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

Temporal trend of first-ever ischaemic stroke incidence from 2010 to 2019 in South Korea: a nationwide retrospective cohort study

OBJECTIVE

Ischaemic stroke incidence is on the decline globally, but the trend in South Korea is unknown. In this study, the 10-year incidence trends of first-ever ischaemic stroke in South Korea were evaluated.

DESIGN, SETTING AND PARTICIPANTS

The National Health Insurance Services medical claim data were used to construct 10 annual cohorts of adults aged 20 years and older, who had not been diagnosed with stroke, to find out the incidence trends of first-ever ischaemic stroke from 2010 to 2019.

OUTCOME MEASURES

The primary outcomes were crude and age-adjusted incidence rates for 10 years. Crude incidence rates of the age groups and incidence age statistics were calculated. For comparison among the income groups, age-adjusted incidence rates were used. Incidence rates in all the groups were analysed separately by sex.

RESULTS

Age-standardised incidence rates of ischaemic stroke per 100 000 were 101.0 in men, and 67.6 in women in 2010; and 92.2 in men, and 55.0 in women in 2019. By age group, there was a decrease in women over 40 years of age, and men over 60 years of age. The relative difference in stroke incidence rates between medical aid beneficiaries and the highest income group increased from 1.5 to 1.87 over 10 years.

CONCLUSIONS

Age-standardised incidence rate of ischaemic stroke has decreased from 2010 to 2019 for both man and women. The incidence rate was stable in the younger age groups and decreased in the older age groups, and the disparities between income groups have widened over the past decade. Stroke prevention strategies are needed for the younger age group and the low-income group. Further research is needed to study the risk factors contributing to the incidence of ischaemic stroke in different groups.

The risk of newly diagnosed cancer in patients with rheumatoid arthritis by TNF inhibitor use: a nationwide cohort study

Background

Tumor necrosis factor (TNF) inhibitors use in patients with rheumatoid arthritis (RA) has raised safety concerns about cancer risk, but study results remain controversial. This largest nationwide study to date compared cancer risk in TNF inhibitor users to non-biologic disease-modifying anti-rheumatic drug (nbDMARD) users in Korean patients with RA.

Methods

Data on all the eligible patients diagnosed with RA between 2005 and 2016 were retrieved from the Korean National Health Information Database. The one-to-one matched patients consisted of the matched cohort. The risks for developing all-type and site-specific cancers were estimated using incidence and incidence rate (IR) per 1000 person-years. Adjusted hazard ratio (HR) and 95% confidence interval (CI) were estimated using a Cox regression model.

Results

Of the 22,851 patients in the before matching cohort, 4592 patients were included in the matched cohort. Treatment with TNF inhibitors was consistently associated with a lower risk of cancer than in the nbDMARD cohort (IR per 1000 person-years, 6.5 vs. 15.6; adjusted HR, 0.379; 95% CI, 0.255–0.563). The adjusted HR (95% CI) was significantly lower in the TNF inhibitor cohort than the nbDMARD cohort for gastrointestinal cancer (0.432; 0.235–0.797), breast cancer (0.146; 0.045–0.474), and genitourinary cancer (0.220; 0.059–0.820).

Conclusions

The use of TNF inhibitors was not associated with an increased risk of cancer development, and rather associated with a lower cancer incidence in Korean patients with RA. Cautious interpretation is needed not to oversimplify the study results as cancer-protective effects of TNF inhibitors. A further study linking claims and clinical data is needed to confirm our results.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02868-w.

Associations between obesity parameters and the risk of incident atrial fibrillation and ischaemic stroke in the different age groups

Objective

Obesity and aging are important predisposing factors to atrial fibrillation (AF) and ischaemic stroke (IS). However, limited data comprehensively evaluated the relationships between obesity measurements and AF and IS in different ages.

Methods

A total of 9,432,332 adults from the Korean National Health Insurance Service Database were included. The study population was categorized into the six age subgroups by an increase every decade from the twenties. We evaluated AF and IS risk according to body mass index (BMI) and waist circumference (WC) in the different age groups.

Results

During a mean follow-up of 8.2 ± 1.0 years, BMI-AF presented a J-shaped association across ages. The highest hazard ratio (HR) of the BMI ≥ 30 kg/m² group was observed in subjects aged 30–39 years [HR 1.80, 95% CI 1.63–1.98, p < 0.001]. Underweight adults over 60 years also presented an increased AF risk. Incident IS risk increased in those with BMI over the normal range in early and midlife, but the association became obscured in adults aged > 60 years. Among the BMI ≥ 30 kg/m² groups, subjects aged 20–29 years presented the highest risk of IS [HR 3.00, 95% CI (2.34–3.84), p < 0.001]. Overall, WC-AF and WC-IS showed positive linear correlations, but the WC-IS association was weak in subjects aged ≥ 40 years.

