National Health Insurance Service-National Sample Research Articles

Association Between Atopic Dermatitis and Meniere's Disease: Nationwide Cohort Study.

Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by relapsing and remitting episodes. Although AD is well-known for its association with other allergic conditions, its relationship with Meniere's disease has not been thoroughly investigated. This study aimed to explore the potential correlation between AD and Meniere's disease. This study utilized data from the National Health Insurance Service-National Sample Cohort, a nationwide population-based database. The AD group was selected from a cohort of 1 million individuals randomly extracted from database. A non-AD group was obtained through Propensity Score Matching. The AD group comprised 84,579 individuals, with an equal number of individuals in the non-AD (control) group. The overall hazard ratio (HR) for Meniere's disease in the AD group was 1.44 (95% confidence interval (CI): 1.31-1.6). Subgroup analysis showed an adjusted HR of 0.42 (95% CI: 0.38-0.48) for Meniere's disease in males, 4.99 (95% CI: 4.45-5.62) in the middle-aged group (40-59 years), and 8.21 (95% CI: 7.21-9.35) in the older age group (≥60 years). Additionally, the adjusted HRs for developing Meniere's disease were higher in patients with comorbidities, including allergic rhinitis (1.18 [95% CI, 1.07-1.32]), allergic contact dermatitis (1.32 [95% CI, 1.19-1.48]), and allergic conjunctivitis (1.54 [95% CI, 1.32-1.82]). Long-term follow-up revealed that the prevalence of Meniere's disease was 1.44 times higher in the AD group compared to the control group. Moreover, older age, female sex, allergic rhinitis, allergic contact dermatitis, and allergic conjunctivitis were identified as factors that increase the risk of developing Meniere's disease. 3 Laryngoscope, 2024.

Fraction of Cancer Attributable to Carcinogenic Drugs in Korea from 2015 to 2030.

This study aims to estimate and project the Population Attributable Fraction (PAF) of cancer incidence and death due to carcinogenic drug use in Korea from 2015 to 2030, to estimate the degree of cancer prevention from exposure to carcinogenic drugs in Korea. Selected carcinogenic drugs were immunosuppressive and antineoplastic drugs classified as group I by the International Agency for Research on Cancer (IARC). Systematic review and meta-analyses were conducted to estimate the relative risk (RR) of cancer associated with carcinogenic drug use. Age was standardized using the annual prevalence rate of the National Health Insurance Service sample cohort (NHIS-NSC) from 2002 to 2013 to calculate the standardized prevalence rate of carcinogenic drug use each year. The PAF of specific cancer incidence and death were calculated using Levin's formula and Monte Carlo methods. The prevalence rates were extrapolated to estimate the trend of PAF from 2015 to 2030. In 2015, carcinogenic drugs attributed to 0.003% and 0.002% among the causes of cancer incidence and death in Korea. However, carcinogenic drugs attributed to 1.1% among the causes of both cancer incidence and death in patients with clinical indications of carcinogenic drugs. The PAF in patients with clinical indications of carcinogenic drugs were significantly high and expected to increase rapidly over time. Since these drugs are listed as essential by the World Health Organization (WHO), and may be difficult to replace, a surveillance system on susceptible populations using group I carcinogenic drugs must be discussed and implemented.

Machine Learning-Based Prediction for Incident Hypertension Based on Regular Health Checkup Data: Derivation and Validation in 2 Independent Nationwide Cohorts in South Korea and Japan.

