Trend in the Incidence of Severe Partial Edentulism among Adults Using the Korean National Health Insurance Service Claim Data, 2014-2018.

PURPOSE: Missing teeth is one of the most important indicators of oral health behavior and the result of dental caries, periodontal disease, and injuries. This study examined a trend in the incidence of severe partial edentulism (SPE) using the Korean National Health Insurance Service (KNHIS) data. MATERIALS AND METHODS: Data of adults aged ≥20 years were obtained from the KNHIS for the 2014-2018 period. SPE was defined in dental information within a population with a treatment history of dental scaling as having 1 to 8 natural teeth. Crude incidence rates (CIRs) and age-standardized incidence rates (AIRs) with 95% confidence interval were calculated per 100000 persons. The Cochran Armitage trend (CAT) test and average annual percentage change were used to analyze SPE trends. RESULTS: The CIRs among Korean adults were from 346.29 to 391.11 in 2014-2016 and from 391.11 to 354.09 in 2016-2018. The AIRs trend statistically increased by 4.31% from 346.29 to 376.80 and decreased by 4.72% from 376.80 to 342.10. The AIRs in men increased by 4.00% and decreased by 3.01%. The AIRs in women decreased by 2.18% and increased by 2.11% (CAT; p<0.01). The AIRs by region and income also showed trends of increase and decrease. CONCLUSION: The study showed that the incidence trend of SPE increased and decreased from 2014 to 2018. This result would be able to aid in the planning of public oral health, and may also serve as fundamental data for verifying the impact of the public oral health policies implemented.

The association between carbon and nitrogen stable isotope ratios of human hair and hypertension.

BACKGROUND: The relationship between stable isotope ratios and dietary protein sources has been reported. However, few studies have examined the effect of stable isotope ratios on metabolic risk in humans. We investigated whether the stable isotope ratios of carbon and nitrogen in human hair are associated with blood pressure and hypertension. METHODS: We conducted a cross-sectional study of 392 subjects (228 men and 164 women). Hair samples of the subjects were used for the measurement of stable isotope ratios of carbon (δ13C) and nitrogen (δ15N). RESULTS: The δ13C and δ15N values showed positive correlations with diastolic blood pressure in the subjects without antihypertensive medication. In the subjects without antihypertensive medication, the multivariable-adjusted odds ratio (95% confidence interval) for hypertension was 1.55 (1.04-2.30) per 1‰ increase in δ15N and 1.22 (0.86-1.73) per 1‰ increase in δ13C, respectively. However, in the subjects with antihypertensive medication, neither δ13C nor δ15N values showed a significant association with hypertension. CONCLUSIONS: The stable isotopic ratio of nitrogen in scalp hair is independently associated with hypertension in subjects without antihypertensive medication. The hair δ15N value might be used as a surrogate marker to screen a high-risk population for hypertension.

Incidence of edentulism among older adults using the Korean National Health Insurance Service database, 2013-2018.

OBJECTIVES: Population aging is rapidly accelerating worldwide. Oral diseases related to aging are also on the rise. This study examined trends in the incidence of edentulism among the older Korean population using data from the Korean National Health Insurance Service (KNHIS). METHODS: Data on older adults, aged ≥75 years of age, were obtained from the KNHIS for the period 2013-2018. Edentulism was defined as a treatment history of complete dentures in the KNHIS database. The exclusion criteria consisted of both disease codes and treatment codes related to conservative dental treatment, including periodontal and extraction treatment afterward. Crude incidence rates (CIRs) and age-standardized incidence rates (AIRs) with 95% confidence intervals were calculated and reported per 100,000 person-years by the direct method. Trends were tested by Cochrane Armitage models. RESULTS: Statistically significant increasing trends in both CIRs and AIRs were found among the older Korean population registered in the KNHIS (CIRs, 707.92 to 895.92; AIRs, 705.11 to 889.68; p<0.01). The incidence tended to increase in both genders (p<0.01). Both CIRs and AIRs in specific regions also showed slight but significant annual increases except for Jeju Island (p<0.01 or <0.05). The incidence showed increasing trends (p<0.01) in all income quintiles apart from the highest quintile. The edentulism incidence was highest in the lowest income group (the first quintile). CONCLUSIONS: Our data showed that the incidence of edentulism among the elderly showed an increasing trend from 2013 to 2018. This result provides a basis for future epidemiological studies on the incidence of edentulism in the older Korean population.