Conclusion

The higher risks of AF and IS according to an increment of BMI and WC were most apparent among the young ages. The association between obesity measurements and IS was not significantly above the midlife. Weight management in the young and integrated risk factor management in the elderly are warranted.

Weight change and the risk of hip fractures in patients with type 2 diabetes: a nationwide cohort study

Both weight gain and weight loss in type 2 diabetic population were associated with increased risk of hip fracture, while maintaining weight lowered the risk of hip fracture. Regarding the risk of hip fracture, we can propose active monitoring to maintain the weight of type 2 diabetes patients.

INTRODUCTION

In type 2 diabetes, patients are often asked to control their weight in order to reduce their diabetic morbidity. The American Diabetes Association recommends that diabetic patients conduct high-intensity interventions for regulating diet, physical activity, and behavior to reduce weight, followed by long-term comprehensive weight maintenance programs. Although such weight control attempts are required in diabetic patients, there are few studies on the effect of weight change on hip fracture in this population. We aim to investigate the association between body weight change and the incidence of hip fracture in subjects with type 2 diabetes using large-scale, nationwide cohort data on the Korean population.

MATERIALS AND METHODS

A total of 1,447,579 subjects (894,204 men and 553,375 women) > 40 years of age, who were diagnosed with type 2 diabetes, were enrolled in this study. Weight change within 2 years was divided into five categories: from weight loss ≥ 10% to weight gain ≥ 10%. The hazard ratios (HRs) and 95% confidence intervals for the incidence of hip fracture were analyzed, compared with the reference of the stable weight group (weight change < 5%).

RESULTS

Among 5 weight change groups, more than 10% weight loss showed the highest HR (HR, 1.605; 95% CI, 1.493 to 1.725), followed by more than 10% weight gain (HR, 1.457; 95% CI, 1.318 to 1.612). The effect of weight change on hip fracture risk was greater in males than in females, and those under 65 years of age were greater than those over 65 years of age. Baseline BMI did not play a role of weight change affecting the risk of hip fracture. The HR for hip fracture of subjects with regular exercise was lower than those without regular exercise.

CONCLUSIONS

In the type 2 diabetes population, both weight gain and weight loss were significantly associated with a higher risk of hip fracture, whereas maintaining body weight reduced the risk of hip fracture the most.

Incident and recurrent herpes zoster for first-line bDMARD and tsDMARD users in seropositive rheumatoid arthritis patients: a nationwide cohort study

BACKGROUND

There is limited information regarding disease-modifying antirheumatic drug (DMARD)-dependent risks of overall, incident, and recurrent herpes zoster (HZ) during first-line biologic DMARD (bDMARD) or targeted synthetic DMARD (tsDMARD) treatment among patients with seropositive rheumatoid arthritis (RA) in terms of HZ risk.

METHODS

A total of 11,720 patients with seropositive RA who were prescribed bDMARD or tofacitinib between January 2011 and January 2019 from the Korean Health Insurance Review & Assessment Service database were studied. A multivariate Cox proportional hazards regression model was adopted to evaluate the adjusted hazard ratio (aHR) with 95% confidence interval (CI) for the risk of HZ dependent on the choice of first-line bDMARDs or tsDMARD, including etanercept, infliximab, adalimumab, golimumab, tocilizumab, rituximab, tofacitinib, and abatacept.

RESULTS

During the 34,702 person-years of follow-up, 1686 cases (14.4%) of HZ were identified, including 1372 (11.7%) incident and 314 (2.7%) recurrent HZs. Compared with that of the abatacept group, tofacitinib increased the overall risk (aHR, 2.46; 95% CI, 1.61-3.76; P<0.001), incidence (aHR, 1.99; 95% CI, 1.18-3.37; P=0.011), and recurrence (aHR, 3.69; 95% CI, 1.77-7.69; P<0.001) of HZ. Infliximab (aHR, 1.36; 95% CI, 1.06-1.74; P=0.017) and adalimumab (aHR, 1.29; 95% CI, 1.02-1.64; P=0.032) also increased the overall HZ risk. Moreover, a history of HZ was found to be an independent risk factor for HZ (aHR, 1.54; 95% CI, 1.33-1.78; P<0.001).

