Impact of walking on life expectancy and lifetime medical expenditure: the Ohsaki Cohort Study.

Abstract

People who spend a longer time walking have lower demands for medical care. However, in view of their longer life expectancy, it is unclear whether their lifetime medical expenditure increases or decreases. The present study examined the association between time spent walking, life expectancy and lifetime medical expenditure.
The authors followed up 27,738 participants aged 40-79 years and prospectively collected data on their medical expenditure and survival covering a 13-year-period. Participants were classified into those walking <1 and ≥1 h per day. The authors constructed life tables and estimated the life expectancy and lifetime medical expenditure from 40 years of age using estimate of multiadjusted mortality and medical expenditure using a Poisson regression model and linear regression model, respectively.
Participants who walked ≥1 h per day have a longer life expectancy from 40 years of age than participants who walked <1 h per day. The multiadjusted life expectancy for those who walked ≥1 h per day was 44.81 years, significantly lower by 1.38 years in men (p=0.0073) in men and 57.78 years in women, non-significantly lower by 1.16 years in women (p=0.2351). In addition to their longer life expectancy, participants who walked ≥1 h per day required a lower lifetime medical expenditure from 40 years of age than participants who walked <1 h per day. The multiadjusted lifetime medical expenditure for those who walked ≥1 h per day was £99 423.6, significantly lower by 7.6% in men (p=0.0048) and £128 161.2, non-significantly lower by 2.7% in women (p=0.2559).
Increased longevity resulting from a healthier lifestyle does not necessarily translate into an increased amount of medical expenditure throughout life. Encouraging people to walk may extend life expectancy and decrease lifetime medical expenditure, especially for men.

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Impact of walking on life expectancy
and lifetime medical expenditure: the
Ohsaki Cohort Study
Masato Nagai,1Shinichi Kuriyama,1,2Masako Kakizaki,1Kaori Ohmori-Matsuda,1
Toshimasa Sone,1Atsushi Hozawa,1,4Miyuki Kawado,5Shuji Hashimoto,5
Ichiro Tsuji1
ABSTRACT
Objective: People who spend a longer time walking
have lower demands for medical care. However, in
view of their longer life expectancy, it is unclear
whether their lifetime medical expenditure increases or
decreases. The present study examined the
association between time spent walking, life
expectancy and lifetime medical expenditure.
Method: The authors followed up 27738 participants
aged 40e79 years and prospectively collected data on
their medical expenditure and survival covering
a 13-year-period. Participants were classified into
those walking <1 and $1 h per day. The authors
constructed life tables and estimated the life
expectancy and lifetime medical expenditure from
40 years of age using estimate of multiadjusted
mortality and medical expenditure using a Poisson
regression model and linear regression model,
respectively.
Results: Participants who walked $1 h per day have
a longer life expectancy from 40 years of age than
participants who walked <1 h per day. The multiadjusted
life expectancy for those who walked $1 h per day was
44.81 years, significantly lower by 1.38 years in men
(p¼0.0073) in men and 57.78 years in women,
non-significantly lower by 1.16 years in women
(p¼0.2351). In addition to their longer life expectancy,
participants who walked $1 h per day required a lower
lifetime medical expenditure from 40 years of age than
participants who walked <1 h per day. The multiadjusted
lifetime medical expenditure for those who walked $1 h
per day was £99423.6, significantly lower by 7.6% in
men (p¼0.0048) and £128161.2, non-significantly lower
by 2.7% in women (p¼0.2559).
Discussion: Increased longevity resulting from
a healthier lifestyle does not necessarily translate into
an increased amount of medical expenditure
throughout life. Encouraging people to walk may
extend life expectancy and decrease lifetime medical
expenditure, especially for men.
INTRODUCTION
Previous studies have agreed that a higher
level of physical activity extends life expect-
ancy.1e4Walking is part of a physically active
lifestyle. Previous studies have indicated that
a longer time spent walking,5e13walking
pace8 14e16and a longer distance walked17 18
are significantly associated with a decreased
risk of mortality.
Wepreviouslyreported
expenditure per month was significantly
reduced among those who spent a longer
time walking, based on the same cohort
dataset as that used here.19Similar findings
have been reported worldwide.20 21However,
thatmedical
To cite: Nagai M, Kuriyama S,
Kakizaki M, et al. Impact of
walking on life expectancy
and lifetime medical
expenditure: the Ohsaki
Cohort Study. BMJ Open
2011;2:e000240. doi:10.
1136/bmjopen-2011-
000240
<Prepublication history for
this paper is available online.