Worldwide, cardiovascular diseases are the primary cause of death, with hypertension as a key contributor. In 2019, cardiovascular diseases led to 17.9 million deaths, predicted to reach 23 million by 2030. This study presents a new method to predict hypertension using demographic data, using 6 machine learning models for enhanced reliability and applicability. The goal is to harness artificial intelligence for early and accurate hypertension diagnosis across diverse populations. Data from 2 national cohort studies, National Health Insurance Service-National Sample Cohort (South Korea, n=244,814), conducted between 2002 and 2013 were used to train and test machine learning models designed to anticipate incident hypertension within 5 years of a health checkup involving those aged ≥20 years, and Japanese Medical Data Center cohort (Japan, n=1,296,649) were used for extra validation. An ensemble from 6 diverse machine learning models was used to identify the 5 most salient features contributing to hypertension by presenting a feature importance analysis to confirm the contribution of each future. The Adaptive Boosting and logistic regression ensemble showed superior balanced accuracy (0.812, sensitivity 0.806, specificity 0.818, and area under the receiver operating characteristic curve 0.901). The 5 key hypertension indicators were age, diastolic blood pressure, BMI, systolic blood pressure, and fasting blood glucose. The Japanese Medical Data Center cohort dataset (extra validation set) corroborated these findings (balanced accuracy 0.741 and area under the receiver operating characteristic curve 0.824). The ensemble model was integrated into a public web portal for predicting hypertension onset based on health checkup data. Comparative evaluation of our machine learning models against classical statistical models across 2 distinct studies emphasized the former's enhanced stability, generalizability, and reproducibility in predicting hypertension onset.

Impact of statin use in head and neck cancer: a nested case-control study.

Dyslipidemia and statin use are associated with an increased risk of various cancers. However, the association in head and neck cancer (HNC) remains unclear. Therefore, this study aimed to investigate the impact of dyslipidemia and statin use on the development of HNC. Using data from the Korean National Health Insurance Service-National Sample Cohort from 2002 to 2019, we compared two groups HNC patients (n = 1006) and matched control participants (n = 4024) after propensity score overlap weighted balancing. The odds ratios (ORs) for HNC development according to dyslipidemia and statin use duration were assessed using propensity score overlap-weighted multivariable logistic regression. Individuals with untreated dyslipidemia had significantly lower odds of developing HNC than those of normal participants (OR 0.70, 95% confidence interval [CI] 0.59-0.82). Conversely, patients with dyslipidemia who received statin therapy (< 60days) showed a nearly two-fold increase in the odds of HNC (OR 1.94, 95% CI 1.29-2.90). Long-term statin use (≥ 60days) aligned the odds with those of normal participants (OR 0.89, 95% CI 0.76-1.04). The adverse effect of short-term statin use on HNC development requires further study, and long-term statin use for dyslipidemia treatment does not increase the odds of HNC.

Trajectories of triglyceride-glucose index changes and their association with all-cause and cardiovascular mortality: a competing risk analysis

BackgroundThe association between changes in insulin resistance, reflected by the triglyceride-glucose (TyG) index, and mortality remains unclear. This study investigated whether longitudinal trajectories of TyG index changes are associated with all-cause and cardiovascular disease (CVD) mortality.MethodsThis retrospective cohort study analyzed data from 233,546 adults aged ≥ 19 years from the Korea National Health Insurance Service-National Sample Cohort. Participants were categorized as having increasing, stable, or decreasing TyG index changes during a 4-year exposure period (2009–2014). Mortality outcomes were assessed during an 8.13-year follow-up period (2015–2021). Cox proportional hazards regression and competing risk analysis were used to evaluate all-cause and CVD mortality.ResultsA total of 7918 mortality events, including 651 CVD deaths, were recorded. Compared with the stable group, adjusted hazard ratios for all-cause mortality were 1.09 (95% CI 1.03–1.15) in the increasing group and 1.23 (95% CI 1.01–1.50) for CVD mortality. An increased TyG index was significantly associated with all-cause mortality in individuals aged < 50 years; men; and individuals with obesity, hypertension, diabetes, and/or dyslipidemia. For CVD mortality, significant associations were found in individuals aged 50–69 years, with obesity, with diabetes, or without dyslipidemia.ConclusionAn increasing TyG index from baseline during follow-up was independently associated with higher risks of all-cause and CVD mortality. Serial monitoring of TyG index changes could enhance risk stratification and inform targeted interventions to reduce insulin resistance, and ultimately lower mortality risk.

Long-term exposure to PM2.5 and mortality: a national health insurance cohort study.