CONCLUSIONS

HZ risk is significantly increased in RA patients with a history of HZ after the initiation of bDMARDs or tsDMARD. The risk of incident and recurrent HZ was higher after tofacitinib treatment in patients with RA than that after treatment with bDMARDs. Individualized characteristics and history of HZ should be considered when selecting bDMARDs or tsDMARD for RA patients considering HZ risks.

Risk of Parkinson's disease in multiple sclerosis and neuromyelitis optica spectrum disorder: a nationwide cohort study in South Korea

BACKGROUND

Neurodegeneration is associated with pathogenesis of both multiple sclerosis (MS) and neuromyelitis optica (NMOSD). Parkinson's disease (PD) is a representative neurodegenerative disease, however, whether MS or NMOSD is associated with risk of PD is not known.

METHODS

MS and NMOSD cohorts were collected from the Korean National Health Insurance Service between 1 January 2010 and 31 December 2017, using International Classification of Diseases 10th revision diagnosis codes and information in the Rare Intractable Disease management programme. The PD incidence rate that occurred after a 1-year lag period was calculated and compared with that of a control cohort matched for age, sex, hypertension, diabetes and dyslipidaemia in a 1:5 ratio.

RESULTS

The incidence rates of PD in patients with MS and NMOSD were 3.38 and 1.27 per 1000 person-years, respectively, and were higher than that of their matched control groups. The adjusted HR of PD was 7.73 (95% CI, 3.87 to 15.47) in patients with MS and 2.61 (95% CI, 1.13 to 6.02) in patients with NMOSD compared with matched controls. In both patients with MS and NMOSD, there were no significant differences in relative risk when stratified by sex, age, diabetes, hypertension and dyslipidaemia.

CONCLUSION

The PD risk was higher in patients with MS and NMOSD compared with healthy controls and was particularly high in patients with MS. Further investigations should be performed to determine the pathophysiology and occurrence of PD in patients with MS and NMOSD.

Prognostic Impact of Neutropenia in Cancer Patients with Septic Shock: A 2009–2017 Nationwide Cohort Study

Simple Summary

The prognostic impact of neutropenia on mortality in cancer patients with septic shock remains controversial despite recent advances in cancer and sepsis management. This study aimed to determine whether neutropenia could be related to an increase in short-term and long-term mortality. This population-based, case–control study used data from the National Health Insurance Service of Korea. Adult cancer patients who presented to the emergency department with septic shock from 2009 to 2017 were analyzed. The 30-day and 1-year mortality rates were evaluated as short-term and long-term outcomes. After adjustment for confounders, neutropenia was independently associated with decreased 30-day and 1-year mortality rates. Neutropenia did not increase mortality in cancer patients with septic shock, suggesting that neutropenia may not be used as a single triage criterion for withholding intensive care in cancer patients presenting to the emergency department with septic shock.

Abstract

(1) Background: Neutropenia’s prognostic impact on mortality in cancer patients with septic shock remains controversial despite recent advances in cancer and sepsis management. This population-based, case–control study aimed to determine whether neutropenia could be related to an increase in short-term and long-term mortality. (2) Methods: This population-based, case–control study used data from the National Health Insurance Service of Korea. Adult cancer patients who presented to the emergency department with septic shock from 2009 to 2017 were included. The 30-day and 1-year mortality rates were evaluated as short-term and long-term outcomes. Cox proportional hazard regression was performed after adjusting for age, sex, Charlson comorbidity index, and neutropenia. (3) Results: In 43,466 adult cancer patients with septic shock, the 30-day and 1-year mortality rates were 52.1% and 81.3%, respectively. In total, 6391 patients had neutropenic septic shock, and the prevalent cancer type was lung cancer, followed by leukemia, non-Hodgkin’s lymphoma, stomach cancer, and colon cancer. Furthermore, 30-day and 1-year mortality was lower in patients with neutropenia than in those without neutropenia. After adjustment for confounders, neutropenia was independently associated with decreased 30-day and 1-year mortality rates. (4) Conclusions: In cancer patients presenting to the emergency department with septic shock, the presence of neutropenia did not increase mortality. This suggests that neutropenia may not be used as a single triage criterion for withholding intensive care in cancer patients presenting to the emergency department with septic shock.