To view these files please
visit the journal online (http://
bmjopen.bmj.com).
Received 28 June 2011
Accepted 25 August 2011
This final article is available
for use under the terms of
the Creative Commons
Attribution Non-Commercial
2.0 Licence; see
http://bmjopen.bmj.com
For numbered affiliations see
end of article.
Correspondence to
Dr Masato Nagai;
m-nagai@med.tohoku.ac.jp
ARTICLE SUMMARY
Article focus
- Medical expenditure per month was reduced
when the amount of time spent walking was
increased.
- Walking is associated with a decreased risk of
mortality.
- In view of the increased life expectancy of those
who walk longer, it is unclear whether lifetime
medical expenditure increases or decreases as
a result.
Key messages
- Lifetime medical expenditure from the age of
40 years for men and women who walked $1 h
per day was reduced by 7.6% and 2.7%,
respectively, in comparison with those who
walked <1 h per day.
- Years of life added as a result of a healthy
lifestyledidnotnecessarily
anincreased amount
expenditure.
translate
lifetime
into
of medical
Strengths and limitations of this study
- This is the first study to investigate the
association between walking, life expectancy
and lifetime medical expenditure.
- We assessed walking using a simple question-
naire, in which we asked the participants to
report only the time spent walking, and did not
ask about walking pace, distance walked or any
distinction between walking for exercise and
other reasons.
Nagai M, Kuriyama S, Kakizaki M, et al. BMJ Open 2011;2:e000240. doi:10.1136/bmjopen-2011-000240
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in view of the increased life expectancy of those who
walk for a longer time, it is unclear whether lifetime
medical expenditure increases or decreases as a result.
In other words, the question to be answered here is
whether a lifelong healthy lifestyle eventually increases
lifetime medical expenditure because of extended life
expectancy.
So far, only one study has examined the association
between physical activity and lifetime costs.4
revealed that people with a high physical activity level
tended to live longer than people with a lower physical
activity level, and that the former had lower lifetime
medical costs than the latter. However, that study was
only a simulation analysis based on assumed variations in
the health and economic effects of active and sedentary
lifestyles.
The objective of the present study was to examine the
association between walking, life expectancy and lifetime
medical expenditure using actual individual data derived
from a population-based 13-year prospective observation
period. The population comprised 27738 Japanese
adults aged 40e79 years living in the community who
were free of any functional limitations or chronic
conditions interfering with physical activity, with an
accrued total of 285342 person-years. This cohort study
has been monitoring survival and medical care utilisa-
tion, and its costs, for all participants.19 22Using this
dataset, we constructed a life table to estimate life
expectancy and lifetime medical expenditure according
to the time spent walking.24 25
This
MATERIALS AND METHODS
Study cohort
The present data were derived from the Ohsaki National
Health Insurance (NHI) Cohort Study.19
conducted a self-administered questionnaire survey of
various lifestyle habits between October and December
1994 for all NHI beneficiaries aged 40e79 years who
lived in the catchment area of Ohsaki Public Health
Center, Miyagi Prefecture, northeastern Japan. Out of
54996 eligible individuals, 52029 (95%) responded.
We excluded 776 participants who had withdrawn
from the NHI before 1 January 1995 because their cost
data were not available. Thus, the remaining 51253
participants formed the study cohort. The study protocol
was approved by the Ethics Committee of Tohoku
University School of Medicine. Participants who had
returnedtheself-administered
signed them were considered to have consented to
participate.
For the present analysis, we excluded participants who
had functional limitation or chronic conditions inter-
fering with physical activity. Physical function status was
assessed using the six-item measure of the Medical
Outcomes Study Short-form General Health Survey.26
Participants were excluded if they stated on the Medical
Outcomes Study questionnaire that they were unable to
perform moderate or vigorous activities (n¼15916). We
22 25We
questionnaires and
excluded participants who reported severe bodily pain
(n¼949), or any history of stroke (n¼474), myocardial
infarction (n¼585) or arthritis (n¼2176). We also
excluded those who died within the first year (n¼174) or
did not provide complete responses in the walking status
questionnaire (n¼3241). Thus, a total of 27738 partici-
pants (15521 men and 12217 women) remained. These
participants were apparently healthy enough to walk for
as long as they wished.
