Can change in prolonged walking be inferred from a short test of gait speed among older adults who are initially well-functioning?
BACKGROUND
The ability to walk for short and prolonged periods of time is often measured with separate walking tests. It is unclear whether decline in the 2-minute walk coincides with decline in a shorter 20-m walk among older adults.


OBJECTIVE
The aim of this study was to describe patterns of change in the 20-m walk and 2-minute walk over 8 years among a large cohort of older adults. Should change be similar between tests of walking ability, separate retesting of prolonged walking may need to be reconsidered.


METHODS
A longitudinal, observational cohort study was conducted.


METHODS
Data were from 1,893 older adults who were well-functioning (≥70 years of age). The 20-m walk and 2-minute walk were repeatedly measured over 8 years to measure change during short and prolonged periods of walking, respectively. Change was examined using a dual group-based trajectory model (dual model), and agreement between walking trajectories was quantified with a weighted kappa statistic.


RESULTS
Three trajectory groups for the 20-m walk and 2-minute walk were identified. More than 86% of the participants were in similar trajectory groups for both tests from the dual model. There was high chance-corrected agreement (kappa=.84; 95% confidence interval=.82, .86) between the 20-m walk and 2-minute walk trajectory groups.


CONCLUSIONS
One-third of the original Health, Aging and Body Composition (Health ABC) study cohort was excluded from analysis due to missing clinic visits, followed by being excluded for health reasons for performing the 2-minute walk, limiting generalizability to healthy older adults.


CONCLUSIONS
Patterns of change in the 2-minute walk are similar to those in the 20-m walk. Thus, separate retesting of the 2-minute walk may need to be reconsidered to gauge change in prolonged walking.
D.K. White, PT, ScD, MSc, Department of Physical Therapy and Athletic Training, Boston University, 635 Commonwealth Ave, 5th Floor, Boston, MA 02215 (USA). white.daniel@gmail.com.
Daniel K
DK
White
T. Neogi, MD, PhD, Clinical Epidemiology Research and Training Unit, Boston University School of Medicine, Boston, Massachusetts.
Tuhina
T
Neogi
W.C. King, PhD, Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania.
Wendy C
WC
King
M.P. LaValley, PhD, Department of Biostatistics, School of Public Health, Boston University.
Michael P
MP
LaValley
S.B. Kritchevsky, PhD, Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, North Carolina.
Stephen B
SB
Kritchevsky
M.C. Nevitt, PhD, Department of Biostatistics and Epidemiology, University of California-San Francisco, San Francisco, California.
Michael C
MC
Nevitt
T.B. Harris, MD, MS, Geriatric Epidemiology, National Institutes of Health, Bethesda, Maryland.
Tamara B
TB
Harris
L. Ferrucci, MD, PhD, Longitudinal Studies Section, National Institutes of Health, Baltimore, Maryland.
Luigi
L
Ferrucci
E.M. Simonsick, PhD, National Institute on Aging, National Institutes of Health, Baltimore, Maryland.
Eleanor M
EM
Simonsick
S. Satterfield, MD, DrPH, Preventive Medicine, University of Tennessee, Memphis, Tennessee.
Suzanne
S
Satterfield
E.S. Strotmeyer, PhD, MPH, Department of Epidemiology, University of Pittsburgh.
Elsa S
ES
Strotmeyer
Y. Zhang, MD, DSc, Clinical Epidemiology Research and Training Unit, Boston University.
Yuqing
Y
Zhang
D000203:Activities of Daily Living; D000368:Aged; D001823:Body Composition; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005684:Gait / Q000502:physiology; D015577:Geriatric Assessment; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D051346:Mobility Limitation; D013997:Time Factors; D016138:Walking / Q000502:physiology*