Laura A. Kurlinski

Predictive Validity and Responsiveness of Patient-Reported and Performance-Based Measures of Function in the Boston RISE Study

BACKGROUND Patient-reported and performance-based measures (PBMs) are commonly used to measure physical function in studies of older adults. Selection of appropriate measures to address specific research questions is complex and requires knowledge of relevant psychometric properties. The aim of this study was to examine the predictive validity for adverse outcomes and responsiveness of a widely used patient-reported measure, the Late-Life Function and Disability Instrument (LLFDI), compared with PBMs. METHODS We analyzed 2 years of follow-up data from Boston RISE, a cohort study of 430 primary care patients aged ≥65 years. Logistic and linear regression models were used to examine predictive validity for adverse outcomes and effect size and minimal detectable change scores were computed to examine responsiveness. Performance-based functional measures included the Short Physical Performance Battery, 400-m walk, gait speed, and stair-climb power test. RESULTS The LLFDI and PBMs showed high predictive validity for poor self-rated health, hospitalizations, and disability. The LLFDI function scale was the only measure that predicted falls. Absolute effect size estimates ranged from 0.54 to 0.64 for the LLFDI and from 0.34 to 0.63 for the PBMs. From baseline to 2 years, the percentage of participants with a change ≥ minimal detectable change was greatest for the LLFDI scales (46-59%) followed by the Short Physical Performance Battery (44%), gait speed (35%), 400-m walk (17%), and stair-climb power test (9%). CONCLUSIONS The patient-reported LLFDI showed comparable psychometric properties to PBMs. Our findings support the use of the LLFDI as a primary outcome in gerontological research.

The Boston Rehabilitative Impairment Study of the Elderly: A Description of Methods

OBJECTIVES To describe the methods of a longitudinal cohort study among older adults with preclinical disability. The study aims to address the lack of evidence guiding mobility rehabilitation for older adults by identifying those impairments and impairment combinations that are most responsible for mobility decline and disability progression over 2 years of follow-up. DESIGN Longitudinal cohort study. SETTING Metropolitan-based health care system. PARTICIPANTS Community-dwelling primary care patients aged ≥65 years (N=430), with self-reported modification of mobility tasks because of underlying health conditions. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Late Life Function and Disability Instrument (LLFDI) (primary outcome); Short Physical Performance Battery and 400-m walk test (secondary outcomes). RESULTS Among 7403 primary care patients identified as being potentially eligible for participation, 430 were enrolled. Participants have a mean age of 76.5 years, are 68% women, and have on average 4.2 chronic conditions. Mean LLFDI scores are 55.5 for Function and 68.9 and 52.3 for the Disability Limitation and Frequency domains, respectively. CONCLUSIONS Completion of our study aims will inform development of primary care-based rehabilitative strategies to prevent disability. Additionally, data generated in this investigation can also serve as a vital resource for ancillary studies addressing important questions in rehabilitative science relevant to geriatric care.

Mild Cognitive Impairment Status and Mobility Performance: An Analysis From the Boston RISE Study

BACKGROUND The prevalence of mild cognitive impairment (MCI) and mobility limitations is high among older adults. The aim of this study was to investigate the association between MCI status and both performance-based and self-report measures of mobility in community-dwelling older adults. METHODS An analysis was conducted on baseline data from the Boston Rehabilitative Impairment Study in the Elderly study, a cohort study of 430 primary care patients aged 65 or older. Neuropsychological tests identified participants with MCI and further subclassified those with impairment in memory domains (aMCI), nonmemory domains (naMCI), and multiple domains (mdMCI). Linear regression models were used to assess the association between MCI status and mobility performance in the Habitual Gait Speed, Figure of 8 Walk, Short Physical Performance Battery, and self-reported Late Life Function and Disability Instruments Basic Lower Extremity and Advanced Lower Extremity function scales. RESULTS Participants had a mean age of 76.6 years, and 42% were characterized with MCI. Participants with MCI performed significantly worse than participants without MCI (No-MCI) on all performance and self-report measures (p < .01). All MCI subtypes performed significantly worse than No-MCI on all mobility measures (p < .05) except for aMCI versus No-MCI on the Figure of 8 Walk (p = .054) and Basic Lower Extremity (p = .11). Moreover, compared with aMCI, mdMCI manifested worse performance on the Figure of 8 Walk and Short Physical Performance Battery, and naMCI manifested worse performance on Short Physical Performance Battery and Basic Lower Extremity. CONCLUSIONS Among older community-dwelling primary care patients, performance on a broad range of mobility measures was worse among those with MCI, appearing poorest among those with nonmemory MCI.