Time spent walking
The self-administered questionnaire included items on
time spent walking. Time spent walking was assessed
through the subject’s response to the question, ‘About
how much time do you walk per day on average?’ The
participants were asked to choose one of three answers:
‘1 h or more,’ ‘30 mind1 h’ or ‘30 min or less.’ In Japan,
the Ministry of Health, Labour and Welfare recom-
mended to walk $1 h per day in Exercise and Physical
Activity Reference for Health Promotion 2006. Then, we
divided the participants into two groups according to the
time spent walking daily: <1 h and $1 h. We had previ-
ously evaluated and reported the validity of self-reported
time spent walking.5 19 27This validation study had
indicated that self-reported walking time was reasonably
reproducible and sufficiently valid for studying the
health effects of walking.
Health-insurance system in Japan
Details of the Japanese NHI system have been described
previously.22 28 29Briefly, everyone living in Japan is
required to enrol in a health-insurance system. The NHI
covers 35% of the Japanese population, mainly farmers,
self employed or retired people. The NHI covers almost
all medical treatment, including diagnostic tests, medi-
cation, surgery, supplies and materials, physicians and
other personnel costs, inpatient care and most dental
treatment. It covers treatment by physicians and nurses
but not that by other professionals such as home health
aides. Payment to medical providers is made on a fee-
for-service basis, where the price of each service is
determined by a uniform national fee schedule.
When a participant withdraws from the NHI system
because of death, emigration or employment, the with-
drawal date and its reason are coded in the NHI with-
drawal history files. We recorded any mortality or
migration by reviewing the NHI withdrawal history files
and collected data on the death of participants by
reviewing the death certificates filed at Ohsaki Public
Health Center. We thus followed up the participants and
prospectively collected data on medical care utilisation
and its costs for all individuals in the cohort from
1 January 1995 to 31 December 2007. Study participants
(16.3%) were lost to follow-up, so their vital status was
unknown.
Statistical analysis
Using the Ohsaki NHI cohort database, we estimated
mortality and medical expenditure for individual age
2
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groups, and for the categories of time spent walking, for
both men and women. We divided age into the following
groups: 40e44, 45e49, 50e54, 55e59, 60e64, 65e69,
70e74, 75e79, 80e84 and $85 years. The multiadjusted
mortalities for each age category were estimated from
a Poisson regression model based on person-years and
the number of deaths from 1996 until 2007. The
dependent variable was mortality, and the independent
variables were age groups, categories of time spent
walking and the following covariates: smoking status
(current and past smoker, or never smoker), alcohol
consumption (current drinker consuming 1e499 g/
week, current drinker consuming $450 g/week, or
never and past drinker), body mass index (BMI:
<21 kg/m2, 21e24.9 kg/m2or $25 kg/m2), self-rated
health (good or not good), sports and physical activity
($3 h/week or <3 h/week), history of hypertension
disease (presence or absence), history of diabetes
mellitus (presence or absence), history of cancer
(presence or absence), history of liver disease (pres-
ence or absence) and history of kidney disease (pres-
ence or absence).19The data on all covariates were
obtained from a self-administered questionnaire. We
estimated the mortality of participants aged $85 years
by multiplying the estimated mortality for the 85e89-
year age group by the ratio of mortality for the same age
group relative to the mortality for $85 years from
complete life tables for the year 2000, as there were few
person-years for participants aged over 90 years in our
dataset.30
Because medical expenditure increases before death,
we separatelycalculated
participants who survived through the index year and for
those who died. The multiadjusted medical expenditure
per year for survivors and decedents, respectively, was
estimated for each of the age groups and the categories
of time spent walking using a linear regression model
adjusted for the above covariates.
The estimates of multiadjusted mortality and medical
expenditure for each age group were used for esti-
mating life expectancy and lifetime medical expendi-
ture from 40 yearsof age.
calculated using Chiang’s analytical method on the
basis of the latest published complete life tables of
Japan for the year 2000.23 30Lifetime medical expen-
diture was estimated from the sum obtained by multi-
plying the static population in life table by the medical
expenditure for survivors and the number of deaths in
the life table by the increased medical expenditure
owing to death, which was calculated by subtracting the
medical expenditure in year of survivors from that in
the period of 1 year before death. That is, the life
expectancy (ex) and lifetime medical expenditure (Me)
for each age group (x) were estimated using the
numbers of survivors (lx), deaths (dx), static population
(Lx), multiadjusted medical expenditure for survivors
(ay) and multiadjusted medical expenditure for the
deceased (by) as follows:
medicalexpenditure for
Life expectancywas
+ is the sum of y$x
ex¼+Ly
lx
Mx¼+?Lyayþdyby
?
lx
The 95% CIs were estimated using a Monte Carlo
simulation with 100 000 replicates based on a Poisson
regression model and linear regression model. All
analyses were used the SAS V.9.1 statistical software
package.
