Data Resource Profile: The National Health Information Database of the National Health Insurance Service in South Korea

Association of short-term particulate matter exposure with suicide death among major depressive disorder patients: a time-stratified case-crossover analysis

There is growing evidence that suggests a potential association between particulate matter (PM) and suicide. However, it is unclear that PM exposure and suicide death among major depressive disorder (MDD) patients, a high-risk group for suicide. We aimed to assess the effect of short-term exposure to PM on the risk of suicide in MDD patients who are at high risk for suicide. We investigated the risk of suicide among 922,062 newly-diagnosed MDD patients from 2004 to 2017 within the Korean National Health Insurance Service (NHIS) database. We identified 3,051 suicide cases from January 1, 2015, to December 31, 2017, within the death statistics database of the Korean National Statistical Office. PMs with aerodynamic diameter less than 2.5 μm (PM2.5), less than 10 μm (PM10), and 2.5–10 μm (PM2.5–10) were considered, which were provided from the National Ambient Air Monitoring System in South Korea. Time-stratified case-crossover analysis was performed to investigate the association of particulate matter exposure to suicide events. The risk of suicide was significantly high upon the high level of exposure to PM2.5, PM2.5–10 (coarse particle) and PM10 on lag 1 (p for trend < 0.05). Short-term exposure to a high level of PM was associated with an elevated risk for suicide among MDD patients. There is a clear dose–response relationship between short-term PM exposures with suicide death among MDD patients. This result will be used as an essential basis for consideration when establishing an air pollution alarm system for reducing adverse health outcomes by PM.

Effects of Fine Particulate Matter on Cardiovascular Disease Morbidity: A Study on Seven Metropolitan Cities in South Korea

Objectives: The primary purpose of this study is to analyze the relationship between the first occurrence of hospitalization for cardiovascular disease (CVD) and particulate matter less than 2.5 μm in diameter (PM2.5) exposure, considering average PM2.5 concentration and the frequency of high PM2.5 concentration simultaneously.

Methods: We used large-scale cohort data from seven metropolitan cities in South Korea. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) using the Cox proportional-hazards model, including annual average PM2.5 and annual hours of PM2.5 concentration exceeding 55.5 μg/m³ (FH55).

Results: We found that the risk was elevated by 11.6% (95% CI, 9.7–13.6) for all CVD per 2.9 μg/m³ increase of average PM2.5. In addition, a 94-h increase in FH55 increased the risk of all CVD by 3.8% (95% CI, 2.8–4.7). Regarding stroke, we found that people who were older and had a history of hypertension were more vulnerable to PM2.5 exposure.

Conclusion: Based on the findings, we conclude that accurate forecasting, information dissemination, and timely warning of high concentrations of PM2.5 at the national level may reduce the risk of CVD occurrence.

Risk of malignancy in kidney transplant recipients: a nationwide population-based cohort study

Background

Post-transplant malignancy is major morbidity complicated in kidney transplantation (KT). In Korea, a few studies have investigated the sex- and age-dependent risk for post-transplant malignancy among KT recipients on a large scale.

Methods

We utilized a national health insurance database in Korea to investigate the relative risk of post-transplant malignancy in 12,634 KT recipients between 2007 and 2017. The same number of patients with acute appendicitis was included as a control group. The relative risk of malignancy was estimated using a multivariable-adjusted Cox model, and interaction analysis was performed to investigate age- and sex-predominant patterns.

Results

KT recipients had an overall 1.8-fold higher risk for post-transplant malignancy with an increased risk for 14 of 29 cancer types, among which Kaposi’s sarcoma, non-Hodgkin’s lymphoma, kidney, uterus, and bladder/urinary tract cancers were most prominent. Although the overall risk for post-transplant malignancy was similar between male and female KT recipients, head and neck cancer had a higher risk among male KT recipients, whereas non-Hodgkin’s lymphoma and bladder/urinary tract cancer had a higher risk among female KT recipients. Overall, the young (< 50 years) KT recipients had a higher risk for post-transplant malignancy than older ones (≥ 50 years), whose pattern was most prominent in non-Hodgkin’s lymphoma. In contrast, breast and nonmelanoma skin cancer showed a higher risk among older KT recipients.

Conclusion

KT recipients had an increased risk for a wide range of cancer types, some of which showed differential risk patterns with age and sex. Our result suggests that focused screening for predominant post-transplant malignancies may be an effective strategy for selected KT recipients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02796-6.

Cysteinyl Leukotriene Receptor Antagonists Associated With a Decreased Incidence of Cancer: A Retrospective Cohort Study

Aim

Cysteinyl leukotrienes receptor antagonists (LTRAs) are promising chemoprevention options to target cysteinyl leukotriene signaling in cancer. However, only a number of randomized clinical trials (RCTs) or observational studies have been conducted to date; thus, the effect of LTRAs on patients is yet to be elucidated. Using insurance claim data, we aimed to evaluate whether LTRAs have cancer preventive effects by observing patients who took LTRAs.

Method

Patients diagnosed with asthma, allergic rhinitis, chronic cough, and have no history of cancer were followed-up from 2005 to 2017. Cox proportional hazard regression analysis was conducted to estimate the hazard ratios (HRs) for cancer risk of LTRA users.

Result

We followed-up (median: 5.6 years) 188,906 matched patients (94,453 LTRA users and 94,453 non-users). LTRA use was associated with a decreased risk of cancer (adjusted HR [aHR] = 0.85, 95% confidence interval [CI] = 0.83–0.87). The cancer risk showed a tendency to decrease rapidly when LTRAs were used in high dose (aHR = 0.56, 95% CI = 0.40–0.79) or for longer durations of more than 3 years (aHR = 0.68, 95% CI = 0.60–0.76) and 5 years (aHR = 0.33, 95% CI = 0.26–0.42). The greater preventive effects of LTRAs were also observed in patients with specific risk factors related to sex, age, smoking, and the presence of comorbidities.

Conclusion

In this study, we found that LTRA use was associated with a decreased risk of cancer. The high dose and long duration of the use of LTRAs correlated with a lower cancer risk. Since LTRAs are not yet used for the prevention or treatment of cancer, our findings could be used for developing a new chemo-regimen or designing feasible RCTs.

Comparative Treatment Persistence with Bone-Targeting Agents Among Asian Patients with Bone Metastases from Solid Tumors: A Multinational Retrospective Cohort Study

BACKGROUND

The efficacy of bone-targeting agents has been confirmed, but the generalizability of results to Asia is in question.

OBJECTIVE

We aimed to evaluate and compare treatment persistence and re-initiation with different bone-targeting agents among patients with bone metastases from solid tumors.

METHODS

This population-based cohort study included patients with bone metastasis with breast, lung, or prostate cancer who initiated bone-targeting agents, including denosumab, zoledronic acid, and pamidronate in Taiwan (2013-17), Hong Kong (2013-17), and Korea (2012-16). We described the patients' persistence with bone-targeting agents, by evaluating the interruption probability, and compared risks of treatment interruption. The rates of re-initiation with index bone-targeting agents were evaluated.

RESULTS

We included 5127 patients (denosumab: 3440, zoledronic acid: 1210, pamidronate: 477) from Taiwan, 883 patients (denosumab: 458, zoledronic acid: 357, pamidronate: 68) from Hong Kong, and 4800 patients (zoledronic acid: 4068, pamidronate: 732) from Korea. Compared with zoledronic acid, denosumab had a lower risk of interruption in Taiwan (adjusted hazard ratio: 0.44; 95% confidence interval 0.40-0.48) and Hong Kong (0.36; 0.28-0.45). However, pamidronate was more likely to be interrupted than zoledronic acid in Taiwan (1.31; 1.11-1.54) and Korea (2.06; 1.83-2.32), but not in Hong Kong (1.13; 0.71-1.78). After discontinuation, original treatments with denosumab in Taiwan and zoledronic acid in Hong Kong were more likely to be resumed, while in Korea, the rates were similar among the bisphosphonates.

CONCLUSIONS

Denosumab was associated with a lower risk of interruption than bisphosphonates in patients with bone metastases in Taiwan and Hong Kong. Further investigations may be required to verify patients' actual reasons for discontinuation.

Senior High School Students' Knowledge and Attitudes Toward Information on Their Health in the Kumasi Metropolis

The study examines senior high school students' understanding and attitudes toward information on their health in the Kumasi Metropolis. Multiple sampling techniques (convenient and simple random sampling techniques) were used in the study. A questionnaire was used to collect data from 391 respondents for the study. Frequencies and percentages were used to analyze the sociodemographic data. Again, the study used Pearson's correlation coefficient to show the degree of relationship between the level of knowledge of health information and attitudes toward seeking and sharing health information. The study found students' knowledge of the causes and symptoms of malaria, cholera, and Sexually Transmitted Infections (STIs) to be appreciably high as a result of readings from textbooks and health professionals. Again, the study found that the students preferred sharing their health information with friends than their parents and schools' authorities. The study further found that the major sources of students' health information included health professionals and textbooks. Lastly, even though some of the students claimed internet sources to their health information, it was not a major source to the student body at large. The study recommends strong health systems on the campuses of senior high schools as they have become communities on their own as a result of the emergence of the free senior high school program. The monitored positive peer-counseling group should also be encouraged by the schools' management and by extension the counseling units for the students to share views on themselves, particularly on health issues where they deem fit.

Cohort Profile: The Korean Vietnam War Veterans' Health Study Cohort (KOVECO)

During the Vietnam War, many troops and citizen were exposed to large amounts of Agent Orange (AO), and the hazardous effects of AO are continuously being researched and reported. The Korean Vietnam War Veterans’ Health Study Cohort (KOVECO) is a retrospective cohort to demonstrate the health status of the Korean Vietnam War veterans and their second-generation offsprings. The KOVECO is a collaboration of data from the Ministry of Patriots and Veterans Affairs and the National Health Insurance Sharing Service from 2002 to 2018. The study participants were all Korean Vietnam War veterans and their second-generation offsprings, and the references were the general population in which gender and region were matched with the participants. As of 2002, 191,272 Vietnam War veterans (1,000,320 comparisons) and 1,963,402 s-generations (1,173,061 references) were included in the cohort. The KOVECO consists of personal information, medical facility visit information, and general health examination information. The KOVECO could act as a health surveillance system, which would be able to detect long-term health effects caused by exposure to AO and provide a direction for policy making through academic research.

