Impact of Obesity on Medical Problems and Quality of Life in Taiwan
American Journal of Epidemiology
Copyright 2004 by the Johns Hopkins Bloomberg School of Public Health
All rights reserved
Impact of Obesity on Medical Problems and Quality of Life in Taiwan
Wen-Ling Tsai 1 2
Chun-Yuh Yang 0 2
Sheng-Fung Lin 2 4
Fu-Min Fang 2 3
0 Institute of Public Health, Kaohsiung Medical University , Kaohsiung , Taiwan
1 Department of Cosmetic Application and Management, Yung Ta Institute of Technology and Commerce , Pintung , Taiwan
2 Graduate Institute of Medicine, Kaohsiung Medical University , Kaohsiung , Taiwan
3 Department of Radiation Oncology, Kaohsiung Chang Gung Memorial Hospital , Kaohsiung , Taiwan
4 Department of Internal Medicine, Kaohsiung Medical University , Kaohsiung , Taiwan
Little is known about the impact of obesity on medical problems and quality of life for people in the Asia-Pacific region. This January 2002-June 2003 cross-sectional study surveyed 6,318 Taiwanese (3,540 men and 2,778 women) visiting health screening centers in southern Taiwan. The authors used the body mass index classification endorsed by the World Health Organization for people in this region. Information was collected on 15 medical problems and quality of life outcomes, measured by the Medical Outcomes Study Short Form 36 questionnaire. After adjustment for age, lifestyle, and sociodemographic factors, and after comparison of subjects with those not overweight or obese (reference group), an increasing trend of body mass index effects based on this reference category was observed on hypertension, hypercholesterolemia, hypertriglyceridemia, type II diabetes, hyperuricemia, pulmonary function impairment, fatty liver disease, and osteoarthritis in both sexes (p < 0.01). Concerning quality of life, an increasing trend of body mass index effects was also observed on the outcomes physical functioning and bodily pain for both sexes and role limitation due to physical problems for women (p < 0.05). Specifically, only the physical functioning domain, including daily activities such as climbing stairs, bending, walking, or some moderate activities, was significantly associated with obesity and was limited to class II obesity. body mass index; cross-sectional studies; gallstones; health; obesity; quality of life Abbreviations: BMI, body mass index; QOL, quality of life; SD, standard deviation; SF-36, Medical Outcomes Study Short Form 36.
Obesity has become a major public health problem of
global significance. The prevalence rate of obesity is
increasing in all parts of the world, both in affluent,
developed countries and in poorer, developing nations. It has been
reported that the prevalence rate of obesity in the United
States increased 50 percent from 1991 to 1998 (1).
According to a national survey in Taiwan conducted from
1992 to 1997, the prevalence rate of obesity was about 25
percent for adult Taiwanese, and mean weight increased 25
kg at all age levels compared with data from a previous
19861988 investigation (2).
Obesity has proven to be associated with a variety of
chronic diseases such as coronary artery disease,
hypertension, type II diabetes, and several cancers and is also
considered the second leading avoidable cause of mortality in
Western countries (3, 4). In addition, a growing body of
literature describes the close association between obesity and
quality of life (QOL) (5). In the past decade, QOL has gained
increasing interest as an outcome measure in clinical
medicine and public health. QOL is based on two fundamental
premises. First, it is a multidimensional construct
incorporating physical, psychological, social, and emotional
functional domains. Second, it is subjective and is reported
according to a persons own experiences. Several studies
have demonstrated that obese people have a lower QOL,
especially regarding the physical aspects of daily life,
compared with their normal-weight counterparts (612).
Body mass index (BMI; weight (kg)/height (m)2) is one of
the most popular anthropometric indices. Different BMI
cutoff points describe obesity in different ethnicities. For
Caucasians, the definition of obesity according to the
international classification endorsed by the World Health
Organization is as follows: 25.029.9 kg/m2, overweight; 30.034.9
kg/m2, class I obesity; 35.039.9 kg/m2, class II obesity; and
40 kg/m2, class III obesity (13). For people in the
AsiaPacific region, the definition differs: 23.024.9 kg/m2,
overweight; 25.029.9 kg/m2, class I obesity; and 30.0 kg/m2,
class II obesity (14). Only a small number of studies have
investigated the association between obesity and medical
problems for people in the Asia-Pacific region. To our
knowledge, the impact of obesity on QOL for people in this
area has not been explored. In this cross-sectional study, we
examined and quantified the impact of obesity, according to
the Asia-Pacific BMI classification, on a wide range of
medical problems and QOL in a large sample of Taiwanese
men and women.