Effect of Pain and Mild Cognitive Impairment on Mobility

To examine the effect of pain and mild cognitive impairment (MCI)—together and separately—on performance‐based and self‐reported mobility outcomes in older adults in primary care with mild to moderate self‐reported mobility limitations.

Neuromuscular Impairments Contributing to Persistently Poor and Declining Lower-Extremity Mobility Among Older Adults: New Findings Informing Geriatric Rehabilitation

OBJECTIVE To identify neuromuscular impairments most predictive of unfavorable mobility outcomes in late life. DESIGN Longitudinal cohort study. SETTING Research clinic. PARTICIPANTS Community-dwelling primary care patients aged ≥65 years (N=391) with self-reported mobility modifications, randomly selected from a research registry. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Categories of decline in and persistently poor mobility across baseline, 1 and 2 years of follow-up in the Lower-Extremity Function scales of the Late-Life Function and Disability Instrument. The following categories of impairment were assessed as potential predictors of mobility change: strength (leg strength), speed of movement (leg velocity, reaction time, rapid leg coordination), range of motion (ROM) (knee flexion/knee extension/ankle ROM), asymmetry (asymmetry of leg strength and knee flexion/extension ROM measures), and trunk stability (trunk extensor endurance, kyphosis). RESULTS The largest effect sizes were found for baseline weaker leg strength (odds ratio [95% confidence interval]: 3.45 [1.72-6.95]), trunk extensor endurance (2.98 [1.56-5.70]), and slower leg velocity (2.35 [1.21-4.58]) predicting a greater likelihood of persistently poor function over 2 years. Baseline weaker leg strength, trunk extensor endurance, and restricted knee flexion motion also predicted a greater likelihood of decline in function (1.72 [1.10-2.70], 1.83 [1.13-2.95], and 2.03 [1.24-3.35], respectively). CONCLUSIONS Older adults exhibiting poor mobility may be prime candidates for rehabilitation focused on improving these impairments. These findings lay the groundwork for developing interventions aimed at optimizing rehabilitative care and disability prevention, and highlight the importance of both well-recognized (leg strength) and novel impairments (leg velocity, trunk extensor muscle endurance).

How Should Disability Be Measured in Older Adults? An Analysis from the Boston Rehabilitative Impairment Study of the Elderly

To determine and compare the predictive validity and responsiveness of the Late‐Life Function and Disability Instrument (LLFDI) frequency and limitation dimensions in assessing two critical dimensions of disability: frequency of and limitations in performance of major life roles.

Leg and Trunk Impairments Predict Participation in Life Roles in Older Adults: Results From Boston RISE

BACKGROUND The physical impairments that affect participation in life roles among older adults have not been identified. Using the International Classification of Functioning Disability and Health as a conceptual framework, we aimed to determine the leg and trunk impairments that predict participation over 2 years, both directly and indirectly through mediation by changes in activities. METHODS We analyzed 2 years of data from the Boston Rehabilitative Impairment Study of the Elderly, a cohort study of 430 primary care patients with self-reported mobility limitation (mean age 77 years; 68% female; average of four chronic conditions). Frequency of and limitations in participation were examined using the Late-Life Disability Instrument. Baseline physical impairments included: leg strength, leg speed of movement, knee range of motion (ROM), ankle ROM, leg strength asymmetry, kyphosis, and trunk extensor endurance. Structural equation modeling with latent growth curve analysis was used to identify the impairments that predicted participation at year 2, mediated by changes in activities. Models were adjusted for baseline participation, age, and gender. RESULTS Leg speed and ankle ROM directly influenced participation in life roles during follow-up (βdirect = 1.39-4.53 and 4.70, respectively). Additionally, ankle ROM and trunk extensor endurance contributed indirectly to participation score at follow-up via effects on changes in activities (βindirect = -1.06 to -4.24 and 1.01 to 4.18, respectively). CONCLUSIONS Leg speed, ankle ROM, and trunk extensor endurance are key physical impairments predicting participation in life roles in older adults. These results have implications for the development of exercise interventions to enhance participation.