We used a purchasing-power parity rate (British
pounds to Japanese yen) of £1.00¼U140.
RESULTS
After 13 years of follow-up, we observed 2936 deaths
(2193 men and 743 women) among the 27738 partici-
pants (15521 men and 12217 women). The mean
medical expenditure per year for survivors who walked
$1 h per day was £1714.2 in men and £1621.4 in women,
significantly lower than for those who walked <1 h per
day(men:
£2064.3,p<0.0001;
p<0.0001). Also, the mean medical expenditure in the
year of death for participants who walked $1 h per day
was £16878.6 in men and £17464.3 in women, which was
not significantly different from those who walked <1 h
per day (men: £16650.0, p¼0.7315; women: £17742.9,
p¼0.8330).
women:
£1878.6,
Baseline characteristics in terms of categories for time
spent walking
Table 1 shows the baseline characteristics of the study
participants according to the categories of time spent
walking for men and women, respectively.
As compared with those who walked <1 h per day,
participants who walked $1 h per day were less likely to
be smokers and obese. Self-reported histories of hyper-
tension, diabetes mellitus and liver disease were all
significantly less prevalent in those who walked $1 h per
day.
Mortality in terms of categories for time spent walking
Figure 1A (for men) and Figure 1B (for women) show
the multiadjusted mortality (per 1000) in each of the age
groups according to the categories of time spent
walking.
In men in each age group, the multiadjusted mortality
was lower in participants who walked $1 h per day than
in those who walked <1 h per day. In women in all age
groups except for the aged 40e44 and 45e49 year
groups, the multiadjusted mortality was lower in partic-
ipants who walked $1 h per day than in those who
walked <1 h per day.
Nagai M, Kuriyama S, Kakizaki M, et al. BMJ Open 2011;2:e000240. doi:10.1136/bmjopen-2011-000240
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Walking and life expectancy and lifetime medical cost

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Table 2 shows the mortality ratio with 95% CIs
according to the categories of time spent walking. In men,
the multiadjusted mortality ratio for participants who
walked $1 h per day was significantly lower than that for
participants who walked <1 h per day (0.90, 95% CI 0.82
to 0.98, p¼0.0153). In women, the multiadjusted mortality
ratio for participants who walked $1 h per day was non-
significantly lower than that for participants who walked
<1 h per day (0.95, 95% CI 0.82 to 1.10, p¼0.4693).
Life expectancy and lifetime medical expenditure in terms
of time spent walking
Table 3 shows the life expectancy and lifetime medical
expenditure from 40 years of age with 95% CIs
according to the categories of time spent walking.
In men, the multiadjusted life expectancy of those who
walked $1 h per day was 44.81 years (95% CI 43.66 to
45.94), which was significantly longer by 1.38 years
(p¼0.0073) than for those who walked <1 h per day
(43.43 years; 95% CI 42.39 to 44.41). In women, the
same results were observed, although the differences did
not reach statistical significance.
In spite of their longer life expectancy, their lifetime
medical expenditure from 40 years of age was signifi-
cantly lower in men and non-significantly lower in
women. The multiadjusted lifetime medical expendi-
ture for participants who walked $1 h per day was
£99423.6 (95% CI 92515.9 to 106694.7), significantly
lower by 7.6% (p¼0.0048) than for those who walked
<1 h per day (£107544.2; 95% CI 101234.0 to
114044.6). Inwomen,the
medical expenditure for participants who walked $1 h
per day was £128161.2 (95% CI 111335.0 to 148494.7),
non-significantly lower by 2.7% (p¼0.2559) than for
multiadjustedlifetime
Table 1Baseline characteristics by time-spent-walking categories in 27738 participants
MenWomen
Time spent walking
<1 h
Time spent walking
<1 h
‡1 hp Value*
‡1 h p Value*
No of subjects
Mean (SD) age
Smoking status (%)
Current and past smoker
Never smoker
Alcohol drinking (%)
Never and past drinker
Current drinker,
1e449 g/week
Current drinker,
$450 g/week
Body mass index (%)
<21 kg/m2
21e24.9 kg/m2
$25 kg/m2
Self-rated health (%)
Good
Not good
Sports and physical activity (%)
$3 h/week
<3 h/week
History of hypertension (%)
Presence
Absence
History of diabetes mellitus (%)
Presence
Absence
History of cancer (%)
Presence
Absence
History of liver disease (%)
Presence
Absence
History of kidney disease (%)
Presence
Absence
*p Values were calculated using the c2test.