Changes in predicted lean body mass, appendicular skeletal muscle mass, and body fat mass and cardiovascular disease

BACKGROUND

Little is known about the association of changes in two body components, muscle and fat mass, with the risk of cardiovascular disease (CVD) among young adults. We investigated the association of changes in predicted lean body mass index (LBMI), appendicular skeletal muscle mass index (ASMI), and body fat mass index (BFMI) with the development of CVD among young adults.

METHODS

This nationwide, population-based cohort study included 3 727 738 young adults [2 406 046 (64.5%) men and 1 321 692 (35.5%) women] aged 20-39 years without a previous history of CVD who underwent two health screening examinations during 2009-2010 and 2011-2012. Using validated and robust prediction equations, we calculated the changes in predicted LBMI, ASMI, and BFMI from the first to the second examinations.

RESULTS

The mean (SD) age was 32.2 (4.9) years, and 2 406 046 (64.5%) of the participants were men. A total of 23 344 CVD events were detected during 22 257 632 person-years of follow-up. Each 1 kg/m² increase in predicted LBMI and ASMI change was associated with a reduced risk of CVD among men [adjusted hazard ratio (aHR): 0.86, 95% confidence interval (CI) 0.82-0.91; aHR: 0.76, 95% CI 0.69-0.82, respectively] and women (aHR: 0.77, 95% CI 0.63-0.95; aHR: 0.75, 95% CI 0.59-0.96). Each 1 kg/m² increase in predicted BFMI change was associated with an increased risk of CVD among men (aHR: 1.16, 95% CI 1.10-1.22) and women (aHR: 1.32, 95% CI 1.06-1.65). In both sexes, decreases in predicted LBMI and ASMI were associated with greater CVD risk, and decreased predicted BFMI was associated with a reduced CVD risk. Those who maintained their BMI between -1 and +1 kg/m² also had a decreased risk of CVD per 1 kg/m² increase in predicted LBMI and ASMI change among men (aHR: 0.86, 95% CI 0.80-0.92; aHR: 0.85, 95% CI 0.76-0.95) and women (aHR: 0.62, 95% CI 0.47-0.83; aHR: 0.59, 95% CI 0.44-0.80) and had a greater risk of CVD per 1 kg/m² increase in predicted BFMI change among men (aHR: 1.17, 95% CI 1.10-1.25) and women (aHR: 1.64, 95% CI 1.20-2.23). Regardless of changes in weight, such as from normal to obese or vice versa, these results were consistent.

CONCLUSIONS

Among young adults, increased predicted muscle mass or decreased predicted fat mass were associated with a reduced risk of development of CVD. Decreased predicted muscle mass or increased predicted fat mass were associated with an elevated risk of development of CVD.

The association between diabetes and hypertension with the number and extent of weight cycles determined from 6 million participants

The purpose of this study was to elucidate the association between weight cycling and clinical outcomes such as type 2 diabetes and hypertension with differential effects of baseline age and obesity. Nationwide data from 6,132,569 healthy adults who underwent five or more health screenings between 2002 and 2011 were analyzed and followed until December 2019 for type 2 diabetes and hypertension. Weight cycling was defined as a change in body weight followed by another change in the opposite direction. Through the Cox proportional hazards model, the number and degree of weight cycles were positively associated with increased risk of type 2 diabetes and hypertension. The hazard ratios (HRs) of weight cycling for type 2 diabetes and hypertension were as high as 1.263 (1.213-1.315) and 1.175 (1.144-1.207) at two or more weight cycles of 10% of body weight (BW), respectively. The association was stronger for females, individuals with normal body weight/BMI, and older individuals. Weight cycling was significantly associated with an increased risk of adverse health outcomes and was stronger in individuals with normal BMI and females, indicating that these people should be informed about the potential risk of weight cycling.

Maternal disease factors associated with neonatal jaundice: a case-control study

Background

Neonatal jaundice is common, and despite the considerable medical costs associated with it, there are still few studies on the maternal factors associated with it. Identification of maternal factors associated with neonatal jaundice is very important in terms of prevention, screening and management of neonatal jaundice. The current study aimed to identify maternal disease factors associated with neonatal jaundice.

Methods

We compared the maternal disease diagnostic codes during pregnancy (study A) and 1 year before conception (study B) in mothers whose insurance claims data included newborns treated for neonatal jaundice before birth registration via the National Health Insurance Service–National Sample Cohort (control group). To decrease the effect of confounding variables, the neonatal jaundice and control groups were matched at a ratio of 1:10 via propensity score matching using covariates including age and income.

Results

The matched samples for studies A and B included 4,026 and 3,278 (jaundice group: 366 and 298) delivery cases, respectively. In both studies, the jaundice group had a higher proportion of patients who underwent cesarean section than the control group. In study A, other diseases of the digestive system had the highest odds ratio (OR) (K92; adjusted OR: 14.12, 95% confidence interval [CI]: 2.70–82.26). Meanwhile, gastritis and duodenitis had the lowest OR (K29; adjusted OR: 0.39, 95% CI: 0.22–0.69). In study B, salpingitis and oophoritis had the highest OR (N70; adjusted OR: 3.33, 95% CI: 1.59–6.94). Heartburn had the lowest OR (R12; adjusted OR: 0.29, 95% CI:0.12–0.71).

Conclusions

This study identified maternal disease factors correlated with neonatal jaundice during pregnancy and 1 year before conception. Maternal risk factors for neonatal jaundice included syphilis and leiomyoma during pregnancy, and salpingo-oophoritis before pregnancy. The protective factors included infection, inflammatory diseases, and dyspepsia.

Analysis of treatment pattern of anti-dementia medications in newly diagnosed Alzheimer's dementia using OMOP CDM

Anti-dementia medications are widely prescribed to patients with Alzheimer's dementia (AD) in South Korea. This study investigated the pattern of medical management in newly diagnosed patients with AD using a standardized data format-the Observational Medical Outcome Partnership Common Data Model from five hospitals. We examined the anti-dementia treatment patterns from datasets that comprise > 5 million patients during 2009-2019. The medication utility information was analyzed with respect to treatment trends and persistence across 11 years. Among the 8653 patients with newly diagnosed AD, donepezil was the most commonly prescribed anti-dementia medication (4218; 48.75%), followed by memantine (1565; 18.09%), rivastigmine (1777; 8.98%), and galantamine (494; 5.71%). The rising prescription trend during observation period was found only with donepezil. The treatment pathways for the three cholinesterase inhibitors combined with N-methyl-D-aspartate receptor antagonist were different according to the drugs (19.6%; donepezil; 28.1%; rivastigmine, and 17.2%; galantamine). A 12-month persistence analysis showed values of approximately 50% for donepezil and memantine and approximately 40% for rivastigmine and galantamine. There were differences in the prescribing pattern and persistence among anti-dementia medications from database using the Observational Medical Outcome Partnership Common Data Model on the Federated E-health Big Data for Evidence Renovation Network platform in Korea.

Non-Alcoholic Fatty Liver Disease Defined by Fatty Liver Index and Incidence of Heart Failure in the Korean Population: A Nationwide Cohort Study

Fatty liver index (FLI) is a simple and useful index that evaluates non-alcoholic fatty liver disease (NAFLD), particularly in large epidemiologic studies. Heart failure (HF) is becoming a burden to public health as the global trend toward an aging society continues. Thus, we investigated the effect of FLI on the incidence of HF using large cohort data from the Korean National Health Insurance health database. Methods and Results: A total of 7,958,538 subjects aged over 19 years without baseline HF (men = 4,142,264 and women = 3,816,274) were included. Anthropometric and biochemical measurements were evaluated. FLI scores were calculated and FLI ≥ 60 was considered as having NAFLD. Hazard ratios (HRs) and 95% confidence intervals (CIs) for HF incidence were analysed using multivariable time-dependent Cox proportional hazard models. During a mean follow up of 8.26 years, 17,104 participants developed HF. The FLI components associated with the incidence of HF and FLI showed a causal relationship with HF; the FLI ≥ 60 group had a higher HR for HF (HR 1.493; 95% CIs 1.41−1.581) than the FLI < 30 group. Subgroup analysis showed that fatty liver (FLI ≥ 60) with age ≥ 65 years or women displayed higher HR for HF than fatty liver with age < 65 or men, respectively. An increase in FLI score significantly increased the HR for HF except for those with a FLI score change from <30 to 30−60. Conclusion: NAFLD defined by FLI and increase in FLI score were associated with the incidence of HF. Further detailed prospective studies are needed.

Postoperative Thromboembolism According to the Type of Surgery: A Nationwide Study in the Republic of Korea

Postoperative thromboembolism (TE) is a serious, but preventable, complication in surgical patients. Orthopedic surgery, neurosurgery, and vascular surgery are considered high risk for TE, and current guidelines recommend TE prophylaxis. However, insufficient data exist regarding TE risk in other general surgeries. This study identified the actual incidence and relative risk of postoperative TE in the real world, according to surgery type. Twenty-six surgeries between 1 December 2017 and 31 August 2019 were selected from the Health Insurance Review and Assessment Service database and analyzed for postoperative TE events. Among all patients, 2.17% had a TE event within 6 months of surgery and 0.75% had a TE event owing to anticoagulant treatment. The incidence of total TE events was the highest in total knee replacement (12.77%), hip replacement (11.46%), and spine surgery (5.98%). The incidence of TE with anticoagulant treatment was the highest in total knee replacement (7.40%), hip replacement (7.20%), and coronary artery bypass graft (CABG) surgery (3.81%). Hip replacement, total knee replacement, CABG surgery, spine surgery, and cardiac surgery except CABG surgery, showed relatively higher risks for total claimed venous TE. The relative risk of venous TE with anticoagulant treatment was the highest for hysterectomy, partial hepatectomy, hip replacement, cardiac surgery except CABG surgery, and total knee replacement. The relative risk of arterial TE was the highest for cardiac surgery, total knee replacement, and hip replacement. In the real world, the incidence of postoperative TE events from total knee replacement and those from hip replacement remain high, and some surgeries could have a relatively higher risk of TE than other surgeries. For patients undergoing these surgeries, studies to reduce the incidence of postoperative TE in clinical practice should be conducted.

