Socioeconomic Status and Number of Children Among Korean Women: The Healthy Twin Study

Objectives: This study aimed to evaluate whether the birth rate is associated with socioeconomic status in the women of the Republic of Korea, where the birth rate is rapidly decreasing.Methods: This study included 732 females from the Healthy Twin Study, a family-twin cohort. The participants were classified into 3 socioeconomic groups according to their average income, education, and occupation. The association between socioeconomic status and number of children was assessed using gamma regression analysis with a generalized linear mixed model, adjusting for the age group, smoking/alcohol status, and family relationships.Results: The group with the highest education level had significantly fewer children compared with the group with the lowest education level (p=0.004). However, no significant associations were found according to household income level. The non-manual labor group had significantly fewer children compared with those working as homemakers (p=0.008).Conclusions: This study aimed to explain the causal relationship between socioeconomic status and number of children. Associations between some socioeconomic status and number of children were found in Korea.Objectives: This study aimed to evaluate whether the birth rate is associated with socioeconomic status in the women of the Republic of Korea, where the birth rate is rapidly decreasing. Methods: This study included 732 females from the Healthy Twin Study, a family-twin cohort. The participants were classified into 3 socioeconomic groups according to their average income, education, and occupation. The association between socioeconomic status and number of children was assessed using gamma regression analysis with a generalized linear mixed model, adjusting for the age group, smoking/alcohol status, and family relationships. Results: The group with the highest education level had significantly fewer children compared with the group with the lowest education level (p=0.004). However, no significant associations were found according to household income level. The non-manual labor group had significantly fewer children compared with those working as homemakers (p=0.008). Conclusions: This study aimed to explain the causal relationship between socioeconomic status and number of children. Associations between some socioeconomic status and number of children were found in Korea.OAIID:oai:osos.snu.ac.kr:snu2013-01/102/0000040632/2SEQ:2PERF_CD:SNU2013-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:NEMP_ID:A077602DEPT_CD:902CITE_RATE:0FILENAME:2.SOCIOECONOMIC STATUS AND NUMBER OF CHILDREN AMONG.pdfDEPT_NM:보건학과EMAIL:[email protected]:

Reproducible Research in Public Health

In this study, we aimed to construct pipelinesof reproducible statistical analysis in healthresearch. The development of pipelines in thisstudy consists of? Automatic suggestions of a summary tabledescribing the general characteristics of thestudy? Univariate analysis of both explanatory andoutcome variables of a study? Graphical presentations of summary andunivariate analyses? Automatic analysis and tabulations of mainresultsbased on frequently used analytical methodsin the health research area (e.g., multiple regression,logistic regression, survival analysis,multilevel analysis, genome-wide associationstudy(GWAS)OAIID:oai:osos.snu.ac.kr:snu2014-01/104/0000040632/3SEQ:3PERF_CD:SNU2014-01EVAL_ITEM_CD:104USER_ID:0000040632ADJUST_YN:NEMP_ID:A077602DEPT_CD:902CITE_RATE:0FILENAME:the r user - 표지 abstracts.pdfDEPT_NM:보건학과CONFIRM:

Linkage Disequilibrium Information within Monozygotic Twin Pairs - a Rationale for Genotyping Twins

