 and 18 studies, respectively. High test-retest reliability was found for the Function component, while results for the Disability component were more variable. Sensitivity to change of the LLFDI was confirmed based on findings from 25 studies. The basic lower extremity subscale and overall summary score of the Function component and limitation dimension of the Disability component were associated with the strongest relative effect sizes.
Conclusions
There is extensive evidence to support the construct validity and sensitivity to change of the LLFDI among various clinical populations of community-dwelling older adults. Further work is needed on predictive validity and values for clinically important change. Findings from this review can be used to guide the selection of the most appropriate LLFDI subscale for use an outcome measure in geriatric research and practice.
doi:10.1186/1471-2318-14-12
PMCID: PMC3909447  PMID: 24476510
Function; Disability; Psychometric properties; Community-dwelling older adults
3.  Development of the Computer-Adaptive Version of the Late-Life Function and Disability Instrument 
Background.
Having psychometrically strong disability measures that minimize response burden is important in assessing of older adults.
Methods.
Using the original 48 items from the Late-Life Function and Disability Instrument and newly developed items, a 158-item Activity Limitation and a 62-item Participation Restriction item pool were developed. The item pools were administered to a convenience sample of 520 community-dwelling adults 60 years or older. Confirmatory factor analysis and item response theory were employed to identify content structure, calibrate items, and build the computer-adaptive testings (CATs). We evaluated real-data simulations of 10-item CAT subscales. We collected data from 102 older adults to validate the 10-item CATs against the Veteran’s Short Form-36 and assessed test–retest reliability in a subsample of 57 subjects.
Results.
Confirmatory factor analysis revealed a bifactor structure, and multi-dimensional item response theory was used to calibrate an overall Activity Limitation Scale (141 items) and an overall Participation Restriction Scale (55 items). Fit statistics were acceptable (Activity Limitation: comparative fit index = 0.95, Tucker Lewis Index = 0.95, root mean square error approximation = 0.03; Participation Restriction: comparative fit index = 0.95, Tucker Lewis Index = 0.95, root mean square error approximation = 0.05). Correlation of 10-item CATs with full item banks were substantial (Activity Limitation: r = .90; Participation Restriction: r = .95). Test–retest reliability estimates were high (Activity Limitation: r = .85; Participation Restriction r = .80). Strength and pattern of correlations with Veteran’s Short Form-36 subscales were as hypothesized. Each CAT, on average, took 3.56 minutes to administer.
Conclusions.
The Late-Life Function and Disability Instrument CATs demonstrated strong reliability, validity, accuracy, and precision. The Late-Life Function and Disability Instrument CAT can achieve psychometrically sound disability assessment in older persons while reducing respondent burden. Further research is needed to assess their ability to measure change in older adults.
doi:10.1093/gerona/gls108
PMCID: PMC3670156  PMID: 22546960
Function; Disability; Computer-adaptive testing; Activity; Participation
4.  An Examination of Healthy Aging Across a Conceptual Continuum: Prevalence Estimates, Demographic Patterns, and Validity 
Background.
Although the notion of healthy aging has gained wide acceptance in gerontology, measuring the phenomenon is challenging. Guided by a prominent conceptualization of healthy aging, we examined how shifting from a more to less stringent definition of healthy aging influences prevalence estimates, demographic patterns, and validity.
Methods.
Data are from adults aged 65 years and older who participated in the Health and Retirement Study. We examined four operational definitions of healthy aging. For each, we calculated prevalence estimates and examined the odds of healthy aging by age, education, gender, and race-ethnicity in 2006. We also examined the association between healthy aging and both self-rated health and death.
Results.
Across definitions, the prevalence of healthy aging ranged from 3.3% to 35.5%. For all definitions, those classified as experiencing healthy aging had lower odds of fair or poor self-rated health and death over an 8-year period. The odds of being classified as “healthy” were lower among those of advanced age, those with less education, and women than for their corresponding counterparts across all definitions.
Conclusions.
Moving across the conceptual continuum—from a more to less rigid definition of healthy aging—markedly increases the measured prevalence of healthy aging. Importantly, results suggest that all examined definitions identified a subgroup of older adults who had substantially lower odds of reporting fair or poor health and dying over an 8-year period, providing evidence of the validity of our definitions. Conceptualizations that emphasize symptomatic disease and functional health may be particularly useful for public health purposes.
doi:10.1093/gerona/glr234
PMCID: PMC3536546  PMID: 22367432
Healthy aging; Measurement; Successful aging
5.  Toward a Common Language of Disablement 
doi:10.1093/gerona/glp093
PMCID: PMC2759568  PMID: 19617528
7.  Evaluation of Patient and Proxy Responses on the Activity Measure for Post Acute Care 
Background and Purpose
Our objective was to examine the agreement between adult patients with stroke and family member or clinician proxies in Activity Measure for Post Acute Care (AM-PAC) summary scores for daily activity, basic mobility, and applied cognitive function.