Risk of Tuberculosis Caused by Fluticasone Propionate versus Budesonide in Chronic Obstructive Pulmonary Disease: A Nationwide Population-Based Study

Background: In chronic obstructive pulmonary disease (COPD), inhaled corticosteroids (ICSs) are recommended for use by patients with frequent exacerbations and blood eosinophilia. However, ICSs are often inappropriately prescribed and overused. COPD studies have reported an increased risk of tuberculosis among ICS users. This study aimed to compare the risk of tuberculosis according to the different ICS components. Methods: This study was conducted using a nationwide, population-based cohort. Patients newly diagnosed with COPD between 2005 and 2018, and treated with either fluticasone propionate or budesonide, were selected. The patients were followed up until the development of tuberculosis. Results: After propensity score matching, 16,514 fluticasone propionate and 16,514 budesonide users were identified. The incidence rate of tuberculosis per 100,000 person-years was 274.73 for fluticasone propionate and 214.18 for budesonide. The hazard ratio of tuberculosis in fluticasone propionate compared with budesonide was 1.28 (95% confidence interval 1.05–1.60). The risk of tuberculosis for fluticasone propionate increased with higher ICS cumulative doses: 1.01 (0.69–1.48), 1.16 (0.74–1.81), 1.25 (0.79–1.97), and 1.82 (1.27–2.62) from the lowest to highest quartiles, respectively. Conclusion: Fluticasone propionate is associated with a higher risk of tuberculosis than budesonide. ICS components can differently affect the risk of tuberculosis in patients with COPD.

Mortality, Disability and Prognostic Factors of Status Epilepticus: A Nationwide Population-Based Retrospective Cohort Study

BACKGROUND AND OBJECTIVES

The outcome of status epilepticus (SE) largely varies depending on clinical characteristics. Risk stratification is necessary for tailoring the aggressiveness of treatment and predicting outcomes of individual patients with SE. In this study, we assessed differences in mortality, neurologic disability, and prognostic factors associated with SE across sociodemographic and clinical characteristics.

METHODS

We conducted a nationwide population-based retrospective cohort study using the National Health Insurance Service (NHIS) database linked with the national death and disability registries. SE was identified from admission or emergency room visits using a diagnostic code of G41 from the International Classification of Disease, 10^th Revision. Individuals with new-onset SE that occurred from January 1, 2010, to December 31, 2018, were included. Active epilepsy, refractoriness of SE, potential etiology, and comorbidities were ascertained by diagnostic codes and/or prescription records from the NHIS database as potential prognostic factors. Outcomes included 30-day and 1-year mortality and neurologic disabilities following SE. Prognostic factors for mortality were assessed by the Cox regression hazard model. We performed a subgroup analysis according to age: pediatric SE (age < 20 years old) and adult SE (age ≥ 20 years old).

RESULTS

A total of 33,814 new-onset SE patients were included (6,818 children/adolescents and 26,996 adults). The 30-day mortality was 8.5% (1.8% in pediatric SE and 10.2% in adult SE), and the 1-year mortality was 25.1% (4.6% in pediatric SE and 30.3% in adult SE). Overall, 10.7% of patients newly acquired neurologic disabilities following SE, with the highest incidence in children aged 5 to 9 years (21.3%). Intractable epilepsy developed in 0.8% of entire SE. Old age, presence of acute etiology, and refractoriness were poor prognostic factors for mortality in both pediatric and adult SE. Male sex, low economic status, no active epilepsy, and comorbidities were additional factors for a poor prognosis in adults.

CONCLUSIONS

New-onset SE was associated with substantial mortality and disability. While SE-related mortality was higher in adults, disabilities developed more commonly in children and adolescents. The major determinants of mortality differed between pediatric and adult SE.

Association of changes in cardiovascular health levels with incident cardiovascular events and mortality in patients with atrial fibrillation

BACKGROUND

Risk factor management is crucial in the management of atrial fibrillation (AF). We investigated the association of changes in cardiovascular health (CVH) levels after AF diagnosis with incident cardiovascular events and mortality.

METHODS

From the Korea National Health Insurance Service database, 76,628 patients newly diagnosed with AF (2005-2015) with information on health examinations before and after AF diagnosis were assessed. According to the change in the 12-point CVH score before and after AF diagnosis, patients were stratified into four groups: consistently low (score 0-7 to 0-7), high-to-low (8-12 to 0-7), low-to-high (0-7 to 8-12), and consistently high (8-12 to 8-12) CVH levels. Risks of cardiovascular events and death were analyzed using weighted Cox regression models with inverse probability of treatment weighting (IPTW) for balance across study groups.

RESULTS

The mean age of study participants was 58.3 years, 50,285 were men (63.1%), and the mean follow-up was 5.5 years. After IPTW, low-to-high (hazard ratio [95% confidence interval], 0.83 [0.76-0.92]) and consistently high (0.80 [0.74-0.87]) CVH levels were associated with a lower risk of ischemic stroke than consistently low CVH. Low-to-high (0.66 [0.52-0.84]) and consistently high (0.52 [0.42-0.64]) CVH levels were associated with a lower risk of acute myocardial infarction. Maintaining high CVH was associated with reduced risks of heart failure hospitalization (0.85 [0.75-0.95]) and all-cause death (0.82 [0.77-0.88]), respectively, compared with consistently low CVH.

