- Email: [email protected]
Gait Speed and Dismobility in Older Adults
Accepted Manuscript Gait Speed and Dismobility in Older Adults Glenn V. Ostir, PhD, Ivonne M. Berges, PhD, Kenneth J. Ottenbacher, PhD, OTR, Steve R. Fisher, PhD, PT, Erik Barr, BA, J. Richard Hebel, PhD, Jack M. Guralnik, MD, PhD PII:
S0003-9993(15)00449-9
DOI:
10.1016/j.apmr.2015.05.017
Reference:
YAPMR 56218
To appear in:
ARCHIVES OF PHYSICAL MEDICINE AND REHABILITATION
Received Date: 16 March 2015 Revised Date:
14 May 2015
Accepted Date: 15 May 2015
Please cite this article as: Ostir GV, Berges IM, Ottenbacher KJ, Fisher SR, Barr E, Hebel JR, Guralnik JM, Gait Speed and Dismobility in Older Adults, ARCHIVES OF PHYSICAL MEDICINE AND REHABILITATION (2015), doi: 10.1016/j.apmr.2015.05.017. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Running Head: Dismobility
Gait Speed and Dismobility in Older Adults.
Glenn V. Ostir, PhD1
Kenneth J. Ottenbacher PhD, OTR2 Steve R. Fisher, PhD, PT3 Erik Barr, BA1
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J. Richard Hebel, PhD1
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Ivonne M. Berges, PhD1
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Jack M. Guralnik, MD, PhD1
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Department of Epidemiology and Public Health, Division of Gerontology, University of Maryland School of
Medicine. 2
School of Health Professions, Division of Rehabilitation Sciences, University of Texas Medical Branch,
3
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Galveston, Texas,
Department of Physical Therapy, University of Texas Medical Branch, Galveston, Texas,
Please address all correspondence to: Glenn Ostir, PhD, Epidemiology and Public Health, Division of
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Gerontology, University of Maryland School of Medicine, Baltimore, Maryland, Phone: 410.706.3907, Fax:
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410.706.4433, Email: [email protected] Acknowledgements: Glenn V. Ostir had full access to all of the data in the study and takes responsibility for the integrity of the data and accuracy of the data analysis. The authors report no conflict of interest. Manuscript was supported by NIA grant R01 AG031178 and the Program on Aging, Trauma and Emergency Care.
ACCEPTED MANUSCRIPT 1 Dismobility 1
Gait Speed and Dismobility in Older Adults.
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ACCEPTED MANUSCRIPT 2 Dismobility ABSTRACT
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Objective.
To classify hospitalized older patients with slow gait speed and test the hypothesis
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that slow gait speed or dismobility is associated with increased mortality-risk.
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Design.
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Setting.
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Prospective study Acute care geriatric hospital unit.
Participants. Older patients (N=289) admitted to a geriatric hospital unit.
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Main Outcome Measure. Two-year survival determined by medical record review and a
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search of the National Death Index.
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Results.
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Two-hundred and thirteen older patients (73.7%) had gait speeds at or below 0.6 m/s and were
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classified with dismobility; 17% (49/289) of the sample died over the two-year follow-up. All but
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five deaths occurred in older patients with dismobility. Older patients with dismobility were more
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than two-and-half times as likely to die than those with gait speeds faster than 0.60 m/s (HR
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2.60; 95% CI 1.01–6.77), after adjusting for age, sex, race/ethnicity, and comorbidity.
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Conclusions. A simple and quick screen for gait speed was evaluated in this study of
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hospitalized older patients. A clinical classification of dismobility could provide the inpatient
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healthcare team with meaningful information about the older patients’ underlying health
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condition(s) and future prognosis, and provides an opportunity to discuss and implement
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treatment options with the patient and his or her family.
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The majority of older patients were female (61.6%) and non-Hispanic white (72.3%).
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KEY WORDS: Gait Speed, Older Adults, Survival, Dismobility
ACCEPTED MANUSCRIPT 3 Dismobility 28
Hospital-based studies are consistent and show slower gait speeds to predict adverse health-related events.1-3 Slower gait speeds have been found as a significant predictor of
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longer hospital stays, discharge to a continuing care facility, and increased difficulty in
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performing activities of daily living after discharge, independent of traditional indicators of
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health status.2;3 Collectively, these studies suggest slower gait speeds signal a critical time
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point in the older patient’s health trajectory.1-4
Because gait speed reflects the integrated functioning of bodily systems including but
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not limited to the nervous, sensory, musculoskeletal and cardio-respiratory systems, its
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assessment has been recommended as part of a standard in-patient geriatric evaluation.5 The
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rationale is that gait speed could complement information traditionally collected on older
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patients, especially those who self-report little or no disability.6 In addition, because gait speed
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is highly reproducible and sensitive to change,7 it may be able to detect small changes in
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physical health that may have otherwise gone unrecognized.8 Despite the recent evidence to
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support the collection of gait speed and recommendations by government agencies for its
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collection, the measurement of gait speed has not been widely adopted for routine use in in-
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patient hospital units. One often cited reason is lack of a clinically meaningful cut-point or
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threshold that would signify important clinical outcomes.9
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Cummings et al10 recently recommended a clinical diagnosis of dismobility be assigned to older men and women with gait speeds of 0.60 m/s or slower. A diagnosis of dismobility (≤ 0.60
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m/s) could provide clinical visibility to a mobility-related health problem and a diagnostic
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mechanism to activate resources directed at resolving treatable conditions contributing to the
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decline in health. A diagnosis of dismobility could be used by physical therapists to develop
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measureable, meaningful mobility targets in consultation with the older patient and plans to
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maintain those targets after hospital discharge.