7363
57.4 (10.6)
8158
57.2 (10.2)
0.2784 6303
57.9 (10.1)
5914
57.6 (9.7)
0.0714
81.9
18.1
79.8
20.2
0.001112.6
87.5
9.9
90.1
<0.0001
26.5
61.3
25.1
62.2
0.111774.7
24.3
75.4
23.9
0.1380
12.212.8 1.10.7
18.5
53.3
28.3
20.5
55.8
23.7
<0.000118.6
50.7
30.7
19.4
52.9
27.7
0.0019
73.1
26.9
79.3
20.7
<0.000172.5
27.5
78.2
21.8
<0.0001
13.2
86.8
18.7
81.3
<0.0001 10.7
89.3
16.6
83.4
<0.0001
21.5
78.5
18.6
81.4
<0.0001 24.2
75.8
20.1
79.9
<0.0001
7.4
92.6
4.8
95.2
<0.00015.1
94.9
3.2
96.8
<0.0001
2.1
97.9
1.8
98.2
0.25632.8
97.2
2.8
97.2
0.9032
6.9
93.1
5.7
94.4
0.0013 3.7
96.3
2.9
97.1
0.0223
2.9
97.1
2.7
97.3
0.34933.6
96.4
2.7
97.3
0.0049
4
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Walking and life expectancy and lifetime medical cost

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those who walked <1 h per day (£131766.8; 95% CI
115902.4 to 150714.3).
DISCUSSION
The present results indicate that the multiadjusted life-
time medical expenditure from the age of 40 years for
those who walked $1 h per day was significantly lower by
7.6% in men and non-significantly lower by 2.7% in
women than for those who walked <1 h per day. This
decrease in lifetime medical expenditure was observed
in spite of a longer life expectancy (1.38 years for men
and 1.16 years for women) among those who walked
$1 h per day. Thus, a healthy lifestyle not only extended
longevity but also decreased the amount of lifetime
medical expenditure, especially men.
We observed statistically significant differences for
men but not for women. Although the differences did
not reach statistical significance, the same results were
observed for women. The reason why the impact of
walking was smaller in women than in men was
unknown. In women, other factors such as obesity and
postmenopausal change might have a stronger impact
on life expectancy and lifetime medical expenditure
than walking.
Comparison with other studies
Four studies have addressed the association between
physical activity level and life expectancy.1e4Addition-
ally, studies investigating associations between time spent
walking,5e13or distance walked17 18and mortality have
consistently shown that participants who have a higher
physical activity have a longer life expectancy and lower
mortality than participants who have a lower physical
activity. Only one study has reported the association
between physical activity and lifetime medical expendi-
ture.4In a simulation study, Keeler et al demonstrated
that if participants with a sedentary lifestyle had exer-
cised regularly, the additional exercise would have
increased their life expectancy by 300 days and saved
£1900 in lifetime costs. Even though there is a difference
between physical activity and walking, this result is
consistent with the present finding that participants who
walked $1 h per day lived longer and had a lower life-
time medical expenditure.
We previously calculated life expectancy and lifetime
medical expenditure in relation to smoking and BMI
from age 40 years using the same dataset as that for the
present study.24The results indicated that lifetime
medical expenditure was lower for smokers than for
non-smokers, reflecting the 3.5-year shorter life expec-
tancy of smokers.24On the other hand, lifetime medical
expenditure was higher for participants who were obese
(BMI$30.0) than for those who were of normal weight
(18.5#BMI<25.0), even though the former lived 2 years
less than the latter (Nagai M, Kuriyama S, Kakizaki M,
et al. Impact of obesity, overweight and underweight on
life expectancy and lifetime medical expenditures. Popul
Health Metr, under review). In fact, both smokers and
obese participants had a shorter life expectancy than
non-smokers and normal-weight participants, whereas
Figure 1 Multiadjusted mortality by time-spent-walking categories in each age group in (A) men and (B) women.
Table 2Mortality ratio for time-spent-walking categories in 27738 participants
Univariate Multiadjusted*
Time spent walkingMortality ratio (95% CI)p ValueMortality ratio (95% CI) p Value
Men
<1 h
$1 h
<1 h
$1 h
1.00
0.87 (0.80 to 0.94)
1.00
0.89 (0.77 to 1.03)
1.00
0.90 (0.82 to 0.98)
1.00
0.95 (0.82 to 1.10)
0.0009 0.0153
Women
0.11350.4693
*Adjusted for age groups, smoking status, alcohol drinking, body mass index, self-rated health, sports and physical activity, and history of
hypertension, diabetes mellitus, cancer, liver disease and kidney disease.