MATERIALS AND METHODS
The data were collected from people visiting the health
screening centers of Chang Gung Memorial Hospital in
southern Taiwan for checkups. Monthly, about 400
Taiwanese visited the units for this reason. Subjects whose
body weight had changed by more than 5 percent in 3
months were excluded from this study. Among the 6,571
Taiwanese consecutively visiting the units from January
2002 to June 2003, 3,540 men and 2,778 women aged 2079
years were enrolled. Of these subjects, 4,798 (2,846 men and
1,952 women) completed the QOL questionnaire. The items
covered in the health checkups included medical history,
physical examinations, and a series of laboratory, radiologic,
and endoscopic examinations. All examinations were
performed and diagnoses confirmed by medical specialists.
A wide range of medical problems was surveyed; these
problems were chosen on the basis of their known relation to
obesity or because they were highly prevalent in Taiwan.
Fifteen medical problems were analyzed and were
categorized according to the body systems affected. This
information is presented in table 1.
Definition of medical problems
Cardiovascular and metabolic system. Sitting blood
pressure was measured by using a standard mercury
sphygmomanometer. Systolic (Korotkoff phase 1) and diastolic
(Korotkoff phase 5) blood pressures were measured twice on
the right upper arm, and the average was used for analysis.
Fasting plasma glucose, total cholesterol, triglyceride, and
serum uric acid were tested by using a Hitachi 7450
biochemical analyzer (Hitachi Ltd., Tokyo, Japan).
Hypertension was defined as a systolic blood pressure of 140
mmHg and/or a diastolic blood pressure of 90 mmHg or
current use of antihypertensive drugs. Type II diabetes
mellitus was defined as a fasting plasma glucose
concentration of 126 mg/dl or current use of antidiabetic agents.
Hyperuricemia was defined as a serum uric acid
concentration of >8.3 mg/dl or current use of agents to treat gout. The
criteria for hypercholesterolemia and hypertriglyceridemia
were a total plasma cholesterol concentration of 200 mg/dl
and a triglyceride level of >150 mg/dl, respectively.
Respiratory system. Spirometry measurements were
performed by using a calibrated rolling seal spirometer
(Spirotrac 6800; Vitalograph, Inc., Lenexa, Kansas) while
subjects were seated. Forced vital capacity and forced
expiratory volume in 1 second were measured. A diagnosis of
pulmonary function impairment was applied if the predicted
forced expiratory volume in 1 second was below 75 percent
and/or the predicted forced vital capacity was below 80
percent. Subjects were diagnosed with chronic obstructive
pulmonary disease if their clinical presentation or history
was compatible with the definitions of asthma, emphysema,
or bronchiectasis and the chest radiograph showed typical
hyperinflation, chronic bronchial infiltration, and/or
Hepatobiliary and gastrointestinal system. Endoscopic
examinations, which included the esophagus, stomach,
duodenum, colon, and rectum, were performed by a
gastroenterologist. A diagnosis of polyps, hemorrhoids, or ulcers
was given from the results of an endoscopic inspection with or
without pathologic examination. A diagnosis of chronic viral
hepatitis was applied if the serum hepatic function test
revealed that the subject was a carrier of hepatitis B and/or C
virus and the hepatic sonography showed a coarse liver
echotexture, uneven liver contour, and partial obliteration of the
hepatic vasculature. A diagnosis of gallstone disease
(cholelithiasis) was given if a stone-like radiologic picture
and/or a mobile echogenic structure with acoustic shadowing
in the gall bladder was found. If the echogram showed increased
sound attenuation of the liver parenchyma with impaired
visualization of the borders of the hepatic vessels, the subject was
diagnosed with fatty liver disease (hepatic steatosis) (15).
Musculoskeletal system. A diagnosis of osteoarthritis
was given if plain radiographic films revealed joint space
narrowing, osteophytosis at articular margins and/or
eburnation of subchondral bone in the knee or hip joint, or apparent
marginal osteophytes and/or interspace narrowing of the
lumbar spinal bones (16).