Development of the Korean Standardized Antimicrobial Administration Ratio as a Tool for Benchmarking Antimicrobial Use in Each Hospital.

BACKGROUND: The Korea National Antimicrobial Use Analysis System (KONAS), a benchmarking system for antimicrobial use in hospitals, provides Korean Standardized Antimicrobial Administration Ratio (K-SAAR) for benchmarking. This article describes K-SAAR predictive models to enhance the understanding of K-SAAR, an important benchmarking strategy for antimicrobial usage in KONAS. METHODS: We obtained medical insurance claims data for all hospitalized patients aged ≥ 28 days in all secondary and tertiary care hospitals in South Korea (n = 347) from January 2019 to December 2019 from the Health Insurance Review & Assessment Service. Modeling was performed to derive a prediction value for antimicrobial use in each institution, which corresponded to the denominator value for calculating K-SAAR. The prediction values of antimicrobial use were modeled separately for each category, for all inpatients and adult patients (aged ≥ 15 years), using stepwise negative binomial regression. RESULTS: The final models for each antimicrobial category were adjusted for different significant risk factors. In the K-SAAR models of all aged patients as well as adult patients, most antimicrobial categories included the number of hospital beds and the number of operations as significant factors, while some antimicrobial categories included mean age for inpatients, hospital type, and the number of patients transferred from other hospitals as significant factors. CONCLUSION: We developed a model to predict antimicrobial use rates in Korean hospitals, and the model was used as the denominator of the K-SAAR.

The cancer risk according to three subtypes of ANCA-associated vasculitis: A propensity score-matched analysis of a nationwide study.

OBJECTIVE: It remains unknown whether cancer risk differs among the three subtypes of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) and what the cancer risk factors are. We conducted a nationwide study in Korea to evaluate the risk of cancer in patients with AAV and to identify the risk factors for cancer. METHODS: We analyzed the Health Insurance Review and Assessment database of Korea and identified 1982 patients diagnosed with AAV between January 1, 2007 and December 31, 2017. The patients and controls with no history of AAV or cancer were matched 1:4 by propensity scores. The study outcome measure was incidence of cancer during 11 years of follow-up. RESULTS: Patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA) numbered 684, 606, and 692, respectively. The overall incidence of cancer was higher among patients with AAV than in controls (HR 1.32, 95% CI 1.08-1.61). The risk of hematological malignancy, lung cancer, and bladder cancer in the GPA group, lung cancer in the MPA group, and hematological malignancy in the EGPA group were significantly higher than in controls (HR 7.39, 3.20, 4.20, 2.86, and 4.65, respectively). Age, male sex, GPA subtype, and cyclophosphamide use were significantly associated with cancer risk in patients with AAV. CONCLUSION: Overall cancer incidence was increased in patients with AAV. Cancer risk was higher in patients with GPA than in those with MPA or EGPA. The use of cyclophosphamide was associated with an increased risk of cancer, while rituximab was not.

Estimation and change of edentulism among the Korean population: Korea National Health and Nutrition Examination Survey 2007-2018.

OBJECTIVES: To estimate the prevalence of edentulism according to the socio-demographic variables of Korean adults between 2007 and 2018 and to analyze the trends. METHODS: This study was conducted using raw data from the Korea National Health and Nutrition Examination Survey (KNHANES) from 2007 to 2018. Edentulism was defined as the absence of upper and lower teeth or the retained root of the missing teeth. To obtain the prevalence of edentulism, complex sample frequency analysis and regression analysis were performed according to the socio-demographic variables to represent the national population. The Korean population structure in 2005 was exploited as a standard population to calculate age-standardized edentulism. RESULTS: The prevalence of edentulism in 2016-2018 was 9.7% in the Korean elderly, and the change of age-standardized edentulism steadily declined over time from 2007, 12.8%. In particular, it decreased by approximately 20% in the period between 2016 and 2018 compared to that in 2007 for those in their 80s. The trend of the prevalence according to gender decreased significantly in women. According to the level of education, the greatest decrease was seen in the group with the lowest education, although the prevalence itself was higher than that seen in those who were more educated. CONCLUSIONS: The prevalence of edentulism among the older Korean population has decreased over time. However, the concern is on those with lower education and men as these groups are still at higher risk for edentulism.

Association between the change of total cholesterol during adolescence and depressive symptoms in early adulthood.