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their lifetime medical expenditure was conversely
increased. These differences could be explained by the
impact of these risk factors on quality of life. Using
prospective data for 16176 adult Caucasians in the
USA,31Reuser et al estimated life expectancy and years of
life with and without activities of daily-living disability in
relation to smoking and BMI, respectively. The results
indicated that smoking decreased both life expectancy
and years of life with activities of daily-living disability,
whereas obesity decreased the former but increased the
latter, thus leading to the conclusion that ‘smoking kills,
and obesity disables’. Reuser’s conclusion is concordant
with the impact of walking on life expectancy and life-
time medical expenditure. Physical activity decreases not
only mortality but also disability,5e13 17 18 32leading to
lower medical expenditure.33For instance, walking has
been significantly associated with a lower risk of cardio-
vascular disease,7stroke,34coronary heart disease,35 36
type 2 diabetes37and hypertension.38Consequently,
walking also reduces expenditure on medication needed
for these conditions.39
Strengths and limitations
This is the first study to have investigated the association
between walking, life expectancy and lifetime medical
expenditure. A major strength of this study was that we
collected individual data on medical expenditure based
on a cohort study of survival and medical-care utilisation,
and its cost, for all participants,19 22 24 28and the NHI
covers almost all medical treatment in Japan. Second, we
conducted a 13-year prospective observation of 27738
Japanese adults aged 40e79 years living in the commu-
nity who were free of any functional limitations or
chronic conditions interfering with physical activity, with
an accrued total of 285342 person-years. Third, in order
to reduce bias or reverse causation in that people did not
walk because of functional limitations that also required
medical expenditure, we excluded participants who, at
the baseline, reported limited physical function or
conditions interfering with physical activity. Additionally,
to control for confounders, we also included various
covariates in our Poisson regression model and linear
regression model.
On the other hand, several limitations should also be
considered. First, we assessed walking using a simple
questionnaire in which we asked the participants to
report only the time spent walking and did not ask about
walking pace, distance walked or any distinction between
walking for exercise and other reasons. Second, a longer
time spent walking may be a reflection of performing
more vigorous activity, making it difficult to distinguish
the impact of walking from other types of physical
activity. However, the present result did not change after
multivariate adjustment.
Conclusions and policy implication
In summary, lifetime medical expenditure was shown to
be decreased in participants who walked $1 h per day,
despite the fact that they lived longer. Increased
longevity resulting from a healthier lifestyle did not
necessarily translate into an increased amount of
medical expenditure throughout life. However, in the
present study, around 50% of study participants walk
<1 h per day. To increase their walking time, the
recommendation of walking with a pedometer may be
useful.40An increase in walking time at the population
level would bring about a tremendous change in
people’s health and medical cost. A campaign to
encourage people to walk for longer and a program to
make walking environments safer and more pleasant
Table 3
participants
Life expectancy and lifetime medical expenditure at age 40 years for time-spent-walking categories in 27738
Time
spent walking
Univariate Multiadjusted*
Estimate95% CI p ValueEstimate95% CIp Value
Men Life expectancy (years) at age 40 years
<1 h
$1 h
Lifetime medical expenditure (₤) at age 40 years
<1 h107023.2
42.41
44.19
41.45 to 43.26
43.15 to 45.19
0.000443.43
44.81
42.39 to 44.41
43.66 to 45.94
0.0073
101093.6 to
113066.3
87812.3 to
101248.0
<0.0001107544.2 101234.0 to
114044.6
92515.9 to
106694.7
0.0048
$1 h 94402.199423.6
Women Life expectancy (years) at age 40 years
<1 h
$1 h
Lifetime medical expenditure (₤) at age 40 years
<1 h123553.0
52.25
54.25
49.79 to 54.92
51.38 to 57.48
0.056956.62
57.78
53.17 to 60.62
54.02 to 62.22
0.2351
111619.5 to
137549.6
102406.6 to
131792.1
0.0644131766.8 115902.4 to
150714.3
111335.0 to
148494.7
0.2559
$1 h115896.0 128161.2
*Adjusted for age groups, smoking status, alcohol drinking, body mass index, self-rated health, sports and physical activity, and history of
hypertension, diabetes mellitus, cancer, liver disease and kidney disease as same as table 2.
6
Nagai M, Kuriyama S, Kakizaki M, et al. BMJ Open 2011;2:e000240. doi:10.1136/bmjopen-2011-000240
Walking and life expectancy and lifetime medical cost

Page 7

should be implemented. This intervention may extend
life expectancy without apparently increasing lifetime
medical expenditure, especially for men.