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ACCEPTED MANUSCRIPT 4 Dismobility 53
The purpose of this study was to compare the risk of death between older adults with and without dismobility. We hypothesized that older adults without dismobility (≤ 0.60 m/s) would
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have higher survival rate in comparison to older adults without dismobility (> 0.60 m/s) over a
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two year period following hospital discharge.
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Methods
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The study sample was drawn from a 20-bed Acute Care for Elders (ACE) hospital unit at the University of Texas Medical Branch from May 2009 to July 2011. Patients included in the
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study were community-living adults aged 65 years or older of either sex. Patients included in
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the study represent the three largest racial and ethnic groups in the US, non-Hispanic white,
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non-Hispanic black and Hispanic. To increase the generalizability of findings to other ACE
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units, the included sample had to have a primary admitting diagnosis of cardiopulmonary
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disease or respiratory or gastrointestinal problems. The three diagnoses account for 87% of
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admissions to ACE hospital units in the U.S.11 Patients were excluded from the study if at time
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of admission they were disorientated to person, place, or time per nursing assessment (18.4%),
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admitted for observation (< 24 hours) (14.0%), or transferred from a nursing home, intensive
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care unit, or day surgery settings (14.8%). Excluded patients did not differ significantly from
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those included in terms age, sex or race/ethnicity. Of the 372 eligible patients, 54 refused to
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attempt the walk and 89 did not attempt the walk for safety reasons. Patients who did not
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complete the walk were on average older than those who did, 77.8 versus 75.4 years (p < 0.05),
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respectively. The final sample included 289 older patients, of these, 57 used a personal
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assistive device (i.e., walker or cane) to complete the walk. The study received approval from
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the university’s institutional review board, and all patients provided written informed consent.
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Data collection
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A trained clinical interviewer completed face-to-face interviews with patients within 24-36
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hours of admission; chart abstractions, via the electronic medical record, were completed within
ACCEPTED MANUSCRIPT 5 Dismobility 72 hours of admission. Information obtained included age in years (65-103), sex, race/ethnicity
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(non-Hispanic white, non-Hispanic black, or Hispanic), and number of comorbid conditions (0, 1,
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2, ≥ 3). A licensed physical therapist assessed the patients’ gait speed within 24-hours of
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admission to the ACE unit. From a standing start, patients were asked to walk 8 feet (2.44
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meters) at their usual pace, and time to completion was recorded to the nearest tenth of a
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second; time was divided by the distance to obtain a mean gait speed (in meters per second).
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Gait speed was used as a continuous measure, and a 5-level (0-0.20, >0.20-0.40, >0.40-0.60,
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>0.60-0.80, and > 0.80 m/s) and 2-level (≤ 0.60 and > 0.60) measure. Vital status was
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determined by a review of medical records and a National Death Index search (NDI, National
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Center for Health Statistics, Hyattsville, MD). Two year survival from date of hospital discharge
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was coded as yes or no; date of death was recorded if the participant had died.
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Statistical analysis
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Means (SDs) were reported for continuous measures and percentages for categorical measures. Relative risks (hazard ratios) and 95% confidence intervals (CIs) were estimated with
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maximum partial likelihood estimates using Cox proportional hazard models.12;13 The
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proportional hazard assumption of the categorical walking speed measures and covariates were
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assessed by Schoenfeld residuals14 as the interaction between walking and log of time and by
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an adjusted hazard plot by category of walking speed. Kaplan-Meier survival curves15 were
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created and the statistical difference in curves was tested using the log-rank test. Adjusted
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Kaplan-Meier estimators15 were obtained by fitting separate Cox proportional hazards12 models
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for the comparison groups. The resulting hazards ratios were then applied to the baseline
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survivor functions to obtain the adjusted survival curves. Testing was 2-sided and p < 0.05 was
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considered significant. All analyses were performed using commercially available software (SAS
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statistical software, version 9.3, SAS Institute, Inc., Cary, NC.).
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Results The sample included 289 older patients. Of these, 148 were aged 65-74, 110 were 7584, and 31 were 85 and older. Most were female (61.6%); and the majority were non-Hispanic
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white (72.3%), 17.3% were non-Hispanic black and 10.4% were Hispanic. Less than half
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(45.3%) were currently married. On average, men reported 3 chronic conditions and women
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2.6. The average gait speed was 0.50 (SD 0.24) m/s, 0.53 and 0.48 m/s for men for women,
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respectively; and the average length of stay was 4.4 (SD 3.2) days. Forty-nine (17.0%) older
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patients died over the two year follow-up.
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The majority (n= 213/289 or 73.7%) had gait speeds at or below 0.6 m/s (dismobility).
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Twenty-four patients were classified with the slowest gait speeds (< 0.20 m/s), and 81 and 108
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patients had recorded gait speeds of 0.2 - 0.40 and 0.41- ≤ 0.60, respectively. Seventy-six
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patients (26.3%) had gait speeds greater than 0.6 m/s. Only 8% of the sample (n=24) had gait
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speeds greater than 0.80 m/s. Figure 1 further shows a possible threshold effect between gait
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speed of 0.60 m/s or slower and increased risk of death. Of the 49 total deaths, 21% (45/213)
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occurred among those classified with dismobility (i.e., walking at or below 0.60 m/s), compared
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with 5% (4/76) of those with gait speeds faster than 0.6 m/s. At two years post hospitalization, 91.4% of patients with gait speeds faster than 0.60 m/s
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were alive compared to 74.5% with gait speeds of 0.60 m/s or slower (p=0.008) (Figure 2).