Previous studies with large data have been widely reported that exposure to fine particulate matter (PM2.5) is associated with all-cause mortality; however, most of these studies adopted ecological time-series designs or have included limited study areas or individuals residing in well-monitored urban areas. However, nationwide cohort studies including cause-specific mortalities with different age groups were sparse. Therefore, this study examined the association between PM2.5 and cause-specific mortality in South Korea using the nationwide cohort. A longitudinal cohort with 187917 National Health Insurance Service-National Sample Cohort participants aged 50-79 years in enrolment between 2002 and 2019 was used. Annual average PM2.5 was collected from a machine learning-based ensemble model (a test R2 = 0.87) as an exposure. We performed a time-varying Cox regression model to examine the association between long-term PM2.5 exposure and mortality. To reduce the potential estimation bias, we adopted generalized propensity score weighting method. The association with long-term PM2.5 (2-year moving average) was prominent in mortalities related to diabetes mellitus [hazard ratio (HR): 1.03 (95% CI: 1.01, 1.06)], circulatory diseases [HR: 1.02 (95% CI: 1.00, 1.03)] and cancer [HR: 1.01 (95% CI: 1.00, 1.02)]. Meanwhile, circulatory-related mortalities were associated with a longer PM2.5 exposure period (1 or 2-year lags), whereas respiratory-related mortalities were associated with current-year PM2.5 exposure. In addition, the association with PM2.5 was more evident in people aged 50-64 years than in people aged 65-79 years, especially in heart failure-related deaths. This study identified the hypothesis that long-term exposure to PM2.5 is associated with mortality, and the association might be different by causes of death. Our result highlights a novel vulnerable population: the middle-aged population with risk factors related to heart failure.

Association Between Migraine and Open-Angle Glaucoma: A Twelve-Year Nationwide Retrospective Korean Cohort Study.

Previous studies have reported that migraine headaches may be one of the possible risk factors for open-angle glaucoma (OAG); however, a consensus has not been reached regarding the association between OAG and migraine. In this study, we examined the risk of developing OAG in migraine patients using a 12-year nationwide cohort. In this study, data from the Korean National Health Insurance Service-National Sample Cohort database from 2002 to 2015 was used to perform a retrospective cohort study. The study included 1,103,302 subjects, out of which 41,148 were diagnosed with migraine during 2003-2008 and were categorized as the migraine group, while 205,741 patients were selected as controls through propensity score matching at a 1:5 ratio. Subjects with migraine or OAG was ascertained based on KCD code. Multivariate Cox regression analysis was used to evaluate the hazard rate of OAG onset in the migraine group, and subgroup analysis was performed to identify any differences based on sex and age. Multivariate Cox regression analysis showed that the incidence of OAG was significantly greater among patients with migraine than among patients in the comparison group (hazard ratio [HR] 1.238; 95% confidence interval [CI] 1.160-1.132, P < 0.001). Moreover, the risk of developing OAG compared to subjects without migraine did not differ according to the presence of an aura (migraine with aura: HR 1.235; 95% CI 1.137-1.342, P < 0.001; migraine without aura: HR 1.248; 95% CI 1.143-1.363, P < 0.001). In subgroup analyses, the patients with migraine under 40-year-old were found to have a greater hazard rate (HR 1.576, 95% CI: 1.268-1.957) of developing OAG in contrast with patients with migraine and over 40-year-old (HR 1.167, 95%CI: 1.089-1.250) when compared to the corresponding non-migraine patients. This study showed that migraine is a significant risk factor for OAG onset in Korean population, and the presence of aura did not affect the hazard rate of OAG development. Patients with migraine showed significantly increased risk of developing OAG in Korean population, without significant differences according to the presence of aura. Our results suggest presence of migraine as a possible risk factor for OAG.

Epidemiological Evidence for Upper Respiratory Infections as a Potential Risk Factor for Meniere's Disease: A Korean National Health Sample Cohort Study.