Recently genome-wide association studies have become a standard gene mapping method, but MZs have been either considered to be redundant or treated as unrelated individuals after randomly selecting one cotwin. It has been a common sense in academia that monozygotic twin (MZ) pairs, although they have unique strengths in detecting non-genomic etiology, do not contribute to gene mapping studies. It is indeed true for linkage analysis, but resemblance of phenotypes between MZ cotwins does include information about linkage disequilibrium (LD) between the genetic markers and postulated disease-susceptibility loci (DSL) when the concordance/discordance rates are compared across genotypes. The authors attempted to formulate a method to detect association and suggest several ways of applying the information using triglyceride and hypertriglyceridemia as a model phenotype. Genome-wide association test findings from the Healthy Twin Study, Korea which do not utilize MZ concordance information were compared with the tests of MZ concordance only from 493 MZs with genetic markers It is natural to assume that if allele D (wild type allele is +) is in LD with true DSL, MZ twins with genotype DD or D+ should have more diseases, and thus concordance rate than those with ++ genotype. Numerically, the observed concordance rate of MZ twins will exceed the expected concordance rate under null hypothesis of non-association (Equation 1) Equation 1 H0: Obs (A*A|DD)= Obs (A*A |D+)= Obs (A*A |++) = (prevalence)2, H1: Obs(A*A|DD)>Obs(A*A|D+)>Obs(A*A|++) and Obs(U*U|DD)<Obs(U*U|D+)< Obs(U*U|++) where "A*A"-the proportion of MZ with both affected, "U*U"-the proportion of MZ with both unaffected, "Obs()"-observed rate, "prevalence"-prevalence rate among general population or study participantsThis can be further formulated by a trend test assuming additive model,or reduced tests assuming dominant model. Extended models can be constructed such as a logistic regression model allowing covariate adjustment or multiple linear regression calculating the sum of covariance between the cotwins for continuous traits.Formula : logit[p(A*A)]= α×covariates + β×num(allele D) + ε : additive modellogit[p(A*A)]= α×covariates + β×I(allele D exists) + ε : dominant model where "I(allele D exists)"-1:D exists,0:not existsWhen we applied the multiple logistic regression test with 5.83 mmol/L as a cut-off for hypertriglyceridemia, 10 markers out of 26523 SNPs in chromosome 11 which exceeded p<10-3 showed p-value of 0.0003~0.001. When we consider p-value of 0.05,0.1,0.15,0.2 and 0.3 as cut-off for the MZ test and p-value of 10-3 and 10-4 as cut-off for GWAS results, the sensitivity/specificity of the MZ tests ranged 0.26~0.56 for sensitivity and 0.69~0.95 for specificity. The MZ test results were combined with family-based GWA results. Our findings show a way to extract LD information from MZ concordance or resemblance when one of cotwin was genotyped. Because the MZ resemblance is independent of other information conventionally used for GWAS, it can be combined with other results. The test can be also used to screen markers to alleviate the burden of multiple testing with appropriate threshold. Given that the MZ will be ever popularly applied for various omics studies, the addition of genomic information will facilitate multi-omics study in twin research.OAIID:oai:osos.snu.ac.kr:snu2012-01/102/0000040632/11SEQ:11PERF_CD:SNU2012-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:NEMP_ID:A077602DEPT_CD:902CITE_RATE:1.635FILENAME:abstract_linkage disequilibrium information within.pdfDEPT_NM:보건학과EMAIL:[email protected]_YN:YCONFIRM:

Dietary Restraint Is Non-Genetically Associated with Change in Body Mass Index: The Healthy Twin Study

Purpose: We aimed to examine if past and more recent body mass index (BMI) changes are associated with eating behavior (EB) traits and whether these associations are due to non-genetic factors. Materials and Methods: In 1321 Korean twins and family members, recent and past BMI change groups were defined using quartiles of BMI change between first and second visits over 2.4±0.9 years and BMI change between 20 years old and second visit, respectively. We applied linear mixed analysis for relationships of past or recent BMI change groups and each EB (restrained, external, and emotional EB using the Dutch Eating Behavior Questionnaire) assessed at second visit after adjusting for household effect and covariates (age, gender, education, medical history of diabetes, hypertension, and dyslipidemia, alcohol use, physical activity, smoking habit, and calorie intake). In monozygotic twin pairs, paired t-test for within-pair comparison and conditional logistic regression analysis were conducted regarding EB. Results: Greater past BMI change was associated with higher restrained eating scores (P for trend=0.031), whereas greater recent BMI change was associated with higher external eating scores (P for trend=0.046). In co-twin-control analysis, twins with greater past BMI change were more likely to have higher restrained eating scores as compared with their co-twins with lower past BMI change (odds ratio 1.80; 95% confidence interval 1.13--2.87), whereas there were no associations between recent BMI change and external eating scores. Conclusion: Greater BMI change since 20 years old is associated with higher dietary restraint, and non-genetic factors explain this relationship.Key Words: Dietary restraint, non-genetic factor, BMI change, twinINTRODUCTIONOAIID:oai:osos.snu.ac.kr:snu2014-01/102/0000040632/4SEQ:4PERF_CD:SNU2014-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:NEMP_ID:A077602DEPT_CD:902CITE_RATE:1.263FILENAME:4.dietary restraint is non-genetically associated with change_0.pdfDEPT_NM:보건학과SCOPUS_YN:YCONFIRM:

