Risk Factors Influencing the Occurrence and Severity of Symptomatic Dry Eye Syndrome: A Cross-sectional Study.

Propose: We aimed to investigate the prevalence and risk factors of dry eye syndrome (DES) among a population-based cohort study.Methods: This cross-sectional study was conducted on 475 subjects (184 men and 291 women) enrolled in the Study Group for Environmental Eye Disease at July 2013. Using the ocular surface disease index (OSDI), we measured the DES severity and defined DES as OSDI score ≥13. Current symptoms of DES and possible risk factors such as body mass index, occupations, comorbidities, exercise, smoking and drinking status were assessed by multivariate logistic regression.Results: Prevalence of DES was significantly higher in women (52.6%) than in men (41.9%) (p < .001). Compared to white-collar workers, blue-collar workers and unemployed persons showed significantly higher DES prevalence and severity. Compared to those with low BMI (<23.0 kg/m2), people with extremely high BMI (≥30.0 kg/m2) had significantly higher odds ratio (OR) of having DES after fully adjusted for sex, age, hypertension, diabetes, menopausal status, hormone replacement therapy, occupation, and lifestyle factors (OR: 2.83, 95% confidence interval: 1.04-7.71).Conclusions: We found some novel factors which have been unknown to the relationship with DES through the five years observation of the cohort. The positive associations of unemployment status, blue-collar work, alcohol habit, and obesity with DES suggests a person's comprehensive condition, not individual factors, contribute significantly in developing DES. Further studies will be helpful to understand the underlying mechanisms.

Cohort Profile: The Cardiovascular and Metabolic Diseases Etiology Research Center Cohort in Korea.

Mortalities from cardiovascular disease in Korea have decreased markedly over the past three decades. The major cardiovascular and metabolic risk factors, however, remain prevalent, and their burden on health is large. The Cardiovascular and Metabolic Diseases Etiology Research Center (CMERC) planned a cohort study in order to identify novel risk factors and to develop evidence-based prevention strategies of cardiovascular and metabolic diseases. The CMERC deliberately designed two prospective cohorts, a community-based general population cohort (the CMERC cohort) and its sister cohort (a hospital-based high-risk patient cohort), covering a broad spectrum of cardiovascular and metabolic diseases. This paper describes the CMERC cohort study of community-dwelling adults aged 30 to 64 years. A total of 8097 adults completed baseline measurement between 2013 and 2018. Baseline measurements assessed socio-demographic factors, medical history, health-related behaviors, psychological health, social network and support, anthropometry, body composition, and resting blood pressure and comprised electrocardiography, carotid artery ultrasonography, fasting blood analysis, and urinalysis. Both active follow-up through an annual telephone survey and a 5-year on-site health examination survey and passive follow-up through secondary data linkage with national databases, such as national death records, have been applied. Researchers interested in collaborative research may contact the corresponding author.

Association between Changes in Anthropometric Indices and in Fasting Insulin Levels among Healthy Korean Adolescents: The JS High School Study.

BACKGROUND: This study investigated the association between changes in anthropometric indices and fasting insulin levels among healthy adolescents and whether the association differed by baseline obesity status. METHODS: This analysis was based on data collected for the JS High School study; 884 healthy adolescents aged 15 to 16 years followed up for 24 to 30 months were included. Changes in anthropometric indices and fasting insulin levels were computed as the difference between baseline and follow-up values. Multivariate linear regression models were used to determine the association between changes in anthropometric indices and fasting insulin levels. Based on body mass index (BMI)-for-age and waist circumference (WC)-for-age percentiles, participants were classified as normal weight (<85th percentile), overweight (85th percentile to <95th percentile), or obese (≥95th percentile). RESULTS: Changes in BMI, WC, waist-hip ratio, and waist-height ratio were significantly associated with changes in fasting insulin levels in both sexes (P<0.05). In analyses stratified by baseline obesity status, the association between change in BMI and change in fasting insulin was significantly stronger in overweight (males: standardized ß=1.136; females: standardized ß=1.262) and obese (males: standardized ß=1.817; females: standardized ß=2.290) participants than in those with normal weight (males: standardized ß=0.957; females: standardized ß=0.976) at baseline. Results were similar for changes in WC. CONCLUSION: Changes in anthropometric indices were positively associated with fasting insulin level increases. Moreover, those who were overweight or obese at baseline had a higher absolute increase in fasting insulin levels per one standard deviation unit increase in anthropometric indices than adolescents with normal weight.

