Sixth Korea National Health Research Articles

High Normal Range of Free Thyroxine is Associated with Decreased Triglycerides and with Increased High-Density Lipoprotein Cholesterol Based on Population Representative Data.

Background: We aimed to evaluate the association between thyroid hormone (free thyroxine, free T4) level and lipid profiles in nationally representative data. Methods: This study was based on cross-sectional survey data from the sixth Korea National Health and Nutrition Examination Survey IV. After exclusion of subjects with a history of thyroid disease or abnormal thyroid function test and those on medication for dyslipidemia and/or cardiovascular disease, a total of 3548 subjects were included in the study. Results: There was a significant decrease in serum triglyceride levels and increase in serum high-density lipoprotein (HDL) cholesterol levels with high free T4 quartiles after adjustment for confounding factors (p for trend = 0.001 and p for trend = 0.014, respectively). Risk of hypertriglyceridemia was significantly decreased (odds ratio of 0.72 (95% confidential interval 0.53–0.98)) in the highest free T4 quartile compared to the lowest free T4 quartile, p = 0.044). Conclusions: Serum free T4 levels within normal range negatively correlated with serum triglyceride level and positively correlated with HDL-cholesterol level. Therefore, a close surveillance in terms of lipid profiles could be considered in subjects with low normal serum free T4 levels.

Dairy Food Consumption is Inversely Associated with the Prevalence of Periodontal Disease in Korean Adults.

Dairy food consumption is known to be inversely associated with periodontal disease. However, there are conflicting results depending on the type of dairy foods. The aim of this study was to determine the relationship between individual dairy food consumption and periodontal disease. A total of 9798 Korean adults, aged ≥30 years, who participated in the fifth and sixth Korea National Health and Nutrition Examination Survey were included in this study’s analysis. Dairy food consumption was measured by the semi-quantitative food frequency questionnaire. Periodontal disease was defined as Community Periodontal Index score ≥3 in more than one of six sextants. Frequent intake of dairy foods (≥7 servings/week) was associated with a 24% lower prevalence of periodontal disease compared with never consumers after adjustment for age, gender, income, education, smoking, alcohol consumption, body mass index, diabetes mellitus status, calcium intake, tooth brushing frequency, and use of dental floss (Odds ratio (OR)= 0.76, 95% CI = 0.63–0.91, p for trend = 0.052). Also, frequent intake of milk (≥7 servings/week) was associated with a 26% lower prevalence of periodontal disease after adjustment for potential confounders (OR = 0.74, 95% CI = 0.61–0.89, p for trend = 0.022). Frequent consumption of dairy food including milk may have a beneficial effect on periodontal disease in the Korean adult population.

Convergent association between socioeconomic status and the blood concentrations of mercury, lead, and cadmium in the Korean adult population: based on the sixth Korea National Health and Nutritional Examination Surveys (KNHANES 2013-2015)

The purpose of this study was to investigate the association between socioeconomic status and blood heavy metal concentration in Korean adult population using the Korea National Health and Nutritional Examination Survey(KNHANES 2013-2015). Multiple logistic regression analysis was used to determine the association between socioeconomic status and the blood heavy metal concentration. Positive association was found between education and income level and blood concentration of mercury while those of lead and cadmium were negatively associated education and income level in Korean adult population (P for trend <0.001). At the point of an increase in the prevalence of heavy metal concentrations in the blood, a national public health policy will be needed to address the inequity of health due to socioeconomic factors.

Factors Related to Smoking Status Among Young Adults: An Analysis of Younger and Older Young Adults in Korea.

ObjectivesYoung adulthood represents a critical developmental period during which the use of tobacco may begin or cease. Furthermore, differences in smoking behaviors between younger (aged 18-24 years) and older (aged 25-34 years) young adults may exist. This study aimed to characterize patterns related to current smoking in younger and older young adults.MethodsThis study used data acquired from the Sixth Korea National Health and Nutrition Examination Survey conducted from 2013 to 2014. A total of 2069 subjects were categorized as younger (712 subjects) and older (1357 subjects) young adults. The chi-square test was used to assess the relationships between smoking status and socio-demographic, health-related, and smoking-related factors. Multivariable logistic regression models were constructed to assess the factors affecting current smoking in these age groups.ResultsThe current smoking prevalence was 18.3% among the younger young adults and 26.0% among the older young adults. Sex, education level, occupation, perceived health status, alcohol consumption, and electronic cigarette use were related to current smoking in both age groups. Secondhand smoke exposure at home and stress levels showed significant relationships with smoking in younger and older young adults, respectively.ConclusionsStrong correlations were found between the observed variables and smoking behaviors among young adults. Determining the factors affecting smoking and designing interventions based on these factors are essential for smoking cessation in young adults.