Increasing evidence suggests that serum lipids are associated with depressive symptoms. However, previous studies have mostly employed a cross-sectional design and assessed middle-aged or older adult populations, making it difficult to discern the impact of lipid changes early in life on the development of depression. Accordingly, we sought to investigate changes in blood cholesterol levels during adolescence and the development of depressive symptoms in early adulthood. This prospective cohort study included participants aged 15-16 years from the JS High School Study (JSHS), with an average follow-up of 6 years. Participants had no diagnosed depression at baseline. Multivariable linear regression models were used to estimate associations between changes in total cholesterol during adolescence and depressive symptoms in adulthood. Changes in total cholesterol during adolescence were classified as "consistently low," "decreased," "moderate," "increased," or "consistently high". In men, depressive symptoms were higher in the consistently low (ß = 3.20, p = 0.036) and increased total cholesterol groups (ß = 3.48, p = 0.017), compared with the moderate group. In the consistently high group, although a positive linear association was observed, it lacked statistical significance (ß = 2.71, p = 0.067). While similar tendencies were noted in women, the associations were not statistically significant. Consistently low or increased total cholesterol levels during adolescence may pose an increased risk of depressive symptoms in early adulthood. These findings suggest that different strategies should be adopted to manage the lipid risk factors with consideration of age and sex.

Development of Antibiotic Classification for Measuring Antibiotic Usage in Korean Hospitals Using a Modified Delphi Method.

In 2019, a project designed to develop a system for measuring and comparing antibiotic usage in hospitals was launched in Korea. As part of this project, we developed a means to classify antibiotic usage in Korean hospitals using a modified Delphi method. In results, the following categories of antibiotic classification were accepted for use in Korean hospitals: 1) broad-spectrum antibacterial agents predominantly used for hospital-onset infections in adults, 2) broad-spectrum antibacterial agents predominantly used for community-acquired infections in adults, 3) antibacterial agents predominantly used for resistant gram-positive infections in adults, 4) narrow-spectrum beta-lactam agents in adults, 5) antibacterial agents predominantly used for extensive antibiotic resistant gram-negative bacteria in adults, and 6) total antibacterial agents.

Blood lead levels in relation to smoking and chronic obstructive pulmonary disease (COPD): a study from Korean National Health and Nutrition Examination Survey (KNHANES).

BACKGROUND: Lead exposure is a resurgent environmental issue globally. Smoking can be a source of lead exposure, although the majority of lead poisonings originate from workplace exposures. However, no study has been undertaken concerning the blood lead levels based on the chronic obstructive pulmonary disease (COPD), smoking status, and other risk factors of COPD. This cross-sectional study was conducted to investigate the blood lead levels according to COPD and clinical variables associated with COPD. METHODS: Data (total number =53,829) were collected from the Korean National Health and Nutrition Examination Survey (IV in 2008 and 2009, V in 2010-2012, and VI in 2013). Multivariable linear regression analyses were performed to determine variables associated with elevated blood lead levels. RESULTS: Univariate regression analysis showed that male sex, older age, smoking, occupation level, income level, education level, and presence of COPD were related to higher blood lead levels, whereas the other co-morbidities including diabetes, hypertension, cerebral stroke, osteoporosis, asthma, and depression were not related (P<0.05). Multivariable regression analysis demonstrated that older age, male sex, smoking, occupation, and education level were independently associated with higher blood lead levels (P<0.05). CONCLUSIONS: Smoking status, occupation, and education level along with old age and male sex were independently associated with higher blood lead levels; however, COPD was not after adjustment of all confounding factors.

Cancer development in patients with COPD: a retrospective analysis of the National Health Insurance Service-National Sample Cohort in Korea.