CONCLUSIONS

Improving CVH levels and maintaining high CVH levels after AF diagnosis is associated with lower risks of subsequent cardiovascular events and mortality.

Secular Trends of Incidence, Prevalence, and Healthcare Economic Burden in ANCA-Associated Vasculitis: An Analysis of the 2002–2018 South Korea National Health Insurance Database

Objectives

The incidence and prevalence of AAV in Asia remain poorly understood, especially in a nationwide setting. This study investigated the incidence, prevalence, and healthcare burden of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in South Korea by analyzing a national database.

Methods

This study included patients with AAV identified from the National Health Insurance Service Database of South Korea from 2002 to 2018. Patients were diagnosed with AAV in a general or tertiary hospital and were registered in the individual payment beneficiaries program or were prescribed glucocorticoids. A calendar-based meteorological definitions were adopted to assess the differences in the incidence of AAV according to season. The average healthcare expenditure and patient outcomes of mortality and end-stage renal disease (ESRD) in patients with AAV were compared to 1:10 age, sex and residential area matched controls.

Results

A total of 2,113 patients [708, 638, and 767 with microscopic polyangiitis (MPA), granulomatosis with polyangiitis, and eosinophilic granulomatosis with polyangiitis, respectively] were identified. The annual incidence and prevalence of AAV increased continuously, and MPA being the most common disease subtype after 2015. The highest incidence and prevalence of AAV was 0.48/100,000 person-years (PY) and 2.40/100,000 PY in 2017 and 2018, respectively. There were no significant differences in monthly and seasonal incidence of AAV. The average expense of medical care, overall mortality, and ESRD rates of patients with AAV were higher in patients with AAV than in controls, especially in the case of MPA.

Conclusion

An increasing trend of AAV diagnosis observed is consistent with the evidence that AAV is more common in recent years; however, a relatively lower incidence and prevalence was observed compared to that in Western countries. The higher medical cost and rates of mortality and ESRD in AAV emphasize the early recognition and implementation of optimal treatment for these patients.

Consecutive gain and loss in body weight and waist circumference with risk of subsequent breast cancer in Korean women

BACKGROUND

This study investigated the association between longitudinal changes in weight and waist circumference and breast cancer risk according to menopausal status.

METHODS

This retrospective cohort study used data from the population-based Korean National Health Insurance Service (NHI) database. The study population included women aged ≥40 years who consecutively underwent three biennial breast cancer screenings between 2009-2014 and were followed up until 2020. The percentage changes in weight and waist circumference during the three screenings were calculated and categorized into five groups based on the level of increase or decrease in these two factors. Hazard ratios (HRs) and 95% confidence intervals (95% CI) for breast cancer risk were calculated and adjusted for other factors.

RESULTS

Of 691,253 premenopausal and 1,519,211 postmenopausal women, 9485 and 12,553 breast cancer cases were identified, respectively, during a median 6.9 follow-up years. Postmenopausal women with two consecutive weight gains had an increased risk of breast cancer risk (HR = 1.11, 95% CI = 1.01 to 1.22); meanwhile, consecutive weight loss was associated with a decreased risk (HR = 0.84, 95% CI = 0.76 to 0.93). Single time and continuous decreases in waist circumference were associated with a decreased risk (HR = 0.91, 95% CI = 0.85 to 0.98, and HR = 0.84, 95% CI = 0.76-0.93), while single time and continuous increases were associated with an increased risk (HR = 1.08, 95% CI = 1.01 to 1.15, and HR = 1.13, 95% CI = 1.04 to 1.22). Single weight gain was associated with the increased breast cancer risk in premenopausal women (HR = 1.07, 95% CI = 1.01 1.13).

CONCLUSIONS

Our findings suggest a dose-response relationship between weight, waist circumference change, and the risk of future breast cancer.

The risk of stroke according to statin medication compliance in older people with chronic periodontitis: an analysis using the Korea National Health Insurance Service-Senior Cohort Database

OBJECTIVES

We investigated the risk of stroke according to statin medication compliance in older people with chronic periodontitis.