Methods
This study involved 67 patients with stroke admitted to a hospital within the Kaiser Permanente of Northern California system and were participants in a parent study on stroke outcomes. Each participant and proxy respondent completed the AM-PAC by personal or telephone interview at the point of hospital discharge and/or during one or more transitions to different post-acute care settings.
Results
The results suggest that for patients with a stroke proxy AM-PAC data are robust for family or clinician proxy assessment of basic mobility function, clinician proxy assessment of daily activity function, but less robust for family proxy assessment of daily activity function and for all proxy groups’ assessment of applied cognitive function. The pattern of disagreement between patient and proxy was, on average, relatively small and random. There was little evidence of systematic bias between proxy and patient reports of their functional status. The degree of concordance between patient and proxy was similar for those with moderate to severe strokes compared with mild strokes.
Conclusions
Patient and proxy ratings on the AM-PAC achieved adequate agreement for use in stroke research where using proxy respondents could reduce sample selection bias. The AM-PAC data can be implemented across institutional as well as community care settings while achieving precision and reducing respondent burden.
doi:10.1161/STROKEAHA.111.619643
PMCID: PMC3291956  PMID: 22343646
stroke outcome; stroke assessment; disability evaluation; rehabilitation
8.  Did the 1997 Balanced Budget Act Reduce Use of Physical and Occupational Therapy Services? 
Objective
To investigate whether use of physical therapy (PT) and occupational therapy (OT) services decreased after the passage of the 1997 Balanced Budget Act (BBA).
Design
Data from the nationally representative Medicare Current Beneficiary Survey (MCBS) were merged with Medicare claims data. We conducted cross-sectional analyses of data from 1995 (n=7978), 1999 (n=7863), and 2001 (n=7973). All analyses used MCBS sampling weights to provide estimates that can be generalized to the Medicare population with 5 common conditions.
Settings
Skilled nursing facilities (SNFs), home health agencies, inpatient rehabilitation facilities (IRFs), and outpatient rehabilitation settings.
Participants
Medicare beneficiaries who participated in the MCBS survey in each of the study years and had 1 or more of the following conditions: acute stroke, acute myocardial infarction, chronic obstructive pulmonary disease, arthritis or degenerative joint disease, or mobility problems.
Interventions
Not applicable.
Main Outcome Measures
Percentage of persons meeting our inclusion criteria who received PT or OT in each setting, and total units of PT and OT received in each setting.
Results
Multivariable logistic regression revealed no statistically significantly differences in the proportion of people who met our inclusion criteria who used PT or OT from home health agencies across the 3 time points. For SNFs, an increase in the odds of receiving PT was statistically significant from 1995 to 1999 (odds ratio [OR]=1.42; 95% confidence interval [CI], 1.19–1.69) and 1995 to 2001 (OR=1.69; 95% CI, 1.39–2.05). For IRF and outpatient settings, a significant increase was observed between 1995 and 2001 (OR=1.71, OR=1.27, respectively). For OT, a statistically significant increase was observed for IRF and outpatient rehabilitation settings from 1995 to 2001. For SNF, the increase was statistically significant from 1995 to 1999 and 1995 to 2001. Mean total PT and OT units received also increased across all settings from 1995 to 2001 except for IRFs.
Conclusions
Despite BBA mandates restricting postacute care expenditures, this nationally representative study showed no decreases in the percentage of Medicare beneficiaries with 5 common diagnoses receiving PT and/or OT across all settings and no decreases in units of PT and/or OT services received between 1995 and 2001 except for those in IRFs. This study suggests that the delivery of PT and OT services did not decline among persons with conditions where rehabilitation services are often clinically indicated.
doi:10.1016/j.apmr.2008.02.010
PMCID: PMC3560913  PMID: 18452725
Medicare; Occupational therapy; Physical therapy; Prospective payment system; Rehabilitation
9.  Creating a Computer Adaptive Test Version of the Late-Life Function & Disability Instrument 
Background
This study applied Item Response Theory (IRT) and Computer Adaptive Test (CAT) methodologies to develop a prototype function and disability assessment instrument for use in aging research. Herein, we report on the development of the CAT version of the Late-Life Function & Disability instrument (Late-Life FDI) and evaluate its psychometric properties.