Eating behaviors and weight over time in a prospective study: the Healthy Twin Study

We examined the relationships of combined initial restrained and external/emotional eating with initial BMI andchange in weight and these subscales over time. BMI and the Dutch Eating Behavior Questionnaire were twicemeasuredin 1361 Korean twins and families (482 men, 879 women) over a period of 2.7±0.9 years. Subjectswere classified by combination of initial sex-specific restrained and external (or emotional) eating tertiles. Linearmixed models were performed after adjusting for confounders at baseline (household, sibling relations, sex, age,education level, smoking, alcohol use, energy intake, physical activity, and medical history). In adjusted models,initial BMI increased with increasing tertiles of initial restrained eating across initial external/emotional eatingtertiles. Weight was less likely to increase over time with increasing tertiles of initial restrained eating in the lowestexternal eating tertile and middle tertile of emotional eating at baseline. Subscale scores decreased over timewith increasing tertiles of corresponding subscales at baseline. These findings suggest that high dietary restraintand external/emotional eating may indicate concurrent high BMI and attenuated weight gain and decreases in correspondingsubscales over time.This work was supported by the 2013 Inje University research grant.OAIID:oai:osos.snu.ac.kr:snu2014-01/102/0000040632/2SEQ:2PERF_CD:SNU2014-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:NEMP_ID:A077602DEPT_CD:902CITE_RATE:1.055FILENAME:2.eating behaviors and weight over time in a prospective_인제대.pdfDEPT_NM:보건학과EMAIL:[email protected]_YN:YCONFIRM:

HERITABILITY OF SALT INTAKE USING HALF-DAY URINE SAMPLES: THE HEALTHY TWIN STUDY

Salt is essential for both life and diet, but excess consumption of salt is an established risk factor of hypertension. Historically, salt intake has increased along with civilization, and the traditional Korean diet, although generally considered to be healthier than westernized one, has been reported to contain high level of salt on average about 13.5g/day which is 2.7-fold higher than the recommended values of WHO. Whether there is a genetic predisposition toward sodium intake level is a basic but interesting question to ponder in the Korean population.A half-day urine (HU) samples were collected for all participants of the Healthy Twin Study. HU collection starts around 7 pm of the day before visit, after completely voiding when time record starts. All the urine after then was collected in a bag until the next day visit for health examination. On site, in the morning, remaining urine was further voided and the time was recorded as final. We selected samples collected more than 8 hours. Urine samples with less than 8 hours collection were not included as these samples require a special formula to estimate 24 hour levels using sodium, potassium and creatinine concentrations. Among 3079 participants of the Healthy Twin Study, urine samples from 1312 individuals (143 pairs of MZ twins, 31 pairs of DZ twins and 961 singletons) sufficed both accurate information on volume and more than 8 hours collection, which were included in the analyses after projecting 24 hour sodium excretion level from simple volume-time calculation.Heritability of 24 hour sodium intake was estimated using a variance components model (SOLAR). The crude heritability of 24 hour sodium intake was 0.34±0.05. After further adjustment for household income which is one of the main factors of socio-economic status (SES) the heritability was not materially changed (0.28±0.1 p=0.007). Various types of shared environments, such as overall household effects, sibling effects, and generation effects, were included in ACE model, but did not account significant contribution to the variation of salt intake. We concluded that although salt intake is mediated through diet and meals are shared among families, genetic predisposition will play an important role in controlling salt intake. Analysis on the preference for salty food and on total amount of food intake is ongoing which will further dissect the genetics and shared environments related to salt intake.OAIID:oai:osos.snu.ac.kr:snu2012-01/102/0000040632/8SEQ:8PERF_CD:SNU2012-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:NEMP_ID:A077602DEPT_CD:902CITE_RATE:1.635FILENAME:abstract_heritablity of salt intake using half-day urine samples the healthy twin study.pdfDEPT_NM:보건학과EMAIL:[email protected]_YN:YCONFIRM:

High-Sensitivity C-Reactive Protein and Cancer

Background: High-sensitivity C-reactive protein (hs-CRP) is a commonly used inflammatory marker. The association between hs-CRP and cancer is less consistent than that between hs-CRP and cardiovascular diseases. This study explored the association between hs-CRP and cancer, using a large database of Korean health examination records.Methods: A total of 80 781 Koreans who visited the health promotion center of a general hospital were included. There were 729 cases of cancer of any primary site during a 3-year period. Subjects with a known cancer or a condition capable of affecting hs-CRP were excluded.Results: Serum hs-CRP was significantly higher in cancer cases (2.9 mg/L) than in non-cases (1.4 mg/L; P 3 mg/L), and the adjusted ORs for cancer were 1.16 (95% CI = 0.95-1.42) for the second highest category and 1.94 (95% CI = 1.51-2.51) for the highest category. After excluding cancer cases detected within I year after the check-up, the associations remained, although the reduced number of cancer cases (n = 88) attenuated the significance of the associations.Conclusions: Serum hs-CRP was positively associated with the risk of cancer, although causality cannot be inferred in this cross-sectional study. The results support the hypothesis that chronic inflammation plays a role in cancer.OAIID:oai:osos.snu.ac.kr:snu2011-01/102/0000040632/2SEQ:2PERF_CD:SNU2011-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:YEMP_ID:A077602DEPT_CD:902CITE_RATE:1.858FILENAME:high-sensitivity c-reactive protein and cancer.pdfDEPT_NM:보건학과SCOPUS_YN:YCONFIRM:

Reproductive factors associated with mammographic density: a Korean co-twin control study

To determine the mechanism by which menstrual and reproductive factors are associated with the risk of breast cancer, we examined the relationships between mammographic density and known menstrual and reproductive risk factors for breast cancer. A co-twin control study was conducted with 122 pairs of monozygotic Korean female twins selected from the Healthy Twin study. Mammographic density was measured from digital mammograms using a computer-assisted method. Information on selected menstrual and reproductive factors was collected through a self-administered questionnaire. Within-pair differences for each mammographic measure were regressed against within-pair differences for each menstrual and reproductive risk factor with an adjustment for body mass index and other menstrual and reproductive factors. The percent dense area was inversely associated with the age at the first full-term childbirth (FFTB) and the number of live births, although the associations were marginally significant with an adjustment for BMI and other reproductive factors. The non-dense area was positively associated with the age at the FFTB and the number of live births. The absolute dense area was positively associated with the duration of breast feeding. The age at menarche was not associated with any component of the mammographic measures. This finding suggests that mammographic density can mediate the protective effect of greater parity against breast cancer, at least in part while age at menarche, age at the FFTB, and breast feeding do not exert their effects through mammographic density.OAIID:oai:osos.snu.ac.kr:snu2011-01/102/0000040632/4SEQ:4PERF_CD:SNU2011-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:YEMP_ID:A077602DEPT_CD:902CITE_RATE:4.431FILENAME:reproductive factors associated with mammographic density a korean co-twin control study.pdfDEPT_NM:보건학과SCOPUS_YN:YCONFIRM:

Association between Personality Traits and Obesity indices: Family and Co-twin Analysis