Measures of BMI
Trained research staff measured height by using a
stadiometer and weight with a calibrated digital scale for
participants who were wearing a clinic gown. BMI was calculated
by dividing weight in kilograms by the square of height in
Measures of QOL
The Medical Outcomes Study Short Form 36 (SF-36)
questionnaire (Taiwan Chinese version) was used to measure
QOL (17). This self-administered questionnaire includes 36
items, in a Likert-type or forced-choice format, and contains
brief indices of the following eight functional domains:
1) physical functioning (10 items, 3-point scale), 2) role
limitation due to physical problems (role physical; four items,
3-point scale), 3) role limitation due to emotional problems
(role emotional; three items, 2-point scale), 4) social
functioning (two items, 5-point scale), 5) bodily pain (two items
Body mass index
Women (n = 2,778)
47.5 (14.6) 49.1 (12.7)
50.0 (11.5) 43.1 (13.7)
47.9 (13.3) 42.4 (12.8) 51.3 (11.4) 54.0 (11.6) 53.8 (13.1)
each, 5- and 6-point scales), 6) vitality (four items, 6-point
scale), 7) mental health (five items, 6-point scale), and
8) general health perception (five items, 5-point scale).
Health change in the past year (one item, 5-point scale) was
also assessed. Scores for each domain ranged from 0 to 100,
with high scores indicating a better status (18, 19). The
Taiwan Chinese SF-36 has been used by other researchers
and has been shown to have good construct validity and high
internal reliability (20, 21).
Measures of potential confounders
All sociodemographic data (age, gender, number of years
of education, annual family income, employment, and
marital status) and lifestyle variables (smoking, alcohol
consumption, and exercise frequency) were obtained by
using a self-administered questionnaire. Alcohol
consumption and smoking status were assessed by using a 3-point
scale (e.g., no history of smoking, past smoking, current
smoking). Frequency of exercise was assessed with the
following question: How many times do you exercise every
Scores for the eight functional domains of the Taiwan
Chinese SF-36 were calculated according to the SF-36
manual (18). Logistic regression analysis (SPSS for
Windows, version 10.0; SPSS, Inc., Chicago, Illinois) was
used to determine odds ratios and associated 95 percent
Each of the diagnosed medical problems or poor QOL
ratings was used as a dependent variable in separate
regression models. The distributions of the scores for the eight
functional domains were examined to identify the cutoff
values for good and poor QOL. Subjects whose score
was less than 66.7 percent were assessed as having a poor
QOL, and those scoring 66.7 percent or above were
considered to have a good QOL. The items for each functional
domain were also dichotomized so that above-average
scores for items with an odd-numbered scale (3 or 5 points)
indicated a good QOL and scores that were average or lower
indicated a poor QOL. For items with an even scale (2, 4, or
6 points), the scores for good and poor QOL were divided
evenly. Dummy variables for BMI (independent variable)
were created by using BMI <23.0 kg/m2 as the reference. For
medical problems, adjustments were made for age,
sociodemographic factors (number of years of education, annual
family income, marital status, and employment), and
lifestyle (smoking, alcohol consumption, and exercise
frequency). For the QOL analysis, additional adjustments
were made for the diagnosed medical problems found to be
significantly correlated with BMI. Statistical significance of
trends was calculated by categorizing exposure variables and
treating scored variables as continuous in logistic regression
analysis. Men and women were analyzed separately because
of expected differences between the sexes in both the
dependent and independent variables.