Association between high-density lipoprotein cholesterol level and pulmonary function in healthy Korean adolescents: the JS high school study.

BACKGROUND: Accumulating evidence suggests that high-density lipoprotein (HDL) cholesterol is associated with pulmonary function and pulmonary disorders. The aim of this study was to evaluate the association between HDL cholesterol and pulmonary function in healthy adolescents. METHODS: This cross-sectional study was based on data collected for the JS High School study. The analysis included 644 adolescents (318 male and 326 female) aged 15-16 years old and free from asthma or chronic obstructive pulmonary disease. Fasting blood samples were collected for hematologic and biochemical assessment. Forced vital capacity volume (FVC) and forced expiratory volume in the 1 s (FEV1) were measured using dry-rolling-seal spirometry. The associations between HDL cholesterol and pulmonary function were analyzed using multiple linear regression models. RESULTS: Among male adolescents, an increase of 1.0 mg/dL in HDL cholesterol was associated with 10 mL decrease in FVC (p = 0.013) and FEV1 (p = 0.013) after adjusting for age, height, weight, alcohol drinking, smoking, physical activity, systolic blood pressure, total cholesterol, triglyceride, and monthly household income. Percent predicted values of FVC (p = 0.036) and FEV1 (p = 0.017) were also inversely associated with HDL cholesterol. However, among female adolescents, HDL cholesterol level was not significantly associated with absolute or percent predictive value of FVC and FEV1. CONCLUSIONS: Higher HDL cholesterol level may be associated with decreased pulmonary function among healthy male adolescents. The sex differences observed in the association between HDL cholesterol and pulmonary function need further investigation.

Cardiovascular and Metabolic Diseases Etiology Research Center (CMERC) cohort: study protocol and results of the first 3 years of enrollment.

Although the etiologies of cardiovascular disease (CVD) are widely understood, the goal of finding a globally effective solution for preventing CVD is unrealistic. Therefore, we aimed to conduct a community-based prospective study on the prevention and management of CVD in Korean adults. This study was designed to recruit 8,000 healthy adults over the course of 5 years. The baseline assessment includes a wide range of established CVD risk factors, including demographic characteristics, medical history, health behaviors, psychological conditions, body size and composition, blood pressure, the augmentation index, carotid ultrasonography, an electrocardiogram, and biochemical indicators, as well as some novel factors, such as social network characteristics, exposure to environmental pollutants, inflammatory markers, hemostatic markers, and immunosenescence markers. Annual telephone interviews and follow-up health examinations at 5-year intervals after the baseline assessment are planned to collect information on changes in health status and its determinants. Additionally, indirect follow-up using secondary data sources will be conducted to obtain information on health services utilization and death. So far, more than 6,000 adults have been enrolled during the first three and a half years, and almost all participants have been tracked by annual telephone follow-up surveys. The data have been uploaded to iCReaT, the clinical research information management system of the Korea National Institute of Health.

Sleep duration and chronic kidney disease: The Korean Genome and Epidemiology Study (KoGES)-Kangwha study.

BACKGROUND/AIMS: Sleep duration affects health in various ways. The objective of this study was to investigate the associations of sleep duration with chronic kidney disease (CKD) in a Korean adult population. METHODS: This cross-sectional analysis was conducted for total of 1,360 participants who completed baseline health examinations for the Korean Genome and Epidemiology Study-Kangwha study in 2010 to 2011. Sleep habits were measured by an interviewer-assisted questionnaire. Sleep duration was calculated based on the number of hours per day participants had slept over the past 1 year. CKD was defined as either proteinuria or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2. Multiple logistic regression models were applied to examine associations between sleep duration and CKD. RESULTS: Women with very long sleep duration (≥ 9 hours/day) were at significantly increased odds for having high serum creatinine (odds ratio [OR], 2.936; 95% confidence interval [CI], 1.176 to 7.326), low eGFR (OR, 3.320; 95% CI, 1.372 to 8.034), and CKD (OR, 3.112; 95% CI, 1.315 to 7.363), compared those with a typical sleep duration (7 to < 8 hours/day), after adjusting for sociodemographic status, socioeconomic status, health behaviors, comorbidities, and sleep quality. Among women, for every 1 hour increase in sleep duration per day, there was a 24.6% increase in the presence of CKD (OR, 1.246; 95% CI, 1.019 to 1.523). However, among men, sleep duration was not significantly associated with CKD. CONCLUSIONS: Very long sleep duration was independently associated with a higher prevalence of CKD among Korean women. Gender may influence this association.