Author affiliations
1Division of Epidemiology, Department of Public Health and Forensic Medicine,
Tohoku University Graduate School of Medicine, Sendai, Japan
2Department of Molecular Epidemiology, Genome Research Center, Tohoku
University Graduate School of Medicine, Sendai, Japan
3Department of Environment and Genome Research Center, Tohoku University
Graduate School of Medicine, Sendai, Japan
4Department of Public Health, Yamagata University Graduate School of
Medical Science, Yamagata, Japan
5Department of Hygiene, Fujita Health University School of Medicine, Toyoake,
Japan
Funding This study was supported by a Health Sciences Research Grant for
Health Services (H21-Choju-Ippan-001, H20-Junkankitou (Seisyu)-Ippan-013,
H22- Junkankitou (Seisyu)-Ippan-012, H23- Junkankitou (Seisyu)-Ippan-005),
Ministry of Health, Labour and Welfare, Japan. MN is a recipient of a Research
Fellowships of the Japan Society for the Promotion of Science for Young
Scientists.
Competing interest None.
Patient consent Obtained.
Ethical approval Ethics approval was provided by the Ethics Committee of
Tohoku University School of Medicine.
Contributors All authors contributed to the design of the study. MN, SK, MK,
KO-M, TS and IT carried out the data collection. MN, SK, AH, MK and SH
carried out the data analysis. MN, MK, KO-M, TS, AH, MK and SH wrote the
report. SK and IT carried out a critical revision of the manuscript. All authors
approved the final version of the report for submission.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data available.
REFERENCES
1.Franco OH, de Laet C, Peeters A, et al. Effects of physical activity on
life expectancy with cardiovascular disease. Arch Intern Med
2005;165:2355e60.
2.Hatziandreu EI, Koplan JP, Weinstein MC, et al. A cost-effectiveness
analysis of exercise as a health promotion activity. Am J Public Health
1988;78:1417e21.
3.Jonker JT, De Laet C, Franco OH, et al. Physical activity and life
expectancy with and without diabetes: life table analysis of the
Framingham Heart Study. Diabetes Care 2006;29:38e43.
4. Keeler EB, Manning WG, Newhouse JP, et al. The external costs of
a sedentary life-style. Am J Public Health 1989;79:975e81.
5.Fujita K, Takahashi H, Miura C, et al. Walking and mortality in Japan:
the Miyagi Cohort Study. J Epidemiol 2004;14(Suppl 1):S26e32.
6.Kujala UM, Kaprio J, Sarna S, et al. Relationship of leisure-time
physical activity and mortality: the Finnish twin cohort. JAMA
1998;279:440e4.
7. LaCroix AZ, Leveille SG, Hecht JA, et al. Does walking decrease the
risk of cardiovascular disease hospitalizations and death in older
adults? J Am Geriatr Soc 1996;44:113e20.
8.Lee IM, Rexrode KM, Cook NR, et al. Physical activity and coronary
heart disease in women: is ‘no pain, no gain’ passe? JAMA
2001;285:1447e54.
9. Morioka S. [A cohort study on the relationship between lifestyles and
total mortality] (in Japanese). Nippon Koshu Eisei Zasshi
1996;43:469e78.
10. Seki N. [Relationships between walking hours, sleeping hours,
meaningfulness of life (ikigai) and mortality in the elderly: prospective
cohort study] (in Japanese). Nippon Eiseigaku Zasshi
2001;56:535e40.
11. Stessman J, Maaravi Y, Hammerman-Rozenberg R, et al. The effects
of physical activity on mortality in the Jerusalem 70-Year-Olds
Longitudinal Study. J Am Geriatr Soc 2000;48:499e504.
12.Wannamethee SG, Shaper AG, Walker M. Physical activity and
mortality in older men with diagnosed coronary heart disease.
Circulation 2000;102:1358e63.
13.Weller I, Corey P. The impact of excluding non-leisure energy
expenditure on the relation between physical activity and mortality in
women. Epidemiology 1998;9:632e5.
Dumurgier J, Elbaz A, Ducimetie `re P, et al. Slow walking speed and
cardiovascular death in well functioning older adults: prospective
cohort study. BMJ 2009;339:b4460.
Tanasescu M, Leitzmann MF, Rimm EB, et al. Exercise type and
intensity in relation to coronary heart disease in men. JAMA
2002;288:1994e2000.
Cooper R, Kuh D, Hardy R. Objectively measured physical capability
levels and mortality: systematic review and meta-analysis. BMJ
2010;341:c4467.