For men (n = 3,540) and women (n = 2,778), respectively,
mean age was 48.6 (standard deviation (SD), 13.0) years and
47.9 (SD, 13.3) years, weight was 70.1 (SD, 15.8) kg and
58.3 (SD, 9.9) kg, height was 168.0 (SD, 24.5) cm and 156.2
(SD, 5.5) cm, and BMI was 24.9 (SD, 3.5) kg/m2 and 24.0
(SD, 4.0) kg/m2 (table 1). Twenty-six percent of the men
were overweight, 39.1 percent had class I obesity, and 5.7
percent had class II obesity. Among the women, 22.1 percent
were overweight, 23.8 percent had class I obesity, and 6.3
percent had class II obesity. Obese men were more likely to
be employed and to have a higher annual family income; in
contrast, obese women were more likely to be unemployed
and to have a lower annual family income. Obese women
tended to have lower educational attainment. On the other
hand, educational attainment did not differ significantly
across BMI categories for men. With regard to lifestyle, the
prevalence rate of current smoking was 53.4 percent for men
and 5.7 percent for women. For both men (61.1 percent) and
women (9.8 percent), current smoking was seen more often
in the class II obesity group. The mean frequency of exercise
per week was 1.7 (SD, 1.3) times for men and 1.6 (SD, 1.4)
times for women. Exercise frequency was inversely
associated with BMI for men, but a clear pattern was not found for
Cardiovascular and metabolic system. The mean value of
systolic blood pressure was 131 (SD, 17) mmHg in men and
128 (SD, 20) mmHg in women. The respective
concentrations of plasma total cholesterol, triglyceride, fasting
glucose, and uric acid were 199 (SD, 63) mg/dl, 147 (SD,
130) mg/dl, 112 (SD, 55) mg/dl, and 7 (SD, 13) mg/dl in men
and 199 (SD, 64) mg/dl, 116 (SD, 83) mg/dl, 107 (SD, 33)
mg/dl, and 7 (SD, 13) mg/dl in women. The prevalence of
hypertension, hypertriglyceridemia, type II diabetes, and
hyperuricemia was higher in men than in women (p < 0.05).
After adjustment for age, lifestyle, and sociodemographic
factors, and comparison of subjects with those not
overweight or obese (reference group), an increasing trend of
BMI effects based on this category was observed for all four
medical variables for both sexes (p < 0.01) (table 2).
Consistency of the BMI effects was generally observed for
most of these variables as a group after we examined the 95
percent confidence intervals within each BMI level. For
men, statistically significant odds ratios for
hypercholesterolemia, hypertriglyceridemia, and hyperuricemia were found
for those in the overweight, class I, or class II obesity group
and for hypertension and type II diabetes in the class I or
class II obesity group. For women, statistically significant
odds ratios for hypertension, hypercholesterolemia,
hypertriglyceridemia, and type II diabetes were found for those in
the overweight, class I, or class II obesity group and for
hyperuricemia in the class I or class II obesity group.
Respiratory system. The mean values of forced vital
capacity and forced expiratory volume in 1 second were 89.4
(SD, 15.9) percent and 85.2 (SD, 14.6) percent in men and
OR 95% CI
Body mass index
(200 mg/dl) 1.2
(>150 mg/dl) 1.8
Type II diabetes (fasting
glucose 126 mg/dl) 1.2
pulmonary disease 0.7
Fatty liver disease 2.0
Chronic viral hepatitis 1.0
Peptic ulcer 1.0
Quality of life (poor)
Physical functioning 1.1
Role physical# 0.9
Role emotional** 1.0
Social functioning 0.9
Bodily pain 1.0
Mental health 0.9
General health 0.9
2.1 1.6, 2.6
1.6 1.3, 1.9
2.9 2.4, 3.7
1.3 1.1, 1.5
2.3 1.7, 3.1
4.2, 10.3 <0.001
1.4 0.9, 1.9
1.5 1.1, 1.9
89.5 (SD, 17.2) percent and 86.7 (SD, 15.2) percent in
women, respectively. An increasing trend of BMI effects
was observed on pulmonary function impairment for both
sexes (p < 0.01). A statistically significant odds ratio was
found only for those of both sexes with class II obesity. In
contrast, for both sexes, the trend of BMI effects on chronic
obstructive pulmonary disease or asthma was not significant.
Hepatobiliary and gastrointestinal system. Of the six
medical variables (gallstones, fatty liver disease, chronic
viral hepatitis, hemorrhoids, peptic ulcer, and
Body mass index
Men (n = 2,846)
Women (n = 1,952)
tinal polyps), an increasing trend of BMI effects was
observed for only fatty liver disease for both sexes (p <
0.01). Conversely, the BMI effects were found to be
consistent but statistically insignificant regarding the other five
variables. For fatty liver disease, the odds ratio was
significant for those in the overweight, class I, or class II obesity
group for both sexes. It was as much as 20 times higher in the
class II obesity group (table 2).
Musculoskeletal system. The prevalence rate of
osteoarthritis was 41.2 percent for men and 41.4 percent for women.
An increasing trend of BMI effects was observed on
osteoarthritis for both sexes (p < 0.01). The odds ratio was
significant for men who had class I or II obesity and for women in
the overweight, class I, or class II obesity group.