Relationship between asthma and dental caries in Korean adults: Data from the Sixth Korea National Health and Nutrition Examination Survey

Relationship between asthma and dental caries in Korean adults: Data from the Sixth Korea National Health and Nutrition Examination Survey

Relationship between oral health status and depressive symptoms in middle-aged women : The sixth Korea National Health and Nutrition Examination Survey (KNHANES Ⅵ)

Relationship between oral health status and depressive symptoms in middle-aged women : The sixth Korea National Health and Nutrition Examination Survey (KNHANES Ⅵ)

Association High-Iodine-Containing Seaweed Soup Consumption after Birth and Subclinical Hypothyroidism in Korean Women: Korea National Health and Nutrition Examination Survey IV (2013–2015)

Background and Objectives: This study was to investigate the association between the previous history of seaweed intake after childbirth and subclinical hypothyroidism (SCH) occurrence in Korean women based on the latest nationally representative epidemiological survey data, the Sixth Korea National Health and Nutrition Examination Survey (KNHANES VI). Materials and Methods: This study used data from KNHANES VI, a cross-sectional, nationally representative survey that comprises a health interview survey, health examination survey, and nutrition survey. Of the initial 22,948 Korean participants enrolled in KNHANES VI, 2,046 women were selected for this analysis. To examine SCH, the thyroid-stimulating hormone (TSH) reference range was defined using a population-based TSH range. Results: Subclinical hypothyroidism was increased in those who consumed seaweed soup after childbirth, but this was not significant (OR 1.3, CI: 0.80-2.13, p=0.293). However, the odd ratio for SCH differed according to the duration of seaweed soup consumption. When seaweed soup was consumed within 1 week after birth, the OR was increased in the crude model (OR 2.61, CI: 1.39-4.89, p=0.002), but this was no longer significant in the adjusted model (OR 1.89, CI: 0.79-4.50). Conclusion: The notable finding from this study is that the previous history of excessive seaweed consumption during post-partum period may not be a risk factor for SCH in Korean women.

The Relationship between Thyroid Function and Different Obesity Phenotypes in Korean Euthyroid Adults.

BackgroundThyroid disease and metabolic syndrome are both associated with cardiovascular disease. The aim of this study was to investigate the correlation between thyroid hormones and obesity sub-phenotypes using nationwide data from Korea, a country known to be iodine replete.MethodsThis study was based on data obtained from the sixth Korea National Health and Nutrition Examination Survey, administered from 2013 to 2015. A total of 13,873 participants aged ≥19 years were included, and classified into four groups: metabolically healthy non-obesity (MHNO), metabolically healthy obesity (MHO), metabolically unhealthy non-obesity (MUNO), and metabolically unhealthy obesity (MUO) by body fat on the basis of body mass index and metabolic health.ResultsAt baseline, serum free thyroxine (fT4) values were significantly higher in the MHNO phenotype (MHNO, 1.27±0.01 ng/dL; MHO, 1.25±0.01 ng/dL; MUNO, 1.24±0.01 ng/dL; MUO, 1.24±0.01 ng/dL, P<0.001) in total study population. However, this significant association no longer remained after adjustment for age, urine iodine concentration, and smoking (P=0.085). After adjustment for confounders, statistically significant association was observed between lower thyroid stimulating hormone (TSH) and MHNO phenotype (P=0.044). In men participants (not women), higher fT4 values were significantly associated with MHNO phenotype (P<0.001). However, no significant association was observed between thyroid function (TSH or fT4) and obesity phenotypes in groups classified by age (cutoff age of 55 years).ConclusionAlthough there was a difference by age and sex, we found that the decrease of TSH and the increase of fT4 values were associated with MHNO.

