Jan. 5, 2011
How fast senior citizens walk appears to be a better gage of how long
they will live than trying to do a more complicated analysis using age,
sex, chronic conditions, smoking history, blood pressure, body mass
index, and hospitalization. This study of senior citizens found walking
gait is especially accurate for predicting remaining life for those age
75 and older.
"Remaining years
of life vary widely in older adults, and physicians should consider life
expectancy when assessing goals of care and treatment plans. However,
life expectancy based on age and sex alone provides limited information
because survival is also influenced by health and functional abilities,"
according to the study in the January 5 issue of the Journal of the
American Medical Association (JAMA).
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centenarians described as open and conscientious.
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The researchers
were motivated to begin the study because there were currently no
well-established approaches to predicting life expectancy that
incorporated health and function. Gait speed, or walking speed, had been
recommended as a potentially useful clinical indicator of well-being
among older adults.
Stephanie
Studenski, M.D., M.P.H., of the University of Pittsburgh, and colleagues
conducted a study to assess the association of gait speed with survival
in older adults and to determine the degree to which gait speed explains
variability in survival after accounting for age and sex.
The study
included a pooled analysis of 9 participating studies (collected between
1986 and 2000), using individual data from 34,485 community-dwelling
adults age 65 years or older with walking speed data available at the
beginning of the study, followed up for 6 to 21 years.
Participants had
an average age of 73.5 years; 59.6 percent were women; and 79.8 percent
were white.
Gait speed was
calculated for each participant using distance in meters and time in
seconds. All studies used instructions to walk at usual pace and from a
standing start. The walk distance varied from 8 feet to 6 meters. The
average gait speed of the participants was 0.92 meters (3 feet) per
second.
During the
course of the study, there were 17,528 deaths. The overall 5-year
survival rate was 84.8 percent; the 10-year survival rate was 59.7
percent.
The researchers
found that gait speed was associated with differences in the probability
of survival at all ages in both sexes, but was especially informative
after age 75 years. At this age, predicted 10-year survival across the
range of gait speeds ranged from 19 percent to 87 percent in men and
from 35 percent to 91 percent in women.
Predicted years
of remaining life for each sex and age increased as gait speed
increased, with a gait speed of about 2.6 feet (0.8 meters)/second at
the median (midpoint) life expectancy at most ages for both sexes.
Gait speeds of
1.0 meter (3.3 feet)/second or higher consistently demonstrated survival
that was longer than expected by age and sex alone. In this older adult
population the relationship of gait speed with remaining years of life
was consistent across age groups, but the absolute number of expected
remaining years of life was larger at younger ages," the authors write.
The researchers
also found that predicted survival based on age, sex, and gait speed was
as accurate as predictions based on age, sex, use of mobility aids, and
self-reported function or as age, sex, chronic conditions, smoking
history, blood pressure, body mass index, and hospitalization.
Why gait
speed matters
The authors
suggest there are several reasons why gait speed may predict survival.
"Walking requires energy, movement control, and support and places
demands on multiple organ systems, including the heart, lungs,
circulatory, nervous, and musculoskeletal systems. Slowing gait may
reflect both damaged systems and a high energy cost of walking."
The researchers
write that there are a number of ways gait speed might be used
clinically, including helping to identify older adults with a high
probability of living for 5 or 10 more years, who may be appropriate
targets for preventive interventions that require years for benefit.
Gait speed might
be used to identify older adults with increased risk of early mortality,
perhaps those with gait speeds slower than 0.6 meter (2 feet)/second.
"In these
patients, further examination is targeted at potentially modifiable
risks to health and survival." Also, gait speed might be monitored over
time, with a decline indicating a new health problem that requires
evaluation.
"The data
provided herein are intended to aid clinicians, investigators, and
health system planners who seek simple indicators of health and survival
in older adults. Gait speed has potential to be implemented in practice,
using a stop watch and a 4-meter (13 feet) course. From a standing
start, individuals are instructed to walk at their usual pace, as if
they were walking down the street, and given no further encouragement or
instructions. The data in this article can be used to help interpret the
results. Gait speed may be a simple and accessible indicator of the
health of the older person," the authors conclude.
Editorial:
Role of Gait Speed in the Assessment of Older Patients
In an
accompanying editorial, Matteo Cesari, M.D., Ph.D., of the Universita
Campus Bio-Medico, Rome, writes that because no evidence definitively
supports the hypothesis that gait speed improvements are associated with
better health-related outcomes, gait speed should not be considered as a
primary target for interventions at this time.
"It represents a
global marker of health status, and an optimal secondary and
complementary outcome to support research findings, clinical decisions,
or both aimed at modifying more pragmatic end points. ...assessing gait
speed in older persons is likely to be a useful research tool and may
have a clinical role. Future research will be needed to determine
whether gait speed has the potential to change the way in which a
patient is defined as geriatric."
Keep up with the latest news for senior citizens, baby
boomers
In an
accompanying editorial, Matteo Cesari, M.D., Ph.D., of the Universita
Campus Bio-Medico, Rome, writes that because no evidence definitively
supports the hypothesis that gait speed improvements are associated with
better health-related outcomes, gait speed should not be considered as a
primary target for interventions at this time. 