BACKGROUND: COPD is a well-known risk factor for lung cancer, independent of smoking behavior. By investigating the retrospective National Health Insurance Service-National Sample Cohort (NHIS-NSC) in Korea, this study attempted to prove the hypothesis that COPD is a risk factor for major cancers developing outside of the lungs. We also aimed to investigate the environmental factors associated with the development of lung cancer in COPD patients. METHODS: This study analyzed data from the NHIS-NSC over a 12-year period. Among the 514,795 subjects in the NHIS-NSC, 16,757 patients who were diagnosed with any cancer from 2002 to 2003 were excluded. This cohort enrolled six arms consisting of never-smokers without COPD (N = 313,553), former smokers without COPD (N = 41,359), smokers without COPD (N = 112,627), never-smokers with COPD (N = 7789), former smokers with COPD (N = 1085), and smokers with COPD (N = 2677). RESULTS: Incident rate of lung cancer per 100,000 person-year was higher according to smoking and COPD (216 in non-COPD and 757 in COPD among never-smokers, 271 in non-COPD and 1266 in COPD among former smokers, 394 in non-COPD and 1560 in COPD among smokers, p <  0.01). Old age, male sex, lower BMI, low exercise level, history of diabetes mellitus, smoking, and COPD were independent factors associated with the development of lung cancer (p <  0.01). Multi-variable analyses showed that COPD, regardless of smoking status, contributed to the development of lung cancer, and colorectal cancer and liver cancer among other major cancers (p <  0.01). CONCLUSION: Our data suggested that COPD was an independent risk factor for the development of lung cancer, and colorectal cancer and liver cancer among other major cancers in the Korean population, regardless of smoking status.

Epidemiological Characterization of a Directed and Weighted Disease Network Using Data From a Cohort of One Million Patients: Network Analysis.

BACKGROUND: In the past 20 years, various methods have been introduced to construct disease networks. However, established disease networks have not been clinically useful to date because of differences among demographic factors, as well as the temporal order and intensity among disease-disease associations. OBJECTIVE: This study sought to investigate the overall patterns of the associations among diseases; network properties, such as clustering, degree, and strength; and the relationship between the structure of disease networks and demographic factors. METHODS: We used National Health Insurance Service-National Sample Cohort (NHIS-NSC) data from the Republic of Korea, which included the time series insurance information of 1 million out of 50 million Korean (approximately 2%) patients obtained between 2002 and 2013. After setting the observation and outcome periods, we selected only 520 common Korean Classification of Disease, sixth revision codes that were the most prevalent diagnoses, making up approximately 80% of the cases, for statistical validity. Using these data, we constructed a directional and weighted temporal network that considered both demographic factors and network properties. RESULTS: Our disease network contained 294 nodes and 3085 edges, a relative risk value of more than 4, and a false discovery rate-adjusted P value of <.001. Interestingly, our network presented four large clusters. Analysis of the network topology revealed a stronger correlation between in-strength and out-strength than between in-degree and out-degree. Further, the mean age of each disease population was related to the position along the regression line of the out/in-strength plot. Conversely, clustering analysis suggested that our network boasted four large clusters with different sex, age, and disease categories. CONCLUSIONS: We constructed a directional and weighted disease network visualizing demographic factors. Our proposed disease network model is expected to be a valuable tool for use by early clinical researchers seeking to explore the relationships among diseases in the future.

Age-differential association between serum uric acid and incident hypertension.

Increasing evidence suggests a positive association between the serum uric acid (SUA) level and incident hypertension. However, the association has been inconsistent based on age, sex, body mass index, and lipid profiles. Thus, we investigated whether there is an interaction between SUA and other risk factors on incident hypertension in the Korean general population. In this study, 808 participants aged 40-79 years were included. They were free of hypertension and major cardiovascular disease at baseline. Incident hypertension was defined as systolic blood pressure (SBP) ≥ 140 mmHg, diastolic blood pressure (DBP) ≥ 90 mmHg, or use of antihypertensive medication. To investigate whether the association between SUA and incident hypertension is modified by other risk factors for hypertension, a generalized linear model and Z test were used. During the mean follow-up of 3.3 years, 11.5% of men and 10.7% of women developed hypertension. The association between SUA and incident hypertension was inconsistent according to participant age (p for interaction = 0.009). The association between SUA level and incident hypertension was positively significant among people aged < 55 years (relative risk 1.74 per 1.0 mg/dL of SUA; p = 0.002), but there was no significant association among people aged ≥ 55 years (p = 0.894). In a secondary analysis, the SUA level was not associated with an increase in SBP, but positively associated with DBP. We observed an age-differential association between SUA level and incident hypertension among Koreans. An increased SUA level can be a trigger for hypertension through early vascular changes in the middle-aged population.

Ultrasonographic findings of re-epithelialized skin after partial-thickness burns.