Factors Influencing Glycemic Control among Type 2 Diabetes Mellitus Patients: The Sixth Korea National Health and Nutrition Examination Survey (2013~2015)

Factors Influencing Glycemic Control among Type 2 Diabetes Mellitus Patients: The Sixth Korea National Health and Nutrition Examination Survey (2013~2015)

Relationship between depression and number of present teeth in Korean elderly: Data from the Sixth Korea National Health and Nutrition Examination Survey

Relationship between depression and number of present teeth in Korean elderly: Data from the Sixth Korea National Health and Nutrition Examination Survey

Cancer site differences in the health-related quality of life of Korean cancer survivors: Results from a Population-based Survey.

We investigated cancer site differences in the health-related quality of life (HRQOL) of cancer survivors. A secondary data analysis was conducted using the sixth Korea National Health and Nutrition Examination Survey (2013-2015). Participants were 15,461 adults (664 cancer survivors) with available EuroQol-5 Dimensions (EQ5D) information. Constructs from the revised Wilson and Cleary's model were examined. HRQOL status was measured using the EQ5D. EQ5D dimensional problems and indices were compared across cancer sites using multiple linear and quantile regression analyses. The most common problems across cancer sites were pain/discomfort and mobility. There were differences in EQ5D dimensional problems by cancer site: problems of usual activities in the cervix-cancer group and anxiety/depression in the thyroid cancer group were prevalent. Those with cervix cancer (vs. stomach) had higher EQ5D index scores; however, no significant differences were observed between other site subgroups. Subjective health perception and socioeconomic factors were significant determinants affecting HRQOL among cancer survivors with low EQ5D index scores. Subjective health status and socioeconomic characteristics are predicted to have a greater impact on survivors with low (vs. high) HRQOL. Socioeconomic and psychological support is essential to increase cancer survivors' HRQOL, regardless of cancer site.

Secular change in waist circumference and waist-height ratio and optimal cutoff of waist-height ratio for abdominal obesity among Korean children and adolescents over 10 years.

PurposeThis study aimed to evaluate the time trends of waist circumference (WC) and waist-height ratio (WHR), and to present WC and WHR distributions with optimal WHR cutoff for abdominal obesity in Korean children and adolescents.MethodsWe performed a retrospective cross-sectional analysis of data from 13,257 children and adolescents (6,987 boys and 6,270 girls) aged 6–18 years who were included in the third to sixth Korea National Health and Nutrition Examination Survey (KNHANES, 2005–2015). Linear regression analyses were used to identify secular changes in WC and WHR by age, sex, and KNHANES waves. A receiver operating characteristic curve analysis was used to determine the optimal WHR cutoff values for abdominal obesity and cardiometabolic risk factors.ResultsThe mean WC and WHR distributions from 2005 to 2015 showed no significant secular changes between the KNHANES 4 waves (P for trend ≥0.05 in all ages and both sexes). The mean WCs in the present study were lower than those in the 2007 Korean National Growth Charts. The mean WHR at ages <13 years was statistically higher in the boys than in the girls, but did not significantly differ between the sexes among those aged 13 to 18 years. The optimal WHR cutoff for abdominal obesity was 0.48 (area under the curve, 0.985; 95% confidence interval, 0.985–0.985) in the 13- to 18-year-old adolescents.ConclusionWC and WHR showed no secular changes over 10 years. The optimal WHR cutoff for abdominal obesity of 0.48 is useful for diagnosing and managing obesity and thus preventing obesity-related cardiometabolic complications in 13- to 18-year-old Korean adolescents.