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Additional analysis showed no overall statistical difference between men and women and risk of
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death (p=0.30), and similarly for those men and women classified with dismobility (p = 0.12).
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In the unadjusted model (Model 1) patients with dismobility had more than threefold risk
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of death compared to those without dismobility (HR 3.25; 95% CI 1.29-8.24) (Table 1). The risk
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of death remained significantly elevated with the inclusion of age, gender and race/ethnicity
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(Model 2), where dismobility had almost at 3 times the risk of death than fast walkers (HR 2.90;
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95% CI 1.12 – 7.51. Model 2 also showed each one-year increase in age significantly
ACCEPTED MANUSCRIPT 7 Dismobility increased the risk of death by 5% (HR 1.05; 95% CI 1.01 – 1.09) and that women had a
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decreased the risk for death (HR 0.55; 95% CI 0.31 – 0.97) compared with men. With the
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inclusion of comorbidity (Model 3), the significant association between dismobility and death
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(HR 2.60; 95% CI 1.01 – 6.77) remained.
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ACCEPTED MANUSCRIPT 8 Dismobility 133 134
Discussion We demonstrated that patients classified with dismobility were at a significantly elevated risk of death. The increased risk remained statistically significant with adjustment for age,
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gender race/ethnicity and comorbidity, suggesting that 0.60 m/s may be an important threshold
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to stratify health risk for both men and women. In our data, only 4 deaths occurred in patients
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with gait speeds faster than 0.60 m/s; conversely 45 (out of 49) deaths occurred among those
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with dismobility. We further found that a test of gait speed could be safely conducted in hospital
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among older adults. No adverse events were reported among those who attempted the short
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walk. The study adds to a growing call for the objective assessment of gait speed on in-patient
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hospital units.
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Given the simplicity, reliability and validity of the gait speed test7 indicates its value as an objective screen for dismobility in hospital. Slow gait speed could provide physicians,
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physical therapists and other members of the health care team with information about the
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patient’s current health status in relation to a particular medical condition or illness and may
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capture unrecognized information about the severity or worsening of underlying chronic
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conditions. We have previously shown gait speed assessed at time of hospital admission to
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predict length of stay and readiness for hospital discharge;2;3 And unlike other indices of health
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status, gait speed is potentially modifiable to treatment.5;9 A recent finding from the LIFE
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Study,16 a randomized controlled clinical trial, showed a structured, moderately intensive
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physical activity program was successful in reducing mobility disability over more than 2 years in
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at-risk older persons.
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Although the association between slow gait speed and poor health outcomes including
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death is known,17 its routine assessment has not been widely endorsed for use in hospital
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settings. However, the adoption of a single cut point to classify patients with dismobility may
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advance its implementation as an objective functional screen. Rolland et al18 reported a gait
ACCEPTED MANUSCRIPT 9 Dismobility 158
speed of 0.60 m/s or slower strongly predicted the probability of not performing a 400-meter
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test. The 400-meter test has been used in community samples to estimate exercise tolerance,
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cardiovascular fitness, and disease severity. In the acute care setting, a cut point of 0.60 m/s may be appropriate to identify health
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risk, and it may contribute to personalize treatment goals. Early identification of dismobility could
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trigger a referral to services such as physical therapy. Potentially modifiable causes of the
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dismobility could be discussed with the patient and an individualized plan of care developed. A
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single, clinically meaningful cut-point for gait speed would also be useful in monitoring the
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functional health of older patients over the course of hospitalization. Once a patient is identified
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with dismobility added efforts may made to identify potential causes of the dismobility; and if
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appropriate initiate treatments of care that could target cardiopulmonary, neurological or
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musculoskeletal systems, and which extend beyond the period of hospitalization.
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The current study has important strengths, including a timed measure of gait speed, a
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reliable and valid marker of mobility function. Assessment of gait speed was performed on an
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in-patient hospital unit and included representative sample of the three largest racial and ethnic
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groups in the U.S., non-Hispanic white, non-Hispanic black and Hispanics. Death was confirmed
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through a National Death Index search over 2-years.
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Study Limitations. Although our study design accounted for the three most common admitting diagnoses for ACE units, because this was a single site study lack of generalizability
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to other hospital units may be an issue. A second limitation was that walking speed was
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collected only at admission. Collection of gait speed at other time points such as discharge may
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have provided valuable additional information on change and how change in gait speed may
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signal future health needs or recovery. Finally, rather than a direct cause of death, gait speed
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maybe a marker of multiple factors affected by health and disease status and severity. From a
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biological perspective, inflammatory pathways such as interleukin 6 and D-Dimer, independent
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ACCEPTED MANUSCRIPT 10 Dismobility of sociodemographic characteristics and health behaviors are linked to mobility function.
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Change in these two inflammatory markers may be an early indication of impending functional
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decline.19-21 From an environmental perspective, pathways that mediate change in mobility are
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less clear but may include socioeconomic status, access to social services, social isolation and
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sedentary behavior.22-24 Research targeting pathways or mechanisms of action is needed to
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inform further work in this area.
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Conclusions.
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There is interest in applying tools that can reliably screen for health status in older patients, quickly and accurately identifying those who may need additional attention to address
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underlying or unrecognized health problems. The strong relationship between gait speed and
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health outcomes found in this study illustrates the importance in identifying older patients
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dismobility.
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ACCEPTED MANUSCRIPT 11 Dismobility References
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(1) Brown CJ, Friedkin RJ, Inouye SK. Prevalence and outcomes of low mobility in hospitalized older patients. J Am Geriatr Soc 2004;52:1263-1270.
