Korean National Health Insurance System Research Articles

Impact of Alcohol Consumption on Cardiovascular Events in Patients Undergoing Percutaneous Coronary Intervention.

Background/Objectives: The impact of alcohol consumption and its restriction on clinical outcomes in patients undergoing percutaneous coronary intervention (PCI) remains elusive. We aimed to investigate the clinical outcomes in drinkers undergoing PCI. Methods: We included 77,409 patients who underwent PCI and a health check-up within one year of the PCI using a nationwide prospective database from the Korean National Health Insurance System. Primary outcomes were major adverse cardiovascular and cerebrovascular events (MACCE), a composite of all-cause mortality, myocardial infarction, coronary revascularization, and stroke. Patients were classified as non-drinkers, within-the-guideline (≤1 standard drink in women and ≤2 in men), and above-the-guideline drinkers based on drinking status at the first health check-up after PCI. Results: During a 4.0-year follow-up duration, MACCE incidence was 19.7% (n = 15,214) (4689 [6.1%] deaths, 1916 [2.5%] MI, 2033 [2.6%] strokes, and 10,086 [13.0%] revascularizations). Both within-the-guideline- (aHR [95%CI], 0.843 [0.773-0.919]) and above-the-guideline drinkers (0.829 [0.784-0.876]) had a lower MACCE risk than the non-drinkers. A characteristic J-curve relationship was observed between the frequency or body weight-adjusted alcohol consumption and MACCE risk, with the lowest risk in the once-per-week and a mild amount per body weight (≤0.33 g/kg/week) group. Drinking habits after PCI were associated with a lower risk of adverse cardiovascular outcomes; those who continued to drink before and after PCI had the lowest risk. Conclusions: Alcohol consumption was associated with a lower risk of adverse outcomes in patients undergoing PCI. Further studies with longer-term follow-up are warranted.

Socioeconomic disparity in utilization of transcatheter aortic valve replacement

Abstract Introduction Transcatheter aortic valve replacement (TAVR) is a major therapeutic option, rapidly replacing surgical aortic valve replacement (SAVR) in patients with aortic stenosis (AS) in recent years. However, the use of TAVR may vary with the socioeconomic status (SES) since new technologies are more likely to have the lower accessibility in some medico-social environments. In South Korean patients with AS, we investigated the difference in the use of TAVR based on SES and whether the difference influences clinical outcomes of patients with AS. Methods Between 2010 and 2020, 30,142 patients newly diagnosed with AS in a tertiary or regional center were investigated through the Korean National Health Insurance System (KNHIS). Patients were received either medical, SAVR or TAVR therapy for AS. The patients were categorized into 3 groups based on the insurance premium level (IPL) of the KNHIS (IPL1, <100 KW; IPL2, 100-249 KW; IPL3, ≥250KW). AS-related death was defined as death by AS, heart failure or ventricular arrhythmia. Cardiovascular (CV) death was defined as AS-related death or death by myocardial infarction or stroke. The study period was divided at year 2015, when the partial coverage for TAVR was implemented by the KNHIS. Results The numbers of patients referred to the tertiary/regional centers have continuously grown for the 11 years but the referring rate has grown even faster since 2015. The proportions of TAVR has increased while that of SAVR has decreased since 2015. TAVR was more frequently chosen by patients with a higher IPL (5.5%, 8.0% and 12.5%, respectively in the IPL1, IPL2 and IPL3, p<0.001), whereas the medical therapy appeared not affected by the IP levels. The patients in the IPL2 (odd ratio [OR] 1.33 [1.20-1.47]) and IPL3 (OR 1.65 [1.45-1.86]) had a higher chance to undergo TAVR than those in the IPL1 whereas the patients in the IPL3 was a lower chance to undergo SAVR than those in the IPL1 (OR 0.86 [0.78-0.94]). In patients with severe AS, the disparities between the IPL1 and IPL3 exaggerated (OR 1.99 [1.70-2.33]) (Figure 1). Higher IPLs were associated with lower risks of CV death and AS-related death. Time-varying Cox proportional hazard models showed that TAVR was associated with a lower risk of CV death than both medical therapy and SAVR in the entire study period and in year 2015 or later, whereas TAVR was associated with a lower risk of AS-related death than the both only in year 2015 or later, after adjustment of relevant covariates including the IPL (Figure 2). The choice of TAVR significantly medicated the associations between IPLs and the risk of CV death (responsible for 3.0% in the IPL2 and 4.1% in the IPL3). Conclusion The SES based on the IPL is independently associated with the choice of TAVR in patients with AS and the association has become stronger since 2015. The disparity in use of TAVR could mediate more frequent CV deaths in patients with the lower IPL.Figure 1Figure 2

A qualitative study on the field experience of genetic counseling in Korea.