TNF inhibitors increase the risk of nontuberculous mycobacteria in patients with seropositive rheumatoid arthritis in a mycobacterium tuberculosis endemic area

The aim of this study is to examine the impact of tumor necrosis factor inhibitors (TNFI) on nontuberculous mycobacterium (NTM) infection in rheumatoid arthritis (RA) patients in a mycobacterium tuberculosis (MTB) endemic area. We selected 1089 TNFI-treated RA patients and 4356 untreated RA patients using propensity-matching analysis according to age, gender, and Charlson comorbidity index using the Korean National Health Insurance Service database from July 2009 to December 2010. Both groups were followed-up until the end of 2016 to measure the incidence of mycobacterial diseases. The incidence rate of NTM in TNFI-treated RA group was similar to those of MTB (328.1 and 340.9 per 100,000 person-years, respectively). The adjusted hazard ratio (aHR) of NTM for TNFI-treated RA compared to untreated RA was 1.751(95% CI 1.105-2.774). The risk of TNFI-associated NTM in RA was 2.108-fold higher among women than men. The age-stratified effects of TNFI on NTM development were significantly high in RA patients aged 50-65 years (aHR 2.018). RA patients without comorbidities had a higher incidence of NTM following TNFI treatment (aHR 1.742). This real-world, observational study highlights the need to increase awareness of NTM in TNFI-treated RA patients in an MTB endemic area.

Estimating Risk of Cardiovascular Disease Among Long-Term Colorectal Cancer Survivors: A Nationwide Cohort Study

Background

Concerns about a growing number of colorectal cancer survivors have emerged regarding cardiovascular disease (CVD) risks. However, there is not yet a predictive tool that can estimate CVD risk and support the management of healthcare as well as disease prevention in terms of CVD risk among long-term colorectal cancer survivors.

Aim

To develop predictive tools to estimate individualized overall and each subtype of CVD risk using a nationwide cohort in South Korea.

Methods and Results

A total of 4,709 newly diagnosed patients with colorectal cancer who survived at least 5 years in the National Health Insurance System were analyzed. Cox proportional hazard regression was used for the identification of independent risk factors for the derivation of predictive nomograms, which were validated in an independent cohort (n = 3,957). Age, fasting serum glucose, γ-glutamyl transpeptidase, Charlson comorbidity index, household income, body mass index, history of chemotherapy, cigarette smoking, and alcohol consumption were identified as independent risk factors for either overall CVD or each subtype of CVD subtype. Based on the identified independent risk factors, six independent nomograms for each CVD category were developed. Validation by an independent cohort demonstrated a good calibration with a median C-index of 0.687. According to the nomogram-derived median score, relative risks of 2.643, 1.821, 4.656, 2.629, 4.248, and 5.994 were found for overall CVD, ischemic heart disease, myocardial infarction, total stroke, ischemic stroke, and hemorrhage stroke in the validation cohort.

Conclusions

The predictive tools were developed with satisfactory accuracy. The derived nomograms may support the estimation of overall and individual CVD risk for long-term colorectal cancer survivors.

Korea hypertension fact sheet 2021: analysis of nationwide population-based data with special focus on hypertension in women

BACKGROUND

The Korean Society of Hypertension has published the Korea Hypertension Fact Sheet 2021 to provide an overview of the magnitude and management status of hypertension and their recent trends.

METHODS

The Fact Sheets were based on the analyses of Korean adults aged 20 years or older of the 1998-2019 Korea National Health and Nutrition Examination Survey and the 2002-2019 National Health Insurance Big Data.

RESULTS

Currently, the population average of systolic/diastolic blood pressure was 119/76 mmHg in Korean adults aged 20 years or older showing little change in the recent decade. It is estimated that 28% of the adult population aged 20 or older (33% of adults aged 30 or older) have hypertension. The estimated number of people with hypertension was 6.30 million for men and 5.77 million for women, and 1.96 million for men and 2.99 million for women among the population aged 65 or older. The number of people diagnosed with hypertension increased from 3.0 million in 2002 to 10.1 million in 2019. During the same period, the number of people using antihypertensive medication increased from 2.5 million to 9.5 million, and the number of people adherent to treatment increased from 0.6 million to 6.9 million. Among antihypertensive prescriptions, 40.6% of the patients received monotherapy, 43.4% received dual therapy, and 16.0% received triple or more therapy. The most commonly prescribed antihypertensive medication was angiotensin receptor blockers (ARB), followed by calcium channel blockers (CCB) and diuretics. In young women, angiotensin-converting enzyme inhibitors (ACEi), ARB and CCB are less frequently prescribed than in men, but 59.5% of hypertensive women aged 20-39 are prescribed ACEi or ARBs. Hypertensive disorders during pregnancy have been increasing over the past 10 years. In 2019, 5.4% of women who gave birth were diagnosed with chronic hypertension and 3.1% with pregnancy-induced hypertension.

CONCLUSIONS

To achieve further improvement in management of hypertension, we need to encourage awareness and treatment in young adults. It is required to develop tailored prevention and management strategies that are appropriate for and inclusive of various demographics.

Remission of type 2 diabetes after gastrectomy for gastric cancer: diabetes prediction score

BACKGROUND

Although type 2 diabetes (T2D) remission after gastric cancer surgery has been reported, little is known about the predictors of postoperative T2D remission.

METHODS

This study used data from a nationwide cohort provided by the National Health Insurance Service in Korea. We developed a diabetes prediction (DP) score, which predicted postoperative T2D remissions using a logistic regression model based on preoperative variables. We applied machine-learning algorithms [random forest, XGboost, and least absolute shrinkage and selection operator (LASSO) regression] and compared their predictive performances with those of the DP score.

RESULTS

The DP score comprised five parameters: baseline body mass index (< 25 or ≥ 25 kg/m²), surgical procedures (subtotal or total gastrectomy), age (< 65 or ≥ 65 years), fasting plasma glucose levels (≤ 130 or > 130 mg/dL), and antidiabetic medications (combination therapy including sulfonylureas, combination therapy not including sulfonylureas, single sulfonylurea, or single non-sulfonylurea]). The DP score showed a clinically useful predictive performance for T2D remission at 3 years after surgery [training cohort: area under the receiver operating characteristics (AUROC) 0.73, 95% confidence interval (CI), 0.71-0.75; validation cohort: AUROC 0.72, 95% CI 0.69-0.75], which was comparable to that of the machine-learning models (random forest: AUROC 0.71, 95% CI 0.68-0.74; XGboost: AUROC 0.70, 95% CI 0.67-0.73; LASSO regression: AUROC 0.75, 95% CI 0.73-0.78 in the validation cohort). It also predicted the T2D remission at 6 and 9 years after surgery.

CONCLUSIONS

The DP score is a useful scoring system for predicting T2D remission after gastric cancer surgery.

The Trend of Psychiatric Visits and Psychiatric Medication Prescription Among People Tested for SARS-CoV-2 During the Initial Phase of COVID-19 Pandemic in South Korea

OBJECTIVE

The objective of this study was to monitor the trend of psychiatric visits and medication prescriptions among people tested for SARS-CoV-2 during the initial phase of coronavirus disease 2019 (COVID-19) pandemic in South Korea.

METHODS

We conducted a population-based cohort study using data from the National Health Insurance Service (NHIS) linked to the Korea Disease Control and Prevention Agency (KDCA) data. The overall trend of psychiatric visits during COVID-19 for each month was compared to the month prior to COVID-19. The number of psychiatric medication prescription records was monitored from January 2019 to May 2020.

RESULTS

A total of 212,678 individuals were tested for SARS-CoV-2 between January 2020 and May 2020. Among these individuals, 72.1% (n=153,309) did not have pre-existing mental illness, and 27.9% (n=59,369) had pre-existing mental illness. We found that most psychiatric visits were made in March, and patients without pre-existing mental illness significantly increased in psychiatric outpatients during the COVID-19 pandemic (p trend<0.001). In addition, psychiatric medication prescriptions were the most prescribed between March and April 2020.

CONCLUSION

We identified a rising trend in psychiatric visits and medication prescriptions among people who were tested for SARSCoV-2 during the initial phase of COVID-19 pandemic in South Korea.

Lifestyle changes and risk of tuberculosis in patients with type 2 diabetes mellitus: A nationwide cohort study

We investigated the impacts of lifestyle changes, namely, smoking, alcohol intake, and exercise, on the development of tuberculosis (TB) in patients with type 2 diabetes mellitus (T2DM). A retrospective population-based cohort study used data from the Korean National Health Insurance system database. We examined subjects diagnosed with T2DM and without previous history of TB between 2009 and 2012 who underwent two serial health examinations. The study participants were classified into each of the four groups based on changes in the patterns of smoking, alcohol intake, and exercise at the time of the second examination. The outcome of the study was newly diagnosed TB in patients with T2DM. Among 1,659,804 included subjects, TB was newly diagnosed with 10,288 subjects. Both consistent smokers (HR 1.406; 95% CI 1.333-1.483) and new smokers (HR 1.185; 95% CI 1.063-1.320) had a higher TB risk than smoking quitters (HR 1.107; 95% CI 1.009-1.216) and never smokers. Both consistent heavy drinkers (HR 1.281; 95% CI 1.172-1.399) and heavy drinking quitters (HR 1.247; 95% CI 1.147-1.356) had a higher TB risk than new heavy drinkers and never drinkers. With respect to exercise, persistent non-exercisers (HR 1.309; 95% CI 1.72-1.399) and exercise quitters (HR 1.164; 95% CI 1.066-1.271) had a higher TB risk than new exercisers. In the subgroup analysis, a significant interaction was observed between lifestyle changes and age. We found that lifestyle changes were associated with development of TB in patients with T2DM. These results suggest that lifestyle management could be a valuable strategy for control of TB in Korea.

Non-alcoholic Fatty Liver Disease and the Risk of Incident Atrial Fibrillation in Young Adults: A Nationwide Population-Based Cohort Study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a multisystem disease including cardiovascular. However, the association between NAFLD and the risk of incident atrial fibrillation (AF), especially in young adults, remains unclear. We aimed to evaluate the association between NAFLD as assessed by the fatty liver index (FLI) and the risk of AF in young adults.

METHODS

We identified individuals aged 20-39 years who underwent health examinations conducted by the Korean National Health Insurance Corporation between January 2009 and December 2012. Individuals with significant liver disease, heavy alcohol consumption, or prevalent AF were excluded. We categorized based on FLI: <30, 30 to <60, and ≥60. Incident AF was evaluated as the primary outcome.

RESULTS

We included 5,333,907 subjects (mean age, 31 ± 5 years; men, 57%). During a mean follow-up of 7.4 ± 1.1 years, 12,096 patients had newly diagnosed AF (incidence rate 0.31 per 1,000 person-years). After adjustment, subjects with FLI 30 to <60 and FLI ≥60 showed a higher risk of AF compared to those with FLI <30 (hazard ratio [HR] 1.21, 95% confidence interval [CI, 1.15-1.27] and HR 1.47, 95% CI [1.39-1.55], p < 0.001, respectively). In women, the increased AF risk was accentuated in the higher FLI group than in the individuals with FLI <30, compared with men (p-for-interaction = 0.023). A higher incident AF risk in the higher FLI groups was consistently observed in various subgroups.

CONCLUSION

Among young adults, NAFLD assessed using FLI was positively correlated with the AF risk. These findings support the evidence of AF screening in young adults with high FLI scores.

Microcalcifications, mammographic breast density, and risk of breast cancer: a cohort study

BACKGROUND

Breast density and microcalcifications are strongly associated with the risk of breast cancer. However, few studies have evaluated the combined association between these two factors and breast cancer risk. We investigated the association between breast density, microcalcifications, and risk of breast cancer.

METHODS

This cohort study included 3,910,815 women aged 40-74 years who were screened for breast cancer between 2009 and 2010 and followed up until 2020. The National Health Insurance Service database includes national health-screening results from the national breast cancer screening program, which is an organized screening program provided every 2 years for all women aged 40 years or older. Breast density was assessed based on the Breast Imaging Reporting and Data System (BI-RADS) 4^th edition, mostly through visual assessment by radiologists. The presence or absence of microcalcifications was obtained from the mammographic results. Cox proportional hazard regression for breast cancer risk was used to estimate hazard ratios (aHRs) adjusted for breast cancer risk factors.

RESULTS

A total of 58,315 women developed breast cancer during a median follow-up of 10.8 years. Women with breast cancer had a higher proportion of microcalcifications than women without breast cancer (0.9% vs. 0.3%). After adjusting for breast density, women with microcalcification had a 3.07-fold (95% confidence interval [CI] 2.82-3.35) increased risk of breast cancer compared to women without microcalcification. The combined association between microcalcification and breast density dramatically increased the risk of breast cancer, corresponding to a higher level of breast density. Among postmenopausal women, the highest risk group was women with BI-RADS 4 and microcalcification. These women had more than a sevenfold higher risk than women with BI-RADS 1 and non-microcalcification (aHR, 7.26; 95% CI 5.01-10.53).

CONCLUSION

Microcalcification is an independent risk factor for breast cancer, and its risk is elevated when combined with breast density.

Maternal and Neonatal Risk Factors Affecting the Occurrence of Neurodevelopmental Disorders: A Population-Based Nationwide Study

To investigate the maternal and neonatal risk factors related to pregnancy and birth affecting the occurrence of neurodevelopmental disorders to their children using the medical claim data for the whole population. The study was conducted on all the babies born in Korea from 2005 to 2009 based on data from the National Health Information Database. All birth records were tracked from birth to December 31, 2015. To analyze factors related to the mother, data related to the mother of the newborn were collected. Increased maternal age was found to increase the risk of cerebral palsy (adjusted odds ratio [aOR] = 1.46, 95% confidence interval [CI] [1.22, 1.75]) and autism spectrum disorder (aOR = 1.48, 95% CI [1.25, 1.76]), while lowering the risk of intellectual disability (aOR = 1.83, 95% CI [1.33, 2.53]) and speech and language impairment (aOR = 1.41, 95% CI [1.08, 1.83]) compared with the reference group aged 25 to 29 years old. The incidence affected by socioeconomic factors varied according to the types of disorders. Among various risk factors, prematurity or low birth weight, problems associated with amniotic fluid or amniotic membrane, preeclampsia or eclampsia, and cesarean section affect the incidence of neurodevelopmental disorders. To reduce the incidence or severity of neurodevelopmental disorders, a better understanding of the risk factors of neurodevelopmental disorders is important. The results of this study can be used as basic data to help such understanding.

Personalized 5-Year Prostate Cancer Risk Prediction Model in Korea Based on Nationwide Representative Data

Prostate cancer is the fourth most common cause of cancer in men in Korea, and there has been a rapid increase in cases. In the present study, we constructed a risk prediction model for prostate cancer using representative data from Korea. Participants who completed health examinations in 2009, based on the Korean National Health Insurance database, were eligible for the present study. The crude and adjusted risks were explored with backward selection using the Cox proportional hazards model to identify possible risk variables. Risk scores were assigned based on the adjusted hazard ratios, and the standardized points for each risk factor were proportional to the β-coefficient. Model discrimination was assessed using the concordance statistic (c-statistic), and calibration ability was assessed by plotting the mean predicted probability against the mean observed probability of prostate cancer. Among the candidate predictors, age, smoking intensity, body mass index, regular exercise, presence of type 2 diabetes mellitus, and hypertension were included. Our risk prediction model showed good discrimination (c-statistic: 0.826, 95% confidence interval: 0.821-0.832). The relationship between model predictions and actual prostate cancer development showed good correlation in the calibration plot. Our prediction model for individualized prostate cancer risk in Korean men showed good performance. Using easily accessible and modifiable risk factors, this model can help individuals make decisions regarding prostate cancer screening.

The Change in Metabolic Syndrome Status and the Risk of Nonviral Liver Cirrhosis

Background: Nonalcoholic fatty liver disease is considered to be the hepatic component of metabolic syndrome (MetS). However, the association between changes in MetS status and the risk of liver cirrhosis (LC) has not been investigated to date. This study assessed the association between changes in MetS and subsequent nonviral LC development. Methods: Data were obtained from the Korean National Health Insurance Service. Individuals who participated in health screenings from both 2009 to 2010 and 2011 to 2012 were included. The primary outcome was LC development according to the static and dynamic MetS status. Subjects were stratified into four groups according to the change in MetS status observed from the two-year interval screening (2009–2011). Cox regression analysis was used to examine the hazard ratios of LC. Results: During a median of 7.3 years of follow-up, 24,923 incident LC cases developed among 5,975,308 individuals. After adjusting for age, sex, smoking, alcohol, regular exercise, and body mass index, the adjusted hazard ratios (95% confidence intervals) for LC development were 1.39 (1.33–1.44) for the MetS-Developed group, 1.32 (1.26–1.37) for the MetS-Recovered group, and 1.51 (1.45–1.56) for the MetS-Sustained group, relative to the MetS-Free group. Stratified analyses according to age, sex, smoking, alcohol intake, exercise, diabetes mellitus, hypertension, dyslipidemia, and chronic kidney disease showed similar results. Conclusions: Both static and dynamic MetS status are independent risk factors for LC development. The risk of LC was the highest in people with sustained MetS and was lower in the MetS-Recovered group than in the MetS-Sustained group. These results suggest that improving a person’s MetS status may be helpful in preventing LC.

Association between female reproductive factors and gout: a nationwide population-based cohort study of 1 million postmenopausal women

BACKGROUND

Previous studies have shown that the incidence and risk factors of gout differs according to sex. However, little research has been done on the association between reproductive factors and gout. We conducted an analysis of a large nationwide population-based cohort of postmenopausal women to determine whether there is an association between reproductive factors and the incidence of gout.

METHODS

A total of 1,076,378 postmenopausal women aged 40-69 years who participated in national health screenings in 2009 were included in the study. The outcome was the occurrence of incident gout, which was defined using the ICD-10 code of gout (M10) in the claim database. Cox proportional hazard models were used for the analyses and stratified analyses according to body mass index (BMI) and the presence/absence of chronic kidney disease (CKD) were performed.

RESULTS

The mean follow-up duration was 8.1 years, and incident cases of gout were 64,052 (incidence rate 7.31 per 1000 person-years). Later menarche, earlier menopause, and a shorter reproductive span were associated with a high risk of gout. No association between parity and gout incidence was observed. Use of oral contraceptives (OC) and hormone replacement therapy (HRT) were associated with an increased risk of gout. The association between reproductive factors and gout was not statistical significant in the high BMI group. The effects of OC and HRT usage on gout were not significant in the CKD group.

CONCLUSION

Shorter exposure to endogenous estrogen was associated with a high risk of gout. Conversely, exposure to exogenous estrogen such as OC and HRT was associated with an increased risk of gout.

Nationwide trends in prevalence of underweight, overweight, and obesity among people with disabilities in South Korea from 2008 to 2017

Objectives

This study investigated the 10-year trends of weight and prevalence of underweight, overweight and obesity according to disability grade and types compared with those without disabilities.

Methods

This serial cross-sectional analysis was conducted using national disability registration data with national general health checkup data from 2008 to 2017. Age-standardized prevalence of underweight and obesity were analyzed for each year, according to the presence, type, and severity of disabilities. Odds of underweight, overweight, obesity, and severe obesity were examined by multinomial logistic regression after adjusting for socio-demographic and clinical variables using data in 2017.

Results

Over 10 million subjects in each year were included in the analysis. In 2017, 14,246,785 people with age between 19 and 110 years were included and 53.1% was men. For 10 years, age-standardized prevalence of obesity and severe obesity showed significant increases regardless of sex and presence of disability. However, age-standardized underweight prevalence in people without disability tended to decrease whereas it was an increase in 2012 and the prevalence has remained steady since in people with disability. People with disabilities had higher odds of underweight compared to those without disability (OR 1.41, 95% CI 1.38–1.44 in male and OR 1.31, 95% CI 1.28–1.34 in female), especially in those with severe disabilities (OR 2.00, 95% CI 1.94–2.06 in male and OR 1.83, 95% CI 1.77–1.89 in female). Women with disabilities are more likely to be obese than those without disabilities regardless of disability severity (OR 1.40, 95% CI 1.38–1.41). Participants with mental disorder showed the highest prevalence of obesity, followed by epilepsy and developmental disability.

Conclusions

Having a disability was associated with higher odds/probability of both obesity and underweight. The intersection of female, severe disability, and mental/developmental disabilities was associated with probability of severe obesity. Simultaneous efforts are needed to develop health policy to reduce both the prevalence of obesity and underweight.

Metformin use and cardiovascular outcomes in patients with diabetes and chronic kidney disease: a nationwide cohort study

BACKGROUND

Metformin has recently been shown not to increase the risk of lactic acidosis in patients with chronic kidney disease (CKD). Thus, the criteria for metformin use in this population has expanded. However, the relationship between metformin use and clinical outcomes in CKD remains controversial.

METHODS

This study considered data from 97,713 diabetes patients with an estimated glomerular filtration rate of <60 mL/min/1.73 m2. The primary outcome was major adverse cardiac and cerebrovascular events (MACCE), and the secondary outcomes were all-cause mortality and incident end-stage renal disease (ESRD).

RESULTS

Metformin users had a significantly higher risk of MACCE than non-users (hazard ratio [HR], 1.20; 95% confidence interval [CI], 1.14-1.26; p < 0.001). However, metformin users had a lower risk of all-cause mortality (HR, 0.78; 95% CI, 0.74-0.81; p < 0.001) and ESRD (HR, 0.44; 95% CI, 0.42-0.47; p < 0.001) during follow-up than non-users did. The relationships between metformin use and clinical outcomes remained consistent in propensity score matching analyses and subgroup analyses of patients with adequate adherence to anti-diabetes medication.

CONCLUSION

Treatment with metformin was associated with an increased risk of MACCE in patients with diabetes and CKD. However, metformin users had a lower risk of all-cause mortality and ESRD during follow-up than non-users did. Therefore, metformin needs to be carefully used in patients with CKD.

Comparison of fracture risk between type 1 and type 2 diabetes: a comprehensive real-world data

Population-based cohort study of 6,548,784 Korean subjects demonstrates that the risk of fracture was higher in patients with diabetes than in nondiabetic subjects. Furthermore, patients with type 1 diabetes were associated with a higher risk of fracture than patients with type 2 diabetes for all measurement sites.

INTRODUCTION

Diabetes mellitus is associated with increased fracture risk. Although the pathophysiologic effect on bone metabolism differs according to the type of diabetes, a higher risk of fracture in patients with diabetes than in nondiabetic patients has been consistently demonstrated. Considering the ever-increasing number of patients with diabetes, we aimed to provide updated information on whether this phenomenon remains valid in real-world settings by using large-scale population datasets.

METHODS

We conducted a retrospective longitudinal study using data from the Korean National Health Insurance Service dataset of preventive health check-ups between January 2009 and December 2016. The hazard ratios were calculated for any fracture, vertebral fracture, and hip fracture and were analyzed according to the presence and type of diabetes. Among 10,585,818 subjects, 6,548,784 were eligible for the analysis (2418 patients with type 1 diabetes mellitus [T1DM] and 506,208 patients with type 2 diabetes mellitus [T2DM]).

RESULTS

The mean follow-up duration (in years) was 7.0 ± 1.3 for subjects without diabetes, 6.4 ± 2.0 for those with T1DM, and 6.7 ± 1.7 for T2DM. Patients with T1DM had a higher incidence rate for all types of fractures per 1000 person-years. The fully adjusted hazard ratios (HRs) for any fracture, vertebral fracture, and hip fracture were higher in T1DM than in T2DM (1.37 [95% confidence interval (CI): 1.23-1.52] for any fracture, 1.33 [95% CI: 1.09-1.63] for vertebral fracture, and 1.99 [95% CI: 1.56-2.53] for hip fracture).

CONCLUSIONS

In this large-scale population analysis, diabetes was associated with a higher risk of all types of fractures. Patients with T1DM had a higher risk of fracture than those with T2DM for all measurement sites, and hip fractures had the highest risk. Therefore, fracture prevention training for patients with diabetes is advisable.

Increasing trend in rhegmatogenous retinal detachment in Korea from 2004 to 2015

Background

To determine the 12-year incidence of and trends in rhegmatogenous retinal detachment (RRD) requiring surgery in Korea.

Methods

This was a nationwide, population-based, retrospective study. We identified 53,179 patients with incident RRD requiring surgery using the Korean National Health Claims Database from 2004 to 2015. We estimated the crude incidence rates and age- and sex-standardized incidence rates per 100,000 person-years in each year during the study period. A joinpoint regression analysis was performed to determine the trend.

Results

The average annual incidence rate was 9.78 (95% CI: 9.70–9.86). Male patients showed an incidence rate (10.68 [95% CI: 10.57–10.80]) 1.20 times that of female patients (8.87 [95% CI: 8.76–8.98]). The incidence showed a bimodal distribution; the highest peak was in the 60–64 year age group (23.77 [95% CI: 23.18–24.35]) and the second peak was in the 20–24 year age group (7.68 [95% CI: 7.41–7.95]). An increasing trend of RRD incidence was observed in the total population throughout the study period using joinpoint analysis (annual percentage change [APC], 2.05; 95% CI: 0.7–3.4). The increasing trend was more prominent among individuals aged under 50 years (APC, 3.44; 95% CI: 2.3–4.6), while among those aged 50 years or above, the increasing incidence was observed only in male patients.

Conclusions

In Korea, the incidence of RRD has increased recently. People in the < 50 year age group accounted for the major part of this significant increase, which is related to the increasing incidence of myopia in the young generation in Asia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-02157-1.

Clinical Association between Gout and Parkinson's Disease: A Nationwide Population-Based Cohort Study in Korea

Background and Objectives: This retrospective cohort study aimed to investigate the association between gout and Parkinson’s disease (PD) in Korea. Materials and Methods: Overall, 327,160 patients with gout and 327,160 age- and sex-matched controls were selected from the Korean National Health Insurance Service (NHIS) database. PD incidence was evaluated by reviewing NHIS records during the period from 2002 to 2019. Patients with a diagnosis of gout (International Classification of Diseases-10 (ICD-10), M10) who were prescribed medications for gout, including colchicine, allopurinol, febuxostat, and benzbromarone for at least 90 days were selected. Patients with PD who were assigned a diagnosis code (ICD-G20) and were registered in the rare incurable diseases (RID) system were extracted. Results: During follow-up, 912 patients with gout and 929 control participants developed PD. The incidence rate (IR) of overall PD (per 1000 person-years) was not significantly different between both groups (0.35 vs. 0.36 in gout and control groups, respectively). The incidence rate ratio (IRR) was 0.98 (95% CI: 0.89–1.07). The cumulative incidence of PD was not significantly different between the groups. No association between gout and PD was identified in univariate analysis (HR = 1.00, 95% CI: 0.91–1.10, p = 0.935). HR increased significantly with old age (HR = 92.08, 198, and 235.2 for 60–69 years, 70–79 years, and over 80 years, respectively), female sex (HR = 1.21, 95% CI: 1.07–1.37, p = 0.002), stroke (HR = 1.95, 95% CI: 1.76–2.16, p < 0.001), and hypertension (HR = 1.16, 95% CI: 1.01–1.34, p = 0.04). Dyslipidemia exhibited an inverse result for PD (HR = 0.6, 95% CI: 0.52–0.68, p < 0.001). Conclusions: This population-based study did not identify an association between gout and PD. Age, female sex, stroke, and hypertension were identified as independent risk factors for PD, and dyslipidemia demonstrated an inverse result for PD.

Clinical Impact of Hormone Replacement Therapy on Atrial Fibrillation in Postmenopausal Women: A Nationwide Cohort Study

Individuals with atrial fibrillation (AF), especially women, have an increased risk of stroke and death. Although hormone replacement therapy (HRT) is widely used in postmenopausal women, the association between HRT use and AF risk is unclear. We aimed to investigate the association between various types of HRT and AF. This was a population-based retrospective cohort study from The Korean National Health Insurance Service-National Sample Cohort (2004–2015). Participants were aged 45–60 years and were free from cardiovascular disease and AF at baseline. Overall, 13,452 (64.03%) women had never received HRT, 5671 (26.99%) had received HRT, and 1885 (8.98%) were currently receiving HRT. In multivariable analysis, the relative hazards for AF were significantly higher among current users (p < 0.001) and lower among past users (p = 0.069). Current users—except those using estradiol-only HRT—had significantly elevated AF risk. Among past users, only estradiol plus progestin HRT users had a reduced AF risk after adjusting for covariates (p = 0.027). Ongoing HRT posed an increased risk of AF. The degree of risk varied based on the specific type of estrogen and progestins co-administration. These findings indicate that, with respect to AF risk, oral estradiol-containing HRT is superior to HRT containing oral conjugated equine estrogen or tibolone.

Cardiovascular risk associated with allopurinol vs. benzbromarone in patients with gout

Aims 

With the high prevalence of gout and associated cardiovascular (CV) diseases, information on the comparative CV safety of individual urate-lowering drugs becomes increasingly important. However, few studies examined the CV risk of uricosuric agents. We compared CV risk among patients with gout who initiated allopurinol vs. benzbromarone.

Methods and results 

Using the Korean National Health Insurance claims data (2002–17), we conducted a cohort study of 124 434 gout patients who initiated either allopurinol (n = 103 695) or benzbromarone (n = 20 739), matched on propensity score at a 5:1 ratio. The primary outcome was a composite CV endpoint of myocardial infarction, stroke/transient ischaemic attack, or coronary revascularization. To account for competing risk of death, we used cause-specific hazard models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the outcomes comparing allopurinol initiators with benzbromarone. Over a mean follow-up of 1.16 years, 2258 patients developed a composite CV event. The incidence rate of the composite CV event was higher in allopurinol initiators (1.81 per 100 person-years) than benzbromarone (1.61 per 100 person-years) with a HR of 1.22 (95% CI 1.05–1.41). The HR for all-cause mortality was 1.66 (95% CI 1.43–1.93) among allopurinol initiators compared with benzbromarone.

Conclusion 

In this large population-based cohort of gout patients, allopurinol was associated with an increased risk of composite CV events and all-cause mortality compared to benzbromarone. Benzbromarone may reduce CV risk and mortality in patients with gout, although more studies are necessary to confirm our findings and to advance our understanding of the underlying mechanisms.

Comparison of risk profiles for new-onset atrial fibrillation between patients aged <60 and ≥60 years

BACKGROUND

Atrial fibrillation (AF) has a heterogeneous pathophysiology according to individual patient characteristics. This study aimed to identify the effects of widely known risk factors on AF incidence according to age and to elucidate the clinical implications of these effects.

METHODS AND RESULTS

We analyzed data from 501,668 subjects (≥18years old) without AF and valvular heart disease from the Korean National Health Insurance Service-National Sample Cohort. The total population was divided into two groups according to age, <60years and ≥60years. AF occurred in 0.7% of the overall population (3,416 of 501,668) during the follow-up period (mean 47.6 months). In Cox regression analysis, age, male sex, previous ischemic stroke, heart failure, and hypertension were related to increased risk of new-onset AF in both age groups. Especially in the <60years age group, risk of new-onset AF was increased by relatively modifiable risk factors: obesity (body mass index ≥25kg/m2; hazard ratio[HR] 1.37 [1.22-1.55], p<0.001, interaction p<0.001), and hypertension (HR 1.93[1.69-2.22], p<0.001, interaction p<0.001). Although interactions were not significant, chronic obstructive pulmonary disease (HR 1.41[1.24-1.60], p<0.001) and chronic kidney disease (HR 1.28[1.15-1.41], p<0.001) showed increased trends of the risk of new-onset AF in the ≥60years age group.

CONCLUSION

The risk profile for new-onset AF was somewhat different between the <60years and the ≥60years age groups. Compared to the ≥60years group, relatively modifiable risk factors (such as obesity and hypertension) had a greater impact on AF incidence in the <60years age group. Different management strategies to prevent AF development according to age may be needed.

Venous Thromboembolism Risk in Asian Patients with Inflammatory Bowel Disease: A Population-Based Nationwide Inception Cohort Study

Background/Aims

Inflammatory bowel disease (IBD) is associated with the occurrence of venous thromboembolism (VTE). However, to date, there have been few studies on the risk of VTE in Asian IBD patients. We aimed to estimate the incidence of VTE in Asian IBD patients and to determine if IBD is related to increased VTE risk.

Methods

We performed a population-based cohort study between 2004 and 2015 using Korean National Health Insurance data. IBD and VTE were defined by ICD-10 codes. Incidence rates of VTE were calculated among patients with IBD and among age- and sex-matched controls. Hazard ratios were estimated using Cox regression with adjustment for multiple variables. We performed additional analyses stratifying by age, sex, Charlson comorbidity index (CCI) score, and disease type.

Results

Among the 45,037 patients with IBD (IBD cohort) and 133,019 matched controls (non-IBD cohort) included in our analysis, 411 IBD patients and 641 controls developed VTE. The IBD cohort had a higher incidence rate ratio and risk of VTE than the non-IBD cohort (incidence rate ratio 1.92 and hazard ratio 1.93). Older age, female sex, higher CCI scores, cardiovascular disease, chronic kidney disease, use of steroids, and hospitalization were significant risk factors for VTE in patients with IBD.

Conclusions

The IBD patients in this study were approximately two times more likely to develop VTE than the non-IBD individuals. Our findings support the need for thromboprophylaxis in Asian IBD patients with various factors that further increase the risk of VTE.

Obesity and Risk of Diabetes Mellitus by Menopausal Status: A Nationwide Cohort Study

Although both obesity and menopause are associated with increased risk of diabetes mellitus (DM), the association between obesity and DM according to menopausal status remains uncertain. Therefore, we conducted a study to examine the relationship between obesity and incidence of diabetes mellitus (DM) in premenopausal and postmenopausal women. Total of 926,196 premenopausal and 1,193,881 postmenopausal women who underwent health examinations from 2009 to 2014 were identified using the database of the Korean National Health Insurance Service. We compared the incidence and risk of DM according to body mass index (BMI) and waist circumference (WC) in the two groups of women. Cox proportional hazards analyses were performed to evaluate the association between the presence of obesity and risk of DM according to menopausal state. During the 7.8-year follow-up period, 37,736 (4.1%) premenopausal women and 121,102 (10.1%) postmenopausal women were diagnosed with DM. Compared to the reference group (BMI 18.5-23), a stronger association between obesity and risk of DM was observed in both pre- and postmenopausal women: multivariable-adjusted hazard ratios and 95% confidence intervals for BMI subgroups <18.5, 23-25, 25-30, and >30 were 0.62 (0.54, 0.70), 1.91 (1.85, 1.97), 3.38 (3.28, 3.47), and 6.25 (6.02, 6.48), respectively (p trend < 0.001) in premenopausal women and 0.87 (0.82, 0.92), 1.44 (1.41, 1.46), 2.00 (1.97, 2.03), and 2.96 (2.89, 3.02) in postmenopausal women (p trend < 0.001, p-interaction < 0.001). A similar trend was observed for WC. Subgroup analyses of women aged 45 to 55 also showed a stronger association with DM in premenopausal than in postmenopausal women. In conclusion, the association between obesity and DM was stronger in premenopausal women than in postmenopausal women. As estrogens are synthesized in adipose tissue by aromatization of androgens after menopause, increased estrogen levels in obese postmenopausal might have a protective effect against DM.

Association between antibiotics use and diabetes incidence in a nationally representative retrospective cohort among Koreans

Numerous studies have reported that antibiotics could lead to diabetes, even after adjusting for confounding variables. This study aimed to determine the causal relationship between antibiotics use and diabetes in a nationally representative cohort. This retrospective cohort study included adults aged 40 years or older who were enrolled in the Korean National Health Insurance Service-Health Screening Cohort. Antibiotic exposure was assessed from 2002 to 2005 and newly diagnosed diabetes mellitus was determined based on diagnostic codes and history of antidiabetic medication use from 2006 to 2015. Multivariate Cox proportional hazards model was used to assess the association between antibiotic use and diabetes incidence. The mean age of the 201,459 study subjects was 53.2 years. People who used antibiotics for 90 or more days had a higher risk of diabetes (adjusted hazard ratio [aHR] 1.16, 95% confidence interval [CI] 1.07–1.26) compared to non-users. Those who used five or more classes of antibiotics had a higher risk of diabetes than those who used one antibiotic class (aHR 1.14; 95% CI 1.06–1.23). The clear dose-dependent association between antibiotics and diabetes incidence supports the judicious use of antibiotics in the future.

Association of L-α Glycerylphosphorylcholine With Subsequent Stroke Risk After 10 Years

IMPORTANCE

L-α glycerylphosphorylcholine (α-GPC, choline alphoscerate) is used globally by individuals older than 50 years based on its potential function as a precursor of acetylcholine. However, choline has previously been linked to a higher risk of cardiovascular disease via trimethylamine-N-oxide, a metabolite of choline by microbiota.

OBJECTIVE

To investigate the association between α-GPC use and subsequent 10-year stroke risk.

DESIGN, SETTING, AND PARTICIPANTS

A population-based, retrospective cohort study was conducted using data from the National Health Insurance Service of South Korea. Participants included men and women aged 50 years or older without underlying stroke or Alzheimer disease (N = 12 008 977).

MAIN OUTCOMES AND MEASURES

All participants were divided into whether they were prescribed α-GPC during 2006-2008. α-GPC users were matched with nonusers for all covariates to create a matched cohort. α-GPC use was further divided into durations less than 2, 2 to 6, 6 to 12, and more than 12 months of α-GPC prescriptions. The adjusted hazard ratios (aHRs) and 95% CIs for total stroke, ischemic stroke, and hemorrhagic stroke from January 1, 2009, to January 31, 2018, were calculated by multivariate Cox proportional hazards regression.

RESULTS

A total of 12 008 977 individuals (6 401 965 [53.3%] women) aged 50 years or older were included in the study. The mean (SD) age was 61.6 (9.4) years for nonusers and 68.3 (10.0) years for users, and that of the matching cohort was 68.2 (9.9) years for both groups. Compared with α-GPC nonusers (n = 11 900 100), users (n = 108 877) had a higher risk for total stroke (aHR, 1.46; 95% CI, 1.43-1.48), ischemic stroke (aHR 1.36; 95% CI, 1.33-1.39), and hemorrhagic stroke (aHR, 1.36; 95% CI, 1.28-1.44). After matching for all covariates, α-GPC users had a higher risk for total stroke (aHR, 1.43; 95% CI, 1.41-1.46), ischemic stroke (aHR, 1.34; 95% CI, 1.31-1.37), and hemorrhagic stroke (aHR, 1.37; 95% CI, 1.29-1.46). Increasing intake of α-GPC was associated with a higher risk for total stroke in a dose-response manner.

CONCLUSIONS AND RELEVANCE

In this cohort study, use of α-GPC was associated with a higher 10-year incident stroke risk in a dose-response manner after adjusting for traditional cerebrovascular risk factors. Future studies are needed to determine the possible mechanisms behind the potential cerebrovascular risk-elevating effects of α-GPC.