Cohort Profile: The JS High School study (JSHS): a cohort study of Korean adolescents.

Major aetiologies of atherosclerotic cardiovascular diseases begin in childhood and atherosclerotic vascular abnormalities can be observed among children and adolescents. Adolescent cohort studies have important advantages because they can observe earlier changes in vascular structure and function. The purpose of the JS High School study (JSHS) is to identify biomarkers predicting or indicating early structural and functional vascular change in adolescents. The JSHS is a prospective cohort study of a Korean adolescent population. The target population of the JSHS was first-graders (aged 14 to17 years) at a high school of South Korea. Enrolment and baseline examinations were conducted in years 2007, 2010, 2011 and 2012. Among the total eligible population of 1115 students, 1071 (96.1%) participated in the study and completed all baseline examinations. Informed consent forms were obtained from each participant and his/her parent or guardian. Baseline examinations include: questionnaires on demographics, health behaviours, medical history, and depression symptoms; fasting blood analysis; anthropometric measurement; body impedance analysis; blood pressure measurement; radial artery tonometry; bone densitometry; pulmonary function tests; and carotid ultrasonography. Participants enrolled from 2007 through 2012 were re-examined after 30 months of follow-up, and those who enrolled in 2012 were re-examined after 24 months of follow-up. The corresponding author may be contacted for potential collaboration and data access.

Secondhand Smoke Exposure and Depressive Symptoms among Korean Adolescents: JS High School Study.

INTRODUCTION: Increasing evidence suggests that secondhand smoke exposure (SHSE) may affect not only physical health, but also mental health. Therefore, we evaluated the association between SHSE and depressive symptoms among Korean adolescents. METHODS: The JS High School Study enrolled 1071 high school freshmen from a rural community of South Korea. The current analysis was limited to 989 adolescents (495 male and 494 female adolescents), after excluding 48 ever-smokers, 3 students with physician-diagnosed depression, and 31 students who did not complete the depression questionnaire. SHSE was assessed using a self-reported questionnaire and was classified into three groups: none, occasional exposure, and regular exposure. Depressive symptoms were assessed according to the Beck Depression Inventory (BDI) score, ranging from 0 to 63, and the presence of depressive symptoms was defined as a BDI score ≥10. RESULTS: Overall, adolescents with SHSE were more likely to have depressive symptoms than those without SHSE (p = 0.042).In a sex-specific analysis treating the BDI score as a continuous variable, regular SHSE was independently associated with higher BDI scores in male adolescents (ß = 2.25, p = 0.026), but not in female adolescents (ß = 1.11, p = 0.253). Compared to no SHSE, the odds ratio for having depressive symptoms among male adolescents with regular SHSE was 2.17 (95% confidence interval, 1.11 to 4.25) after adjusting for age, body mass index, and study year, and 3.65 (95% confidence interval, 1.52 to 8.73) after adjusting for age, body mass index, study year, exercise, and household income. CONCLUSION: Regular exposure to secondhand smoke was associated with having depressive symptoms among Korean male adolescents.

Comparison of Formulas for Calculating Low-density Lipoprotein Cholesterol in General Population and High-risk Patients with Cardiovascular Disease.