202 203 204
(2) Ostir GV, Berges I, Kuo YF, Goodwin JS, Ottenbacher KJ, Guralnik JM. Assessing gait speed in acutely ill older patients admitted to an acute care for elders hospital unit. Arch Intern Med 2012;172:353-358.
205 206 207
(3) Ostir GV, Berges IM, Kuo YF, Goodwin JS, Fisher SR, Guralnik JM. Mobility activity and its value as a prognostic indicator of survival in hospitalized older adults. J Am Geriatr Soc 2013;61:551-557.
208 209 210
(4) Volpato S, Cavalieri M, Sioulis F et al. Predictive value of the Short Physical Performance Battery following hospitalization in older patients. J Gerontol A Biol Sci Med Sci 2011;66:89-96.
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(5) Abellan Van KG, Rolland Y, Andrieu S et al. Gait speed at usual pace as a predictor of adverse outcomes in community-dwelling older people an International Academy on Nutrition and Aging (IANA) Task Force. J Nutr Health Aging 2009;13:881-889.
214 215 216
(6) Brach JS, Perera S, VanSwearingen JM, Hile ES, Wert DM, Studenski SA. Challenging gait conditions predict 1-year decline in gait speed in older adults with apparently normal gait. Phys Ther 2011;91:1857-1864.
217 218 219
(7) Ostir GV, Volpato S, Fried LP, Chaves P, Guralnik JM. Reliability and sensitivity to change assessed for a summary measure of lower body function: results from the Women's Health and Aging Study. J Clin Epidemiol 2002;55:916-921.
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(8) Studenski S, Perera S, Wallace D et al. Physical performance measures in the clinical setting. J Am Geriatr Soc 2003;51:314-322.
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(9) Studenski SA. Gait speed in hospitalized older people: comment on "assessing gait speed in acutely ill older patients admitted to an acute care for elders hospital unit". Arch Intern Med 2012;172:358-359.
225 226
(10) Cummings SR, Studenski S, Ferrucci L. A diagnosis of dismobility--giving mobility clinical visibility: a Mobility Working Group recommendation. JAMA 2014;311:2061-2062.
227 228 229
(11) Jayadevappa R, Bloom BS, Raziano DB, Lavizzo-Mourey R. Dissemination and characteristics of acute care for elders (ACE) units in the United States. Int J Technol Assess Health Care 2003;19:220-227.
230 231 232 233
(12) Cox DR. Regression models and life tables. Journal of the Royal Statistical Society Series B-Methodological. 34, 187-220. 1972.
234 235 236
(14) Schoenfeld DA, Gelber RD. Designing and analyzing clinical trials which allow institutions to randomize patients to a subset of the treatments under study. Biometrics 1979;35:825-829.
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(13) Cox DR. Statistical significance tests. Br J Clin Pharmacol 1982;14:325-331.
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(15) Kaplan ALM P. Nonparametric estimation from incomplete observation. Journal of the American Statistical Association. 53, 457-481. 2015.
243 244
(17) Studenski S, Perera S, Patel K et al. Gait speed and survival in older adults. JAMA 2011;305:50-58.
245 246 247
(18) Rolland YM, Cesari M, Miller ME, Penninx BW, Atkinson HH, Pahor M. Reliability of the 400-m usual-pace walk test as an assessment of mobility limitation in older adults. J Am Geriatr Soc 2004;52:972-976.
248 249 250
(19) Cohen HJ, Pieper CF, Harris T, Rao KM, Currie MS. The association of plasma IL-6 levels with functional disability in community-dwelling elderly. J Gerontol A Biol Sci Med Sci 1997;52:M201-M208.
251 252 253
(20) Cohen HJ, Harris T, Pieper CF. Coagulation and activation of inflammatory pathways in the development of functional decline and mortality in the elderly. Am J Med 2003;114:180-187.
254 255 256
(21) Ferrucci L, Penninx BW, Leveille SG et al. Characteristics of nondisabled older persons who perform poorly in objective tests of lower extremity function. J Am Geriatr Soc 2000;48:1102-1110.
257 258 259 260
(22) Koster A, Bosma H, Kempen GI, van Lenthe FJ, van Eijk JT, Mackenbach JP. Socioeconomic inequalities in mobility decline in chronic disease groups (asthma/COPD, heart disease, diabetes mellitus, low back pain): only a minor role for disease severity and comorbidity. J Epidemiol Community Health 2004;58:862-869.
261 262 263
(23) Mackenbach JP, Borsboom GJ, Nusselder WJ, Looman CW, Schrijvers CT. Determinants of levels and changes of physical functioning in chronically ill persons: results from the GLOBE Study. J Epidemiol Community Health 2001;55:631-638.
264 265 266 267 268
(24) Mendes de Leon CF, Gold DT, Glass TA, Kaplan L, George LK. Disability as a function of social networks and support in elderly African Americans and Whites: the Duke EPESE 1986--1992. J Gerontol B Psychol Sci Soc Sci 2001;56:S179-S190.
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(16) Pahor M, Guralnik JM, Ambrosius WT et al. Effect of structured physical activity on prevention of major mobility disability in older adults: the LIFE study randomized clinical trial. JAMA 2014;311:2387-2396.
ACCEPTED MANUSCRIPT
Table 1. Dismobility and 2-year risk of death in Older Adults admitted to an Acute Care Geriatric
Measure
Model 1
Model 3
95% CI
HR
95% CI
3.25 1.29 – 8.24
2.90
1.23 – 7.51
Age (continuous)
1.05
1.01 – 1.09
1.05 1.01 – 1.10
Female
0.55
0.31 – 0.97
0.58 0.33 – 1.04
0.77
0.50 – 1.19
0.80 0.51 – 1.24
Dismobility (> 0.6 versus
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≤ 0.6 m/s)
Race / Ethnicity
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Comorbidity (0-4)
HR
95% CI
2.60 1.00 – 6.77
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HR
Model 2
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Hospital Unit.