Table 3 shows the unadjusted prevalence of poor QOL for
the eight functional domains of the SF-36. After adjustment
for age, lifestyle, sociodemographic factors, and medical
problems, a statistically significant (p < 0.05), increasing
trend of BMI effects was found on physical functioning and
bodily pain for both sexes and for role physical for women.
The only statistically significant odds ratio was the one
corresponding to physical functioning for those subjects
with class II obesity (men: odds ratio = 3.2, 95 percent
confidence interval: 2.1, 5.1; women: odds ratio = 2.7, 95 percent
confidence interval: 1.7, 4.5) (table 2). Otherwise, the
individual items of the physical functioning domain are
presented in table 4. Odds ratios were statistically significant
for moderate activities, bending, walking, and climbing
several stairs for both sexes; and for lifting or carrying
groceries, climbing one flight of stairs, and self-bathing or
dressing for women.
Taiwan is located in the center of the East-Asian island arc
and has a population of 22 million. Most of the islands
inhabitants are the descendants of immigrants from
Mainland China. With an improving economy and changing
habits influenced by Western diets, obesity is becoming a
threatening health problem for people on this island.
Recently, a national nutritional survey revealed that 24.5
percent of the male and 25.2 percent of the female adults in
Taiwan were obese, and this prevalence was particularly
high (men: 36.6 percent; women: 44.6 percent) among those
aged 4564 years (2).
Most studies examining the risk of medical problems
associated with obesity are based on data from Caucasians in
Europe or the United States. It has been shown that for the
same body fat level, age, and gender, Chinese BMI is 1.9 kg/
m2 lower than that of Caucasians (22). The increased risks of
medical problems associated with obesity are found to occur
at a lower BMI in Asians compared with Caucasians (23,
24). However, the optimal cutoff points for BMI to define
overweight Asian persons or obesity are still controversial.
A cutoff point of 24.2 for overweight individuals and 26.4
for obesity was suggested in Taiwan (2). When predictive
values for some cardiovascular risk factors are tested in
Mainland China, the recommended optimal cutoff points for
BMI are 24.0 for overweight and 28.0 for obese individuals
(25). In 2000, the World Health Organization redefined the
BMI cutoff points as 23.0/25.0 for overweight/obese
individuals in the Asia-Pacific region (14). So far, data on
disease association with obesity using this classification
endorsed by the World Health Organization are still sparse in
the literature, and most studies have focused solely on
cardiovascular disease. Ours carried out a more
comprehensive survey of medical problems and of QOL among
overweight and obese individuals defined by this classification.
flight of stairs 0.8
Walking >1 km
Walking 500 m
Walking 100 m
Men (n = 2,846)
Body mass index
Women (n = 1,952)
According to the World Health Organization, medical
problems greatly or moderately associated with obesity
include type II diabetes, insulin resistance, gallstone disease,
dyslipidemia, breathlessness, sleep apnea, coronary heart
disease, hypertension, osteoarthritis, and hyperuricemia
(26). In addition, there are some less-well-known
complications of obesity such as fatty liver disease, pulmonary
function impairment, endocrine abnormalities, and obstetric
complications (27). Surveying all of these probable
complications of obesity was not possible in this cross-sectional
study because our data were limited to those that could be
investigated by the routine procedures of health screening.
Among the 15 medical problems we investigated, an
increasing and significant trend of BMI effects based on this
category was observed on hypertension,
hypercholesterolemia, hypertriglyceridemia, type II diabetes,
hyperuricemia, pulmonary function impairment, fatty liver disease,
and osteoarthritis for both sexes. Except for gallstone
disease, these results are generally compatible with the
recognized medical problems associated with obesity in
There are mainly two types of gallstones: cholesterol and
pigment stones. Gallstones found in Caucasians are most
commonly the cholesterol type, which are associated with
obesity. In contrast, gallstones found in Oriental people are
mainly the pigment type, which are usually associated with
chronic hemolytic states and bacterial infections rather than
obesity (28, 29). Even though these two types of stones were
not distinguishable in the echogram, we speculate that the
higher prevalence of pigment stones in our study population
might explain the lack of association with obesity. A study of
2,228 Japanese men aged 4955 years receiving a retirement
health examination, including an ultrasound scan, also failed
to find an association between obesity and gallstone disease
Several recent studies have demonstrated a positive
association between obesity and asthma, although their
causeeffect relations remain to be determined (31, 32). For our
subjects, we failed to demonstrate the BMI effect on chronic
obstructive pulmonary disease or asthma. However, a
crosssectional survey from Mainland China revealed that both
extremes of the BMI distribution (underweight and obesity)
were significantly associated with symptomatic asthma in
men and women (33). A longitudinal survey with more
uniform criteria for the disease is needed before an
association between obesity and asthma for Asian people can be
The patterns of some medical problems were different
between men and women; for example, men had a higher
prevalence of hypertension, hypertriglyceridemia, type II
diabetes, and hyperuricemia. However, the gender
difference in the association of medical problems with BMI was
not as remarkable in our sample because it was found in
another study (34). Potential age differences were also
examined by stratifying into three groups (2039, 4059,
and 6079 years). The medical problems associated with
BMI were generally similar across the three age strata,
despite the statistical inconsistency and instability of some of
the medical problems in the age group 6079 years due to the
relatively smaller sample size (data not shown).