METHODS

Chronic periodontitis patients were extracted from the National Health Insurance Service-Senior Cohort Database from 2002 to 2014. Among 255,056 chronic periodontitis patients, 41,412 patients with statin prescriptions for 28 days or more were included. The study population was divided into the top 25% of medication compliance group (TSG) and the lower 25% of medication compliance group (BSG). After 1:1 propensity score matching was performed, the final number of patients in the BSG and TSG was 6,172 each. To analyze the risk of stroke, a Cox proportional hazard model was performed to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs) after adjusting for age, sex, income level, hypertension, diabetes, and Charlson comorbidity index.

RESULTS

In the Kaplan-Meier curve, the disease-free probability was prominently lower in the BSG than in the TSG (p for log-rank= 0.001). The HR in the multivariable-adjusted model for stroke occurrence in the TSG compared to the BSG was 0.79 (95% CI, 0.67 to 0.92; p= 0.002). Subgroup analyses showed significant associations between compliance to statin medication and stroke, especially in female, people 85 years or older, and patients with comorbidities.

CONCLUSIONS

Increasing compliance to statins may reduce stroke risk in older adults with chronic periodontitis. Therefore, in order to increase medication compliance among older people with chronic periodontitis, it is necessary for medical staff to make efforts to provide effective medication guidance.

The Association Between Adequate Prenatal Care and Severe Maternal Morbidity Among Teenage Pregnancies: A Population-Based Cohort Study

Background

The aim of this study was to examine whether inadequate prenatal care affect the risk of severe maternal morbidity in teenage pregnancies.

Methods

We included 23,202 delivery cases among adolescent mothers aged between 13 and 19 years old with ≥ 37 weeks' gestational age. Data were derived from the National Health Insurance Service National Delivery Cohort in Korea between 2003 and 2018. We used a generalized estimating equation model while adjusting for numerous covariates to determine the adjusted relative risk (RR) associated with severe maternal morbidity. The main outcome measures were severe maternal morbidity and the Kessner Adequacy of Prenatal Care Index.

Results

Severe maternal morbidity occurred in 723 (3.1%) of the 23,202 investigated delivery cases. The risk of severe maternal morbidity was 1.8-fold higher among adolescent mothers who had received inadequate prenatal care (RR, 1.81, 95% confidence interval [CI], 1.39–2.37) and 1.6-fold higher among those who had received intermediate prenatal care (RR, 1.59, 95% CI, 1.33–1.87) compared to those with adequate prenatal care. Synergistic effects of inadequate prenatal care and maternal comorbidities affected severe maternal morbidity.

Conclusion

This study confirmed that inadequate prenatal care is associated with increased risk of severe maternal morbidity among pregnant teenagers. Notably, maternal comorbidity and inadequate prenatal care produced synergistic effects on severe maternal morbidity. Public health policy makers should focus on the development and implementation of programs to ensure that adequate prenatal care and financial/healthcare support is provided to teenage mothers during their pregnancies.

Maternal Pre-Pregnancy Obesity and Gestational Diabetes Mellitus Increase the Risk of Childhood Obesity

Previous studies have shown inconsistent results regarding the effects of maternal gestational diabetes mellitus (GDM) and pre-pregnancy obesity (PPO) on childhood obesity. This study aimed to determine the risk for early childhood obesity based on maternal GDM and PPO. This nationwide study used data obtained from the National Health Information Database in South Korea. The participants were divided into four groups based on maternal GDM and PPO, and 1:1 matching was performed. Each group had 1319 participants. A generalized estimating equation model was used to analyze the changes in body mass index percentile of children with age, and simple and multiple conditional logistic regression models were used to compare the prevalence of childhood obesity at 5 years. Children whose mothers had both PPO and GDM, only PPO, or only GDM had a 4.46 (95% CI: 3.28−6.05, p < 0.001), 3.11 (95% CI: 2.27−4.26, p < 0.001), or 1.58 (95% CI: 1.12−2.23, p = 0.010) times higher risk, respectively, of developing childhood obesity than children whose mothers had neither PPO nor GDM. Maternal PPO increases the risk for childhood obesity to a higher degree than maternal GDM, and the presence of both increases the risk even further.