Meniere's disease (MD) is a chronic inner ear disorder characterized by tinnitus, ear fullness, episodic vertigo, and fluctuating hearing loss, which significantly impacts quality of life and poses management challenges. Recent evidence suggests that upper respiratory infections (URIs) may contribute to MD's onset. This study examines the potential link between URIs and MD using data from the Korean National Health Insurance Service-National Sample Cohort (2002-2019). We analyzed 19,721 individuals with MD and 78,884 matched controls, adjusting for demographic factors and comorbidities using propensity score matching. Our results showed that individuals with a URI within one year prior to the index date exhibited a 2.01-fold greater likelihood of developing MD (95% confidence interval [CI] = 1.91-2.11, p < 0.001), while those with URIs within two years demonstrated a 1.54-fold higher probability (95% CI = 1.50-1.59, p < 0.001). Furthermore, we found that even remote URIs occurring up to two years before the index date significantly increased the risk of developing MD, underscoring the need for long-term patient follow-up. Overall, our study suggests that individuals with a history of URI may have an elevated risk of developing MD over multiple time frames, regardless of demographic or health profiles.

Effect of comorbidities on mortality in patients with nontuberculous mycobacterial infection in Korea: National Health Insurance Service-National Sample Cohort data

Patients with nontuberculous mycobacteria (NTM) infection have multiple comorbidities, but the impact of comorbidities on mortality are not well known. We aimed to compare the mortality between people with and without NTM infection and associated comorbidities and their prognostic value on mortality using National Health Insurance Service-National Sample Cohort data from 2006 to 2019. In this matched cohort study, people with and without NTM infection aged 20–89 years were matched 1:4 by sex, age, region, and income. The hazard ratios (HRs) with 95% confidence intervals (CIs) of mortality in patients with NTM infection were estimated using a Cox proportional hazard regression model. In total, 2421 patients with NTM infection (mean age, 54.8 years) and 9684 controls were included. NTM-infected patients had a significantly increased risk of mortality than matched controls in the multivariable model adjusted for age, sex, region, income, and Charlson comorbidity index (aHR = 1.88, 95% CI 1.65–2.14). Among patients with NTM infection, respiratory comorbidities including chronic obstructive pulmonary disease, asthma, interstitial lung disease, and moderate to severe liver disease and malignancy were positively associated with mortality. NTM infection was independently associated with an increased risk of mortality, and mortality risk in patients with NTM infection may be increased by coexisting comorbidities.

Association Between Type 1 Diabetes Mellitus and Incident Gastrointestinal Cancer in Korean Population: A Nationwide Retrospective Cohort Study.

The age-standardised incidence ratio of gastrointestinal cancers in type 1 diabetes (T1D) patients has been reported to be higher than that in the general population. After adjusting for shared risk factors, we aimed to explore the association between T1D and gastrointestinal cancer and examine how this relationship varies by age and sex. This retrospective cohort study included 268,179 participants from the Korean National Health Insurance Service-National Sample Cohort. The primary outcome is the incident of gastrointestinal cancers, based on diagnostic codes. Multivariate Cox regression analyses were performed to assess the association between T1D and gastrointestinal cancers. Of the 268,179 participants, 2681 had T1D at baseline and were followed for 12.98 (± 2.92) years. Compared with non-T1D, T1D patients had a significantly increased risk of all gastrointestinal cancer (adjusted hazard ratio [aHR]: 1.403, 95% confidence interval [CI]: 1.253-1.573). T1D patients increased risks of oesophageal cancer (aHR: 1.864, 95% CI: 1.038-3.349), gastric cancer (aHR: 1.313, 95% CI: 1.066-1.616), colon cancer (aHR: 1.365, 95% CI: 1.110-1.678), liver cancer (aHR: 1.388, 95% CI: 1.115-1.727), and pancreatic cancer (aHR: 1.716, 95% CI: 1.182-2.492). The consistency of this association persisted among both male and female, with its strength increasing with older age. The risk of gastrointestinal cancer was significantly increased in T1D patients. Older male T1D patients exhibit a higher risk, suggesting the need for targeted attention in their care.

Burden of Herpes Zoster in Individuals With Chronic Conditions in the Republic of Korea: A Nationwide Population-Based Database Study

Abstract Background Chronic conditions (CCs) may increase the risk of herpes zoster (HZ) infection, leading to a greater healthcare burden in these individuals compared to those without CCs. It is therefore clinically important to quantify HZ disease burden in individuals with and without CCs, given the rapidly aging population in the Republic of Korea (ROK). Methods This retrospective cohort study examines the trends in incidence rates (IRs) and incidence rate ratios (IRRs) in individuals aged ≥18 years with CCs, using the National Health Insurance Service National Sample Cohort (NHIS-NSC) database from 2010 to 2019. These patients were stratified by age group, sex, HZ complications, and CCs. The annual average number of HZ patients, IRs, and IRRs were calculated for individuals with and without CCs. Results In total, 729 347 patients with HZ were eligible for the study. HZ IRs were highest in patients with diabetes, followed by chronic obstructive pulmonary disease, chronic kidney disease, asthma, and chronic liver disease, with HZ IRRs following a similar trend. Overall, HZ IRs generally increased with age, typically peaking at 60–64 or 65–69 years, and were similar for females and males. HZ IRs were highest among patients without complications, followed by HZ with other, cutaneous, ocular, and neurologic complications across all CCs. For each of the CCs, HZ IRs were consistently higher than those of the non-CC population regardless of sex. Conclusions The findings of this study reiterate the importance of HZ prevention for healthy aging, especially for CC populations at increased risk of HZ in the ROK.

Lifestyle Factors, Sociodemographic Characteristics and Incident Hypertension: A Prospective Analysis of the Korean National Health Insurance Service Sample Cohort.

Hypertension is a significant chronic disease globally, and lifestyle modifications are crucial for the prevention of this disease. We conducted a longitudinal analysis of the associations between lifestyle factors and the incidence of hypertension, stratified by sociodemographic characteristics. We analyzed 113,022 adults (65,315 men), aged 20 years or older from the Korean National Health Insurance Service-National Sample Cohort 2.0 who participated in health screening between 2002 and 2003. Lifestyle factors (smoking, drinking, physical activity) were assessed at baseline using self reports, and incident hypertension was defined based on physician diagnoses. Cox proportional hazards regression models were used to assess associations. During an 11.6-year follow-up, 26,812 new cases of hypertension were identified. The risk of hypertension was high among men and women who smoked over 20 cigarettes daily (men: hazard ratio [HR]: 1.15; 95% confidence interval [CI], 1.08-1.21; women: HR: 1.62; 95% CI 1.17-2.25) and those who drank over 1.5 bottles of alcohol daily (men, HR: 1.18; 95% CI, 1.12-1.24; women, HR: 1.23; 95% CI 1.02-1.47). These associations tended to be high in high-income men (HR: 1.09; 95% CI, 1.04-1.14), low-income women (HR: 1.19; 95% CI, 1.05-1.35) and non-obese women (HR: 1.13; 95% CI, 1.01-1.27) who currently smoked. Physical activity was inversely associated with incident hypertension in men (HR: 0.96; 95% CI, 0.93-0.99). Unhealthy lifestyle factors, such as heavy smoking and drinking, was associated with an increased risk of hypertension, with variations by income, BMI, and sex. These findings underscore the importance of tailored, population-specific prevention strategies to address hypertension disparities.

Healthcare Utilization and Discrepancies by Income Level Among Patients With Newly Diagnosed Type 2 Diabetes in Korea: An Analysis of National Health Insurance Sample Cohort Data.

