BackgroundThe incidence of thyroid nodules has increased worldwide in recent years. Thyroid dysfunction is a potential risk factor for hypercholesterolemia, cardiovascular disease, osteoporosis, arrhythmia, and neuropsychiatric disease. This study investigated the prevalence and annual incidence of thyroid nodules, hypothyroidism, and hyperthyroidism in Koreans.MethodsIn this nationwide population-based cohort study, 51,834,660 subjects were included using the National Health Information database from 2006 to 2015, after the exclusion of subjects with thyroid cancer.ResultsThe prevalence in Korea in 2015 of thyroid nodules, hypothyroidism in patients taking thyroid hormone, and hyperthyroidism in patients undergoing treatment was 15.82/1,000 population, 15.94/1,000 population, and 2.76/1,000 population, respectively. All these diseases were more prevalent among women than among men. The number of incident cases of these three thyroid diseases steadily increased from 2006 to 2012, and then decreased through 2015. The incidence of thyroid nodules, hypothyroidism treated with thyroid hormone, and treated hyperthyroidism was 6.79/1,000 population, 1.76/1,000 population, and 0.55/1,000 population, respectively, in Korea in 2015. The use of methimazole continuously increased, from 33% of total antithyroid drug prescriptions in 2006 to 74.4% in 2015, and it became the most frequently prescribed antithyroid drug in Korea. In contrast, the use of propylthiouracil continuously decreased.ConclusionThis was the first nationwide study of the prevalence and annual incidence of thyroid nodules, hypothyroidism, and hyperthyroidism to take into account recent changes and to include the current status of patients receiving treatment.

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Background Waist circumference (WC) is a well-known obesity index that predicts cardiovascular disease (CVD). We studied the relationship between baseline WC and development of incident myocardial infarction (MI) and ischemic stroke (IS) using a nationwide population-based cohort, and evaluated if its predictability is better than body mass index (BMI). Methods Our study included 21,749,261 Koreans over 20 years of age who underwent the Korean National Health Screening between 2009 and 2012. The occurrence of MI or IS was investigated until the end of 2015 using National Health Insurance Service data. Results A total of 127,289 and 181,637 subjects were newly diagnosed with MI and IS. The incidence rate and hazard ratio of MI and IS increased linearly as the WC level increased, regardless of adjustment for BMI. When the analyses were performed according to 11 groups of WC, the lowest risk of MI was found in subjects with WC of 70 to 74.9 and 65 to 69.9 cm in male and female, and the lowest risk of IS in subjects with WC of 65 to 69.9 and 60 to 64.9 cm in male and female, respectively. WC showed a better ability to predict CVD than BMI with smaller Akaike information criterion. The optimal WC cutoffs were 84/78 cm for male/female for predicting MI, and 85/78 cm for male/female for predicting IS. Conclusion WC had a significant linear relationship with the risk of MI and IS and the risk began to increase from a WC that was lower than expected.

BackgroundAge-related decreases in lean mass represent a serious health problem. We aimed to analyze the risks of rapid decreases in lean mass by age and sex in relatively young Korean adults during a 4-year follow-up study.MethodsA total of 65,856 non-diabetic participants (59.5% men, mean age 39.1 years) in a health screening program were subjected to bioimpedance body composition analyses and metabolic parameter analyses at baseline and after 4 years. The participants were sub-divided according to age, and additionally to six groups by age and the degree of body weight change over the 4-year period. The actual changes in body weight, lean mass, and fat mass and the percent changes over the 4-year period were assessed.ResultsThe percent change in lean mass decreased and the percent change of fat mass increased with increasing age in every age and sex group. However, the annual percent decrease in lean mass and percent increase in fat mass were significantly higher among women than among men (−0.26% vs. −0.15% and 0.34% vs. 0.42%, respectively; P<0.01). Participants who were older than 50 years and had a weight loss <−5% during the 4 years had significantly greater decreases in lean mass and smaller decreases in fat mass, compared to those who were younger than 50 years. An odds ratio analysis to determine the lowest quartile of the percent change in lean mass according to age group revealed that participants older than 60 years had a significantly increased risk of a rapid decrease in the lean mass percentage (2.081; 95% confidence interval, 1.678 to 2.581).ConclusionEven in this relatively young study population, the lean mass decreased significantly with age, and the risk of a rapid decrease in lean mass was higher among women than among men. Furthermore, the elderly exhibited a significantly more rapid decrease in lean mass, compared with younger participants.

Background: Short stature and leg length are associated with risk of diabetes and obesity. However, it remains unclear whether this association is observed in Asians. We evaluated the association between short stature and increased risk for diabetes using the Korean National Health Screening (KNHS) dataset. Methods: We assessed diabetes development in 2015 in 21,122,422 non-diabetic Koreans (mean age 43 years) enrolled in KNHS from 2009 to 2012 using International Classification of Diseases 10th (ICD-10) code and anti-diabetic medication prescription. Risk was measured in age-and sex-dependent quintile groups of baseline height (20 to 39, 40 to 59, ≥60 years). Results: During median 5.6-year follow-up, 532,918 cases (2.5%) of diabetes occurred. The hazard ratio (HR) for diabetes development gradually increased from the 5th (reference) to 1st quintile group of baseline height after adjustment for confounding factors (1.

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