In Korea, genetic counseling services began with the opening of genetic clinics in the early 1990s; in recent years, demand for these services has increased. However, genetic counseling is not an officially recognized healthcare service under the Korean national health insurance system; further, its certification is not recognized as a medical qualification. To clarify the role and significance of genetic counselors, this study examined their field experiences. To this end, we conducted focus group interviews with 11 certified genetic counselors, six advanced practice nurses, and four regular nurses. The interviews were transcribed verbatim and examined using thematic analysis. We found that even though Korea did not recognize their roles, the participants met their responsibilities and primary duties. In addition, they faced challenges during counseling due to a lack of formal education in genetics and genomics. Moreover, they encountered dilemmas related to the legal and ethical aspects of decision support for family testing or prenatal diagnosis due to the complexity of rare genetic disorders. However, they attempted to acquire the specialized knowledge needed to support patients with rare genetic disorders and their families, gradually developing practical experience and specialized knowledge. Therefore, it is necessary to develop manuals, establish systems, and improve working environments to provide high-quality and specialized genetic counseling. Additionally, there is a need for national support, such as establishing set wages for genetic counselors, developing a national qualification certification system, and securing dedicated personnel.

One-year mortality and associated factors in older hospitalized COVID-19 survivors: a Nationwide Cohort Study in Korea

This study aimed to evaluate the 1-year mortality rate among older patients with COVID-19 discharged from hospital and to identify risk factors associated with this outcome. Using a COVID-19 dataset from the Korean National Health Insurance System, this study’s evaluation period spanned from October 8, 2020, through December 31, 2021. The primary outcome was the 1-year mortality rate following hospital discharge. A logistic regression model was employed for multivariable analysis to estimate the odds ratios for the outcomes, and the Kaplan-Meier method was used to analyze differences in 1-year survival rates. Among the 66,810 COVID-19 patients aged 60 years or older who were hospitalized during the study period, the in-hospital mortality rate was 4.8% (n = 3219). Among the survivors (n = 63,369), the 1-year mortality rate was 4.9% (n = 3093). Non-survivors, compared to survivors, were significantly older (79.2 ± 9.5 vs. 68.9 ± 7.8, P < 0.001) and exhibited a lower rate of COVID-19 vaccination (63.0% vs. 91.7%, P < 0.001). Additionally, non-survivors experienced a higher incidence of organ dysfunction, along with a greater proportion of required mechanical ventilation (14.6% vs. 1.0%, P < 0.001) and extracorporeal membrane oxygenation (4.0% vs. 0.1%, P < 0.001). Multivariable logistic regression analysis identified older age, male sex, cardiovascular disease, immunosuppression, organ dysfunction, illness severity, and corticosteroid use during hospitalization as factors associated with death within 1 year after hospital discharge. However, vaccination was found to have a long-term protective effect against death among COVID-19 survivors. The 1-year mortality rate after hospital discharge for older COVID-19 patients was comparable to the in-hospital mortality rate for these patients in Korea. The long-term mortality rate among hospitalized older COVID-19 patients was influenced by demographic factors and the severity of illness experienced during hospitalization.

Association between colchicine use and adverse cardiovascular events in patients with gout: a nationwide nested case-control study.