Straight and Curved Path Walking Among Older Adults in Primary Care: Associations With Fall-Related Outcomes

Most falls among community‐dwelling older adults occur while walking. Simple walking tests that require little resources and can be interpreted quickly are advocated as useful screening tools for fall prone patients.

Health Characteristics, Neuromuscular Attributes, and Mobility Among Primary Care Patients With Symptomatic Lumbar Spinal Stenosis: A Secondary Analysis

Background and Purpose: Mobility problems are common among older adults. Symptomatic lumbar spinal stenosis (SLSS) is a major contributor to mobility limitations among older primary care patients. In comparison with older primary care patients with mobility problems but without SLSS, it is unclear how mobility problems differ in older primary care patients with SLSS. The purpose of this study was to compare health characteristics, neuromuscular attributes, and mobility status in a sample of older primary care patients with and without SLSS who were at risk for mobility decline. We hypothesized that patients with SLSS will manifest poorer health and greater severity of neuromuscular impairments and mobility limitations. Methods: This is a secondary analysis of the Boston Rehabilitative Study of the Elderly (Boston RISE). Fifty community-dwelling primary care patients aged 65 years or older at risk for mobility decline met inclusion criteria. SLSS was determined on the basis of computerized tomography (CT) scan and self-reported symptoms characteristic of neurogenic claudication. Outcome measures included health characteristics, neuromuscular attributes (trunk endurance, limb strength, limb speed, limb strength asymmetry, ankle range of motion [ROM], knee ROM, kyphosis, sensory loss), and mobility (Late-Life Function and Disability Instrument: basic and advanced lower extremity function subscales, 400-meter walk test, habitual gait speed, and Short Physical Performance Battery score). Health characteristics were collected at a baseline assessment. Neuromuscular attributes and mobility status were measured at the annual visit closest to conducting the CT scan. Results and Discussion: Five participants met criteria for having SLSS. Differences are reported in medians and interquartile ranges. Participants with SLSS reported more global pain, a greater number of comorbid conditions [SLSS: 7.0 (2.0) vs no-SLSS: 4.0 (2.0), P < .001], and experienced greater limitation in knee ROM [SLSS: 115.0° (8.0°) vs no-SLSS: 126.0° (10.0°), P = .04] and advanced lower extremity function than those without SLSS. A limitation of this study was its small sample size and therefore inability to detect potential differences across additional measures of neuromuscular attributes and mobility. Despite the limitation, the differences in mobility for participants with SLSS may support physical therapists in designing interventions for older adults with SLSS. Participants with SLSS manifested greater mobility limitations that exceeded meaningful thresholds across all performance-based and self-reported measures. In addition, our study identified that differences in mobility extended beyond not just walking capacity but also across a variety of tasks that make up mobility for those with and without SLSS. Conclusion: Among older primary care patients who are at risk for mobility decline, patients with SLSS had greater pain, higher levels of comorbidity, greater limitation in knee ROM, and greater limitations in mobility that surpassed meaningful thresholds. These findings can be useful when prioritizing interventions that target mobility for patients with SLSS.

A Novel Approach to Identifying Trajectories of Mobility Change in Older Adults

Objectives To validate trajectories of late-life mobility change using a novel approach designed to overcome the constraints of modest sample size and few follow-up time points. Methods Using clinical reasoning and distribution-based methodology, we identified trajectories of mobility change (Late Life Function and Disability Instrument) across 2 years in 391 participants age ≥65 years from a prospective cohort study designed to identify modifiable impairments predictive of mobility in late-life. We validated our approach using model fit indices and comparing baseline mobility-related factors between trajectories. Results Model fit indices confirmed that the optimal number of trajectories were between 4 and 6. Mobility-related factors varied across trajectories with the most unfavorable values in poor mobility trajectories and the most favorable in high mobility trajectories. These factors included leg strength, trunk extension endurance, knee flexion range of motion, limb velocity, physical performance measures, and the number and prevalence of medical conditions including osteoarthritis and back pain. Conclusions Our findings support the validity of this approach and may facilitate the investigation of a broader scope of research questions within aging populations of varied sizes and traits.