BACKGROUND: This study aimed to investigate the difference between ultrasonographic findings of normal skin and those of re-epithelialized skin after partial-thickness burns and to evaluate the relationship between these findings and clinical outcomes. METHODS: This study retrospectively analysed the ultrasound images of re-epithelialized skin after partial-thickness burns and contralateral normal skin from January 2016 to December 2016. A total of 155 lesions from 148 patients were analysed with ultrasound images, and healing time was documented. The scar status of each lesion was evaluated through medical records and photographs. We analysed the difference in ultrasonographic findings between normal skin and re-epithelialized skin after partial-thickness burns and statistically analysed the relationship between healing time, scar status and ultrasonographic findings. RESULTS: The re-epithelialized skin after partial-thickness burns was significantly thicker than the contralateral normal skin, and the echogenicity was significantly lower. The ultrasound images of the re-epithelialized skin after partial-thickness burns showed the characteristic findings of low-echogenic bands (LEB), and the proportion of LEB thickness is strongly correlated with healing time. In the multivariate analysis of scar status, only the proportion of LEB thickness was statistically significant. CONCLUSION: In this study, we found that there were ultrasonographic differences between re-epithelialized skin after partial-thickness burns and normal skin and that an LEB of varying thickness was formed after re-epithelialization. The thickness of the LEB in re-epithelialized skin after partial-thickness burns increased with healing time and was related to scar status.

Aminotransferase levels, body mass index, and the risk of diabetes: a prospective cohort study.

PURPOSE: To investigate whether the relationship between body mass index (BMI) and incident diabetes is modified by different alanine or aspartate aminotransferases (ALT or AST) levels. METHODS: We carried out an analysis of 6484 participants aged 40 years or older using data from the Korean Genome Epidemiology Study. The serum aminotransferase levels were stratified into low and high groups according to the median values and classified into three groups: both low, either high, and both high. To assess the association between BMI and incident diabetes according to the serum aminotransferase levels, multiple logistic regression models were used. RESULTS: In participants with high levels of both ALT and AST, compared with the first BMI quartile, the adjusted odds ratios for incident diabetes of the second, third, and fourth BMI quartiles were 1.72 (95% confidence interval, 0.84-3.55), 2.19 (1.11-4.33), and 3.08 (1.60-5.90), respectively (P trend < .001). In participants with either high ALT or AST, the adjusted odds ratios were 3.58 (1.23-10.41), 2.65 (0.90-7.76), and 5.28 (1.86-15.02), respectively (P trend = .005). However, in participants with both low ALT and AST levels, high BMI was not independently associated with the risk of incident diabetes. CONCLUSIONS: There was a strong association between BMI and incident diabetes among individuals with high aminotransferase levels, whereas no association was observed among those with low aminotransferase levels.

Relative contribution of obesity and menopause to the association between serum adiponectin and incident metabolic syndrome.

OBJECTIVE: Metabolic syndrome is closely linked to obesity. Menopause may play a critical role in understanding the pathophysiology of metabolic syndrome in women. We investigated the relative contribution of obesity and menopause to the association between serum adiponectin levels and the development of metabolic syndrome. METHODS: A prospective cohort study was conducted in which a total of 1,219 women without metabolic syndrome were examined at baseline (2005-2008) and followed up (2008-2011). Women were divided according to tertiles of serum adiponectin levels and menopause status, and then stratified into four groups: the nonobese with high adiponectin; the nonobese with low adiponectin; the obese with high adiponectin; and the obese with low adiponectin. RESULTS: During an average 2.5-year follow-up, 44 premenopausal women (9.8%) and 161 postmenopausal women (20.9%) developed metabolic syndrome. The obese group with low serum adiponectin demonstrated an increased risk for developing metabolic syndrome in both premenopausal (odds ratio [OR] 5.92, 95% confidence interval [CI] 2.24-15.66) and postmenopausal women (OR 4.22, 95% CI 2.41-7.36). However, the inverse association between serum adiponectin levels and incidence of metabolic syndrome was observed in premenopausal women with obesity (OR 0.16, 95% CI 0.03-0.81), but not in postmenopausal women with obesity (OR 0.55, 95% CI 0.27-1.14). CONCLUSIONS: High serum adiponectin levels showed no inverse association with metabolic syndrome in postmenopausal women with obesity. These findings may suggest a need for closer management of metabolic risk in postmenopausal women.

Sex difference in the effect of the fasting serum glucose level on the risk of coronary heart disease.