The association between colchicine use and the primary prevention of atherosclerotic cardiovascular disease (ASCVD) remains unknown. This study aimed to explore the association between colchicine use and new development of ASCVD and ASCVD-related mortality in patients with incident gout. This nested case-control study utilized the nation-wide claims database of the Korean National Health Insurance System. Patients without a history of ASCVD who developed incident gout and were newly started on allopurinol as first-line therapy between 2011 and 2016 were initially screened. Individuals who experienced ASCVD event or ASCVD-related mortality during the follow-up period were matched with four controls for age, sex, income, residential area, co-morbidities, and medications. The main exposure was colchicine use, assessed by 1) the cumulative defined daily doses (cDDDs) and 2) the cumulative duration. For secondary analyses, the risk of ASCVD events and ASCVD-related mortality were examined, separately. Overall, 9,346 patients with ASCVD event or ASCVD-related mortality were matched with 35 070 controls. The patient population was predominantly male. Compared with non-users, a curvilinear relationship between higher cDDDs of colchicine and the odds of ASCVD event was observed; the odds ratios (95% confidence interval) were were 1.09 (1.04-1.15) for <90 cDDDs, 1.20 (1.07-1.33) for 80-179 cDDDs, and 1.21 (1.09-1.35) for ≥180 cDDDs. This association was similarly observed for ASCVD events and ASCVD-related mortality, respectively. Colchicine use was associated with an increased risk of ASCVD in patients with newly diagnosed gout who did not have a prior history of ASCVD.

The Consolidation of Risk Pools in the National Health Insurance Program of the Republic of Korea: Analysis of the Political Processes

ABSTRACT South Korea is one of the few countries that has successfully consolidated its national risk pools into a single-payer health insurance system. This study analyzes national health insurance (NHI) consolidation in South Korea between 1980 and 2003, drawing lessons for countries seeking to consolidate their risk pools. The paper contextualizes the development of the South Korean national health insurance system and the consolidation of its risk pools in the changes in the political environment, particularly the processes of political democratization. It examines how these processes have affected the societal meanings and roles of the health insurance system. The paper focuses on two policy stages. During the agenda-setting stage, the government and employers emphasized the efficiency of the health insurance system. This emphasis contributed to the failure of a consolidation plan that emphasized equity over efficiency. However, as democratization expanded, the power of civil society movements and the popular demand for equity grew stronger. During the policy adoption phase, consolidation of health insurance trusts in South Korea was achieved through social and political processes that influenced public opinion, expanded civil society participation in decision-making, and worked with the government to integrate health insurance organizations and funds.

Association Between Frequency of Rehabilitation Therapy and Long-Term Mortality After Stroke: A Nationwide Cohort Study.

Previous studies have demonstrated conflicting results regarding the effects of rehabilitation therapy on poststroke mortality. We aimed to investigate the association between rehabilitation therapy, including both inpatient and outpatient treatment, within the first 6 months after stroke and long-term all-cause mortality in patients with stroke using the Korean National Health Insurance System data. A total of 10 974 patients newly diagnosed with stroke using the International Classification of Diseases, Tenth Revision, codes (I60-I64) between 2003 and 2019 were enrolled and followed up for all-cause mortality until 2019. Follow-up for mortality began 6 months after the index event. Poststroke patients were categorized into 3 groups according to the frequency of rehabilitation therapy: no rehabilitation therapy, ≤40 sessions and >40 sessions. Cox proportional hazards models were used to assess the mortality risk according to rehabilitation therapy stratified by disability severity measured based on activities of daily living 6 months after stroke onset. Within 6 months after stroke, 6738 patients (61.4%) did not receive rehabilitation therapy, whereas 2122 (19.3%) received ≤40 sessions and 2114 (19.3%) received >40 sessions of rehabilitation therapy. Higher frequency of rehabilitation therapy was associated with significantly lower poststroke mortality in comparison to no rehabilitation therapy (hazard ratio [HR], 0.88 [95% CI, 0.79-0.99]), especially among individuals with severe disability after stroke (mild to moderate: HR, 1.02 [95% CI, 0.77-1.35]; severe: HR, 0.74 [95% CI, 0.62-0.87]). In the context of stroke type, higher frequency of rehabilitation therapy was associated with reduced mortality rates compared with no rehabilitation therapy only in patients with hemorrhagic stroke (ischemic: HR, 1.04 [95% CI, 0.91-1.18]; hemorrhagic: HR, 0.60 [95% CI, 0.49-0.74]). We found a positive association between rehabilitation therapy within 6 months after stroke onset and long-term mortality in patients with stroke. A higher frequency of rehabilitation therapy would be recommended for poststroke patients, especially those with hemorrhagic stroke and severe disability.