Methods
We employed confirmatory factor analysis, IRT methods, validation, and computer simulation analyses of data collected from 671 older adults residing in residential care facilities. We compared accuracy, precision, and sensitivity to change of scores from CAT versions of two Late-Life FDI scales with scores from the fixed-form instrument. Score estimates from the prototype CAT versus the original instrument were compared in a sample of 40 older adults.
Results
Distinct function and disability domains were identified within the Late-Life FDI item bank and used to construct two prototype CAT scales. Using retrospective data, scores from computer simulations of the prototype CAT scales were highly correlated with scores from the original instrument. The results of computer simulation, accuracy, precision, and sensitivity to change of the CATs closely approximated those of the fixed-form scales, especially for the 10- or 15-item CAT versions. In the prospective study each CAT was administered in less than 3 minutes and CAT scores were highly correlated with scores generated from the original instrument.
Conclusions
CAT scores of the Late-Life FDI were highly comparable to those obtained from the full-length instrument with a small loss in accuracy, precision, and sensitivity to change.
PMCID: PMC2718692  PMID: 19038841
outcome assessment (Health Care); geriatrics; rehabilitation
10.  A Longitudinal Comparison of Five Preference-weighted Health State Classification Systems in Persons with Intervertebral Disc Herniation 
doi:10.1177/0272989X10380924
PMCID: PMC3535472  PMID: 21098419
Health State Preferences, Utilities, and Valuation; Health status indicators; Spine diseases; Quality of life; Economic evaluation; SPORT; Scale Validation; Cost-utility Analysis; Cost-effectiveness Analysis
11.  The contribution of osteoarthritis to functional limitations and disability 
Clinics in geriatric medicine  2010;26(3):387-399.
Synopsis
This article uses the Disablement Model conceptual framework to guide an analysis of the importance of OA in the development of disability. The Disablement Model describes the development and progression of disablement from impairments to specific functional limitations and disability, and the hypothesized role of predisposing risk factors, extra-individual factors, and intra-individual factors. A wide range of population and clinical studies have characterized the unequivocal contribution of arthritis to the development of functional limitations and disability. Evidence overwhelmingly supports a significant, moderate independent contribution of arthritis to the onset and progression of functional limitations and disability. With respect to important risk factors for the development of functional limitations and disability among those with OA, the evidence provides strong support for the role of physical impairments along with other predisposing and intra-individual factors such as age; body mass index, obesity, lack of exercise, comorbid conditions, depression; and depressive symptoms. Extra-individual factors included need for aids and assistance, and lack of access to public or private transportation. Future disablement research must clarify the causal mechanisms behind a potential risk factor’s impact on disability and delineate the interplay between and among the various hypothesized steps in the disablement process.
doi:10.1016/j.cger.2010.04.001
PMCID: PMC3529154  PMID: 20699161
osteoarthritis; arthritis; function; disability; activity; participation; disablement
12.  A Multidimensional Computer Adaptive Test Approach to Dyspnea Assessment 
Objective
To develop and test a prototype dyspnea computer adaptive test.
Design
Prospective study.
Setting
Two outpatient medical facilities.
Participants
A convenience sample of 292 adults with COPD.
Interventions
Not applicable
Main Outcome Measure
We developed a modified and expanded item bank and computer adaptive test (CAT) for the Dyspnea Management Questionnaire (DMQ), an outcome measure consisting of four dyspnea dimensions: dyspnea intensity, dyspnea anxiety, activity avoidance, and activity self-efficacy.
Results
Factor analyses supported a four-dimensional model underlying the 71 DMQ items. The DMQ item bank achieved acceptable Rasch model fit statistics, good measurement breadth with minimal floor and ceiling effects, and evidence of high internal consistency reliability (α = 0.92 to 0.98). Using CAT simulation analyses, the DMQ-CAT showed high measurement accuracy compared to the total item pool (r = .83 to .97, p < .0001) and evidence of good to excellent concurrent (r = −.61 to −0.80, p < .0001) validity. All DMQ-CAT domains showed evidence for known-groups validity (p ≤ 0.001).