The use of qualitative healthcare services or its discrepancy between different income levels of the type 2 diabetes (T2D) patients has seldom been studied concurrently. The present study is unique that regarding T2D patients of early stages of diagnosis. Aimed to assess the utilization of qualitative healthcare services and influence of income levels on the inequality of care among newly diagnosed patients with T2D. A retrospective cohort study of 7590 patients was conducted by the National Health Insurance Service National Sample Cohort 2.0 from 2002 to 2015. Insured employee in 2013 with no history of T2D between 2002 and 2012 were included. The standard of diabetes care includes hemoglobin A1c (HbAlc; 4 times/y), eyes (once/y) and lipid abnormalities (once/y). Multivariate logistic regression analysis was performed to examine the difference between income levels and inequality of care. From years 1 to 3, rates of appropriate screening fell from 16.9% to 14.1% (HbA1c), 15.8% to 14.5% (eye), and 59.2% to 33.2% (lipid abnormalities). Relative to income class 5 (the highest-income group), HbA1 screening was significantly less common in class 2 (year 2: odds ratio [OR], 0.78; 95% confidence interval [CI], 0.61 to 0.99; year 3: OR, 0.79; 95% CI, 0.69 to 0.91). In year 1, lipid screening was less common in class 1 (OR, 0.84; 95% CI, 0.73 to 0.98) than in class 5, a trend that continued in year 2. Eye screening rates were consistently lower in class 1 than in class 5 (year 1: OR, 0.73; 95% CI, 0.60 to 0.89; year 2: OR, 0.63; 95% CI, 0.50 to 0.78; year 3: OR, 0.81; 95% CI, 0.67 to 0.99). Newly diagnosed T2D patients have shown low rate of HbA1c and screening for diabetic-related complications and experienced inequality in relation to receiving qualitative diabetes care by income levels.

Chronic periodontitis and risk of lung cancer: a nationwide cohort study.

The impact of long-term chronic periodontal conditions on the risk of lung cancer could not be accurately evaluated. Our aim was to provide more evidence on the connection between chronic periodontitis (CP) and lung cancer using a nationwide dataset. This study used data from the Korean National Health Insurance Service National Sample Cohort. We enrolled 72,658 individuals with CP (CP cohort) between 2005 and 2019 and 1:1 age- and sex-matched controls without CP (non-CP cohort). During the median follow-up period of 5.1 (interquartile range, 2.8-8.0) years, 0.56% (n = 405/72,658) of the CP cohort and 0.29% (n = 212/72,658) of the matched non-CP cohort developed lung cancer, with incidence rates of 8.3 and 4.5 per 10,000 person-years. The risk of incident lung cancer was significantly higher in the CP cohort than in the matched non-CP cohort (adjusted hazard ratio = 2.27, 95% confidence interval = 1.94-2.65). The risk of incident lung cancer was 2.45-fold and 2.10-fold higher in mild and moderate-to-severe CP cohorts than in the matched non-CP control. The risk of incident lung cancer was especially higher in the 40-59 age group, females, and never-smokers than their counterparts. We demonstrate that the risk of incident lung cancer is higher in individuals with CP than in those without. The risk of lung cancer was especially high in individuals with more severe CP, females, never-smokers, and obese populations.

Survival benefit of inhaled corticosteroids in patients with chronic obstructive pulmonary disease: a nationwide cohort study

The role of inhaled corticosteroids (ICS) in chronic obstructive pulmonary disease (COPD) is debated. We investigated whether the administration of ICS could lower the mortality risk in patients with COPD. We utilized the Korean National Health Insurance Service-National Sample Cohort database from 2002 to 2019. We included patients who had claim codes for COPD and inhalation respiratory medicine at least twice a year. A time-dependent Cox regression model was employed to estimate the association between ICS usage and survival. The cumulative dose of ICS was classified into three groups, and the mortality risk was compared among these groups. Of 16,463 included patients, there were 4395 (26.7%) deaths during the mean follow-up period of 5.0 years. The time-dependent Cox regression model demonstrated that ICS users had a significantly lower mortality risk compared to non-users (adjusted hazard ratio, 0.89; 95% CI, 0.83–0.94; p < 0.001), particularly among individuals aged ≥ 55 years, women, never smokers, and those with history of asthma or coronary heart disease. Higher cumulative dose groups were associated with a lower mortality risk compared to the lowest cumulative dose group. In conclusion, the administration of ICS seemed to be associated with a lower mortality risk in patients with COPD.