Calcium Supplementation, Risk of Cardiovascular Diseases, and Mortality: A Real-World Study of the Korean National Health Insurance Service Data

Few studies have investigated the effects of calcium supplementation on cardiovascular outcomes in individuals with low calcium intake in real-world settings. This study examined the association between calcium supplementation and cardiovascular outcomes in the Korean population in a real-world setting. This large retrospective cohort study included patients aged ≥45 years first prescribed calcium supplements in 2010. Age- and sex-matched controls were recruited among those who had no prescription for calcium supplements. Longitudinal data were collected on 31 December 2018. Kaplan−Meier estimation and Cox proportional hazard regression analysis were performed. The cumulative incidence of acute myocardial infarction, ischemic stroke, and death was significantly higher in the calcium supplementation group than in the control group (p < 0.05 by log-rank test). The calcium supplementation group had a significantly higher risk of myocardial infarction, ischemic stroke, and death than the control group. Compared to the control group, the hazard ratios (95% confidence intervals) of the incidence of myocardial infarction, stroke, and death in the supplementation group were 1.14 (1.03−1.27), 1.12 (1.05−1.20), and 1.40 (1.32−1.50), respectively, after adjusting for confounding variables. Considering the associated cardiovascular risk, calcium supplementation for osteoporosis treatment should be administered cautiously.

Severity of underweight and risk of fracture: a Korean nationwide population-based cohort study

Underweight is an important modifiable risk factor for fractures. However, there have been few large cohort studies regarding the relationship between underweight and fracture in the general population. We investigated the risk of fracture development according to underweight severity in a large population cohort. This nationwide cohort study included 2,896,320 people aged ≥ 40 years who underwent national health checkups in 2009 and were followed up to identify the incidence of fracture until December 31, 2018. After applying the exclusion criteria that included overweight and obese individuals, the study population was divided according to body mass index (BMI) into normal weight (18.5 ≤ BMI < 23.0), mild underweight (17.5 ≤ BMI < 18.5), moderate underweight (16.5 ≤ BMI < 17.5), and severe underweight (BMI < 16.5) groups. Cox proportional hazards regression analyses were performed to calculate the hazard ratios for risk of fracture according to underweight severity. Severely underweight participants had a 28% increased fracture risk (adjusted hazard ratio [HR] 1.28, 95% confidence interval [CI] 1.20-1.37) compared with those of normal weight. In addition, fracture risk was increased by 14% in individuals with moderate underweight (adjusted HR 1.14, 95% CI 1.08-1.19) and 9% in those with mild underweight (adjusted HR 1.09, 95% CI 1.06-1.13). The severity of underweight was significantly associated with risk of fracture.

Association of the presence of allergic disease with subsequent risk of liver cancer in a nationwide retrospective cohort among Koreans

A number of studies have proposed an inverse association between allergic diseases and risk of cancer, but only a few studies have specifically investigated the risk of primary liver cancer, including hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). The aim of this study was to evaluate the association of allergic diseases with risk of primary liver cancer. We conducted a retrospective cohort study of the Korean National Health Insurance Service database consisted of 405,512 Korean adults ages 40 and above who underwent health screening before January 1st, 2005. All participants were followed up until the date of liver cancer, death, or December 31st, 2013, whichever happened earliest. Those who died before the index date or had pre-diagnosed cancer were excluded from the analyses. Cox proportional hazards regression was used to determine the adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for risk of primary liver cancer according to the presence of allergic diseases, including atopic dermatitis, asthma, and allergic rhinitis. The aHR (95% CI) for overall liver cancer among allergic patients was 0.77 (0.68–0.87) compared to those without allergic disease. Allergic patients had significantly reduced risk of HCC (aHR, 0.72; 95% CI 0.62–0.85) but not ICC (aHR, 0.95; 95% CI 0.73–1.22). The presence of allergies was associated with significantly lower risk of liver cancer among patients whose systolic blood pressure is lower than 140 mmHg (aHR, 0.64; 95% CI 0.62–0.78 for overall liver cancer; aHR, 0.64; 95% CI 0.52–0.78 for HCC) but this effect was not observed among patients whose systolic blood pressure is higher than 140 mmHg (aHR, 0.91; 95% CI 0.71–1.18 for overall liver cancer; aHR, 0.91; 95% CI 0.71–1.18 for HCC) The aHR (95% CI) for overall liver cancer of allergic patients with and without chronic hepatitis virus infection were 0.60 (95% CI 0.44–0.81) and 0.77 (95% CI 0.64–0.93), respectively. In addition, allergic patients without cirrhosis showed significantly lower risk of overall liver cancer (aHR, 0.73; 95% CI 0.63–0.83). Patients with allergic diseases have significantly lower risk of primary liver cancer compared to those without allergic diseases, which supports the rationale for immunotherapy as an effective treatment for liver cancer.

Association of antibiotics exposure within the first 2 years after birth with subsequent childhood type 1 diabetes

PURPOSE

Antibiotics prescription in early life can cause dysbiosis, an imbalance of gut microbiota. We aimed to reveal the relationship between antibiotics exposure during the first 2 years after birth and type 1 diabetes risk in children under 8 years of age using a nationally representative data from South Korea.