Impact of perioperative COVID-19 infection on postoperative complication in cesarean section using Korean National Health insurance data

The vulnerability during pregnancy has raised concerns about the potential impact of COVID-19 on obstetric anesthesia, an essential aspect of maternal care during cesarean section procedures. To evaluate the influence of COVID-19 infection on obstetric anesthesia during cesarean section, we analyzed the data from Korean National Health Insurance System (NHIS). This retrospective study utilized data from Korean NHIS. We included patients admitted with operation codes specific to cesarean section between January 1, 2020, and December 31, 2021. We classified patients into a COVID (+) group with a diagnosis code (U071) 30 days around surgery and a COVID (−) group without the code in the same period. The primary outcome was 30-day mortality that was defined as death within 30 days of admission due to any causes. Secondary outcomes were pulmonary complications (pneumonia, acute respiratory distress syndrome [ARDS], pulmonary thromboembolism [PTE], or unexpected postoperative mechanical ventilation), ICU admission, cardiac arrest, myocardial infarction [MI], other thromboembolic events, surgical site infection, sepsis, acute renal failure [ARF], and hepatic failure. Among 75,268 patients who underwent cesarean section, 107 had a COVID-19 diagnosis code, while 75,161 did not. After 1:4 propensity score matching (PSM), 535 patients were included in each group. 30-day mortality showed no significant differences between the two groups both before and after PSM. The COVID (+) group demonstrated significantly elevated rates of pneumonia, ARDS, PTE, and surgical site infection both before and after PSM. Hospital length of stay and admission costs were also significantly longer and higher, respectively, in the COVID (+) group before and after PSM. In subgroup analysis, no differences were observed in mortality and postoperative complications based on the anesthesia method after matching. COVID-19 infection is associated with increased rates of postoperative complications, including pneumonia, ARDS, PTE, surgical site infection, longer hospital stays, and increased admission costs, in patients who underwent cesarean section.

Increased Risk of Fracture after Traumatic Amputation: A Nationwide Retrospective Cohort Study.

The physiological changes and alterations in gait following amputation may increase the risk of fractures. However, there is insufficient research on fracture risk in amputees. Therefore, this study intended to analyze whether the risk of new fractures increases after traumatic amputations. This population-based, retrospective cohort study used data from the Korean National Health Insurance System database. The study included 19,586 participants who had undergone an amputation and 76,645 matched controls. The incidence of any fracture and site-specific fractures (vertebral, hip, and others) according to amputation site(s) and severity of disability due to amputation were evaluated using Cox proportional hazard regression analysis. During the mean follow-up of 4.2 years, amputees had a higher incidence rate (IR) of any fracture (adjusted HR [aHR] 1.47, 95% CI 1.36-1.60), vertebral fracture (aHR 1.63, 95% CI 1.44-1.85), hip fracture (aHR 1.85, 95% CI 1.39-2.46), and other fracture (aHR 1.34, 95% CI 1.20-1.49) compared to that of controls. In the presence of disability, the risks were further increased and were highest among amputees with severe disabilities. All fracture risks were higher in amputees than they were in controls, regardless of lower limb or upper limb amputation. This cohort study demonstrated that traumatic amputees experienced higher incidence of all fractures than did individuals without amputations, and this risk increases with severity of disability. This finding underscores the importance of early screening and lifestyle interventions to address fracture risk in traumatic amputees.

Risk of Heart Disease in Patients With Amputation: A Nationwide Cohort Study in South Korea.

Amputation confers disabilities upon patients and is linked to substantial morbidity and death attributed to heart disease. While some studies have focused on traumatic amputees in veterans, few studies have focused on traumatic amputees within the general population. Therefore, the present study aimed to assess the risk of heart disease in patients with traumatic amputation with disability within the general population using a large-scale nationwide population-based cohort. We used data from the Korean National Health Insurance System. A total of 22 950 participants with amputation were selected with 1:3 age, sex-matched controls between 2010 and 2018. We used Cox proportional hazard models to calculate the risk of myocardial infarction, heart failure, and atrial fibrillation among amputees. Participants with amputation had a higher risk of myocardial infarction (adjusted hazard ratio [aHR], 1.30 [95% CI, 1.14-1.47]), heart failure (aHR, 1.27 [95% CI, 1.17-1.38]), and atrial fibrillation (aHR, 1.17 [95% CI, 1.03-1.33]). The risks of myocardial infarction and heart failure were further increased by the presence of disability (aHR, 1.43 [95% CI, 1.04-1.95]; and aHR, 1.38 [95% CI, 1.13-1.67], respectively). We demonstrate an increased risk of myocardial infarction, heart failure, and atrial fibrillation among individuals with amputation, and the risk further increased in those with disabilities. Clinicians should pay attention to the increased risk for heart disease in patients with amputation.

Fracture Risk Among Stroke Survivors According to Poststroke Disability Status and Stroke Type.

Stroke survivors face physical and cognitive challenges, leading to an increased dependency and a higher fall risk. We aimed to investigate the impact of poststroke disability and stroke type on fracture risk at various sites compared with matched controls. This retrospective cohort study used data from the Korean National Health Insurance System database (2010-2018), including patients with stroke and 1:1 matched controls. Stroke survivors were grouped based on the presence and severity of their poststroke disability and stroke type. The primary outcome was a newly diagnosed fracture, analyzed by Cox proportional hazard regression analyses adjusting for potential confounders. Among 223 358 stroke survivors (mean age, 64.8±10.9 years; 61.2% men), 16 344 fractures occurred during a mean follow-up of 3.7±2.5 years. In matched controls (n=322 161; mean age, 65.4±11.2 years; 61.3% men), 20 398 fractures were identified. Stroke survivors had increased overall fracture risk compared with matched controls (adjusted hazard ratio [aHR], 1.40 [95% CI, 1.37-1.43]). Specifically, hip fracture risk was even greater in stroke survivors (incidence rate per 1000 person-years, 4.7 [95% CI, 4.5-4.8]; aHR, 2.42 [95% CI, 2.30-2.55]) than controls (incidence rate, 2.2 [95% CI, 2.1-2.3]). The risk of vertebral fractures (aHR, 1.29 [95% CI, 1.25-1.34]) and other fractures (aHR, 1.19 [95% CI, 1.15-1.23]) was also higher than that of the control group. Hip fracture risk was the highest among stroke survivors with severe poststroke disability (aHR, 4.82 [95% CI, 4.28-5.42]), although vertebral or other fracture risk was the highest among those with mild poststroke disability. No significant difference in fracture risk was found between hemorrhagic and ischemic stroke survivors when stratified by disability status. Our findings showed increased subsequent fracture risk among stroke survivors, particularly those with poststroke disability and for hip fracture. Bone health assessment and treatment should be emphasized as an essential part of stroke management.

Rotavirus Hospitalization in Early Childhood: Fine Motor Skills and Cognition at 6 Years Old in a Population-Based Cohort Study.

Rotavirus is linked to severe childhood gastroenteritis and neurological complications, but its impact on neurodevelopment remains uncertain. We examined data from 1 420 941 Korean children born between 2009 and 2011, using the Korean National Health Insurance System. We assessed neurodevelopmental outcomes at age 6 years using the validated Korean Developmental Test, covering 6 major domains, with propensity score-based inverse probability weighting including consideration of covariates sex, birth weight, changes in body weight from birth to 4-6 months of age, head circumference at 4-6 months of age, residence at birth, economic status, infant feeding types, and birth year. The main analysis that encompassed 5451 children with rotavirus hospitalization and 310 874 unexposed individuals revealed heightened odds of suspected delays in fine motor skills and cognition among exposed children. Our results suggest an association between rotavirus-related hospitalization in infancy and suspected delays in fine motor function and cognition in 6 year olds.

Abstract 3465: Association with total reproductive year and the risk of biliary tract cancer in women

Abstract Background: Many studies have reported that female reproductive factors, such as parity, age at menarche or menopause, breastfeeding, or age at first birth, were associated with or not associated with the development of biliary tract cancer (BTC). Our study was planned to determine whether a long-term rather than transient exposure was associated with the risk of BTC, including total reproductive year, which was defined as the time from menarche to menopause throughout the life cycle. Methods: This nationwide cohort study included 1,059,533 women with natural menopausal women aged 40-69 years who underwent the periodic health check-up provided by the Korean National Health Insurance System in 2009. The median follow-up period was 9.3 years. Cox proportional hazard regression analysis was performed to estimate the risk of BTC based on the female reproductive factors. Results: During the 9,867,152 person-years of follow-up, 4,198 patients (0.4%) were newly diagnosed with BTC. The incidence of BTC was significantly increased in subjects younger than 40 years at menopause compared with those aged 40 years or older (HR 1.341, 95% CI, 1.095-1.642). This trend was consistent even when menopause age was subdivided into 5-year intervals (&amp;lt;40 vs. 40−44, 45−49, 50-54, and ≥ 55 years) for those aged 40 years or older. When compared by categorization into four quartiles, the incidence of BTC tended to be numerically lower than that of the bottom 25% with the lowest age of menopause (designated as Q1 reference group). Compared to those with total reproductive year of 30 years or more, the incidence of BTC increased significantly in the group with less than 30 years of total reproductive year (HR 1.106, 95% CI, 1.014-1.206). This tendency was significantly reproduced in comparison by categorizing the entire group into quartiles. Compared to the lower 25% group (designated as Q1 reference group), the risk of BTC showed a significant linear inverse correlation with the longer total reproductive year. Q1 group has significantly higher incidence of BTC compared to the other groups (p &amp;lt; 0.001). This trend was repeated in various subgroup analysis. Conclusions: In conclusion, this study demonstrated that women under the age of 40 at menopause had an increased risk of BTC compared to those over 40 years of age. Similarly, a longer period of total reproductive year was associated with a lower risk of BTC, suggesting a protective female hormonal effect on BTC. Total reproductive year may be more reliable indicator in that it reflects the actual lifetime exposure to female hormones. Citation Format: Chi Hoon Maeng, Kyungdo Han, Joo-Hyun Park, Jung Yong Hong. Association with total reproductive year and the risk of biliary tract cancer in women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3465.

Risk of thrombosis, hemorrhage and leukemic transformation in patients with myeloproliferative neoplasms: A nationwide longitudinal cohort study

IntroductionThere are few large-scale, population-based studies detailing the risks of thrombosis, hemorrhage, leukemic transformation in patients with myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). MethodsWe performed a nationwide longitudinal cohort study using the Korean National Health Insurance System (NHIS) database. MPN patients (n = 11,991) and their 1:4 age- and sex-matched controls (n = 47,964) were enrolled. The risk of thrombosis, hemorrhage, leukemic transformation was estimated using a Cox proportional hazards regression, and stratified analyses were performed for related factors. ResultsDuring a median of 7.8 years of follow-up, 30.1 % of MPN patients (3614/11,991) and 19.0 % of the matched controls (9141/47,964) developed arterial thrombosis, 11.6 % of MPN patients (1397/11,991) and 6.4 % of the matched controls (3099/47,964) developed venous thrombosis and 18.7 % of MPN patients (2251/11,991) and 12.1 % of the matched controls (5836/47,964) developed hemorrhage. 4.9 % of MPN patients (597/11,991) and 0.1 % of matched controls (50/47,964) developed leukemia. The overall risk of developing thrombosis, hemorrhage, leukemic transformation was higher in MPN patients (adjusted hazard ratio [aHR] 1.695, 95 % confidence interval [CI]: 1.629–1.765 for arterial thrombosis, aHR 1.963, 95 % CI: 1.838–2.096 for venous thrombosis, and aHR 1.714, 95 % CI: 1.630–1.802 for hemorrhage) than in the controls. Patients with MPNs had a 10-year cumulative incidence of leukemic transformation of 6.2 %. ConclusionThe patients with MPNs have a higher risk of thrombosis, hemorrhage, and leukemic transformation than matched controls. Strategies are warranted to reduce the risk of thrombosis, hemorrhage, and leukemic transformation in MPN patients.

Increased metabolic variability in Korean patients with new onset bipolar disorder: a nationwide cohort study.

The aim of this study was to determine associations between changes of metabolic parameters and the development of BD using nationally representative data. We used health examination data provided by the South Korean National Health Insurance System (NHIS) (n = 8,326,953). The variability of each metabolic parameter including weight circumference, blood pressure, fasting blood glucose, high-density lipoprotein cholesterol, and triglyceride levels was caculated using variability independent of mean (VIM) indices. The presence of metabolic syndrome was associated with new onset BD. Each metabolic parameter with high variability was associated with a higher risk of new onset BD compared to those with low variability after adjusting for age, sex, smoking, alcohol drinking, regular exercise, income status, baseline diabetes, hypertension, and dyslipidemia. As the number of highly variable metabolic parameters increased, the risk for new onset depression also increased even after covariates adjustment. The associations between new onset BD and metabolic variability were greater in populations with age > 50 years. In addition, these associations remained significant after adjusting for the presence of depression prior to diagnoses of BD. Our results suggest possibility of metabolic variability as an independent environmental risk factor for BD even after adjusting for the presence of metabolic syndrome.

Incidence of bronchiectasis in patients with acromegaly: a cohort study.

Associations between acromegaly and several respiratory diseases, such as obstructive lung disease or sleep apnea, have been suggested, but the relationship between bronchiectasis and acromegaly is unclear. We investigated whether acromegaly is related to the development of bronchiectasis. Using the Korean National Health Insurance System database between 2006 and 2016, we studied the relationship between acromegaly and bronchiectasis in patients with acromegaly (n=2593) and controls (1:5 age- and sex-matched subjects without acromegaly, n=12965) with a mean follow-up period of 8.9 years. Cox proportional hazards regression analysis was used to assess the risk of bronchiectasis in patients with acromegaly compared with controls after adjusting for age, sex, household income, place, type 2 diabetes, hypertension, and dyslipidemia. The mean age of the participants was 47.65 years, and male subjects comprised 45.62% of the cohort. The incidence rate of bronchiectasis in patients with acromegaly was 3.64 per 1,000 person-years and was significantly higher than that in controls (2.47 per 1,000 person-years) (log-rank test p = 0.002). In multivariable Cox proportional hazards regression modeling, the risk of bronchiectasis was significantly higher in patients with acromegaly than that in controls (HR: 1.49; 95% CI: 1.15-1.94, p = 0.0025) after adjusting for age, sex, household income, place, type 2 diabetes, hypertension, and dyslipidemia. Our results suggest that acromegaly may be associated with bronchiectasis.

Incidence and risk factors of age-related macular degeneration in patients with Parkinson's disease: a population-based study.

The association between age-related macular degeneration (AMD) and Parkinson' disease (PD) remains unclear. The aim of the present study was to assess the incidence of AMD in patients with PD, elucidate differences by age and sex, and investigate potential risk factors for AMD. Data were extracted from the Korean National Health Insurance System database, which covers 97% of the Korean population (2002 through 2019). We calculated the incidence of newly diagnosed AMD in patients with PD and used Cox proportional-hazards models to estimate risk factors for AMD, presenting adjusted hazard ratios (aHR) with 95% confidence intervals (CI). Of 172,726 patients with PD, 15,800 were newly diagnosed with AMD during the follow-up, including 5,624 men and 10,176 women. The overall incidence of AMD in patients with PD was 13.59 per 1,000 person-years. Stratified by age group and sex, the incidence was higher in women aged 40-69, and conversely higher in men aged 70-89. Risk of AMD was high in older age groups (aHR = 4.36, 95% CI: 3.74-5.09 in the 70 s), female sex (aHR = 1.07, 95% CI: 1.04-1.11), patients with diabetes mellitus (DM) (aHR = 1.14, 95% CI: 1.10-1.18), and patients with hyperlipidemia (aHR = 1.17, 95% CI: 1.13-1.21). Our findings suggest that the AMD incidence is higher in patients with PD than in the general population, with varying patterns of sex differences across age groups. Particularly, old age, female sex, presence of DM, and hyperlipidemia are potential risk factors. Therefore, clinicians should pay greater attention to AMD in patients with PD.

Association between migraine and the risk of vascular dementia: A nationwide longitudinal study in South Korea.