Personality traits of an individual affect one's attitude towards life and one's life style factors determining health status. Since emotional disruption, such as depression and mood disorders, and unhealthy life habits are established risk factors of obesity, investigating the association between personality, life style, and obesity will lead to development of efficient intervention or preventive measure for obesity, according to their personality profiles. To this end, we attempted to explore the associations between Temperament and Character Inventory (TCI)'s seven dimensions and obesity indices: body mass index (BMI), waist circumference, waist hip ratio (WHR), trunk and total body fat percent measured by Dual-energy X-ray absorptiometry (DXA) in Korean twins and their families Additionally, we aim to discriminate environmental and genetic effect of TCI on obesity using pair-wise analysis of each and combined monozygotic twins (MZ), dizygotic twins (DZ) and sibling pairs adjusted for age and sex. We expected that estimating non-genetic association between personality traits and obesity will specifically show potential target chains interconnecting personality, life style and obesity.A total of 3079 individuals (1217 men, 661 families) of the Healthy Twin Study in Korea were involved in this study. This population includes 531 MZ pairs, 120 DZ pairs, and 1172 sibling pairs. Association between TCI and obesity was analyzed using adjusting for age, sex, smoking history and alcohol consumption. A random effect model (REM) was applied to adjust familial correlations. For co-twin and sib-pair analyses pair-wise regression models using pairwise-difference values were used. In conventional regression analyses (REM), among seven domains of TCI, novelty seeking had the strongest association with BMI. Decreased persistence (β =-0.0003), self-directedness (β =-0.00024), cooperativeness (β =-0.00028), and self-transcendence (β =-0.00026) had association with WHR. In pair-wise regression model, an association between persistence and WHR /trunk fat percent were further dissected; βW in MZ data was higher than βW in DZ-sibling data and pooled data, indicating that persistence is associated obesity, and in this association, there are more environmental effects than genetic effect.The results all confirm the previous findings that self-transcendence resulted with negative association with WHR. By comparing the βW of different datasets, we could conclude that there is high environmental effect on the association, and that there is more environmental effect on the TCI associated obesity than genetic effect. Suggesting an individual's personality profiles can be integrated into personalized intervention of obesity.OAIID:oai:osos.snu.ac.kr:snu2012-01/102/0000040632/9SEQ:9PERF_CD:SNU2012-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:NEMP_ID:A077602DEPT_CD:902CITE_RATE:1.635FILENAME:abstract_association between personality traits and.pdfDEPT_NM:보건학과SCOPUS_YN:YCONFIRM:

Phenotypic and Genetic Relationships between Kidney Function and Carotid Intima-Media Thickness in Koreans: The Healthy Twin Study

Background: The phenotypic and genetic relationships between carotid intima-media thickness (CIMT) and estimated glomerular filtration rate (eGFR) or urinary albumin-creatinine ratio (ACR) were evaluated in Korean twins and families. Methods: We recruited 688 participants (296 individual twins and 392 singletons, age 30-74 years) who were without myocardial infarction and stroke among participants in the Healthy Twin Study. eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. CIMT was measured using B-mode carotid ultrasound. Covariates were sex, Framingham risk scores, alcohol use, exercise, BMI, high-sensitivity C-reactive protein and triglycerides. Quantitative genetic and linear mixed analyses were performed. Results: In adjusted models there were associations between kidney function and CIMT with [beta] estimates ranging from -0.022 to -0.032 between eGFR and CIMT, and from 0.042-0.060 between ACR and CIMT. The covariate-adjusted heritabilities for eGFR, ACR and composite CIMT were 0.75, 0.32 and 0.45, respectively (p < 0.001). The adjusted genetic correlation between eGFR and CIMT was from -0.20 to -0.28 (p < 0.05), whereas there was no genetic correlation between ACR and CIMT. Conclusion: Kidney function is a surrogate marker of carotid atherosclerosis and further studies of the pleiotropic relationships between CIMT and eGFR are warranted. Copyright (C) 2012 S. Karger AG, BaselOAIID:oai:osos.snu.ac.kr:snu2012-01/102/0000040632/16SEQ:16PERF_CD:SNU2012-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:YEMP_ID:A077602DEPT_CD:902CITE_RATE:1.596FILENAME:phenotypic and genetic relationships between kidney function and carotid intima-media thickness in koreans the healthy twin study.pdfDEPT_NM:보건학과SCOPUS_YN:YCONFIRM: