Dong Phil Choi

Prevalence of Dyslipidemia among Korean Adults: Korea National Health and Nutrition Survey 1998-2005.

Background Dyslipidemia is a disorder of lipid metabolism, including elevated total cholesterol, elevated triglyceride, elevated low density lipoprotein cholesterol (LDL-C), and decreased high density lipoprotein cholesterol (HDL-C). The objective of this study was to investigate recent changes in the prevalence of dyslipidemia and also the rates of awareness, treatment, and control of dyslipidemia among Korean adults. Methods Dyslipidemia is defined according to the National Cholesterol Education Program-Adult Treatment Panel III as total cholesterol ≥240 mg/dL, LDL-C ≥160 mg/dL, HDL-C <40 mg/dL, and triglyceride ≥200 mg/dL. The prevalence of dyslipidemia was estimated for adults aged ≥20 years using the Korea National Health and Nutrition Survey (KNHANES) in 1998 (n=6,923), 2001 (n=4,882), and 2005 (n=5,323). Rates of awareness, treatment and control of dyslipidemia were calculated for adults aged ≥30 years using the KNHANES in 2005 (n=4,654). Results The prevalence of dyslipidemia (aged ≥20 years) increased from 32.4% in 1998 to 42.6% in 2001 and 44.1% in 2005. Compared with the KNHANES in 1998, the prevalence of dyslipidemia was 47% (95% confidence interval [CI], 35% to 59%) higher in 2001 and 61% (95% CI, 49% to 75%) higher in 2005. In 2005, only 9.5% of people with dyslipidemia were aware of the disease, 5.2% used lipid-lowering medication, and 33.2% of patients with treatment reached treatment goals. Conclusion The prevalence of dyslipidemia in Korea gradually increased between 1998 and 2005. These findings suggest that more intense efforts for the prevention and treatment of dyslipidemia may lead to further improvement in the management of dyslipidemia.

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.

Six-year survival and causes of death among stroke patients in Korea.

Background: Stroke is the second leading cause of death in Korea but long-term survival of Korean stroke patients has not been studied. Thus, we examined 6-year survival and causes of death in a nationally representative inpatient sample. Methods: Between January 2000 and March 2000 in 152 sample hospitals, 4,299 first-ever stroke patients were identified and followed-up for vital status until December 2005. Mortality and mortality-related factors were evaluated by the Kaplan-Meier method and Cox proportional hazard regression analysis. Results: Ischemic stroke was the most common subtype (62.9%), followed by intracerebral hemorrhage (ICH, 21.2%), and subarachnoid hemorrhage (SAH, 6.4%). Six-year mortality was estimated at 37.1% for all strokes, 37.2% for ischemic, 41.0% for ICH, and 29.2% for SAH. Common causes of death were stroke (58.2%), malignancies (10.3%), other cardiovascular diseases (7.7%), and diabetes (6.8%). Six-year mortality was associated with old age (hazard ratio 1.70 per 10 years, 95% CI 1.62–1.78), male sex (1.29, 1.16–1.43), subtypes of ICH (1.30, 1.15–1.48) and SAH (1.43, 1.14–1.80), longer hospital admission (1.01 per 10 days, 1.00–1.03), and loss of consciousness (1.32, 1.13–1.55). Conclusions: More than 60% of Korean patients with first-ever stroke survived to 6 years. Major causes of death were stroke, cancer, cardiovascular diseases, and diabetes.

Gender differences in the association between smoking and dyslipidemia: 2005 Korean National Health and Nutrition Examination Survey.

BACKGROUND Smoking has been reported to be associated with abnormal lipid metabolism. However, it remains uncertain whether adverse metabolic effects of smoking on dyslipidemia differ with gender. The objective of this study was to investigate the association between smoking and dyslipidemia in men and women. METHODS We analyzed data from 2166 men and 3003 women aged ≥20 years assessed in the Third Korea National Health and Nutrition Examination Survey (2005). Dyslipidemia was defined according to the National Cholesterol Education Program-Adult Treatment Panel III. RESULTS The prevalence of dyslipidemia was higher in men than in women. The odds ratios (95% confidence interval) of dyslipidemia associated with current smoking were 1.35 (0.98-1.85) in men and 1.92 (1.19-3.10) in women (p for interaction with gender <0.001). After stratification by components of dyslipidemia, women smokers showed higher odds ratios of having high triglyceride and low high-density lipoprotein cholesterol than men smokers. The association between current heavy-smoking (≥20 pack-years) and dyslipidemia was stronger in women than in men. CONCLUSIONS The association between smoking and dyslipidemia was significantly different between men and women. Women smokers might be more susceptible to develop dyslipidemia than men smokers.

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.

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.

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.

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.

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 (β=-0.003, p=0.039) in a univariate analysis. However, the association was not significant after adjustment for sex and age (β=-0.002, p=0.123) or after adjustment for sex, age, body mass index, smoking status, alcohol intake, and regular exercise (β=-0.003, p=0.247). Conclusion Our findings suggest that vitamin D is not independently associated with insulin resistance in Korean men and women.

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.