Interrupted time series analysis of chronic periodontitis-related procedures before and after the scaling reimbursement policy in Korea.

To study the use of a quasi-experimental design to assess the effects of scaling reimbursement policies on the incidence of chronic-periodontitis procedures. Interrupted time series analysis was used to compare the effects before and after policy implementation using data on the number of periodontitis-related procedures from the Korean National Health Insurance Service-National Sample Cohort (n = 740,467) and the Health Screening Cohort (n = 337,904). Periodontitis-related procedures with diagnosis codes were categorized into basic (scaling or root planing), intermediate (subgingival curettage) and advanced (tooth extraction, periodontal flap surgery, bone grafting for alveolar bone defects or guided tissue regeneration). Subjects' demographics and comorbidities were considered. The incidence rate of immediate changes and gradual effects before and after policy implementation was assessed. Following the policy implementation from July 2013, an immediate increase was observed in total and basic procedures. No significant changes were noted in intermediate and advanced procedures initially. A decrease in the slope of intermediate procedures was observed in both databases. Advanced procedures showed varied trends, with no change in the National Sample Cohort but an increase in the Health Screening Cohort, particularly among subjects with comorbidities. Following the new policy implementation, the number of intermediate procedures decreased while the number of advanced procedures increased, especially among patients with comorbidities. These findings offer valuable insights on policy evaluation.

Association between Gastric Cancer and Osteoporosis: A Longitudinal Follow-Up Study Using a National Health Sample Cohort.

Gastric cancer (GC) survivors may be more likely to develop osteoporosis. However, few studies on the relationship between GC and osteoporosis have been conducted on large patient populations. We aimed to determine the incidence of osteoporosis and identify related factors by comparing patients with GC and matched controls using the Korean National Health Insurance Service-National Sample Cohort (KNHIS-NSC). This study included 9078 patients with GC and 36,312 controls (1:4 propensity score-matched for sex, age, residence, and income). The hazard ratio (HR) for osteoporosis was significantly greater for GC patients than for controls according to Charlson Comorbidity Index (CCI) score-adjusted models (adjusted HR = 1.13). Kaplan-Meier analysis revealed that the cumulative incidence of osteoporosis during the follow-up period commencing from the index date was significantly greater in GC patients than in the controls (p = 0.0087). A positive correlation of osteoporosis with GC was detected for those aged < 65 years, males, and those with CCI scores = 0. In conclusion, the study findings suggest that men with GC aged < 65 years may be at an increased risk for osteoporosis. Research into additional risk factors and the optimal timing of interventions are needed to prevent fractures and minimize bone loss in GC survivors.

Inhaled Corticosteroids and the Risk of Nontuberculous Mycobacterial Infection in Chronic Airway Disease: A Nationwide Population-Based Study.

Chronic airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD), are increasingly being treated with inhaled corticosteroid (ICS). However, ICSs carry potential infection risks, particularly nontuberculous mycobacteria (NTM). This study investigated the association between ICS use and NTM infection risk using national insurance data, particularly for individuals with chronic airway diseases. We conducted a nationwide population-based study using data from the National Health Insurance Service-National Sample Cohort in South Korea from 2002 to 2019. The cohort included 57,553 patients diagnosed with COPD or asthma. To assess the risk of NTM infection, we used Cox proportional hazards models and propensity score-based inverse probability of treatment weighting (IPTW) to ensure a balanced analysis of covariates. Of the 57,553 patients (mean age 56.0 years, 43.2% male), 16.5% used ICS and 83.5% did not. We identified 63 NTM infection cases, including nine among ICS users and 54 among non-users. Before and after IPTW, ICS use was associated with a higher risk of NTM infection (adjusted hazard ratio [HR], 4.01; 95% confidence interval [CI], 1.48 to 15.58). Higher risks were significant for patients ≥65 years (adjusted HR, 6.40; 95% CI, 1.28 to 31.94), females (adjusted HR, 10.91; 95% CI, 2.24 to 53.20), never-smokers (adjusted HR, 6.31; 95% CI, 1.49 to 26.64), systemic steroid users (adjusted HR, 50.19; 95% CI, 8.07 to 312.19), and those with higher comorbidity scores (adjusted HR, 6.64; 95% CI, 1.19 to 37.03). ICS use in patients with chronic airway diseases might increase the risk of NTM infection, particularly in older females, never-smokers, and systemic steroid users.