METHODS

The final study population consisted of 63,434 children from the National Health Insurance Service (NHIS) database from 2008 to 2015. The primary exposure of interest was antibiotics prescription in first 2 years after birth. The analysis was conducted with cumulative defined daily dose (cDDD; 0-29, 30-59, ≥ 60 cDDD), the number of antibiotics classes (0-3, 4, ≥5 classes), and age at first antibiotics prescription (0-119, 120-239, ≥ 240 days). Age, sex, household income, and overweight were considered as potential confounding covariates.

RESULTS

Compared to those within the less than 30 cDDD, other groups that were prescribed more antibiotics did not have a significant difference in diabetes risk (aHR 0.86, 95% CI 0.37-2.02 in ≥ 60 cDDD). The number of antibiotics classes and age at first antibiotics prescriptions were also not associated with the risk of type 1 diabetes. The development of diabetes was not related to the cDDD, the number of antibiotics classes, and age at first antibiotics prescription according to subgroup analysis which was stratified by overweight.

CONCLUSIONS

Antibiotics exposure within the first 2 years of life was not associated with subsequent diabetes risk. Future studies using a larger number of long-term follow-up data are needed.

Combined Effects of Chronic Kidney Disease and Nonalcoholic Fatty Liver Disease on the Risk of Cardiovascular Disease in Patients with Diabetes

Background: We investigated the combined effect of chronic kidney disease (CKD) and nonalcoholic fatty liver disease (NAFLD) on the risk of cardiovascular disease (CVD) in patients with type 2 diabetes. Methods: Data were obtained from the Korean National Health Insurance Service. Patients with diabetes who participated in health screenings from 2009 to 2011 were included. The fatty liver index (FLI) was used as a surrogate marker for NAFLD. Results: During a mean follow-up of 6.9 years, 40,863 incidents of myocardial infarction (MI), 58,427 strokes, and 116,977 deaths were reported in 1,607,232 patients with type 2 diabetes. After adjusting for conventional risk factors, patients with CKD and NAFLD showed the highest risk of MI and stroke (hazard ratio (HR) = 1.49; 95% confidence interval (CI): 1.42–1.57 and stroke, HR = 1.48; 95% CI: 1.41–1.54, respectively) compared with those without either CKD or NAFLD. Both overall and cardiovascular mortality were highest in the CKD/NAFLD group compared with other groups (HR = 2.00; 95% CI: 1.94–2.06, and HR = 2.20; 95% CI: 2.07–2.35, respectively). Advanced liver fibrosis was significantly associated with an increased risk of CVD in patients with NAFLD. Proteinuria was significantly associated with incidence of CVD events in patients with CKD. Conclusions: The combination of CKD and NAFLD was associated with an increased risk of CVD and mortality in patients with type 2 diabetes. Close monitoring and appropriate management of CKD and NAFLD may be warranted to prevent CVD in these patients.

Association between Proton Pump Inhibitor Use and Risk of Hepatocellular Carcinoma: A Korean Nationally Representative Cohort Study

(1) Background: The association between proton pump inhibitor (PPI) use and hepatocellular carcinoma (HCC) has been controversial, especially in the general population. We aimed to determine the impact of PPI on HCC risk in participants without liver cirrhosis or chronic hepatitis virus infection. (2) Methods: We assessed 406,057 participants from the Korean National Health Insurance Service database who underwent health screening from 2003 to 2006. We evaluated exposure to PPI before the index date using a standardized daily defined dose (DDD) system. The association of proton pump inhibitor use with the risk of HCC was evaluated using multivariable-adjusted Cox proportional hazards regression. (3) Results: Compared with non-users, PPI use was not associated with the HCC risk in low (<30 DDDs; aHR, 1.07; 95% CI, 0.91−1.27), intermediate (30 ≤ PPI < 60 DDDs; aHR, 0.96; 95% CI, 0.73−1.26), and high (≥60 DDDs; aHR, 0.86; 95% CI, 0.63−1.17) PPI groups in the final adjustment model. In addition, risks of cirrhosis-associated HCC and non-cirrhosis-associated HCC were not significantly associated with PPI use. The results remained consistent after excluding events that occurred within 1, 2, and 3 years to exclude pre-existing conditions that may be associated with the development of HCC. We also found no PPI-associated increase in HCC risk among the selected population, such as those with obesity, older age, and chronic liver diseases. (4) Conclusions: PPI use may not be associated with HCC risk regardless of the amount. We call for future studies conducted in other regions to generalize our findings.

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.

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.

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.

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.