BACKGROUND AND OBJECTIVES: Low-density lipoprotein cholesterol (LDL-C), an established cardiovascular risk factor, can be generally determined by calculation from total cholesterol, high-density lipoprotein cholesterol, and triglyceride concentrations. The aim of this study was to compare LDL-C estimations using various formulas with directly measured LDL-C in a community-based group and hospital-based group among the Korean population. SUBJECTS AND METHODS: A total of 1498 participants were classified into four groups according to triglyceride concentrations as follows: <100, 100-199, 200-299, and ≥300 mg/dL. LDL-C was calculated using the Friedewald, Chen, Vujovic, Hattori, de Cordova, and Anandaraja formulas and directly measured using a homogenous enzymatic method. Pearson's correlation coefficients, intraclass correlation coefficients (ICC), Passing & Bablok regression, and Bland-Altman plots were used to evaluate the performance of six formulas. RESULTS: The Friedewald formula had the highest accuracy (ICC=0.977; 95% confidence interval 0.974-0.979) of all the triglyceride ranges, while the Vujovic formula had the highest accuracy (ICC=0.876; 98.75% confidence interval 0.668-0.951) in people with triglycerides ≥300 mg/dL. The mean difference was the lowest for the Friedewald formula (0.5 mg/dL) and the percentage error was the lowest for the Vujovic formula (30.2%). However, underestimation of the LDL-C formulas increased with triglyceride concentrations. CONCLUSION: The accuracy of the LDL-C formulas varied considerably with differences in triglyceride concentrations. The Friedewald formula outperformed other formulas for estimating LDL-C against a direct measurement and the Vujovic formula was suitable for hypertriglyceridemic samples; it could be used as an alternative cost-effective tool to measure LDL-C when the direct measurement cannot be afforded.

Inter-Arm Difference in Brachial Blood Pressure in the General Population of Koreans.

BACKGROUND AND OBJECTIVES: We investigated the inter-arm difference in blood pressure of the general Korean population to identify associated factors. SUBJECTS AND METHODS: A total of 806 participants aged 30 to 64 years without history of major cardiovascular disease were analyzed in this cross-sectional study. They participated in the Cardiovascular and Metabolic Disease Etiology Research Center cohort study that began in 2013. Brachial blood pressure was measured simultaneously for both arms using an automated oscillometric device equipped with two cuffs in seated position. After five minutes of rest, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured three times. The average of the three measurements was used for analysis. Multivariate logistic regression models were used to identify factors associated with inter-arm differences in blood pressure. RESULTS: The mean inter-arm difference was 3.3 mmHg for SBP and 2.0 mmHg for DBP. Large inter-arm differences (≥10 mmHg) in SBP and in DBP were found in 3.7% and 0.9% of subjects, respectively. A large inter-arm difference in SBP was associated with mean SBP (p=0.002) and C-reactive protein (p=0.014) while a large inter-arm different in DBP was only associated with body mass index (p=0.015). Sex, age, and anti-hypertensive medication use were not associated with differences in inter-arm blood pressure. CONCLUSION: Large inter-arm difference in blood pressure is only present in a small portion of healthy Korean adults. Our findings suggest that high SBP, chronic inflammation, and obesity may be associated with larger difference in inter-arm blood pressure.

Association between Obesity Indices and Insulin Resistance among Healthy Korean Adolescents: The JS High School Study.

OBJECTIVE: To investigate whether indices of obesity are associated with insulin resistance in Korean adolescents. METHODS: This study was conducted as a cross-sectional analysis of 817 healthy adolescents aged 15-16 years without diabetes. Percentiles group of weight-for-height, body mass index (BMI)-for-age, waist circumference (WC)-for-age, and skin fold thickness (SFT)-for-age were based on the 2007 Korean National Growth Charts. Percentiles of waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), and percent body fat were calculated for the study population. Insulin resistance was estimated by homeostatic model assessment (HOMA-IR). Logistic regression models were used to estimate odds ratio for insulin resistance according to seven obesity indices. Generalized linear models were used to assess the associations between obesity indices and continuous HOMA-IR levels. RESULTS: Sex and age-adjusted odds ratios (95% confidence interval) for insulin resistance, defined as HOMA-IR>2.50, of the 75-94th and ≥95th percentiles of weight-for-height were 3.87 (2.38-6.30) and 11.37 (5.87-22.02), compared to the <50th percentile. Corresponding odds ratios were 3.27 (2.02-5.28) and 11.72 (6.05-22.73) for BMI-for-age, 4.72 (2.82-7.88) and 13.22 (6.42-27.23) for WC-for-age, 3.67 (2.27-5.94) and 13.58 (6.71-27.48) for WHR, 4.78 (2.99-7.67) and 12.84 (6.23-26.46) for WHtR, 2.62 (1.61-4.26) and 6.68 (3.46-12.90) for SFT-for-age, and 2.29 (1.33-4.26) and 10.06 (4.39-23.06) for body fat. These associations were more prominent when insulin resistance was defined as HOMA-IR>3.16 and were stronger in males than in females. Continuous measure of HOMA-IR was significantly associated with body weight, BMI, WC, WHR, WHtR, and SFT in both sexes (p<0.001), and with percent body fat in males only (p<0.001). CONCLUSION: Our findings suggest that obesity indices are positively associated with insulin resistance in apparently healthy adolescents.