Background Rates of Adverse Events of Special Interest for COVID-19 Vaccine Safety Monitoring in South Korea

Objectives: This study aimed to estimate background incidence rates (IR) for adverse events of special interest (AESI) associated with COVID-19 vaccines in South Korea. Methods: We used data from the Korean National Health Insurance Service-National Sample Cohort from January 1, 2015 to December 31, 2019, with IR calculated annually. Eight AESIs including acute myocarditis, acute pericarditis, acute disseminated encephalomyelitis (ADEM), acute transverse myelitis (ATM), encephalitis, anaphylaxis, Bell’s palsy, and lymphadenitis were evaluated. Two operational strategies were implemented: a broad definition using ICD-10 codes for primary or secondary diagnoses to enhance sensitivity, and a narrow definition integrating ICD-10 codes with procedure and drug codes for enhanced accuracy and specificity. IR was calculated by dividing the number of incident cases by the total person-time at risk, with separate analyses by sex and age. Results: During the study period, the incidence of anaphylaxis, Bell’s palsy, and lymphadenitis under the broad definition continued to increase. Under the narrow definition, there were no reported cases of acute myocarditis or Bell’s palsy from 2015 to 2019. Additionally, the incidence rates for acute pericarditis, ADEM, ATM, encephalitis, anaphylaxis, and lymphadenitis were lower than those calculated under the broad definition. Males generally had higher rates, except for Bell’s palsy and lymphadenitis. Most AESIs were more common in individuals aged 65 and older, whereas ADEM and lymphadenitis were higher in children aged 0-19 years. Conclusions: Variability in AESI rates emphasizes the importance of considering definitions and demographics when establishing background rates for surveillance, which is a critical aspect of monitoring vaccine safety.

Long-term exposure to PM2.5 and mortality in a national cohort in South Korea: effect modification by community deprivation, medical infrastructure, and greenness

BackgroundLong-term exposure to PM2.5 has been linked to increased mortality risk. However, limited studies have examined the potential modifying effect of community-level characteristics on this association, particularly in Asian contexts. This study aimed to estimate the effects of long-term exposure to PM2.5 on mortality in South Korea and to examine whether community-level deprivation, medical infrastructure, and greenness modify these associations.MethodsWe conducted a nationwide cohort study using the National Health Insurance Service-National Sample Cohort. A total of 394,701 participants aged 30 years or older in 2006 were followed until 2019. Based on modelled PM2.5 concentrations, 1 to 3-year and 5-year moving averages of PM2.5 concentrations were assigned to each participant at the district level. Time-varying Cox proportional-hazards models were used to estimate the association between PM2.5 and non-accidental, circulatory, and respiratory mortality. We further conducted stratified analysis by community-level deprivation index, medical index, and normalized difference vegetation index to represent greenness.ResultsPM2.5 exposure, based on 5-year moving averages, was positively associated with non-accidental (Hazard ratio, HR: 1.10, 95% Confidence Interval, CI: 1.01, 1.20, per 10 µg/m3 increase) and circulatory mortality (HR: 1.22, 95% CI: 1.01, 1.47). The 1-year moving average of PM2.5 was associated with respiratory mortality (HR: 1.33, 95% CI: 1.05, 1.67). We observed higher associations between PM2.5 and mortality in communities with higher deprivation and limited medical infrastructure. Communities with higher greenness showed lower risk for circulatory mortality but higher risk for respiratory mortality in association with PM2.5.ConclusionsOur study found mortality effects of long-term PM2.5 exposure and underlined the role of community-level factors in modifying these association. These findings highlight the importance of considering socio-environmental contexts in the design of air quality policies to reduce health disparities and enhance overall public health outcomes.