1.60 0.95 – 2.69
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Figure 1. Probability of death two-years post hospital discharge.
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Figure 2. Unadjusted two-year survival by gait speed.
S0003-9993(15)00449-9
DOI:
10.1016/j.apmr.2015.05.017
Reference:
YAPMR 56218
To appear in:
ARCHIVES OF PHYSICAL MEDICINE AND REHABILITATION
Received Date: 16 March 2015 Revised Date:
14 May 2015
Accepted Date: 15 May 2015
Please cite this article as: Ostir GV, Berges IM, Ottenbacher KJ, Fisher SR, Barr E, Hebel JR, Guralnik JM, Gait Speed and Dismobility in Older Adults, ARCHIVES OF PHYSICAL MEDICINE AND REHABILITATION (2015), doi: 10.1016/j.apmr.2015.05.017. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Running Head: Dismobility
Gait Speed and Dismobility in Older Adults.
Glenn V. Ostir, PhD1
Kenneth J. Ottenbacher PhD, OTR2 Steve R. Fisher, PhD, PT3 Erik Barr, BA1
SC
J. Richard Hebel, PhD1
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Ivonne M. Berges, PhD1
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Jack M. Guralnik, MD, PhD1
1
Department of Epidemiology and Public Health, Division of Gerontology, University of Maryland School of
Medicine. 2
School of Health Professions, Division of Rehabilitation Sciences, University of Texas Medical Branch,
3
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Galveston, Texas,
Department of Physical Therapy, University of Texas Medical Branch, Galveston, Texas,
Please address all correspondence to: Glenn Ostir, PhD, Epidemiology and Public Health, Division of
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Gerontology, University of Maryland School of Medicine, Baltimore, Maryland, Phone: 410.706.3907, Fax:
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410.706.4433, Email: [email protected] Acknowledgements: Glenn V. Ostir had full access to all of the data in the study and takes responsibility for the integrity of the data and accuracy of the data analysis. The authors report no conflict of interest. Manuscript was supported by NIA grant R01 AG031178 and the Program on Aging, Trauma and Emergency Care.
ACCEPTED MANUSCRIPT 1 Dismobility 1
Gait Speed and Dismobility in Older Adults.
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ACCEPTED MANUSCRIPT 2 Dismobility ABSTRACT
5 6
Objective.
To classify hospitalized older patients with slow gait speed and test the hypothesis
7
that slow gait speed or dismobility is associated with increased mortality-risk.
8
Design.
9
Setting.
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Prospective study Acute care geriatric hospital unit.
Participants. Older patients (N=289) admitted to a geriatric hospital unit.
11
Main Outcome Measure. Two-year survival determined by medical record review and a
12
search of the National Death Index.
13
Results.
14
Two-hundred and thirteen older patients (73.7%) had gait speeds at or below 0.6 m/s and were
15
classified with dismobility; 17% (49/289) of the sample died over the two-year follow-up. All but
16
five deaths occurred in older patients with dismobility. Older patients with dismobility were more
17
than two-and-half times as likely to die than those with gait speeds faster than 0.60 m/s (HR
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2.60; 95% CI 1.01–6.77), after adjusting for age, sex, race/ethnicity, and comorbidity.
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Conclusions. A simple and quick screen for gait speed was evaluated in this study of
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hospitalized older patients. A clinical classification of dismobility could provide the inpatient
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healthcare team with meaningful information about the older patients’ underlying health
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condition(s) and future prognosis, and provides an opportunity to discuss and implement
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treatment options with the patient and his or her family.
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KEY WORDS: Gait Speed, Older Adults, Survival, Dismobility
ACCEPTED MANUSCRIPT 3 Dismobility 28
Hospital-based studies are consistent and show slower gait speeds to predict adverse health-related events.1-3 Slower gait speeds have been found as a significant predictor of
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longer hospital stays, discharge to a continuing care facility, and increased difficulty in
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performing activities of daily living after discharge, independent of traditional indicators of
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health status.2;3 Collectively, these studies suggest slower gait speeds signal a critical time
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point in the older patient’s health trajectory.1-4
Because gait speed reflects the integrated functioning of bodily systems including but
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not limited to the nervous, sensory, musculoskeletal and cardio-respiratory systems, its
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assessment has been recommended as part of a standard in-patient geriatric evaluation.5 The
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rationale is that gait speed could complement information traditionally collected on older
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patients, especially those who self-report little or no disability.6 In addition, because gait speed
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is highly reproducible and sensitive to change,7 it may be able to detect small changes in
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physical health that may have otherwise gone unrecognized.8 Despite the recent evidence to
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support the collection of gait speed and recommendations by government agencies for its
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collection, the measurement of gait speed has not been widely adopted for routine use in in-
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patient hospital units. One often cited reason is lack of a clinically meaningful cut-point or
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threshold that would signify important clinical outcomes.9
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Cummings et al10 recently recommended a clinical diagnosis of dismobility be assigned to older men and women with gait speeds of 0.60 m/s or slower. A diagnosis of dismobility (≤ 0.60
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m/s) could provide clinical visibility to a mobility-related health problem and a diagnostic
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mechanism to activate resources directed at resolving treatable conditions contributing to the
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decline in health. A diagnosis of dismobility could be used by physical therapists to develop
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measureable, meaningful mobility targets in consultation with the older patient and plans to
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maintain those targets after hospital discharge.