Gestational diabetes mellitus and the role of intercurrent type 2 diabetes on long-term risk of cardiovascular events

Recent studies have shown that gestational diabetes mellitus (GDM) is associated with an increased risk for cardiovascular disease. GDM has also been shown to be a risk factor for type 2 diabetes (T2DM) after pregnancy. However, there is limited evidence regarding the role of intercurrent T2DM on the relationship between GDM and future CVD. Thus, we investigated the risks of incident cardiovascular events among women with GDM during pregnancy compared to women without GDM and whether the increased CVD risk is dependent on intercurrent development of T2DM. We conducted a population-based retrospective cohort study using the Korean National Health Insurance Service claims database. Outcomes were the first occurrence of any CVD (myocardial infarction, treatment with coronary revascularization, heart failure, and cerebrovascular disease). Cox proportional hazard models were used to assess the association between GDM and incident CVD events, using landmark analysis at 4 years. A total of 1,500,168 parous women were included in the analysis, of which 159,066 (10.60%) had GDM. At a median follow-up of 12.8 years, 13,222 incident cases of total CVD were observed. Multivariable-adjusted hazard ratio for total CVD among women with prior GDM, compared with those without GDM, was 1.08 (95% CI 1.02-1.14). Further classifying GDM by progression to T2DM in relation to total CVD risk indicated a positive association for GDM with progression to T2DM vs no GDM or T2DM (HR 1.74; 95% CI 1.40-2.15), and no statistically significant association for GDM only (HR 1.06; 95% CI 1.00-1.12). GDM with subsequent progression to T2DM were linked with an increased risk of cardiovascular diseases. These findings highlight the need for more vigilant postpartum screening for diabetes and the implementation of diabetes interventions in women with a history of GDM to reduce future CVD risk.

Screening Leads to Overestimated Associations of Thyroid Dysfunction and Thyroiditis with Thyroid Cancer Risk

Simple Summary

The association of thyroid dysfunction and thyroiditis with the risk of thyroid cancer is an important issue in clinical practice, and is controversial due to various confounders, including screening effects. In this large-sample, population-based, nationwide study, we demonstrated that the screening effect likely significantly contributed to the positive associations of thyroid dysfunction and thyroiditis with thyroid cancer. After adjustment for this confounder, thyroid cancer risk was positively associated with hypothyroidism and thyroiditis but negatively associated with hyperthyroidism and Graves’ disease. Multiple subgroup analyses showed consistent results. Given these overestimated associations, we suggest that unnecessary and excessive concerns or screening tests for thyroid cancer could be reduced in patients with thyroid dysfunction or thyroiditis.

Abstract

We aimed to assess the relationships of functional thyroid disease and thyroiditis with subsequent thyroid cancer, which is controversial due to various confounders, and the effect of thyroid disease workup on this association. We used the cohort data from 2002 to 2015 (Study I, n = 28,330) and the entire data from 2002 to 2019 (Study II, n = 883,074) of the Korean National Health Insurance Service database, and performed logistic regression and subgroup analyses with various covariates. In Study I, hypothyroidism, thyroiditis, autoimmune thyroiditis, hyperthyroidism, and Graves’ disease showed positive associations with thyroid cancer. In Study II, after adjustment for covariates including the number of thyroid function tests, the ORs for thyroid cancer were significantly reduced in all thyroid diseases. Hypothyroidism, thyroiditis, and autoimmune thyroiditis were positively associated (adjusted odds ratio, OR (95% confidence interval, CI) 1.28 (1.25–1.32), 1.36 (1.31–1.42), and 1.17 (1.11–1.24), respectively), whereas hyperthyroidism and Graves’ disease were negatively associated with thyroid cancer (adjusted OR (95% CI) 0.80 (0.77–0.83) and 0.69 (0.65–0.74), respectively). Multiple subgroup analyses in both studies showed consistent results. In this large population-based, nationwide study, we confirmed that thyroid disease workup leads to overestimation of associations of thyroid dysfunction and thyroiditis with thyroid cancer risk.

Effects of the Mental Health and Welfare Law revision on schizophrenia patients in Korea: an interrupted time series analysis

Background

High rates of involuntary hospitalization and long lengths of stay have been problematic in Korea. To address these problems, the Mental Health and Welfare Law was revised in 2016, mainly to protect patient rights by managing involuntary admissions. The aim of this study was to evaluate the impact of the revised Mental Health and Welfare Law on deinstitutionalization by using routinely collected data from hospital admissions and continuity of mental health service use after hospital discharge as proxy measures of deinstitutionalization.

Methods

We used monthly-aggregated claims-based data with a principal or secondary diagnosis of schizophrenia from 2012 to 2019, collected by the National Health Insurance Service. Outcome variables included rates of first admission; discharges; re-admissions within 7, 30, and 90 days; outpatient visits after discharge within 7 and 30 days; and continuity of visits, at least once a month for 6 months after discharge. Using interrupted time series analysis, we estimated the change in levels and trends of the rates after revision, controlling for baseline level and trend.

Results

There was no significant change in first admission and discharge rates after the revision. Immediately after the revision, however, the rates of re-admission within 7 and 30 days dropped significantly, by 2.24% and 1.99%, respectively. The slopes of the re-admission rate decreased significantly, by 0.10% and 0.14%, respectively. The slopes of the re-admission rate within 90 days decreased (0.001%). The rates of outpatient visits within 7 and 30 days increased by 1.98% and 2.72%, respectively. The rate of continuous care showed an immediate 4.0% increase.

Conclusions

The revision had slight but significant effects on deinstitutionalization, especially decreasing short-term re-admission and increasing immediate outpatient service utilization.

Combination of Statin and Ezetimibe versus Statin Monotherapy on Cardiovascular Disease and Type 2 Diabetes Incidence among Adults with Impaired Fasting Glucose: a Propensity-Matched Nationwide Cohort Study

Objective

We investigated the effects of statin-ezetimibe combination therapy compared with statin-only treatment on the hazard of incident type 2 diabetes (T2D), myocardial infarction (MI), and stroke among adults with impaired fasting glucose (IFG) in a real-world setting.

Methods

The Korean National Health Insurance Service datasets from 2002 to 2017 were used for this propensity-matched nationwide cohort study. Among 56,633 IFG patients without baseline cardiovascular disease (CVD) and/or T2D who initiated statin therapy with or without ezetimibe, 1,155 with statin-ezetimibe combination therapy were matched based on a propensity score at a 1:5 ratio with 5,775 patients who received statin monotherapy. The hazards of T2D, MI, and stroke were compared between these treatment groups.

Results

The incidence rate per 1,000 person-years was 19.62 (statin monotherapy group) and 21.02 (combined treatment group) for T2D, 1.53 (statin monotherapy group) and 1.70 (combined treatment group) for MI, and 1.99 (statin monotherapy group) and 2.06 (combined treatment group) for stroke. The hazards of T2D, MI, and stroke were not significantly different between the statin monotherapy group and the statin-ezetimibe combination therapy group.

Conclusion

The combination of ezetimibe in addition to statin treatment was not associated with a significantly different risk of T2D and CVDs compared with statin monotherapy in Korean adults with IFG.

The Prognostic Significance of Body Mass Index and Metabolic Parameter Variabilities in Predialysis CKD: A Nationwide Observational Cohort Study

BACKGROUND

The association between variabilities in body mass index (BMI) or metabolic parameters and prognosis of patients with CKD has rarely been studied.

METHODS

In this retrospective observational study on the basis of South Korea's national health screening database, we identified individuals who received ≥3 health screenings, including those with persistent predialysis CKD (eGFR <60 ml/min per 1.73 m² or dipstick albuminuria ≥1). The study exposure was variability in BMI or metabolic parameters until baseline assessment, calculated as the variation independent of the mean and stratified into quartiles (with Q4 the highest quartile and Q1 the lowest). We used Cox regression adjusted for various clinical characteristics to analyze risks of all-cause mortality and incident myocardial infarction, stroke, and KRT.

RESULTS

The study included 84,636 patients with predialysis CKD. Comparing Q4 versus Q1, higher BMI variability was significantly associated with higher risks of all-cause mortality (hazard ratio [HR], 1.66; 95% confidence interval [95% CI], 1.53 to 1.81), P [for trend] <0.001), KRT (HR, 1.20; 95% CI, 1.09 to 1.33; P<0.001), myocardial infarction (HR, 1.19; 95% CI, 1.05 to 1.36, P=0.003), and stroke (HR, 1.19; 95% CI, 1.07 to 1.33, P=0.01). The results were similar in the subgroups divided according to positive or negative trends in BMI during the exposure assessment period. Variabilities in certain metabolic syndrome components (e.g., fasting blood glucose) also were significantly associated with prognosis of patients with predialysis CKD. Those with a higher number of metabolic syndrome components with high variability had a worse prognosis.

CONCLUSIONS

Higher variabilities in BMI and certain metabolic syndrome components are significantly associated with a worse prognosis in patients with predialysis CKD.

Impact of smoking on the development of idiopathic pulmonary fibrosis: results from a nationwide population-based cohort study

BACKGROUND

Smoking has been considered an important risk factor for idiopathic pulmonary fibrosis (IPF) incidence. However, there are no population-based large-scale studies demonstrating the effects of smoking on the development of IPF. We aimed to evaluate the effect of smoking on IPF development using a nationwide population-based cohort.

METHODS

Using the Korean National Health Information Database, we enrolled individuals who had participated in the health check-up service between 2009 and 2012. Participants having a prior diagnosis of IPF were excluded. The history of smoking status and quantity was collected by a questionnaire. We identified all cases of incident IPF through 2016 on the basis of ICD-10 codes for IPF and medical claims. Cox proportional hazards models were used to calculate the adjusted HR (aHR) of the development of IPF.