Conclusions
The DMQ-CAT reliably and validly captured four distinct dyspnea domains. Multidimensional dyspnea assessment in COPD is needed to better measure the effectiveness of pharmacologic, pulmonary rehabilitation, and psychosocial interventions in not only alleviating the somatic sensation of dyspnea but also reducing dysfunctional emotions, cognitions, and behaviors associated with dyspnea, especially for anxious patients.
doi:10.1016/j.apmr.2011.05.020
PMCID: PMC3526016  PMID: 21963123
Dyspnea; COPD; Outcomes assessment; Reliability; Validity
13.  Clinical Meaningfulness of the Changes in Muscle Performance and Physical Function Associated With Testosterone Administration in Older Men With Mobility Limitation 
Context.
Testosterone in Older Men with Mobility Limitations Trial determined the effects of testosterone on muscle performance and physical function in older men with mobility limitation. Trial’s Data and Safety Monitoring Board recommended enrollment cessation due to increased frequency of adverse events in testosterone arm. The changes in muscle performance and physical function were evaluated in relation to participant’s perception of change.
Methods.
Men aged 65 years and older, with mobility limitation, total testosterone 100–350 ng/dL, or free testosterone less than 50 pg/mL, were randomized to placebo or 10 g testosterone gel daily for 6 months. Primary outcome was leg-press strength. Secondary outcomes included chest-press strength, stair-climb, 40-m walk, muscle mass, physical activity, self-reported function, and fatigue. Proportions of participants exceeding minimally important difference in study arms were compared.
Results.
Of 209 randomized participants, 165 had follow-up efficacy measures. Mean (SD) age was 74 (5.4) years and short physical performance battery score 7.7 (1.4). Testosterone arm exhibited greater improvements in leg-press strength, chest-press strength and power, and loaded stair-climb than placebo. Compared with placebo, significantly greater proportion of men receiving testosterone improved their leg-press and chest-press strengths (43% vs 18%, p = .01) and stair-climbing power (28% vs 10%, p = .03) more than minimally important difference. Increases in leg-press strength and stair-climbing power were associated with changes in testosterone levels and muscle mass. Physical activity, walking speed, self-reported function, and fatigue did not change.
Conclusions.
Testosterone administration in older men with mobility limitation was associated with patient-important improvements in muscle strength and stair-climbing power. Improvements in muscle strength and only some physical function measures should be weighed against the risk of adverse events in this population.
doi:10.1093/gerona/glr100
PMCID: PMC3202898  PMID: 21697501
Testosterone; Minimally important difference; Mobility limitation; Older men; Function promoting therapies
14.  Linking the Activity Measure for Post-acute Care and the Quality of Life Outcomes in Neurological Disorders 
Objective
To use item response theory (IRT) methods to link physical functioning items in the Activity Measure for Post-acute Care (AM-PAC) and the Quality of Life Outcomes in Neurological Disorders (Neuro-QOL)
Design
Secondary data analysis of the physical functioning items of AM-PAC and Neuro-QOL. We used a non-equivalent group design with 36 core items common to both instruments. We used a test characteristic curve transformation method to for linking AM-PAC and Neuro-QOL scores. Linking was conducted so that both raw scores and scaled AM-PAC and Neuro-QOL scores (converted-logit scores with mean = 50 and SD = 10) could be compared.
Setting
AM-PAC items were administered to rehabilitation patients in post-acute care settings. Neuro-QOL items were administered to a community sample of adults via the Internet.
Participants
The AM-PAC sample consisted of 1,041 post acute care patients; the Neuro-QOL sample was 549 community-dwelling adults.
Interventions
Not applicable.
Main Outcome Measures
25 Mobility items and 11 ADL items common to both instruments were included in the analysis.
Results
Neuro-QOL items were linked to the AM-PAC scale using the Generalized Partial Credit Model. Mobility and ADL subscale scores from the two instruments were calibrated to the AM-PAC metric.
Conclusions
An IRT-based linking method placed AM-PAC and NeuroQOL Mobility and ADL scores on a common metric. This linking allowed estimation of AM-PAC Mobility and ADL subscale scores based on Neuro-QOL Mobility and ADL subscale scores, and vice versa. The accuracy of these results should be validated in a future sample in which participants respond to both instruments.
doi:10.1016/j.apmr.2011.01.026
PMCID: PMC3372982  PMID: 21958921
outcome assessment (Health Care); linking; neurological diseases; rehabilitation
15.  Adverse Events Associated with Testosterone Administration 
The New England journal of medicine  2010;363(2):109-122.
Background
Testosterone supplementation has been shown to increase muscle mass and strength in healthy older men. The safety and efficacy of testosterone treatment in older men who have limitations in mobility have not been studied.
