Trajectories of gait speed predict mortality in well-functioning older adults: the Health, Aging and Body Composition study.
BACKGROUND
Although gait speed slows with age, the rate of slowing varies greatly. To date, little is known about the trajectories of gait speed, their correlates, and their risk for mortality in older adults.


METHODS
Gait speed during a 20-m walk was measured for a period of 8 years in initially well-functioning men and women aged 70-79 years participating in the Health, Aging and Body Composition study. We described the trajectories of gait speed and examined their correlates using a group-based mixture model. Also risk associated with different gait speed trajectories on all-cause mortality was estimated using a Cox-proportional hazard model.


RESULTS
Of 2,364 participants (mean age, 73.5 ± 2.9 years; 52% women), we identified three gait speed trajectories: slow (n = 637), moderate (n = 1,209), and fast decline (n = 518). Those with fast decline slowed 0.030 m/s per year or 2.4% per year from baseline to the last follow-up visit. Women, blacks, and participants who were obese, had limited knee extensor strength, and had low physical activity were more likely to have fast decline than their counterparts. Participants with fast decline in gait speed had a 90% greater risk of mortality than those with slow decline.


CONCLUSIONS
Despite being well-functioning at baseline, a quarter of older adults experienced fast decline in gait speed, which was associated with an increased risk of mortality.
Department of Physical Therapy and Athletic Training, Boston University, Boston, Massachusetts, USA. dwtbn@bu.edu
Daniel K
DK
White
Tuhina
T
Neogi
Michael C
MC
Nevitt
Christine E
CE
Peloquin
Yanyan
Y
Zhu
Robert M
RM
Boudreau
Jane A
JA
Cauley
Luigi
L
Ferrucci
Tamara B
TB
Harris
Susan M
SM
Satterfield
Eleanor M
EM
Simonsick
Elsa S
ES
Strotmeyer
Yuqing
Y
Zhang
D000368:Aged; D000375:Aging / Q000502:physiology; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000706:statistics & numerical data; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment / Q000379:methods; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009026:Mortality; D053580:Muscle Strength / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D014481:United States; D016138:Walking / Q000502:physiology*