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ACCEPTED MANUSCRIPT 4 Dismobility 53
The purpose of this study was to compare the risk of death between older adults with and without dismobility. We hypothesized that older adults without dismobility (≤ 0.60 m/s) would
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have higher survival rate in comparison to older adults without dismobility (> 0.60 m/s) over a
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two year period following hospital discharge.
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Methods
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The study sample was drawn from a 20-bed Acute Care for Elders (ACE) hospital unit at the University of Texas Medical Branch from May 2009 to July 2011. Patients included in the
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study were community-living adults aged 65 years or older of either sex. Patients included in
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the study represent the three largest racial and ethnic groups in the US, non-Hispanic white,
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non-Hispanic black and Hispanic. To increase the generalizability of findings to other ACE
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units, the included sample had to have a primary admitting diagnosis of cardiopulmonary
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disease or respiratory or gastrointestinal problems. The three diagnoses account for 87% of
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admissions to ACE hospital units in the U.S.11 Patients were excluded from the study if at time
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of admission they were disorientated to person, place, or time per nursing assessment (18.4%),
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admitted for observation (< 24 hours) (14.0%), or transferred from a nursing home, intensive
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care unit, or day surgery settings (14.8%). Excluded patients did not differ significantly from
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those included in terms age, sex or race/ethnicity. Of the 372 eligible patients, 54 refused to
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attempt the walk and 89 did not attempt the walk for safety reasons. Patients who did not
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complete the walk were on average older than those who did, 77.8 versus 75.4 years (p < 0.05),
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respectively. The final sample included 289 older patients, of these, 57 used a personal
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assistive device (i.e., walker or cane) to complete the walk. The study received approval from
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the university’s institutional review board, and all patients provided written informed consent.
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Data collection
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A trained clinical interviewer completed face-to-face interviews with patients within 24-36
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hours of admission; chart abstractions, via the electronic medical record, were completed within
ACCEPTED MANUSCRIPT 5 Dismobility 72 hours of admission. Information obtained included age in years (65-103), sex, race/ethnicity
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(non-Hispanic white, non-Hispanic black, or Hispanic), and number of comorbid conditions (0, 1,
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2, ≥ 3). A licensed physical therapist assessed the patients’ gait speed within 24-hours of
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admission to the ACE unit. From a standing start, patients were asked to walk 8 feet (2.44
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meters) at their usual pace, and time to completion was recorded to the nearest tenth of a
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second; time was divided by the distance to obtain a mean gait speed (in meters per second).
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Gait speed was used as a continuous measure, and a 5-level (0-0.20, >0.20-0.40, >0.40-0.60,
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>0.60-0.80, and > 0.80 m/s) and 2-level (≤ 0.60 and > 0.60) measure. Vital status was
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determined by a review of medical records and a National Death Index search (NDI, National
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Center for Health Statistics, Hyattsville, MD). Two year survival from date of hospital discharge
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was coded as yes or no; date of death was recorded if the participant had died.
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Statistical analysis
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Means (SDs) were reported for continuous measures and percentages for categorical measures. Relative risks (hazard ratios) and 95% confidence intervals (CIs) were estimated with
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maximum partial likelihood estimates using Cox proportional hazard models.12;13 The
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proportional hazard assumption of the categorical walking speed measures and covariates were
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assessed by Schoenfeld residuals14 as the interaction between walking and log of time and by
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an adjusted hazard plot by category of walking speed. Kaplan-Meier survival curves15 were
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created and the statistical difference in curves was tested using the log-rank test. Adjusted
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Kaplan-Meier estimators15 were obtained by fitting separate Cox proportional hazards12 models
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for the comparison groups. The resulting hazards ratios were then applied to the baseline
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survivor functions to obtain the adjusted survival curves. Testing was 2-sided and p < 0.05 was
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considered significant. All analyses were performed using commercially available software (SAS
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statistical software, version 9.3, SAS Institute, Inc., Cary, NC.).
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Results The sample included 289 older patients. Of these, 148 were aged 65-74, 110 were 7584, and 31 were 85 and older. Most were female (61.6%); and the majority were non-Hispanic
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white (72.3%), 17.3% were non-Hispanic black and 10.4% were Hispanic. Less than half
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(45.3%) were currently married. On average, men reported 3 chronic conditions and women
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2.6. The average gait speed was 0.50 (SD 0.24) m/s, 0.53 and 0.48 m/s for men for women,
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respectively; and the average length of stay was 4.4 (SD 3.2) days. Forty-nine (17.0%) older
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patients died over the two year follow-up.
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The majority (n= 213/289 or 73.7%) had gait speeds at or below 0.6 m/s (dismobility).
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Twenty-four patients were classified with the slowest gait speeds (< 0.20 m/s), and 81 and 108
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patients had recorded gait speeds of 0.2 - 0.40 and 0.41- ≤ 0.60, respectively. Seventy-six
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patients (26.3%) had gait speeds greater than 0.6 m/s. Only 8% of the sample (n=24) had gait
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speeds greater than 0.80 m/s. Figure 1 further shows a possible threshold effect between gait
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speed of 0.60 m/s or slower and increased risk of death. Of the 49 total deaths, 21% (45/213)
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occurred among those classified with dismobility (i.e., walking at or below 0.60 m/s), compared
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with 5% (4/76) of those with gait speeds faster than 0.6 m/s. At two years post hospitalization, 91.4% of patients with gait speeds faster than 0.60 m/s
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were alive compared to 74.5% with gait speeds of 0.60 m/s or slower (p=0.008) (Figure 2).