Methods
Community-dwelling men, 65 years of age or older, with limitations in mobility and a total serum testosterone level of 100 to 350 ng per deciliter (3.5 to 12.1 nmol per liter) or a free serum testosterone level of less than 50 pg per milliliter (173 pmol per liter) were randomly assigned to receive placebo gel or testosterone gel, to be applied daily for 6 months. Adverse events were categorized with the use of the Medical Dictionary for Regulatory Activities classification. The data and safety monitoring board recommended that the trial be discontinued early because there was a significantly higher rate of adverse cardiovascular events in the testosterone group than in the placebo group.
Results
A total of 209 men (mean age, 74 years) were enrolled at the time the trial was terminated. At baseline, there was a high prevalence of hypertension, diabetes, hyperlipidemia, and obesity among the participants. During the course of the study, the testosterone group had higher rates of cardiac, respiratory, and dermatologic events than did the placebo group. A total of 23 subjects in the testosterone group, as compared with 5 in the placebo group, had cardiovascular-related adverse events. The relative risk of a cardiovascular-related adverse event remained constant throughout the 6-month treatment period. As compared with the placebo group, the testosterone group had significantly greater improvements in leg-press and chest-press strength and in stair climbing while carrying a load.
Conclusions
In this population of older men with limitations in mobility and a high prevalence of chronic disease, the application of a testosterone gel was associated with an increased risk of cardiovascular adverse events. The small size of the trial and the unique population prevent broader inferences from being made about the safety of testosterone therapy.
doi:10.1056/NEJMoa1000485
PMCID: PMC3440621  PMID: 20592293
16.  Use of Physical and Occupational Therapy by Medicare Beneficiaries within Five Conditions: 1994-2001 
Objective
To examine use of physical therapy (PT) and occupational therapy (OT) among Medicare beneficiaries nationwide before and after the 1997 Balanced Budget Act (BBA), which introduced prospective payment for rehabilitation services.
Design
We analyzed responses from the longitudinal Medicare Current Beneficiary Survey, merged with Medicare claims, to track PT and OT rates and intensity (units of service) from 1994 through 2001. This observational study focused on elderly and disabled Medicare beneficiaries within five conditions: stroke, acute myocardial infarction, chronic obstructive pulmonary disease, arthritis, and lower extremity mobility problems. We used cubic smoothing spline functions to describe trends in service intensity over time and generalized estimating equations to assess changes in service intensity.
Results
Controlling for demographic characteristics, adjusted mean level of PT and OT intensity rose significantly between 1994 and 2001 for all five conditions. Service intensity leveled off in 1999 for OT and 2000 for PT. With few exceptions, PT and OT intensity was not significantly associated with patients’ demographic characteristics.
Conclusions
Medicare beneficiaries with conditions that can potentially benefit from PT and/or OT continued to get these services at similar – and sometimes increasing – intensity during years following passage of the BBA.
doi:10.1097/PHM.0b013e318198a791
PMCID: PMC3341629  PMID: 19190486
Physical Therapy; Occupational Therapy; Medicare; Prospective Payment
17.  Replenishing a computerized adaptive test of patient-reported daily activity functioning 
Quality of Life Research  2009;18(4):461-471.
Purpose
Computerized adaptive testing (CAT) item banks may need to be updated, but before new items can be added, they must be linked to the previous CAT. The purpose of this study was to evaluate 41 pretest items prior to including them into an operational CAT.
Methods
We recruited 6,882 patients with spine, lower extremity, upper extremity, and nonorthopedic impairments who received outpatient rehabilitation in one of 147 clinics across 13 states of the USA. Forty-one new Daily Activity (DA) items were administered along with the Activity Measure for Post-Acute Care Daily Activity CAT (DA-CAT-1) in five separate waves. We compared the scoring consistency with the full item bank, test information function (TIF), person standard errors (SEs), and content range of the DA-CAT-1 to the new CAT (DA-CAT-2) with the pretest items by real data simulations.
Results
We retained 29 of the 41 pretest items. Scores from the DA-CAT-2 were more consistent (ICC = 0.90 versus 0.96) than DA-CAT-1 when compared with the full item bank. TIF and person SEs were improved for persons with higher levels of DA functioning, and ceiling effects were reduced from 16.1% to 6.1%.
Conclusions
Item response theory and online calibration methods were valuable in improving the DA-CAT.
doi:10.1007/s11136-009-9463-5
PMCID: PMC3339485  PMID: 19288222
Outcomes assessment; Quality of life; Item response theory; Activities of daily living (ADL)
18.  A Computer-Adaptive Disability Instrument for Lower Extremity Osteoarthritis Research Demonstrated Promising Breadth, Precision and Reliability 
Journal of Clinical Epidemiology  2009;62(8):807-815.