Association between Body Shape Index, Perceived Body Shape and Self-Rated Health, Quality of Life in Korean Adults population Using Sixth Korea National Health and Nutrition Examination Survey

Association between Body Shape Index, Perceived Body Shape and Self-Rated Health, Quality of Life in Korean Adults population Using Sixth Korea National Health and Nutrition Examination Survey

The association between shift work and chronic kidney disease in manual labor workers using data from the Korea National Health and Nutrition Examination Survey (KNHANES 2011\u20132014)

ObjectiveKidneys are organs having a biological clock, and it is well known that the disruption of the circadian rhythm increases the risk of chronic kidney disease (CKD), including the decline of renal and proteinuria. Because shift work causes circadian disruption, it can directly or indirectly affect the incidence of chronic kidney disease. Therefore, the purpose of this study was to investigate the association between shift work and chronic kidney disease using a Korean representative survey dataset.MethodsThis study was comprised of 3504 manual labor workers over 20 years of age from data from the fifth and sixth Korea National Health and Nutrition Examination Survey (2011–2014). The work schedules were classified into two types: day work and shift work. The estimated glomerular filtration rate, which is the ideal marker of renal function, was estimated according to the Chronic Kidney Disease Epidemiology Collaboration creatinine equation, and chronic kidney disease was defined as urinary albumin to a creatinine ratio equal to or high than 30 mg/g and/or estimated glomerular filtration rate lower than 60 mL/min/1.73 m2. The cross-tabulation analysis and multivariate logistic regression analysis were performed to confirm the association between shift work and chronic kidney disease stratified by gender.ResultsThe risk of CKD showed a significant increase (odds ratio = 2.04, 95% confidence interval = 1.22, 3.41) in the female worker group. The same results were obtained after all confounding variables were adjusted (odds ratio = 2.34, 95% confidence interval = 1.35, 4.07). However, the results of the male worker group were not significant.ConclusionsIn this study using nationally representative surveys, we found that the risk of CKD was higher female workers and shift work. Future prospective cohort studies will be needed to clarify the causal relationship between shift work and CKD.

Relationship between rheumatoid arthritis and periodontal disease in Korean adults: Data from the Sixth Korea National Health and Nutrition Examination Survey, 2013 to 2015.

This study aims to investigate the relationship between rheumatoid arthritis and periodontal disease using data from the Sixth Korea National Health and Nutrition Examination Survey (KNHANES, 2013 to 2015). Of 22,948 KNHANES participants, 14,264 who were aged ≥19 years and responded to questions pertaining to periodontal disease and rheumatoid arthritis were analyzed. Periodontal status was measured using the Community Periodontal Index. The authors used a complex sampling analysis by applying an individual sampling weighting to maintain the rolling survey sampling method. To determine the prevalence of rheumatoid arthritis and periodontal disease, a Chi-squared test was performed. Logistic regression analysis was performed after controlling for selected variables to determine relevance. The prevalence of rheumatoid arthritis in patients with periodontal disease was 1.6%, which was higher than in individuals without periodontal disease (1.5%). The prevalence of periodontal disease in individuals with rheumatoid arthritis was 28.4%, which was higher than in subjects without rheumatoid arthritis (27.9%). The risk for periodontal disease was 1.64 times higher in individuals with rheumatoid arthritis than in those without rheumatoid arthritis. Regardless of age or sex, the risk for periodontal disease was 1.97 times higher in the presence of rheumatoid arthritis. However, other logistic regression analysis models, when adjusted for socioeconomic-, health-, and oral health-related factors, did not yield statistically significant findings. The study results suggest a possible relationship between rheumatoid arthritis and periodontal disease. Further large cohort studies investigating causal relationships between rheumatoid arthritis and periodontal disease are needed.

Predictive data mining for diagnosing periodontal disease: the Korea National Health and Nutrition Examination Surveys (KNHANES V and VI) from 2010 to 2015.

This study aimed to identify patients with the highest risk of periodontal disease (PD), and to provide recommendations for the effective use and application of data mining (DM) techniques when establishing evidence-based dental-care policies for vulnerable groups at a high risk of PD. This study used the SEMMA (Sample, Explore, Modify, Model, and Assess) methodology to construct DM models based on data acquired from the fifth and sixth Korea National Health and Nutrition Examination Surveys (2000-2015). We analyzed the sociodemographic and comorbidity variables that influence PD by applying the popular DM techniques of decision-tree, neural-network, and regression models, and also attempted to improve the predictive power and reliability by comparing the results obtained by these three models. Our comparisons of the three DM algorithms confirmed that the average squared error, misclassification rate, receiver operating characteristic index, Gini coefficient, and Kolmogorov-Smirnov test results were the most appropriate for the decision-tree model. The analysis of the decision-tree model revealed that age and smoking status exert major effects on the risk of PD, and that stress and education level exert effects in rural areas, whereas education level, sex, hyperlipidemia, and alcohol intake exert effects in urban areas. We demonstrated that the decision-tree model is an effective DM technique for identifying the complex risk factors for PD. These results are expected to be helpful in improving the equality and efficacy of dental-care policies for vulnerable groups at a high risk of PD.