Effects of age, sex, and menopausal status on blood cholesterol profile in the korean population.

BACKGROUND AND OBJECTIVES: To investigate age-specific and sex-specific distributions of blood cholesterol in the general Korean population. SUBJECTS AND METHODS: We analyzed data for 8284 men and 9246 women aged ≥10 years who participated in the fifth (2010-2012) Korea National Health and Nutrition Examination Survey. Age-specific means, medians, and selected percentiles were calculated for men, premenopausal women, and postmenopausal women. RESULTS: Median total cholesterol (TC) level increased with age across all age groups, from 147 to 196 mg/dL in males and from 159 to 210 mg/dL in females. Triglyceride (TG) levels increased with age in females; however, in males, TG levels rapidly increased during young adulthood, peaked at 50-54 years, and then decreased. High density lipoprotein-cholesterol (HDL-C) levels were higher in females than in males and decreased with increasing age in both males and females. Low density lipoprotein-cholesterol (LDL-C) levels increased with age across all age groups, from 89 to 127 mg/dL in males and from 82 to 113 mg/dL in females. Lipoprotein-cholesterol fraction (TC/HDL-C, LDL-C/HDL-C, TG/HDL-C, non-HDL-C) levels increased with age in females, but increased more rapidly in males during young adulthood and decreased after middle age. CONCLUSION: Blood cholesterol levels and lipoprotein-cholesterol fractions present different distributions by age, sex, and menopausal status.

Serum 25-hydroxyvitamin D and insulin resistance in apparently healthy adolescents.

PURPOSE: Vitamin D deficiency is a common condition that is associated with diabetes and insulin resistance. However, the association between vitamin D and insulin resistance has not been fully studied, especially in the general adolescent population. Therefore, we assessed the association between serum 25-hydroxyvitamin D [25(OH)D] level and insulin resistance among apparently healthy Korean adolescents. METHODS: A total of 260 (135 male and 125 female) adolescents in a rural high school were assessed for serum 25(OH)D, fasting plasma glucose, and insulin. All of the participants were aged 15 to 16 years old, and without known hypertension or diabetes. Serum 25(OH)D was analyzed both as a continuous and categorical variable in association with insulin resistance. Insulin resistance was estimated by homeostasis model assessment (HOMA-IR). Increased insulin resistance was operationally defined as a HOMA-IR value higher than the sex-specific 75th percentile. RESULTS: In male adolescents, every 10 ng/ml decrease in 25(OH)D level was associated with a 0.25 unit increase in HOMA-IR (p = 0.003) after adjusting for age and BMI. Compared to those in the highest quartile, male adolescents in the lowest 25(OH)D quartile were at significantly higher risk for insulin resistance: unadjusted odds ratio 4.06 (95% CI, 1.26 to 13.07); age and BMI adjusted odds ratio 3.59 (95% CI, 1.03 to 12.57). However, 25(OH)D level, either in continuous or categorical measure, was not significantly associated with insulin resistance among female adolescents. CONCLUSIONS: This study suggests that serum 25(OH)D level may be inversely associated with insulin resistance in healthy male adolescents.

Association between serum 25-hydroxyvitamin D level and insulin resistance in a rural population.