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Additional analysis showed no overall statistical difference between men and women and risk of
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death (p=0.30), and similarly for those men and women classified with dismobility (p = 0.12).
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In the unadjusted model (Model 1) patients with dismobility had more than threefold risk
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of death compared to those without dismobility (HR 3.25; 95% CI 1.29-8.24) (Table 1). The risk
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of death remained significantly elevated with the inclusion of age, gender and race/ethnicity
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(Model 2), where dismobility had almost at 3 times the risk of death than fast walkers (HR 2.90;
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95% CI 1.12 – 7.51. Model 2 also showed each one-year increase in age significantly
ACCEPTED MANUSCRIPT 7 Dismobility increased the risk of death by 5% (HR 1.05; 95% CI 1.01 – 1.09) and that women had a
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decreased the risk for death (HR 0.55; 95% CI 0.31 – 0.97) compared with men. With the
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inclusion of comorbidity (Model 3), the significant association between dismobility and death
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(HR 2.60; 95% CI 1.01 – 6.77) remained.
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Discussion We demonstrated that patients classified with dismobility were at a significantly elevated risk of death. The increased risk remained statistically significant with adjustment for age,
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gender race/ethnicity and comorbidity, suggesting that 0.60 m/s may be an important threshold
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to stratify health risk for both men and women. In our data, only 4 deaths occurred in patients
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with gait speeds faster than 0.60 m/s; conversely 45 (out of 49) deaths occurred among those
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with dismobility. We further found that a test of gait speed could be safely conducted in hospital
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among older adults. No adverse events were reported among those who attempted the short
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walk. The study adds to a growing call for the objective assessment of gait speed on in-patient
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hospital units.
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Given the simplicity, reliability and validity of the gait speed test7 indicates its value as an objective screen for dismobility in hospital. Slow gait speed could provide physicians,
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physical therapists and other members of the health care team with information about the
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patient’s current health status in relation to a particular medical condition or illness and may
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capture unrecognized information about the severity or worsening of underlying chronic
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conditions. We have previously shown gait speed assessed at time of hospital admission to
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predict length of stay and readiness for hospital discharge;2;3 And unlike other indices of health
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status, gait speed is potentially modifiable to treatment.5;9 A recent finding from the LIFE
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Study,16 a randomized controlled clinical trial, showed a structured, moderately intensive
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physical activity program was successful in reducing mobility disability over more than 2 years in
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at-risk older persons.
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Although the association between slow gait speed and poor health outcomes including
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death is known,17 its routine assessment has not been widely endorsed for use in hospital
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settings. However, the adoption of a single cut point to classify patients with dismobility may
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advance its implementation as an objective functional screen. Rolland et al18 reported a gait
ACCEPTED MANUSCRIPT 9 Dismobility 158
speed of 0.60 m/s or slower strongly predicted the probability of not performing a 400-meter
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test. The 400-meter test has been used in community samples to estimate exercise tolerance,
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cardiovascular fitness, and disease severity. In the acute care setting, a cut point of 0.60 m/s may be appropriate to identify health
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risk, and it may contribute to personalize treatment goals. Early identification of dismobility could
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trigger a referral to services such as physical therapy. Potentially modifiable causes of the
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dismobility could be discussed with the patient and an individualized plan of care developed. A
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single, clinically meaningful cut-point for gait speed would also be useful in monitoring the
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functional health of older patients over the course of hospitalization. Once a patient is identified
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with dismobility added efforts may made to identify potential causes of the dismobility; and if
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appropriate initiate treatments of care that could target cardiopulmonary, neurological or
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musculoskeletal systems, and which extend beyond the period of hospitalization.
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The current study has important strengths, including a timed measure of gait speed, a
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reliable and valid marker of mobility function. Assessment of gait speed was performed on an
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in-patient hospital unit and included representative sample of the three largest racial and ethnic
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groups in the U.S., non-Hispanic white, non-Hispanic black and Hispanics. Death was confirmed
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through a National Death Index search over 2-years.
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Study Limitations. Although our study design accounted for the three most common admitting diagnoses for ACE units, because this was a single site study lack of generalizability
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to other hospital units may be an issue. A second limitation was that walking speed was
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collected only at admission. Collection of gait speed at other time points such as discharge may
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have provided valuable additional information on change and how change in gait speed may
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signal future health needs or recovery. Finally, rather than a direct cause of death, gait speed
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maybe a marker of multiple factors affected by health and disease status and severity. From a
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biological perspective, inflammatory pathways such as interleukin 6 and D-Dimer, independent
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ACCEPTED MANUSCRIPT 10 Dismobility of sociodemographic characteristics and health behaviors are linked to mobility function.
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Change in these two inflammatory markers may be an early indication of impending functional
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decline.19-21 From an environmental perspective, pathways that mediate change in mobility are
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less clear but may include socioeconomic status, access to social services, social isolation and
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sedentary behavior.22-24 Research targeting pathways or mechanisms of action is needed to
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inform further work in this area.
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Conclusions.
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There is interest in applying tools that can reliably screen for health status in older patients, quickly and accurately identifying those who may need additional attention to address
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underlying or unrecognized health problems. The strong relationship between gait speed and
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health outcomes found in this study illustrates the importance in identifying older patients
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dismobility.
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ACCEPTED MANUSCRIPT 11 Dismobility References
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(1) Brown CJ, Friedkin RJ, Inouye SK. Prevalence and outcomes of low mobility in hospitalized older patients. J Am Geriatr Soc 2004;52:1263-1270.
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(2) Ostir GV, Berges I, Kuo YF, Goodwin JS, Ottenbacher KJ, Guralnik JM. Assessing gait speed in acutely ill older patients admitted to an acute care for elders hospital unit. Arch Intern Med 2012;172:353-358.