In addition to medical problems, reports show that obesity
is also an independent factor affecting QOL. The SF-36 is
the most widely used instrument for assessing QOL in the
context of obesity. Most researchers who used the SF-36 to
survey the general population found that obesity was mainly
associated with the physical rather than the mental aspects of
QOL. In Caucasian samples, increased body weight was
associated with lower physical functioning, role physical,
vitality, bodily pain, and general health scores (612). To our
knowledge, our study is the first to explore the association
between obesity and QOL in non-Caucasians. For our
subjects, a significant trend of BMI effects was also
observed on physical functioning and bodily pain for both
sexes and for role physical for women. Specifically, only the
physical functioning domain, including daily activities such
as climbing stairs, bending, walking, or some moderate
activities, was significantly associated with obesity and was
limited to subjects with class II obesity. Except for some
individual items in the physical functioning domain,
differences in gender or age were not as remarkable as they were
in other studies (7, 8, 11). A national survey of the general
population is needed to determine whether racial or cultural
differences play a role in the impact of obesity on QOL.
The response rate for the Taiwan Chinese SF-36 was 76
percent for our subjects. The sociodemographic variables were
compared between those who did and did not respond, but no
selection bias was detected. Illiteracy was the main reason for
nonresponse, indicating a need to provide assistance with
reading the questionnaire in an understandable dialect for
participants not familiar with the Chinese characters.
The limitations of this study deserve comment. First, the
analyses were based on cross-sectional data and were limited
to those who requested a health checkup. Selection bias may
have existed, although we adjusted for many potential
confounders. Some medical problems may develop slowly
and will not be detected unless a persistent prospective
survey or more accurate instrumentation is developed. We
cannot rule out the possibility of reverse causality between
the medical problem or QOL and obesity (i.e., decreased
QOL might lead to obesity) in this cross-sectional survey.
Second, we did not use linear regression analysis to
determine the relations between the QOL scores and obesity
indices because the scores were not distributed normally
(data not shown). Therefore, we used logistic regression
analysis and introduced cutoff points to define good and
poor QOL for the eight functional domains of the SF-36.
There are no definite cutoff points for these functional
domains to define good and poor. The choice of 66.7
percent as the cutoff point for our subjects was partly
arbitrary and partly based on the values used in related reports
(7, 34). Third, we did not use other anthropometric indices to
detect regional obesity. BMI is an overall index of obesity.
Therefore, we may have missed some medical problems or
functional domains that tend to be associated with central
obesity rather than general obesity.
In conclusion, on the basis of this cross-sectional study
using the convenience sample, we observed an increasing
and significant trend of BMI effects on some medical
problems and QOL for people in Taiwan. This result indicates
that overweight or obese Taiwanese people are at increased
risk of developing a medical problem such as hypertension,
hypercholesterolemia, hypertriglyceridemia, type II
diabetes, hyperuricemia, pulmonary function impairment, fatty
liver disease, or osteoarthritis. In addition, severely obese
Taiwanese are prone to have poorer physical functioning,
especially regarding daily physical activities.
This project was supported by grant
NSC91-2320-B182A-010 from the National Science Council of Taiwan.
The authors are grateful to the staff of the health screening
centers of Kaohsiung Chang Gung Memorial Hospital for
their assistance in recruiting subjects for this study: Dr.
JungFu Chen, Ya-Hui Lee, Mei-Pei Lin, Yu-Chen Chang,
LeeYun Wang, Hsiao-Chen Yang, Shu-I Chuang, and
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