Joohon Sung

Serum cholesterol, haemorrhagic stroke, ischaemic stroke, and myocardial infarction: Korean national health system prospective cohort study.

Abstract Objective To investigate risk factors, such as heavy alcohol consumption, that might explain any increased risk of haemorrhagic stroke associated with low blood cholesterol. Design Prospective cohort study. Setting Korea. Participants 787 442 civil servants (661 700 men, 125 742 women) aged 30-64. Main outcome measures Cardiovascular risk factors were assessed at biennial health check. Data on morbidity and mortality were ascertained from 1990 to 2001 using hospital admissions and mortality surveillance systems. Results 6328 cases of ischaemic stroke (6021 men, 307 women), 3947 cases of haemorrhagic stroke (3748 men, 199 women), 3170 cases of undefined stroke (2902 men, 268 women), and 4417 cases of myocardial infarction (4305 men, 112 women) occurred. Ischaemic stroke and myocardial infarction were strongly and positively associated with blood cholesterol (hazard ratio per 1 mmol/l cholesterol 1.20 (95% confidence 1.16 to 1.24) and 1.48 (1.43 to 1.53), respectively). Haemorrhagic stroke showed an inverse association in fully adjusted models (0.91, 0.87 to 0.95). This inverse association was confined to participants with hypertension. When stratified by concentration of γ glutamyl transferase (GGT), an indicator of alcohol consumption, the association was not seen in participants with low concentrations of GGT, and it was independent of hypertension in those with high concentrations of GGT (> 80 U/l). Conclusion High alcohol consumption may underlie the association between low blood cholesterol and increased risk of haemorrhagic stroke.

Which Obesity Indicators Are Better Predictors of Metabolic Risk? : Healthy Twin Study

No consensus exists as to the most sensitive and specific obesity indicator associated with metabolic risk factors. We aimed to validate anthropometry as the predictor for obesity‐related metabolic risk factors through comparison with direct body composition measures in Korean adults. A total of 995 Korean women and 577 Korean men who participated in the Healthy Twin study were the subjects. Anthropometric measurements included BMI, waist circumference (WC), waist‐to‐hip ratio (WHR), and waist‐to‐height ratio (WHTR). Direct body composition measures included the percentage of body fat (%BF) measured using dual‐energy X‐ray absorptiometry scanners and bioelectrical impedance analyzer (BIA). The following criteria were used to define abnormal metabolic risk factors: blood pressure ≥ 130/85 mm Hg, fasting glucose (≥ 100 mg/dl), insulin (≥ 25 μU/ml), homeostasis model assessment (HOMA) (≥ 2.61), high‐density lipoprotein (HDL) (<40 mg/dl for men or <50 mg/dl for women), triacylglycerol (≥ 150 mg/dl), uric acid (>7 mg/dl for men or >6 mg/dl for women), high‐sensitivity C‐reactive protein (hs‐CRP) (≥ 2.11 mg/l). In multiple regression analyses (adjusted for age, education, smoking, alcohol, exercise and past/current medical history, and treated families as a random effect), WC, WHTR, and BMI were consistently associated with all metabolic risk factors regardless of the subjects gender. Some of the areas under the receiver‐operating characteristic curves regarding abnormal metabolic risk factors were significantly higher for the three indicators of central obesity than for %BF. Our study validates the usefulness of anthropometry over direct body fat measures to predict metabolic risks.

Factors associated with immunoprophylaxis failure against vertical transmission of hepatitis B virus

In spite of adequate immunoprophylaxis, perinatal transmission of hepatitis B virus (HBV) has not been completely eliminated. This study evaluated the factors associated with the failure of HBV immunoprophylaxis. The study participants were 144 children who were born to HBsAg-seropositive mothers of known HBeAg status and they had received HB immune globulin and HB vaccine within 24xa0hours after birth followed by two further administrations of HB vaccine as recommended. Seventeen of the children (11.8%) suffered immunoprophylaxis failure, defined by HBsAg-seropositivity. The rate of HBV immunoprophylaxis failure was 12%, 0%, 21%, 0%, and 27% among the children born to HBsAg-seropositive, HBeAg-seronegative, HBeAg-seropositive, undetectable HBV DNA, and detectable HBV DNA mothers, respectively. The failure of HBV immunoprophylaxis was significantly associated with maternal HBeAg-seropositivity and HBV DNA seropositivity. To identify those children at high risk of HBV immunoprophylaxis failure, maternal HBeAg and HBV DNA need to be assessed prior to childbirth.