PURPOSE: A low serum 25-hydroxyvitamin D [25(OH)D] level in the blood has been correlated with an increased risk of diabetes mellitus; however, the association between serum 25(OH)D level and insulin resistance has not been established in a Korean rural population. The aim of this study was to investigate the independent association between serum 25(OH)D level and insulin resistance in rural Korean adults. MATERIALS AND METHODS: This study used data from the Korean Genome Epidemiology Study-Kangwha Study. In the 2011 study, 1200 adults completed health examinations. In an ancillary study, serum 25(OH)D level was measured in a subsample (n=813). After excluding those taking vitamin D supplements, a cross-sectional analysis was carried out on 807 participants (324 men and 483 women) aged 40 to 89 years old. Measured from overnight fasting blood samples, glucose and insulin levels were used to calculate the homeostasis model assessment for insulin resistance (HOMA-IR). Measures of glucose, insulin, and HOMA-IR were log-transformed for parametric tests. RESULTS: Serum 25(OH)D level was inversely associated with HOMA-IR (ß=-0.003, p=0.039) in a univariate analysis. However, the association was not significant after adjustment for sex and age (ß=-0.002, p=0.123) or after adjustment for sex, age, body mass index, smoking status, alcohol intake, and regular exercise (ß=-0.003, p=0.247). CONCLUSION: Our findings suggest that vitamin D is not independently associated with insulin resistance in Korean men and women.

The Korean urban rural elderly cohort study: study design and protocol.

BACKGROUND: Korea is one of the fastest aging countries and is expected to become a super-aged society within 12 years. The Korean Urban Rural Elderly (KURE) study was developed to evaluate the epidemiological characteristics and establish the prevention and management of major disorders of the elderly in Korea. METHODS/DESIGN: The KURE study is a community-based prospective cohort study on health, aging, and common geriatric disorders of Korean elderly persons aged at least 65 years. To construct a cohort reflecting both urban and rural areas, we selected 2 representative communities in the country. To establish multidisciplinary approaches to geriatric health, this study was performed by researchers in the divisions of geriatrics, preventive medicine, endocrinology, and sociology. The baseline examinations began in 2012; the study will follow more than 4,000 elderly Koreans over 10 years. The first and second follow-up health examinations will be performed every 4 years. Every 2 years after each health examination, inter-assessment interview will be conducted to improve participant retention. DISCUSSION: The KURE study will provide longitudinal epidemiologic data on health, aging, and common geriatric disorders of the elderly in Korea. This is a comprehensive, multidisciplinary study of the elderly with respect to biological, physical, socio-economic, and environmental factors. The results of this study will contribute to improve public health and welfare policies for the aging society in Korea.

Association between depressive symptoms and bone stiffness index in young adults: the Kangwha study.

OBJECTIVE: Young adulthood is an important period for both bone and mental health. This study investigated the association between depressive symptoms and bone density in apparently healthy Korean men and women aged 29-32 years. METHODS: This study is a cross-sectional analysis of data from 123 men and 133 women who completed follow-up examinations of the Kangwha study in 2010-2011. Bone stiffness index (SI) was measured at the os calcis using a quantitative ultrasound device. Depressive symptoms were evaluated using the Korean version of the Beck Depression Inventory (K-BDI) and classified as normal (K-BDI <10), mild (K-BDI 10-15), and moderate to severe (K-BDI ≥16). RESULTS: Moderate to severe depressive symptoms were prevalent among 11.4% of men and 19.6% of women. Higher K-BDI scores were significantly correlated to SI in men, before (ρ = -0.286, p = 0.001) and after (ρ = -0.228, p = 0.013) adjustment for covariates. Men with depressive symptoms tended to have a lower SI; multivariate-adjusted mean SI in men with normal, mild, and moderate to severe depressive symptoms was 104.1±3.1, 100.9±5.9, and 94.1±7.8, respectively (p for trend = 0.021). In contrast, no significant correlations were identified in women. CONCLUSIONS: Depressive symptoms were significantly associated with lower SI in men, but not in women. Further studies are necessary to evaluate the impact of depression on developing osteoporosis or osteoporotic fractures later in life.

Factors Associated with a Low-sodium Diet: The Fourth Korean National Health and Nutrition Examination Survey.