Objective
To develop and evaluate a prototype measure (OA-DISABILITY-CAT) for osteoarthritis research using Item Response Theory (IRT) and Computer Adaptive Test (CAT) methodologies.
Study Design and Setting
We constructed an item bank consisting of 33 activities commonly affected by lower extremity (LE) osteoarthritis. A sample of 323 adults with LE osteoarthritis reported their degree of limitation in performing everyday activities and completed the Health Assessment Questionnaire-II (HAQ-II). We used confirmatory factor analyses to assess scale unidimensionality and IRT methods to calibrate the items and examine the fit of the data. Using CAT simulation analyses, we examined the performance of OA-DISABILITY-CATs of different lengths compared to the full item bank and the HAQ-II.
Results
One distinct disability domain was identified. The 10-item OA-DISABILITY-CAT demonstrated a high degree of accuracy compared with the full item bank (r=0.99). The item bank and the HAQ-II scales covered a similar estimated scoring range. In terms of reliability, 95% of OA-DISABILITY reliability estimates were over 0.83 versus 0.60 for the HAQ-II. Except at the highest scores the 10-item OA-DISABILITY-CAT demonstrated superior precision to the HAQ-II.
Conclusion
The prototype OA-DISABILITY-CAT demonstrated promising measurement properties compared to the HAQ-II, and is recommended for use in LE osteoarthritis research.
doi:10.1016/j.jclinepi.2008.10.004
PMCID: PMC3328293  PMID: 19216052
outcome assessment (Health Care); osteoarthritis; clinical trials; disability; item response theory; computer adaptive testing
19.  Outcome Measurement for COPD: Reliability and Validity of the Dyspnea Management Questionnaire 
Respiratory medicine  2010;105(3):442-453.
Background
The Dyspnea Management Questionnaire (DMQ) is a measure of the psychosocial and behavioral responses to dyspnea for adults with COPD. The research objectives were to evaluate the reliability and validity of an expanded DMQ item pool, as a preliminary step for developing a computer adaptive test.
Methods
The original 66 items of the DMQ were used for the analyses. The sample included 63 women and 44 men with COPD (n = 107) recruited from two urban medical centers. We used confirmatory factor analysis to test the factor structure of the DMQ and its underlying cognitive-behavioral theoretical base. The internal consistency and test-retest reliability, and breadth of coverage of the expanded DMQ item bank were also evaluated.
Results
Five distinct dyspnea domains were confirmed using 56 original items of the DMQ: dyspnea intensity, dyspnea anxiety, activity avoidance, activity self-efficacy, and strategy satisfaction. Overall, the breadth of items was excellent with a good match between sample scores and item difficulty. The DMQ-56 showed good internal consistency reliability (α = .85 to .96) and good preliminary test-retest reliability over a 3-week interval (ICC = .69 to .92).
Conclusions
The DMQ demonstrated acceptable levels of reliability and validity for measuring multidimensional dyspnea outcomes after medical, psychological, and behavioral interventions for adults with COPD.
doi:10.1016/j.rmed.2010.09.002
PMCID: PMC3061305  PMID: 20884194
dyspnea; anxiety; chronic obstructive pulmonary disease; outcomes research; item response theory; cognitive-behavioral therapy
20.  Does Post-Acute Care Site Matter? A longitudinal study assessing functional recovery after a stroke 
Objective
To determine the impact of post acute care site on stroke outcomes. Following a stroke, patients may receive post acute care in a number of different sites: inpatient rehabilitation (IRF), skilled nursing facility (SNF), and home health care/outpatient (HH/OP). We hypothesized that patients who received IRF would have better six-month functional outcomes than those who received care in other settings after controlling for patient characteristics.
Design
Prospective Cohort Study.
Setting
Four Northern California hospitals which are part of a single health maintenance organization.
Participants
222 patients with stroke enrolled between February 2008 and July 2010.
Intervention
Not Applicable.
Main Outcome Measure
Baseline and 6 month assessments were performed using the Activity Measure for Post Acute Care (AM-PAC™), a test of self-reported function in three domains: Basic Mobility, Daily Activities, and Applied Cognition.