Healthy Twin: A Twin-family Study of Korea - Protocols and Current Status

Healthy Twin is a twin family study extension of the existing Korean Twin-Family Register. Healthy Twin recruits adult like-sex twins over the age of 30 and their adult family members. Healthy Twin protocols are primarily tailored to the study of the quantitative trait loci of complex traits as well as to the role of environment in the etiology of complex diseases. A full-length survey is underway, including questionnaires, health examinations and the collection of biological specimens. So far, 820 individuals (169 twin pairs and their families) have participated in the survey and 1068 individual twins (608 twin pairs) have replied to the mailed zygosity questionnaire as of July 2006. The first phase (2005-2006) of Healthy Twin will recruit 1550 individuals (including about 380 twin pairs), and the second phase a proposed 1500 to 2500 additional participants. We report study protocols and zygosity and the distribution of family size of the study participants.

Socioeconomic Status and Cardiovascular Disease Among Men: The Korean National Health Service Prospective Cohort Study

OBJECTIVESnWe examined the association between socioeconomic status (SES) and myocardial infarction and stroke subtypes, including the possible mediating influence of cardiovascular risk factors.nnnMETHODSnWe evaluated data on 578756 Korean male public servants aged 30 to 58 years from August 1, 1990, to July 31, 2001.nnnRESULTSnSES had inverse associations with mortality because of myocardial infarction and stroke subtypes, which were not changed by an adjustment for, or stratification by, cardiovascular risk factors. For nonfatal events, SES had positive, null, and inverse associations with myocardial infarction, ischemic stroke, and hemorrhagic stroke, respectively. The association between SES and nonfatal myocardial infarction depended on the presence of risk factors and was positive only among men who had cardiovascular risk factors. Case-fatality after hospital admission for cardiovascular diagnoses was significantly lower among higher SES groups, even after risk factor adjustment.nnnCONCLUSIONSnInverse SES associations with cardiovascular diseases were not mediated by cardiovascular risk factors among men who were undergoing economic transition. Socioeconomically patterned access to medical care may partly explain these socioeconomic gradients.

Varying Patterns of BMI Increase in Sex and Birth Cohorts of Korean Adults

Objective: The Korean population has recently experienced a rapid increase in obesity associated with lifestyle changes arising from economic growth. We examined trends in BMI by analyzing sex‐specific birth cohorts using 3,400,727 measurements from 1,662,477 Korean adults.

Different risk factor profiles between subtypes of ischemic stroke. A case-control study in Korean men.

Ischemic stroke is composed of subtypes with variable underlying pathogenesis and studies on ischemic stroke as a whole may inadequately evaluate risk factors, being influenced by subtype distribution among studied population. This study aimed to evaluate risk factors associated with individual ischemic stroke subtypes defined by the Trial of ORG10172 in Acute Stroke Treatment. In a case-control study (290 first-ever ischemic stroke cases and 1160 individually matched controls without stroke) nested within Korean male public servants cohort, a range of potential risk factors measured at periodic health surveys prior to the onset of stroke event were examined using conditional logistic regression analysis. Increased risk for large-artery atherosclerosis was associated with hypercholesterolemia (≥ 6.2xa0mmol/L), hypertension, and smoking. Increased risk for small-artery occlusion was associated with hypertension, hyperglycemia (≥ 7.0xa0mmol/L), and frequent alcohol intake. No specific risk factor was identified for cardioembolism. For combined ischemic stroke, hypercholesterolemia, hyperglycemia, hypertension, and smoking were associated with the increased risk, but the relative odds were much smaller than those estimated from subtype analysis. Significance of risk factors evaluated for subtypes, rather than ischemic stroke as a whole, should be reflected in preventive efforts against the burden of ischemic stroke.

The Korean Twin Registry--methods, current stage, and interim results.

The Korean Twin Registry is the first nationwide twin study in Korea. We compiled 154,783 twin pairs from existing nation-wide data sources, mainly from address and national health insurance data. The coverage of this registry was almost complete for the twins born since 1970, but less complete as age increased, so that there were only 990 pairs who were born before 1930. The twins health examination (N = 54,390 persons) and questionnaire (N = 44,546 persons) results were incorporated into the registry, yielding 12,894 and 9074 concordantly informative pairs. Morbidity and mortality outcomes have been followed up since 1990, for most diseases. For preliminary analysis of complex diseases, we selected ventricular septal defects (VSD) in young twins, stomach and colorectal cancers in adult twins. We identified 353 VSDs, 284 stomach cancers, and 116 colorectal cancers among twins. The prevalence rates of cancers, but not that of VSD, were lower in twins than those in population. The difference in the cancer prevalence was marked for twins born before 1926, implying some degree of selection. Like-sex (LS) twins showed familial recurrence risks (lambdaLS) of 41.2 for VSD and 22.4 for colorectal cancers, and 1.74 for stomach cancers. For opposite-sex (OS) twins, we could estimate lambdaOS of 19.8 for VSD only. These results were compatible with previous studies for VSD and colorectal cancers, but not for stomach cancers. Despite the strength in size, availability of health outcomes, and some lifestyle and basic laboratory data, we need accurate zygosity information to improve the validity of the results.