RESULTS

A total of 25 113 individuals (0.11%) with incident IPF were identified out of 23 242 836 participants registered in the database. The risk of IPF was significantly higher in current and former smokers than in never smokers, with an aHR of 1.66 (95% CI 1.61 to 1.72) and 1.42 (95% CI 1.37 to 1.48), respectively. Current smokers had a higher risk of IPF than former smokers (aHR 1.17, 95% CI 1.13 to 1.21). The risk of IPF development increased as the smoking intensity and duration increased.

CONCLUSION

Smoking significantly increased the risk of IPF development. Current smokers had a higher risk of IPF than former smokers. A dose-response relationship was observed between smoking and the development of IPF.

Carbon Monoxide Poisoning and Developing Ischemic Heart Disease: A Nationwide Population-Based Nested Case-Control Study

Although there are several case reports showing that carbon monoxide (CO) poisoning causes ischemic heart disease (IHD), no large-scale epidemiological studies have shown a significant association between the two. To investigate the association between CO poisoning and IHD, a nested case-control study of 28,113 patients who experienced CO poisoning and 28,113 controls matched by sex and age was performed using the nationwide health database of South Korea. Based on a conditional logistic regression, there was a significantly higher risk of IHD among the CO poisoning group than among the control group (adjusted hazard ratio [HR], 2.16; 95% confidence interval [CI], 1.87–2.49). The risk of IHD after CO poisoning was higher among the younger age group under 40 years (adjusted HR, 4.85; 95% CI, 3.20–7.35), and it was much greater among those with comorbidities (adjusted HR, 10.69; 95% CI, 2.41–47.51). The risk of IHD was the highest within the first two years after CO poisoning (adjusted HR, 11.12; 95% CI, 4.54–27.22). Even if more than six years had passed, the risk was still significantly higher than among the control group (adjusted HR, 1.55; 95% CI, 1.27–1.89). The analyses imply that CO poisoning is associated with an increased risk of IHD.

Association Between Kidney Function, Proteinuria and the Risk of Multiple Myeloma: A Population-Based Retrospective Cohort Study in South Korea

Purpose

While renal impairment is one of the first clinical manifestations of multiple myeloma (MM), declined renal function may conversely be a risk factor for cancers including MM. In this study, we investigated the relationship between chronic kidney disease and MM at a population level.

Materials and Methods

A total of 9,809,376 adults who participated in a nationwide health screening program and had no MM, cancer or end-stage renal disease at baseline were investigated for incidence of MM. The impact of estimated glomerular filtration rate (eGFR) and random urine dipstick proteinuria, and interactive associations of the two factors on the MM incidence were evaluated.

Results

The general incidence of MM was 4.8 per 100,000 person-years (mean follow-up of 8.3 years). Participants with eGFR < 60 mL/min/1.73 m² (5.8% of participants) had higher MM incidence than those with eGFR ≥ 60 mL/min/1.73 m² (adjusted hazard ratio, 1.29; 95% confidence interval, 1.17 to 1.43). When eGFR was graded into five levels, there was a significant inverse dose-response relationship between eGFR level and MM incidence at the lower eGFR levels (reference: eGFR 60–89 mL/min/1.73 m²). A dose-response relationship was also found with degree of dipstick proteinuria and incidence of MM.

Conclusion

Adults with decreased renal function indicated either by decreased eGFR or presence of proteinuria are at a higher risk of developing MM compared to those without, and there is a dose-response relationship between the severity of renal impairment and MM incidence.

Physical Activity after Colorectal Cancer Diagnosis and Mortality in a Nationwide Retrospective Cohort Study

Simple Summary

Physical activity can help to prevent colorectal cancer, but its importance after cancer diagnosis has not been validated. In this nationwide insurance data-based study of 43,596 colorectal cancer patients, a high level of physical activity after colorectal cancer diagnosis was negatively associated with a risk of death in both colon and rectal cancer patients, particularly in the surgically treated group. Our findings support the importance of the physical activity among colorectal cancer patients.

Abstract

Physical activity reduces the risk of colon cancer, but its prognostic impact after cancer diagnosis remains unclear. To evaluate the association between post-diagnosis activity and cause-specific mortality, we reconstructed a colorectal cancer patient cohort from the 2009–16 Korean National Health Insurance Service (NHIS) database. Subgroup analyses were performed by treatment group. In total, 27,143 colon cancer patients and 16,453 rectal cancer patients were included in the analysis (mean follow-up, 4.3 years; median 4.0 years). In the surgically treated group, a high level of activity (the weighted sum of the frequencies for walking, moderate, and vigorous activity greater than or equal to 3 times/week) was inversely associated with all-cause mortality (colon cancer: HR, 0.79; 95% CI, 0.72 to 0.88; rectal cancer: HR, 0.75; 95% CI, 0.66 to 0.86) and colorectal cancer-specific mortality (colon cancer: HR, 0.85; 95% CI, 0.76 to 0.97; rectal cancer: HR, 0.77; 95% CI, 0.66 to 0.90). No significant results were shown for cardiovascular disease-specific mortality. No association was shown in patients who received chemoradiotherapy without surgery. The present study may provide evidence for post-diagnosis physical activity as a prognostic factor in colorectal cancer, particularly in surgically treated early-stage patients.

Associations between obesity, metabolic health, and the risk of breast cancer in East Asian women

BACKGROUND

This study examined the associations between metabolic syndrome(MetS), obesity, their combination as a metabolic obesity phenotype, and the risk of breast cancer in East Asian postmenopausal women.

METHODS

A total of 3,095,336 postmenopausal cancer-free women aged 40-79 years who underwent the National Health Insurance Service health examination between 2009 and 2010 were included. The incidence of invasive breast cancer was followed up until 2018. The presence of obesity (body mass index[BMI] ≥25 kg/m²), MetS, and each component of MetS was investigated.

RESULTS

Obesity and MetS were associated with breast cancer risk, but when the effects of obesity and MetS were mutually adjusted, the associations were attenuated, especially for MetS. Only elevated fasting blood glucose levels and waist circumference increased the risk of breast cancer after adjusting for BMI. Compared to metabolically healthy normal-weight women, metabolically unhealthy normal-weight women, metabolically healthy obese, and metabolically unhealthy obese women had an increased risk of breast cancer.

CONCLUSIONS

Obesity and MetS were independently associated with an increased risk of breast cancer in postmenopausal women, despite the relationship between MetS and breast cancer appearing to result from a partial association with BMI. Postmenopausal women should be encouraged to control their weight and metabolic health.

A nationwide study of patients with monoclonal gammopathy of undetermined significance with a 10-year follow-up in South Korea

In clinical practice, most patients with monoclonal gammopathy of undetermined significance (MGUS) undergo long-term follow-up without disease progression. There is insufficient real-world data about how closely and whether anything other than disease progression should be monitored. Herein, we performed a nationwide study of 470 patients with MGUS with a 10-year follow-up to determine the patterns of disease progression and other comorbidities. During the follow-up period, 158 of 470 patients with MGUS (33.62%) progressed to symptomatic monoclonal gammopathies. Most of these were multiple myeloma (134/470 patients, 28.51%), and those diagnosed within 2 years after diagnosis of MGUS was high. Approximately 30-50% of patients with MGUS had hypertension, diabetes, hyperlipidemia, and osteoarthritis at the time of diagnosis, and these comorbidities were newly developed during the follow-up period in approximately 50% of the remaining patients with MGUS. Approximately 20-40% of patients with MGUS have acute or chronic kidney failure, thyroid disorders, disc disorders, peripheral neuropathy, myocardial infarction, stroke, and heart failure during the follow-up period. Altogether, when MGUS is diagnosed, close follow-up of the possibility of progression to multiple myeloma is required, especially within 2 years after diagnosis; simultaneously, various comorbidities should be considered and monitored during the follow-up of patients with MGUS. Continuous research is needed to establish appropriate follow-up guidelines.

Mortality is not associated with paclitaxel-coated devices usage in peripheral arterial disease of lower extremities

A recent meta-analysis addressed increased risk of death following revascularization with paclitaxel-coated devices in femopopliteal artery. We evaluated differences in all-cause mortality and amputation free survival between peripheral arterial disease (PAD) patients who were treated with paclitaxel-coated devices and non-paclitaxel-coated devices. This was retrospective population-based cohort study from the National Health Insurance Service claims in South Korea from 2015 to 2019. Multivariate Cox regression analyses after propensity score matching were applied to identify all-cause mortality and amputation-free survival. After propensity score matching, there were 6090 patients per group. The median follow-up days was 580 days (interquartile range [IQR] 240–991 days) and 433 days (IQR 175–757 days) for the non-paclitaxel-coated device group and paclitaxel-coated device group, respectively. Multivariate analysis adjusted for age, sex, diabetes, hypertension, warfarin, and new oral anticoagulants showed that the mortality rate associated with paclitaxel-coated devices was not significantly higher than non-paclitaxel-coated devices (hazard ratio [HR] 0.992; 95% CI 0.91–1.08). The rate of amputation events was higher in patients with paclitaxel-coated devices than those with non-paclitaxel-coated devices (HR 1.614; 95% CI 1.46–1.78). In this analysis, the mortality rate in patients with PAD was not associated with the use of paclitaxel-coated devices, despite a higher amputation rate.

Latent Tuberculosis Infection Screening and Treatment in Congregate Settings (TB FREE COREA): Demographic Profiles of Interferon-Gamma Release Assay Cohort

In 2017, the Korean government launched an unprecedentedly large-scaled latent tuberculosis infection (LTBI) screening project which covered more than a million individuals in congregate settings. A total of 1,047,689 participants of source population (n = 2,336,157) underwent LTBI testing from 2017 to 2018. The overall LTBI test uptake rate during this project was 44.8%. Workers in daycare centers (83.5%) and kindergartens (78.9%) showed high participation rate. A total of 1,012,206 individuals with valid results of interferon-gamma release assay (IGRA) were selected to constitute the IGRA cohort. Most of the enrolled participants in the IGRA cohort were in their working age. Approximately, three-quarters of total enrolled population were female. Investigating the LTBI prevalence, stages of LTBI care cascade, natural history of LTBI, efficacy of LTBI treatment and cost-effectiveness of LTBI screening are feasible within this IGRA cohort.