Results
Of the 222 patients analyzed, 36% went home with no treatment, 22% received HH/OP care, 30% included IRF in their care trajectory, and 13% included SNF (but not IRF) in their care trajectory. At six months, after controlling for important variables such as age, functional status at acute care discharge, and total hours of rehabilitation, patients who went to an IRF had functional scores that were at least 8 points higher (twice the minimally detectable change for the AM-PAC) than those who went to a SNF in all 3 domains and in two out of three functional domains compared to those who received HH/OP care.
Conclusions
Patients with stroke may make more functional gains if their post-acute care includes an IRF. This finding may have important implications as post-acute care delivery is reshaped through health care reform.
doi:10.1016/j.apmr.2012.09.033
PMCID: PMC3584186  PMID: 23124133
stroke outcome; stroke assessment; disability evaluation; rehabilitation
21.  Community Environmental Factors Are Associated With Disability in Older Adults With Functional Limitations: The MOST Study 
Background
There is limited evidence supporting the hypothesized environment–disability link. The objectives of this study were to (a) identify the prevalence of community mobility barriers and transportation facilitators and (b) examine whether barriers and facilitators were associated with disability among older adults with functional limitations.
Methods
Four hundred and thirty-five participants aged 65+ years old with functional limitations were recruited from the Multicenter Osteoarthritis Study, a prospective study of community-dwelling adults with or at risk of developing symptomatic knee osteoarthritis. Presence of community barriers and facilitators was ascertained by the Home and Community Environment survey. Two domains of disability, (a) daily activity limitation (DAL) and (b) daily activity frequency (DAF), were assessed with the Late-Life Disability Instrument. Covariates included age, gender, education, race, comorbidity, body mass index, knee pain, and functional limitation. Multivariable logistic regression was used to examine adjusted associations of community factors with presence of DAL and DAF.
Results
Approximately one third of the participants lived in a community with high mobility barriers and low transportation facilitators. High mobility barriers was associated with greater odds of DAL (odds ratio [OR] = 2.0, 95% confidence interval [CI] 1.2–3.1) after adjusting for covariates, and high transportation facilitators was associated with lower odds of DAL (OR = 0.5, 95% CI 0.3–0.8) but not with DAF in adjusted models.
Conclusion
People with functional limitations who live in communities that were more restrictive felt more limited in doing daily activities but did not perform these daily activities any less frequently.
doi:10.1093/gerona/glp182
PMCID: PMC2905834  PMID: 19995830
Activities of daily living; Environment; Residential characteristics
22.  Are features of the neighborhood environment associated with disability in older adults? 
Disability and rehabilitation  2010;32(8):639-645.
Purpose
To explore the association of features of a person’s neighborhood environment with disability in daily activities.
Method
We recruited 436 people age 65 years and over (mean 70.4 years (sd=3.9)) with functional limitations from the Multicenter Osteoarthritis Study (MOST). Features of the neighborhood environment were assessed using the Home and Community Environment (HACE) survey. The Late-Life Disability Instrument (LLDI) was used to assess disability in daily activities. We used logistic regression to examine the association of individual environmental features with disability.
Results
Older adults whose neighborhoods did not have parks and walking areas less frequently engaged in a regular fitness program (OR=0.4, 95%CI [0.2 0.7]), and in social activities (OR= 0.5, 95%CI [0.3 1.0]). Those whose neighborhoods had adequate handicap parking had 1.5 to 1.8 higher odds of engagement in several social and work role activities. The presence of public transportation was associated with 1.5 to 2.9 higher odds of not feeling limited in social, leisure, and work role activities, and instrumental activities of daily living.
Conclusion
Our exploratory study suggests that parks and walking areas, adequate handicap parking, and public transportation are associated with disability in older adults.
doi:10.3109/09638280903254547
PMCID: PMC2908013  PMID: 20205576
Environment; Elderly
23.  Evaluation of the late life disability instrument in the lifestyle interventions and independence for elders pilot (LIFE-P) study 
Background
The late life disability instrument (LLDI) was developed to assess limitations in instrumental and management roles using a small and restricted sample. In this paper we examine the measurement properties of the LLDI using data from the Lifestyle Interventions and Independence for Elders Pilot (LIFE-P) study.
Methods
LIFE-P participants, aged 70-89 years, were at elevated risk of disability. The 424 participants were enrolled at the Cooper Institute, Stanford University, University of Pittsburgh, and Wake Forest University. Physical activity and successful aging health education interventions were compared after 12-months of follow-up. Using factor analysis, we determined whether the LLDI's factor structure was comparable with that reported previously. We further examined how each item related to measured disability using item response theory (IRT).