We aimed to examine the potential association between migraine and vascular dementia (VaD) using a nationwide population database. Migraine and VaD showed similar structural and functional changes in pathophysiology process and shared common risk factors, However, whether migraine prevalence increases VaD incidence remains controversial. This retrospective population-based cohort study used the medical records from the Korean National Health Insurance System database. Migraine (G43) was defined by using the Tenth Revision of the International Classification of Diseases code. More than two migraine diagnoses at least 3 months apart were defined as "chronic migraine". Cox proportional hazards model estimated hazard ratios (HRs) of VaD for group comparisons. We included 212,836 patients with migraine and 5,863,348 individuals without migraine. During 10 years of follow-up, 3,914 (1.8%) and 60,258 (1.0%) patients with and without migraine, respectively, were newly diagnosed with VaD. After adjustment, patients with migraine showed a 1.21-fold higher risk of VaD than those without migraine (HR = 1.21; 95% confidence interval (CI): 1.17-1.25). Patients with chronic migraine showed a higher cumulative incidence of VaD than those with episodic migraine. The adjusted HR for the VaD incidence with migraine was higher in: (1) patients aged <65 years; (2) women; (3) patients without hypertension, diabetes, or atrial fibrillation; and (4) non-smokers. Migraine is associated with an increased risk of VaD, particularly in chronic migraine patients. Incidence of VaD in the setting of migraine may have distinct pathophysiology from that of VaD with traditional cardiovascular risks.

Cancer Incidence Among Residents Near Coal-Fired Power Plants Based on the Korean National Health Insurance System Data.

Cancer is a leading cause of death worldwide, posing a significant threat to human health and life expectancy. Numerous existing studies explored the correlation between coal-fired power plants and cancer development. Currently, Chungcheongnam-do Province hosts 29 coal-fired power plants, constituting half of the total 58 plants across South Korea. This study assessed the cancer incidence by proximity to coal-fired power plants in Chungcheongnam-do Province, Korea. In this study, the exposed group comprised individuals residing within a 2-km radius of the coal-fired power plants, whereas the control group comprised individuals who had no prior residency within the 2-km radius of such plants or elsewhere in the province. Standardized incidence ratios were calculated using the cancer incidence cases retrieved from the National Health Insurance System data from 2007 to 2017. The study found that exposed men had a 1.11 (95% confidence interval [CI], 1.09-1.21) times higher risk of developing all cancer types and a 1.15 (95% CI, 1.09-1.22) times higher risk of developing cancers excluding thyroid cancer compared with control men. Exposed women had a 1.05 (95% CI, 1.00-1.14) times higher risk of developing all cancer types and a 1.06 (95% CI, 0.98-1.13) times higher risk of developing cancers excluding thyroid cancer than did control women. The colorectal, liver, prostate, and bladder cancer incidence rates were significantly higher in exposed men than that in all control groups. The incidence of esophageal, stomach, liver, and lung cancers were significantly higher in exposed women compared with all control groups. The residents near coal-fired power plants had a higher risk of developing cancer than did those living in other areas. In the future, long-term follow-up investigations in residents living in the vicinity of power plants are warranted.

Risk of Developing Hypertension in Atopic Dermatitis Patients Receiving Long-term and Low-dose Cyclosporine: A Nationwide Population-based Cohort Study.

Cyclosporine (CS) is a first-line immunosuppressive agent used to manage moderate to severe atopic dermatitis (AD). To date, the risk of developing hypertension associated with the long-term use of low-dose CS in AD patients is understudied. To determine the cumulative dose-dependent effect of CS on the risk of developing hypertension in patients with AD. A nationwide population-based retrospective cohort with 1,844,009 AD patients was built from the Korean National Health Insurance System database from 2005 to 2009. A Cox proportional-hazard regression analysis was performed according to patients' CS treatment history adjusted for potential confounders. Current use of CS was associated with an increased risk of developing hypertension (adjusted hazard ratio, 4.442; 95% confidence interval, 3.761-5.247). Among the current CS users, a higher cumulative dose of CS (≥39,725 mg) or longer cumulative use of CS (≥182 days), was significantly associated with an increased risk of developing hypertension. The incidence of CS-associated hypertension is very low when using low-dose treatment regimens for AD. However, the current use or a high cumulative dose of CS for treating patients with AD increases the risk of developing hypertension. Precaution is needed when prescribing CS for long-term treatment of AD.