Hakim AA, Petrovitch H, Burchfiel CM, et al. Effects of walking on
mortality among nonsmoking retired men. N Engl J Med
1998;338:94e9.
Lee IM, Paffenbarger RS Jr. Associations of light, moderate, and
vigorous intensity physical activity with longevity. The Harvard Alumni
Health Study. Am J Epidemiol 2000;151:293e9.
Tsuji I, Takahashi K, Nishino Y, et al. Impact of walking upon medical
care expenditure in Japan: the Ohsaki Cohort Study. Int J Epidemiol
2003;32:809e14.
Jones TF, Eaton CB. Costebenefit analysis of walking to prevent
coronary heart disease. Arch Fam Med 1994;3:703e10.
Perkins AJ, Clark DO. Assessing the association of walking with
health services use and costs among socioeconomically
disadvantaged older adults. Prev Med 2001;32:492e501.
Tsuji I, Nishino Y, Ohkubo T, et al. A prospective cohort study on
National Health Insurance beneficiaries in Ohsaki, Miyagi Prefecture,
Japan: study design, profiles of the subjects and medical cost during
the first year. J Epidemiol 1998;8:258e63.
Chiang CL. The Life Table and Its Applications. Malabar: Robert E
Krieger Publishing Company, 1984.
Hayashida K, Imanaka Y, Murakami G, et al. Difference in lifetime
medical expenditures between male smokers and non-smokers.
Health Policy 2010;94:84e9.
Kuriyama S, Shimazu T, Ohmori K, et al. Green tea consumption and
mortality due to cardiovascular disease, cancer, and all causes in
Japan: the Ohsaki study. JAMA 2006;296:1255e65.
Stewart AL, Hays RD, Ware JE Jr. The MOS short-form general
health survey. Reliability and validity in a patient population. Med
Care 1988;26:724e35.
Tsubono Y, Tsuji I, Fujita K, et al. Validation of walking questionnaire
for population-based prospective studies in Japan: comparison with
pedometer. J Epidemiol 2002;12:305e9.
Kuriyama S, Tsuji I, Ohkubo T, et al. Medical care expenditure
associated with body mass index in Japan: the Ohsaki Study. Int J
Obes Relat Metab Disord 2002;26:1069e74.
Nakamura K, Okamura T, Kanda H, et al. Medical costs of obese
Japanese: a 10-year follow-up study of National Health Insurance in
Shiga, Japan. Eur J Public Health 2007;17:424e9.
Statistics and Information Department Minister’s Secretariat, Ministry
of Health, Labour and Welfare of Japan. The 20th Life Tables. Tokyo:
Health and Welfare Statistics Association, Japan, 2000.
Reuser M, Bonneux LG, Willekens FJ. Smoking kills, obesity
disables: a multistate approach of the US Health and Retirement
Survey. Obesity (Silver Spring) 2009;17:783e9.
Clark DO. The effect of walking on lower body disability among older
blacks and whites. Am J Public Health 1996;86:57e61.
Mitra S, Findley PA, Sambamoorthi U. Health care expenditures of
living with a disability: total expenditures, out-of-pocket
expenses, and burden, 1996 to 2004. Arch Phys Med Rehabil
2009;90:1532e40.
Hu FB, Stampfer MJ, Colditz GA, et al. Physical activity and risk of
stroke in women. JAMA 2000;283:2961e7.
Hakim AA, Curb JD, Petrovitch H, et al. Effects of walking on
coronary heart disease in elderly men: the Honolulu Heart Program.
Circulation 1999;100:9e13.
Manson JE, Hu FB, Rich-Edwards JW, et al. A prospective study of
walking as compared with vigorous exercise in the prevention of
coronary heart disease in women. N Engl J Med 1999;341:650e8.
Hu FB, Sigal RJ, Rich-Edwards JW, et al. Walking compared with
vigorous physical activity and risk of type 2 diabetes in women:
a prospective study. JAMA 1999;282:1433e9.
Hayashi T, Tsumura K, Suematsu C, et al. Walking to work and the
risk for hypertension in men: the Osaka Health Survey. Ann Intern
Med 1999;131:21e6.
Williams PT. Reduced diabetic, hypertensive, and cholesterol
medication use with walking. Med Sci Sports Exerc 2008;40:433e43.
Snyder A, Colvin B, Gammack JK, et al. Pedometer use increases
daily steps and functional status in older adults. J Am Med Dir Assoc.
Published Online First: 7 October 2010. doi:10.1016/j.
jamda.2010.06.007.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
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Walking and life expectancy and lifetime medical cost