OBJECTIVE: Diabetic women have a greater relative risk of coronary heart disease than diabetic men. However, the sex difference in the effect of fasting serum glucose levels below the diabetic range on the risk of coronary heart disease is unclear. We investigated whether the association between nondiabetic blood glucose levels and the incident risk of coronary heart disease is different between men and women. METHODS: The fasting serum glucose levels and other cardiovascular risk factors at baseline were measured in 159,702 subjects (100,144 men and 59,558 women). Primary outcomes were hospital admission and death due to coronary heart disease during the 11-year follow-up. RESULTS: The risk for coronary heart disease in women significantly increased with impaired fasting glucose levels (≥110mg/dL) compared to normal glucose levels (<100mg/dL), whereas the risk for coronary heart disease in men was significantly increased at a diabetic glucose range (≥126mg/dL). Women had a higher hazard ratio of coronary heart disease associated with the fasting serum glucose level than men (p for interaction with sex=0.021). CONCLUSIONS: The stronger effect of the fasting serum glucose levels on the risk of coronary heart disease in women than in men was significant from a prediabetic range (≥110mg/dL).

Association between Nitrogen Stable Isotope Ratios in Human Hair and Serum Levels of Leptin.

Stable isotope ratios have been reported to be potential biomarkers of dietary intake and nutritional status. High serum levels of leptin, a hormone which regulates energy metabolism and food intake, are associated with insulin resistance and metabolic syndrome. However, little is known about the association between stable isotope ratios and the metabolic risk in humans. We investigated whether the carbon and nitrogen stable isotope ratios in hair are associated with serum leptin levels. Hair samples were collected from 399 healthy adults (233 men and 166 women) aged 40 to 70 years of a community-based cohort in Korea and the bulk stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were measured for all hair samples. Serum leptin levels were analyzed by radioimmunoassay. δ15N showed positive correlations with serum leptin levels. In multivariate models, increasing δ15N were associated with elevated serum leptin levels (defined as ≥ the median values), whereas δ13C were not significantly associated with serum leptin levels. The odds ratio (95% confidence interval) per 1‰ increase in δ15N for an elevated serum leptin level was 1.58 (1.11-2.26). In participants with high body mass index, δ15N showed positive associations with serum leptin levels, whereas these associations were not seen in participants with low body mass index. The nitrogen stable isotopic ratio in hair is positively associated with serum leptin levels. The hair δ15N could be used as a clinical marker to estimate metabolic risk.

Current status of and strategies for hepatitis C control in South Korea.

Chronic hepatitis C (CHC) is caused by hepatitis C virus (HCV) infection. HCV infection causes acute hepatitis, and the majority of those infected progress to chronic hepatitis, and some of them develop cirrhosis and hepatocellular carcinoma. Transmission of HCV is parenteral, and the major transmission routes include drug abuse, insecure injections or medical procedures, contaminated syringes or needles, sexual contact with an HCV-infected person, vertical infection of newborns by infected mothers, the transfusion of blood or blood products contaminated with viruses, and organ transplants. As no vaccine against HCV is available, HCV management involves blocking routes of transmission transmission, screening for HCV infection, and protecting liver disease progression by treatment. Highly potent oral direct antiviral agents are now available. Therefore, early detection through nation-wide screening program and appropriate treatment should be implemented to improve the quality of life of patients with HCV. Furthermore, for the effective HCV control in South Korea, The organization of an 'integrated national viral hepatitis control system' is desirable.

Combined Effect of Initial and Longitudinal Increases in γ-Glutamyltransferase on Incident Metabolic Syndrome: ARIRANG Study.

PURPOSE: Although γ-glutamyltransferase (GGT) is well known to be associated with metabolic syndrome (MS), prospective data on baseline and longitudinal changes in GGT levels and incident cases of MS are limited. We aimed to examine prospective associations between changes in GGT levels over time, as well as at baseline, and incident MS in Korean adults. MATERIALS AND METHODS: A total of 2579 Korean adults free of MS were followed up for 2.6 years. Data were collected from 2005-2008 (baseline) and from 2008-2011 (follow-up). Serum GGT levels were determined by enzymatic methods. RESULTS: During follow-up, 558 participants (21.6%) developed MS. A gradual increase in the incidence of MS was observed across GGT quartiles. After adjustment for confounding factors, the odds ratio and 95% confidence interval (CI) for new onset MS, comparing the highest to the lowest quartiles of baseline GGT, was 2.07 (95% CI: 1.52-2.80). The odds ratio for the highest GGT changes (>4 IU/L increase) in comparison to the lowest GGT changes (<-5 IU/L decrease) was 1.75 (95% CI: 1.32-2.33). Among participants with baseline GGT concentrations