Long-term Exposure to PM10 Increases Lung Cancer Risks: A Cohort Analysis.

PURPOSE: Although lung cancer incidences in female never-smokers have increased, few studies focus on explicit investigation. We aimed to investigate the relationship between long-term exposure to ambient particulate matter sized 10 µm or less in diameter (PM10) and the incidence of lung cancer within different genders and smoking status populations. MATERIALS AND METHODS: We included Seoul metropolitan residents, aged between 20 and 65 years, who underwent a national health screening examination from 2005-2007 and were followed up until 2015. Individual-level long-term exposure to PM10 was assessed based on subject home addresses. To assess the relationship between PM10 and lung cancer, we estimated hazard ratios (HRs) for increased lung cancer incidence from a 10 µg/m3 increase in PM10. RESULTS: Among 5,831,039 individuals, 36,225 (0.6%) developed lung cancer within the 7 years observed. In females, the majority (94.4%) of lung cancer development was found in never-smokers. In adjusted analyses, a significant relationship between lung cancer development and PM10 was observed in males, regardless of smoking status (never-smoker: HR, 1.14 [95% confidence interval (CI), 1.13 to 1.15]; ex-smoker: HR, 1.16 [95% CI, 1.14 to 1.17]; current smoker: HR, 1.18 [95% CI, 1.17 to 1.19]). We also found significant associations in female never- or ex-smokers with smaller HRs (never-smoker: HR, 1.06 [95% CI, 1.05 to 1.07]; ex-smoker: HR, 1.13 [95% CI, 1.02 to 1.23]; current smoker: HR, 1.04 [95% CI, 0.99 to 1.10]). CONCLUSION: Our findings suggest that long-term exposure to PM10 is associated with lung cancer development. A novel approach to lung cancer screening needs to be considered depending on the exposed PM10 level.

Evaluating the Prevalence and Incidence of Bronchiectasis and Nontuberculous Mycobacteria in South Korea Using the Nationwide Population Data.

Although the prevalence and incidence of bronchiectasis are rising worldwide, basic epidemiologic data have not been reported in Korea. Therefore, this study was conducted to investigate epidemiological characteristics of bronchiectasis and NTM (nontuberculous mycobacteria) pulmonary diseases in Korea using the National Health Insurance Service-National Sample Cohort (NHIS-NSC) data. The relative risks of prevalence and incidence after adjusting for demographic characteristics were evaluated by multivariate Poisson regression. The result of this study showed the prevalence and incidence rates of bronchiectasis and NTM to be epidemiologically similar to each other with a few slight differences, while the prevalence rate of bronchiectasis was not significantly different by gender, and its incidence rate was significantly lower in women than in men. Both the prevalence and incidence of NTM were significantly higher in women than in men. Both the prevalence and incidence rates of bronchiectasis and NTM were significantly lower in the age group below 40-49 years, and significantly higher in the age groups thereafter. As there were gender differences of bronchiectasis and NTM, gender-sensitive risk management should be available. In addition, since both bronchiectasis and NTM increase in prevalence and incidence after the age of 40-49, early detection and intervention strategies targeting the appropriate age group are needed.

Incidence of Psoriasis in Patients with Inflammatory Bowel Disease: A Nationwide Population-Based Matched Cohort Study.

BACKGROUND: Emerging data suggest that inflammatory bowel disease (IBD) and psoriasis are associated, sharing common genetic predispositions and immunological mechanisms. However, concrete data on psoriasis risk in IBD patients compared to the general population are limited. OBJECTIVE: We investigated the risk of developing psoriasis in IBD patients compared to controls without IBD. METHODS: Using the Korean National Health Insurance Database, patients diagnosed with Crohn's disease (CD) or ulcerative colitis (UC) between 2005 and 2008 were age- and sex-matched 1:4 to non-IBD subjects from 2003 to 2018. IBD patients were defined by combining the International Classification of Diseases 10th revision code and at least one prescription of IBD-specific medications. Disease phenotypes, including psoriasis severity and psoriatic arthritis, were also identified. We investigated newly diagnosed psoriasis from 2009 to 2018. Incidence rates and risk of psoriasis were assessed with multivariate Cox regression models. Subgroup analyses for age and sex, and sensitivity analysis involving tumor necrosis factor (TNF) inhibitor-naïve patients were performed. RESULTS: During nearly a decade of follow-up, 20,152 IBD patients were identified (14,619 [72.54%] UC and 5,533 [27.46%] CD). Among them, 439 patients were newly diagnosed with psoriasis (incidence rate of 217.68 per 100,000 person-years and 228.62 per 100,000 person-years for UC and CD, respectively). The psoriasis risk was higher in IBD patients than in the matched controls (adjusted hazard ratio, aHR, 2.95, 95% confidence interval, CI, 2.60-3.33). Moreover, IBD patients aged <30 years were at an increased risk (aHR 3.35, 95% CI 2.58-4.35), a trend that was unchanged across all psoriasis phenotypes. Sensitivity analysis of TNF inhibitor-naïve patients revealed consistent results. CONCLUSIONS: IBD patients were more likely to develop psoriasis compared to non-IBD subjects, including younger patients at an elevated risk regardless of TNF inhibitor use. This advocates the interplay between IBD and psoriasis; thus, inspection of cutaneous manifestation and dermatological consultation may be helpful in IBD patients at risk.