205 206 207
(3) Ostir GV, Berges IM, Kuo YF, Goodwin JS, Fisher SR, Guralnik JM. Mobility activity and its value as a prognostic indicator of survival in hospitalized older adults. J Am Geriatr Soc 2013;61:551-557.
208 209 210
(4) Volpato S, Cavalieri M, Sioulis F et al. Predictive value of the Short Physical Performance Battery following hospitalization in older patients. J Gerontol A Biol Sci Med Sci 2011;66:89-96.
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(5) Abellan Van KG, Rolland Y, Andrieu S et al. Gait speed at usual pace as a predictor of adverse outcomes in community-dwelling older people an International Academy on Nutrition and Aging (IANA) Task Force. J Nutr Health Aging 2009;13:881-889.
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(6) Brach JS, Perera S, VanSwearingen JM, Hile ES, Wert DM, Studenski SA. Challenging gait conditions predict 1-year decline in gait speed in older adults with apparently normal gait. Phys Ther 2011;91:1857-1864.
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(7) Ostir GV, Volpato S, Fried LP, Chaves P, Guralnik JM. Reliability and sensitivity to change assessed for a summary measure of lower body function: results from the Women's Health and Aging Study. J Clin Epidemiol 2002;55:916-921.
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(8) Studenski S, Perera S, Wallace D et al. Physical performance measures in the clinical setting. J Am Geriatr Soc 2003;51:314-322.
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(9) Studenski SA. Gait speed in hospitalized older people: comment on "assessing gait speed in acutely ill older patients admitted to an acute care for elders hospital unit". Arch Intern Med 2012;172:358-359.
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(10) Cummings SR, Studenski S, Ferrucci L. A diagnosis of dismobility--giving mobility clinical visibility: a Mobility Working Group recommendation. JAMA 2014;311:2061-2062.
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(11) Jayadevappa R, Bloom BS, Raziano DB, Lavizzo-Mourey R. Dissemination and characteristics of acute care for elders (ACE) units in the United States. Int J Technol Assess Health Care 2003;19:220-227.
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(12) Cox DR. Regression models and life tables. Journal of the Royal Statistical Society Series B-Methodological. 34, 187-220. 1972.
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(14) Schoenfeld DA, Gelber RD. Designing and analyzing clinical trials which allow institutions to randomize patients to a subset of the treatments under study. Biometrics 1979;35:825-829.
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(13) Cox DR. Statistical significance tests. Br J Clin Pharmacol 1982;14:325-331.
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(15) Kaplan ALM P. Nonparametric estimation from incomplete observation. Journal of the American Statistical Association. 53, 457-481. 2015.
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(17) Studenski S, Perera S, Patel K et al. Gait speed and survival in older adults. JAMA 2011;305:50-58.
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(18) Rolland YM, Cesari M, Miller ME, Penninx BW, Atkinson HH, Pahor M. Reliability of the 400-m usual-pace walk test as an assessment of mobility limitation in older adults. J Am Geriatr Soc 2004;52:972-976.
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(19) Cohen HJ, Pieper CF, Harris T, Rao KM, Currie MS. The association of plasma IL-6 levels with functional disability in community-dwelling elderly. J Gerontol A Biol Sci Med Sci 1997;52:M201-M208.
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(20) Cohen HJ, Harris T, Pieper CF. Coagulation and activation of inflammatory pathways in the development of functional decline and mortality in the elderly. Am J Med 2003;114:180-187.
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(21) Ferrucci L, Penninx BW, Leveille SG et al. Characteristics of nondisabled older persons who perform poorly in objective tests of lower extremity function. J Am Geriatr Soc 2000;48:1102-1110.
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(22) Koster A, Bosma H, Kempen GI, van Lenthe FJ, van Eijk JT, Mackenbach JP. Socioeconomic inequalities in mobility decline in chronic disease groups (asthma/COPD, heart disease, diabetes mellitus, low back pain): only a minor role for disease severity and comorbidity. J Epidemiol Community Health 2004;58:862-869.
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(23) Mackenbach JP, Borsboom GJ, Nusselder WJ, Looman CW, Schrijvers CT. Determinants of levels and changes of physical functioning in chronically ill persons: results from the GLOBE Study. J Epidemiol Community Health 2001;55:631-638.
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(24) Mendes de Leon CF, Gold DT, Glass TA, Kaplan L, George LK. Disability as a function of social networks and support in elderly African Americans and Whites: the Duke EPESE 1986--1992. J Gerontol B Psychol Sci Soc Sci 2001;56:S179-S190.
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(16) Pahor M, Guralnik JM, Ambrosius WT et al. Effect of structured physical activity on prevention of major mobility disability in older adults: the LIFE study randomized clinical trial. JAMA 2014;311:2387-2396.
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Table 1. Dismobility and 2-year risk of death in Older Adults admitted to an Acute Care Geriatric
Measure
Model 1
Model 3
95% CI
HR
95% CI
3.25 1.29 – 8.24
2.90
1.23 – 7.51
Age (continuous)
1.05
1.01 – 1.09
1.05 1.01 – 1.10
Female
0.55
0.31 – 0.97
0.58 0.33 – 1.04
0.77
0.50 – 1.19
0.80 0.51 – 1.24
Dismobility (> 0.6 versus
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Race / Ethnicity
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HR
95% CI
2.60 1.00 – 6.77
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Model 2
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1.60 0.95 – 2.69
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Figure 1. Probability of death two-years post hospital discharge.
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Figure 2. Unadjusted two-year survival by gait speed.