OBJECTIVES: The low-sodium diet is a known preventive factor for hypertension and cardiovascular disease. Factors associated with low-sodium diets should be identified to reduce sodium intake effectively. This study was conducted to identify factors correlated with a low-sodium diet. METHODS: This cross-sectional study analyzed data from a total of 14,539 Koreans aged 20 years or older, who participated in the Fourth (2007-2009) Korean National Health and Nutrition Examination Survey. A low-sodium diet was defined as having ≤2,000 mg/day based on 24-hour recalls. Multiple logistic regression models were used to assess sex, age, education, number of family members, household income, occupation, alcohol drinking, total energy intake, frequency of eating out, and hypertension management status for their associations with low-sodium diets. RESULTS: Among all participants, only 13.9% (n=2,016) had low-sodium diets. In the multivariate analysis, 40-49 years of age, clerical work jobs, higher total energy intake, and frequent eating out were inversely associated with low-sodium diets. And female sex and living-alone were associated with low-sodium diets. Lower frequency of eating out was significantly associated with low-sodium diets, even after adjusting for total energy intake and other potential confounders. Adjusted odds ratios (95% confidence interval) for a low-sodium diet were 1.97 (1.49-2.61), 1.47 (1.13-1.91), 1.24 (0.96-1.61), and 1.00 (reference) in people who eat out <1 time/month, 1-3 times/month, 1-6 times/week, and ≥1 time/day, respectively. CONCLUSIONS: Our study suggests that sex, age, number of family members, occupation, total energy intake, and lower frequency of eating out were associated with a low-sodium diet in Korean adults.

Association between serum uric acid level and metabolic syndrome.

OBJECTIVES: Serum uric acid levels have been reported to be associated with a variety of cardiovascular conditions. However, the direct association between uric acid levels and metabolic syndrome remains controversial. Thus, we evaluated the association of serum uric acid levels and metabolic syndrome in a community-based cohort study in Korea. METHODS: We performed cross-sectional analysis of baseline data of 889 males and 1491 females (aged 38 to 87) who participated in baseline examinations of the Korean Genome and Epidemiology Study: Kanghwa study. Blood samples were collected after at least an 8 hour fast. Uric acid quartiles were defined as follows: <4.8, 4.8-<5.6, 5.6-<6.5, ≥6.5 mg/dL in males; and <3.8, 3.8-<4.3, 4.3-<5.1, ≥5.1 mg/dL in females. Metabolic syndrome was defined by the National Cholesterol Education Program Adult Treatment Panel III Criteria with adjusted waist circumference cutoffs (90 cm for males; 80 cm for females). The association between serum uric acid quartiles and metabolic syndrome was assessed using multivariate logistic regression. RESULTS: The odds ratio for having metabolic syndrome in the highest versus lowest quartiles of serum uric acid levels was 2.67 (95% confidence interval [CI], 1.60 to 4.46) in males and 2.14 (95% CI, 1.50 to 3.05) in females after adjusting for age, smoking, alcohol intake, body mass index, total cholesterol, HbA1c, albumin, γ-glutamyltransferase, blood urea nitrogen, and log C-reactive protein. The number of metabolic abnormalities also increased gradually with increasing serum uric acid levels (adjusted p for trend < 0.001 in both sexes). CONCLUSIONS: Higher serum uric acid levels are positively associated with the presence of metabolic syndrome in Korean males and females.

The association between serum albumin levels and metabolic syndrome in a rural population of Korea.

OBJECTIVES: A positive association between serum albumin levels and metabolic syndrome has been reported in observation studies, but it has not been established in the Korean population. The purpose of this study was to evaluate the association between serum albumin levels and the presence of metabolic syndrome among a sample of apparently healthy Korean adults. METHODS: This cross-sectional study analyzed data of 3189 community-dwelling people (1189 men and 2000 women) who were aged 40 to 87 years and were living in a rural area in Korea. Serum albumin levels were classified into quartile groups for each sex. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III guidelines with an adjusted waist circumference cut-off value (≥90 cm for men and ≥85 cm for women). An independent association between serum albumin levels and metabolic syndrome was assessed by multiple logistic regression analysis. RESULTS: Higher serum albumin levels were associated with increased prevalence of metabolic syndrome. The odds ratio (95% confidence interval) of the prevalence of metabolic syndrome for the highest versus the lowest serum albumin quartiles was 2.81 (1.91 to 4.14) in men and 1.96 (1.52 to 2.52) in women, after adjusting for age, smoking status, alcohol consumption, and physical activity. When each metabolic abnormality was analyzed separately, higher serum albumin levels were significantly associated with hypertriglyceridemia and hyperglycemia in both sexes, and with abdominal obesity in men. CONCLUSIONS: These results suggest that higher serum albumin levels are positively associated with an increased risk of metabolic syndrome in Korean adults.