Results
The factor structure for the limitation domain within the LLDI in the LIFE-P study did not corroborate previous findings. However, the factor structure using the abbreviated version was supported. Social and personal role factors were identified. IRT analysis revealed that each item in the social role factor provided a similar level of information, whereas the items in the personal role factor tended to provide different levels of information.
Conclusions
Within the context of community-based clinical intervention research in aged populations, an abbreviated version of the LLDI performed better than the full 16-item version. In addition, the personal subscale would benefit from additional research using IRT.
Trial registration
The protocol of LIFE-P is consistent with the principles of the Declaration of Helsinki and is registered at http://www.ClinicalTrials.gov (registration # NCT00116194).
doi:10.1186/1477-7525-8-115
PMCID: PMC2984553  PMID: 20925931
24.  A functional difficulty and functional pain instrument for hip and knee osteoarthritis 
Arthritis Research & Therapy  2009;11(4):R107.
Introduction
The objectives of this study were to develop a functional outcome instrument for hip and knee osteoarthritis research (OA-FUNCTION-CAT) using item response theory (IRT) and computer adaptive test (CAT) methods and to assess its psychometric performance compared to the current standard in the field.
Methods
We conducted an extensive literature review, focus groups, and cognitive testing to guide the construction of an item bank consisting of 125 functional activities commonly affected by hip and knee osteoarthritis. We recruited a convenience sample of 328 adults with confirmed hip and/or knee osteoarthritis. Subjects reported their degree of functional difficulty and functional pain in performing each activity in the item bank and completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Confirmatory factor analyses were conducted to assess scale uni-dimensionality, and IRT methods were used to calibrate the items and examine the fit of the data. We assessed the performance of OA-FUNCTION-CATs of different lengths relative to the full item bank and WOMAC using CAT simulation analyses.
Results
Confirmatory factor analyses revealed distinct functional difficulty and functional pain domains. Descriptive statistics for scores from 5-, 10-, and 15-item CATs were similar to those for the full item bank. The 10-item OA-FUNCTION-CAT scales demonstrated a high degree of accuracy compared with the item bank (r = 0.96 and 0.89, respectively). Compared to the WOMAC, both scales covered a broader score range and demonstrated a higher degree of precision at the ceiling and reliability across the range of scores.
Conclusions
The OA-FUNCTION-CAT provided superior reliability throughout the score range and improved breadth and precision at the ceiling compared with the WOMAC. Further research is needed to assess whether these improvements carry over into superior ability to measure change.
doi:10.1186/ar2760
PMCID: PMC2745788  PMID: 19589168
25.  An Exploratory Analysis of Functional Staging Using an Item Response Theory Approach 
Objectives
To develop and explore the feasibility of a functional staging system (defined as the process of assigning subjects, according to predetermined standards, into a set of hierarchical levels with regard to their functioning performance in mobility, daily activities, and cognitive skills) based on item response theory (IRT) methods using short-forms of the Activity Measure for Post-Acute Care (AM-PAC); and to compare the criterion validity and sensitivity of the IRT-based staging system to a non-IRT-based staging system developed for the FIM instrument.
Design
Prospective, longitudinal cohort study of patients interviewed at hospital discharge and 1, 6, and 12 months after inpatient rehabilitation.
Setting
Follow-up interviews conducted in patients’ homes.
Participants
Convenience sample of 516 patients (47% men; sample mean age, 68.3y) at baseline (retention at the final follow-up, 65%) with neurologic, lower-extremity orthopedic, or complex medical conditions.
Interventions
Not applicable
Main Outcome Measures
AM-PAC basic mobility, daily activity, and applied cognitive activity stages; FIM executive control, mobility, activities of daily living, and sphincter stages. Stages refer to the hierarchical levels assigned to patient’s functioning performance.
Results
We were able to define IRT-based staging definitions and create meaningful cut scores based on the 3 AM-PAC short-forms. The IRT stages correlated as well or better to the criterion items than the FIM stages. Both the IRT-based stages and the FIM stages were sensitive to changes throughout the 6-month follow-up period. The FIM stages were more sensitive in detecting changes between baseline and 1-month follow-up visit. The AM-PAC stages were more discriminant in the follow-up visits.
Conclusions
An IRT-based staging approach appeared feasible and effective in classifying patients throughout long-term follow-up. Although these stages were developed from short-forms, this staging methodology could also be applied to improve the meaning of scores generated from IRT-based computerized adaptive testing in future work.
doi:10.1016/j.apmr.2007.11.036
PMCID: PMC2677141  PMID: 18503798
Outcome assessment (health care); Rehabilitation

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