The Prevalence of Osteoarthritis and Risk Factors in the Korean Population: The Sixth Korea National Health and Nutrition Examination Survey (VI-1, 2013).

BackgroundKnee osteoarthritis is highly prevalent, especially among the elderly. However, its risk factors have not been well identified, especially in the Korean population. This study aimed to assess the epidemiologic characteristics and risk factors of knee osteoarthritis in the Korean population.MethodsData of 2,280 (1,295 women) participants of the 2013 Korea National Health and Nutrition Examination Survey aged ≥50 years who underwent knee radiography were analyzed. According to the American College of Rheumatology clinical/radiographic classification criteria, knee osteoarthritis was defined as knee pain and radiographic knee osteoarthritis. The association between risk factors and knee osteoarthritis was analyzed using the chi-square test and binominal logistic regression.ResultsThe participants had an average age of 62.6 years; 56.8% of them were women. The average body mass index was 24.2 kg/m2, and 296 (13%) participants were diagnosed with knee osteoarthritis. After adjustment for multiple risk factors, age of ≥65 years (adjusted odds ratio [OR], 2.552; 95% confidence interval [CI], 1.868–3.486), female sex (OR, 2.050; 95% CI, 1.275–3.295), obesity (body mass index, ≥25.0 kg/m2 ; OR, 1.563; 95% CI, 1.191–2.051), hypertension (OR, 1.394; 95% CI, 1.052–1.846), low educational level (lower than or equal to elementary school: OR, 4.761; 95% CI, 2.131–10.635; middle school: OR, 3.184; 95% CI, 1.375–7.369), and low strength exercise frequency (<2 times/wk; OR, 1.829; 95% CI, 1.202–2.784) increased the risk of knee osteoarthritis.ConclusionOld age, sex, obesity, hypertension, low educational level, and low strength exercise frequency were found to be risk factors for knee osteoarthritis.

Effects of Physical Activity and Sedentary Time on Obesity: The Sixth Korea National Health and Nutrition Examination Survey 2013

Effects of Physical Activity and Sedentary Time on Obesity: The Sixth Korea National Health and Nutrition Examination Survey 2013

Effects of Physical Activity and Sitting Time on Diabetes Control: The Sixth Korea National Health and Nutrition Examination Survey 2013

Effects of Physical Activity and Sitting Time on Diabetes Control: The Sixth Korea National Health and Nutrition Examination Survey 2013

Rheumatoid arthritis is associated with early tooth loss: results from Korea National Health and Nutrition Examination Survey V to VI.

Background/aimsTo examine the association between rheumatoid arthritis (RA) and periodontitis or tooth loss.MethodsThe study used data from the fifth and sixth Korea National Health and Nutrition Examination Surveys conducted from 2010 to 2015. RA was defined as participant-reported physician-diagnosed RA that was being treated. Periodontitis and the number of natural teeth were determined by dental examination. Periodontitis was defined according to the community periodontal index (periodontal probing depth ≥ 4 mm). The association between RA and periodontitis or tooth loss was examined after controlling for confounding variables (e.g., age, smoking status, socioeconomic status, dental caries, frequency of toothbrushing, body mass index, alcohol consumption, and diabetes) in men and women. Subgroup analyses stratified by age were also performed.ResultsThe study enrolled 20,297 participants aged ≥ 19 years (157 RA patients and 20,140 non-RA controls). There was no association between RA and periodontitis or tooth loss in men and women. Subgroup analyses in those aged < 60 years revealed a non-significant association between RA and periodontitis (adjusted odds ratio, 1.53; p = 0.162), but they revealed a significant association between RA and tooth loss (adjusted β, 0.20; p = 0.042).ConclusionsRA was not associated with periodontitis, but was associated with tooth loss in younger adults. Younger RA patients are more likely to suffer tooth loss than general younger population; thus dental management is required.