Korean J Fam Med. 2013;34:385-392
http://dx.doi.org/10.4082/kjfm.2013.34.6.385
Sociodemographic Characteristics of Underweight Korean Adults: Korea National Health and Nutrition Examination Survey, 2007-2010
Original Article
Sung Il Park, Young Gyu Cho*, Jae Heon Kang, Hyun Ah Park, Kyoung Woo Kim, Yang Im Hur, Hye Jin Kang Department of Family Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea Background: Underweight is associated with increased risk of mortality and morbidity. It is reported that the prevalence of underweight is increasing among Korean young women. However, there have been few studies on sociodemographic factors related to being underweight. This study was conducted to elucidate the sociodemographic characteristics of Korean underweight adults. Methods: This study is a cross-sectional study of 7,776 adults aged 25 to 69 years using data from the Korea National Health and Nutrition Examination Survey, 2007–2010. Study subjects were composed of underweight and normal-weight adults excluding overweight adults. Body mass index was calculated from measured height and weight. Health behaviors such as smoking, drinking, and physical activity were surveyed through self-administered questionnaires, and socioeconomic status, marital status, and history of morbidity were surveyed through face-to-face interviews. Results: Women had a higher frequency of underweight (10.4% vs. 7.0%, P < 0.001) than men. Among men, current smoking (odds ratio [OR], 1.62) and past history of cancer (OR, 2.55) were independently related to underweight. Among women, young age (OR, 2.06), former smoking (OR, 1.69), and being unmarried (OR, 1.56) were identified as independently related factors of underweight. In addition, among both men and women, alcohol drinking (men OR, 0.57; women OR, 0.77) and past history of chronic diseases (men OR, 0.55; women OR, 0.43) were independently related to a lower frequency of underweight. Conclusion: We showed that various sociodemographic factors were associated with underweight. It was ascertained that there were differences in the sociodemographic factors related to underweight between Korean men and women.
Keywords: Underweight; Sex; Social Characteristics; Demographic Factors
Received: June 27, 2013, Accepted: September 23, 2013
INTRODUCTION
*Corresponding Author: Young Gyu Cho Tel: +82-2-2270-0097, Fax: +82-2-2270-0560 E-mail: [email protected] Korean Journal of Family Medicine
Copyright © 2013 The Korean Academy of Family Medicine This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Korean J Fam Med
Healthy weight refers to a range of weight that is optimal for health, which is defined as a body mass index (BMI) of 18.5 to 24.9 kg/m2.1) Individuals whose weights are below or above this range are considered to have unhealthy weights because of increased health risks. Although both obesity and underweight are related to an increased risk of mortality2) and morbidity,3-5) health risks of underweight are less known than those of obesity.
Vol. 34, No. 6 Nov 2013
| 385
Sung Il Park, et al: Sociodemographic Characteristics of Underweight Korean Adults
Among Korean women aged 20 years and over, the age-
were excluded, leaving 18,518 individuals. Because the aim of
adjusted prevalence of underweight insignificantly increased
this study was to reveal the sociodemographic characteristics of
between 1998 and 2007 (5.5% → 6.7%, P for trend = 0.199),
underweight adults compared with normal-weight adults, we did
while the age-adjusted prevalence of underweight among Korean
additional exclusion of overweight adults who had a BMI ≥ 23.0
men decreased from 4.8% in 1998 to 2.8% in 2007 (P for trend =
kg/m2. Finally, data of 7,776 individuals (2,772 men and 5,004
0.020). Especially among women aged 20 to 39, the prevalence
women) who were assessed to be underweight (BMI ≤ 18.4 kg/
of underweight had a significant increasing tendency from 8.2%
m2) or normal weight (BMI, 18.5 to 22.9 kg/m2) were available
in 1998 to 13.2% in 2007 (P for trend = 0.003) unlike that among
for the final analysis.
6)
6)
men. Khang and Yun emphasized that more national studies regarding the increasing tendency of underweight prevalence among young Korean women are warranted. 7)
2. Measurements Anthropometric measurements were carried out wearing
In a previous study of a Canadian population using the
light clothing and no shoes by a trained professional research
National Population Health Survey, underweight people were
team at a mobile examination center. Height and weight were
more likely to be females, youth under 25 years of age, singles,
measured to one decimal place using a calibrated stadiometer
current smokers and individuals with poor self-perceived health.
(SECA 225; SECA Deutschland, Hamburg, Germany) and scale
8)
In another study of female students in Poland, underweight was
(GL-6000-20; CASKOREA, Seoul, Korea), respectively. BMI
shown to be related to higher socioeconomic status (SES). Shin
was calculated using the formula: weight (kg) ÷ (height [m])2.
et al.9) showed that underweight prevalence varied significantly
Health behaviors such as smoking, drinking, and physical
depending on maternal education level and residential district.
activity were investigated through self-administered questionnaires.
However, there have been only few epidemiologic studies on the
Smoking status was classified into three groups (non-smokers,
sociodemographic characteristics of Korean underweight adults.
ex-smokers, and current smokers), and drinking status was
Furthermore, previous studies have limitations such as including
classified into two groups (< 1 times/mo and ≥ 1 times/mo).
only adolescent girls or college female students as study subjects.
Physical activity was assessed by the Korean version of the
This study was conducted to elucidate the sociodemographic
International Physical Activity Questionnaire (IPAQ) short form.
characteristics of underweight Korean adults using data from
Physical activity level was calculated as a continuous score and
Korea National Health and Nutrition Examination Survey
was categorized into three groups (low, moderate, and high) in
(KNHANES), 2007–2010.
accordance with the guidelines for data processing and analysis of the IPAQ.11)
METHODS
SES, marital status, and history of morbidity were investigated through face-to-face interviews. Education level, occupation, and household income were investigated as indicators of SES.
1. Study Population
Education level was classified into three groups (≥ college
We used data from KNHANES, 2007–2010 for this study.
graduation, high school graduation, and ≤ middle school
The design of KNHANES was introduced in a previous study10)
graduation). Occupation was also classified into three groups
in detail; it was a nationwide representative survey with a complex,
(non-manual workers, manual workers, and other [soldiers,
stratified, multistage, cluster-sampling design used to assess the
students, homemakers, and unemployed]) by the Korean
health and nutritional status of the non-institutionalized civilian
Standard Classification of Occupation revised in 2007. For
population in Korea. A total of 20,063 individuals who were
classification of household income level, household equivalent
25 to 69-years-of-age participated in KNHANES, 2007–2010.
income was calculated using the formula: total family income
Among them, pregnant women (n = 150), individuals who
÷ √the number of family members. After that, household
did not conduct a measure of height or weight (n = 1,236),
equivalent income was categorized into tertiles (high, middle, and
and those who failed to complete the questionnaires (n = 159)
low) for each survey year. Marital status was classified into three
386 |
Vol. 34, No. 6 Nov 2013
Korean J Fam Med
Sung Il Park, et al: Sociodemographic Characteristics of Underweight Korean Adults
groups (married, unmarried, and other [divorced, separated, and
Table 1. General characteristics of study subjects
widowed]). Subjects were asked about their history of diagnosed
Men (unweighted n=2,772)
Women (unweighted n=5,004)
25–39
42.1 (1.2)
50.9 (1.0)
40–54
36.9 (1.1)
35.7 (0.9)
55–69
21.0 (0.9)
13.4 (0.6)
Characteristic
chronic diseases such as hypertension, diabetes, dyslipidemia, stroke, ischemic heart disease, arthritis, asthma, renal failure, or liver cirrhosis and were considered as having a history of chronic disease if they had a history of a physician diagnosing any kind of chronic disease. Subjects were asked about their history of cancer of the stomach, liver, colon, breast, cervix, lung, and other organs, and were considered as having a history of cancer if they had a history of a physician diagnosing any kind of cancer.
Age group (y)
Weight status Underweight
7.0 (0.6)
10.4 (0.5)
93.0 (0.6)
89.6 (0.5)
Low
34.4 (1.0)
42.0 (0.9)
Moderate
35.2 (1.0)
37.6 (0.8)
High
30.4 (1.0)
20.5 (0.7) 6.9 (0.5)
Normal weight Physical activity categories
3. Statistical Analysis We performed all analyses by taking into account the KNHANES sampling data according to the instructions of
Smoking status
raw data analysis of KNHANES. Data were expressed as mean
Current smoker
52.8 (1.0)
± standard error or percentage ± standard error. The simple
Ex-smoker
26.3 (0.9)
4.2 (0.4)
Non-smoker
20.9 (0.8)
88.8 (0.5)
≥1
76.2 (1.0)
45.4 (0.8)
http://dx.doi.org/10.4082/kjfm.2013.34.6.385
Sociodemographic Characteristics of Underweight Korean Adults: Korea National Health and Nutrition Examination Survey, 2007-2010
Original Article
Sung Il Park, Young Gyu Cho*, Jae Heon Kang, Hyun Ah Park, Kyoung Woo Kim, Yang Im Hur, Hye Jin Kang Department of Family Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea Background: Underweight is associated with increased risk of mortality and morbidity. It is reported that the prevalence of underweight is increasing among Korean young women. However, there have been few studies on sociodemographic factors related to being underweight. This study was conducted to elucidate the sociodemographic characteristics of Korean underweight adults. Methods: This study is a cross-sectional study of 7,776 adults aged 25 to 69 years using data from the Korea National Health and Nutrition Examination Survey, 2007–2010. Study subjects were composed of underweight and normal-weight adults excluding overweight adults. Body mass index was calculated from measured height and weight. Health behaviors such as smoking, drinking, and physical activity were surveyed through self-administered questionnaires, and socioeconomic status, marital status, and history of morbidity were surveyed through face-to-face interviews. Results: Women had a higher frequency of underweight (10.4% vs. 7.0%, P < 0.001) than men. Among men, current smoking (odds ratio [OR], 1.62) and past history of cancer (OR, 2.55) were independently related to underweight. Among women, young age (OR, 2.06), former smoking (OR, 1.69), and being unmarried (OR, 1.56) were identified as independently related factors of underweight. In addition, among both men and women, alcohol drinking (men OR, 0.57; women OR, 0.77) and past history of chronic diseases (men OR, 0.55; women OR, 0.43) were independently related to a lower frequency of underweight. Conclusion: We showed that various sociodemographic factors were associated with underweight. It was ascertained that there were differences in the sociodemographic factors related to underweight between Korean men and women.
Keywords: Underweight; Sex; Social Characteristics; Demographic Factors
Received: June 27, 2013, Accepted: September 23, 2013
INTRODUCTION
*Corresponding Author: Young Gyu Cho Tel: +82-2-2270-0097, Fax: +82-2-2270-0560 E-mail: [email protected] Korean Journal of Family Medicine
Copyright © 2013 The Korean Academy of Family Medicine This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Korean J Fam Med
Healthy weight refers to a range of weight that is optimal for health, which is defined as a body mass index (BMI) of 18.5 to 24.9 kg/m2.1) Individuals whose weights are below or above this range are considered to have unhealthy weights because of increased health risks. Although both obesity and underweight are related to an increased risk of mortality2) and morbidity,3-5) health risks of underweight are less known than those of obesity.
Vol. 34, No. 6 Nov 2013
| 385
Sung Il Park, et al: Sociodemographic Characteristics of Underweight Korean Adults
Among Korean women aged 20 years and over, the age-
were excluded, leaving 18,518 individuals. Because the aim of
adjusted prevalence of underweight insignificantly increased
this study was to reveal the sociodemographic characteristics of
between 1998 and 2007 (5.5% → 6.7%, P for trend = 0.199),
underweight adults compared with normal-weight adults, we did
while the age-adjusted prevalence of underweight among Korean
additional exclusion of overweight adults who had a BMI ≥ 23.0
men decreased from 4.8% in 1998 to 2.8% in 2007 (P for trend =
kg/m2. Finally, data of 7,776 individuals (2,772 men and 5,004
0.020). Especially among women aged 20 to 39, the prevalence
women) who were assessed to be underweight (BMI ≤ 18.4 kg/
of underweight had a significant increasing tendency from 8.2%
m2) or normal weight (BMI, 18.5 to 22.9 kg/m2) were available
in 1998 to 13.2% in 2007 (P for trend = 0.003) unlike that among
for the final analysis.
6)
6)
men. Khang and Yun emphasized that more national studies regarding the increasing tendency of underweight prevalence among young Korean women are warranted. 7)
2. Measurements Anthropometric measurements were carried out wearing
In a previous study of a Canadian population using the
light clothing and no shoes by a trained professional research
National Population Health Survey, underweight people were
team at a mobile examination center. Height and weight were
more likely to be females, youth under 25 years of age, singles,
measured to one decimal place using a calibrated stadiometer
current smokers and individuals with poor self-perceived health.
(SECA 225; SECA Deutschland, Hamburg, Germany) and scale
8)
In another study of female students in Poland, underweight was
(GL-6000-20; CASKOREA, Seoul, Korea), respectively. BMI
shown to be related to higher socioeconomic status (SES). Shin
was calculated using the formula: weight (kg) ÷ (height [m])2.
et al.9) showed that underweight prevalence varied significantly
Health behaviors such as smoking, drinking, and physical
depending on maternal education level and residential district.
activity were investigated through self-administered questionnaires.
However, there have been only few epidemiologic studies on the
Smoking status was classified into three groups (non-smokers,
sociodemographic characteristics of Korean underweight adults.
ex-smokers, and current smokers), and drinking status was
Furthermore, previous studies have limitations such as including
classified into two groups (< 1 times/mo and ≥ 1 times/mo).
only adolescent girls or college female students as study subjects.
Physical activity was assessed by the Korean version of the
This study was conducted to elucidate the sociodemographic
International Physical Activity Questionnaire (IPAQ) short form.
characteristics of underweight Korean adults using data from
Physical activity level was calculated as a continuous score and
Korea National Health and Nutrition Examination Survey
was categorized into three groups (low, moderate, and high) in
(KNHANES), 2007–2010.
accordance with the guidelines for data processing and analysis of the IPAQ.11)
METHODS
SES, marital status, and history of morbidity were investigated through face-to-face interviews. Education level, occupation, and household income were investigated as indicators of SES.
1. Study Population
Education level was classified into three groups (≥ college
We used data from KNHANES, 2007–2010 for this study.
graduation, high school graduation, and ≤ middle school
The design of KNHANES was introduced in a previous study10)
graduation). Occupation was also classified into three groups
in detail; it was a nationwide representative survey with a complex,
(non-manual workers, manual workers, and other [soldiers,
stratified, multistage, cluster-sampling design used to assess the
students, homemakers, and unemployed]) by the Korean
health and nutritional status of the non-institutionalized civilian
Standard Classification of Occupation revised in 2007. For
population in Korea. A total of 20,063 individuals who were
classification of household income level, household equivalent
25 to 69-years-of-age participated in KNHANES, 2007–2010.
income was calculated using the formula: total family income
Among them, pregnant women (n = 150), individuals who
÷ √the number of family members. After that, household
did not conduct a measure of height or weight (n = 1,236),
equivalent income was categorized into tertiles (high, middle, and
and those who failed to complete the questionnaires (n = 159)
low) for each survey year. Marital status was classified into three
386 |
Vol. 34, No. 6 Nov 2013
Korean J Fam Med
Sung Il Park, et al: Sociodemographic Characteristics of Underweight Korean Adults
groups (married, unmarried, and other [divorced, separated, and
Table 1. General characteristics of study subjects
widowed]). Subjects were asked about their history of diagnosed
Men (unweighted n=2,772)
Women (unweighted n=5,004)
25–39
42.1 (1.2)
50.9 (1.0)
40–54
36.9 (1.1)
35.7 (0.9)
55–69
21.0 (0.9)
13.4 (0.6)
Characteristic
chronic diseases such as hypertension, diabetes, dyslipidemia, stroke, ischemic heart disease, arthritis, asthma, renal failure, or liver cirrhosis and were considered as having a history of chronic disease if they had a history of a physician diagnosing any kind of chronic disease. Subjects were asked about their history of cancer of the stomach, liver, colon, breast, cervix, lung, and other organs, and were considered as having a history of cancer if they had a history of a physician diagnosing any kind of cancer.
Age group (y)
Weight status Underweight
7.0 (0.6)
10.4 (0.5)
93.0 (0.6)
89.6 (0.5)
Low
34.4 (1.0)
42.0 (0.9)
Moderate
35.2 (1.0)
37.6 (0.8)
High
30.4 (1.0)
20.5 (0.7) 6.9 (0.5)
Normal weight Physical activity categories
3. Statistical Analysis We performed all analyses by taking into account the KNHANES sampling data according to the instructions of
Smoking status
raw data analysis of KNHANES. Data were expressed as mean
Current smoker
52.8 (1.0)
± standard error or percentage ± standard error. The simple
Ex-smoker
26.3 (0.9)
4.2 (0.4)
Non-smoker
20.9 (0.8)
88.8 (0.5)
≥1
76.2 (1.0)
45.4 (0.8)