The Association between Community Water Fluoridation and Bone Diseases: A Natural Experiment in Cheongju, Korea.

The present study aimed to investigate the association between bone diseases and community water fluoridation (CWF). An ecological study with a natural experiment design was conducted in Cheongju, South Korea, from 1 January 2004 to 31 December 2013. The community water fluoridation program was implemented in Cheongju and divided into CWF and non-CWF areas. To observe adverse health effects related to bone diseases, we conducted a spatio-temporal analysis of the prevalence of hip fracture, osteoporosis, and bone cancer in residents who have lived in CWF and non-CWF areas using National Health Insurance Service data. First, we used standardized incidence ratios to estimate the disease risk. Second, the hierarchical Bayesian Poisson spatio-temporal regression model was used to investigate the association between the selected bone diseases and CWF considering space and time interaction. The method for Bayesian estimation was based on the R-integrated nested Laplace approximation (INLA). Comparing the CWF area with the non-CWF area, there was no clear evidence that exposure to CWF increased health risks at the town level in Cheongju since CWF was terminated after 2004. The posterior relative risks (RR) of hip fracture was 0.95 (95% confidence intervals 0.87, 1.05) and osteoporosis was 0.94 (0.87, 1.02). The RR in bone cancer was a little high because the sample size very small compared to the other bone diseases (RR = 1.20 (0.89, 1.61)). The relative risk of selected bone diseases (hip fractures, osteoporosis, and bone cancer) increased over time but did not increase in the CWF area compared to non-CWF areas. CWF has been used to reduce dental caries in all population groups and is known for its cost-effectiveness. These findings suggest that CWF is not associated with adverse health risks related to bone diseases. This study provides scientific evidence based on a natural experiment design. It is necessary to continue research on the well-designed epidemiological studies and develop public health prevention programs to help in make suitable polices.

Factors associated with the rates of coronary artery bypass graft and percutaneous coronary intervention.

BACKGROUND: Korea has seen a rapid increase in the use of percutaneous coronary intervention (PCI) with the ratio of PCI to coronary artery bypass graft (CABG) the highest in the world. This study was performed to examine the factors associated with the rates of CABG and PCI. METHODS: The data were acquired from the National Health Insurance database in Korea in 2013. We calculated the age-sex standardized rates of CABG and PCI. We examined the factors associated with the CABG and PCI rates by performing a regression analysis. RESULTS: The rate of CABG showed a negative association with the deprivation index score, and other factors, such as the number of providers or hospital beds, did not show any significant association with the CABG rate. The rate of PCI had a strong negative association with the number of cardiothoracic surgeons and a strong positive association with the number of hospital beds. CONCLUSIONS: The positive association between the PCI rate and the number of hospital beds suggests that the use of PCI may be driven by the supply of beds, and the inverse association between the PCI rate and the number of cardiothoracic surgeons indicates the overuse of PCI due to lack of the providers of CABG. Policy measures should be taken to optimize the use of revascularization procedures, the choice of which should primarily be based on the patient's need.

Geographic variation and factors associated with rates of knee arthroplasty in Korea-a population based ecological study.

BACKGROUND: The recent increase in knee arthroplasty (KA) use in Korea is among the highest in the world. The rapid increase in KA use suggests that the KA use in Korea could have been affected by medically unjustifiable factors. This study aimed to examine the geographic variation in the rate of KA and its associated factors in Korea. METHODS: We used the data from the National Health Insurance in Korea in 2013, from which a total of 67,086 claims for KA were obtained. We calculated the age-sex-standardized KA rates of the entire population and the crude rates of the age groups 0-64 and 65 and over in 251 districts. We assessed the geographic variation of the KA rates and examined the associated factors with a multivariate linear regression with the KA rate as a dependent variable. RESULTS: The overall rate of KA in Korea was 132.7 per 100,000 persons. The rates of KA showed a four-fold variation. The deprivation index score and the number of beds in the small to medium sized hospitals showed a positive association with the rates of KA while the number of orthopedic surgeons showed a negative association. CONCLUSIONS: Korea has been experiencing a rapid increase in the use of KA for the last decade or so, which was most prominent among the elderly population aged 65 and older. Our results suggest that the higher rate of KA is strongly related to a higher supply of beds and the socioeconomically deprived conditions. Considering that the decision concerning KA has room for discretion and also affects a considerable portion of health care expenditures, the use of KA should be thoroughly monitored with more emphasis on standardization in the decision making process and preventive measures that can lessen the need for KA.

Chasms in Achievement of Recommended Diabetes Care among Geographic Regions in Korea.

BACKGROUND: Although effective care for type 2 diabetes (T2DM) is well known, considerable inadequate care has been still existed. Variations in achievement of the recommended quality indicators inT2DM care among small areas are not well known in Korea. This study examined the quality of care T2DM care and its geographical variations. METHODS: We used the national health insurance database and national health screening database. Seven quality indicators were used to evaluate continuity of care (medication possession ratio), process of care (hemoglobin A1c test, lipid profile, microalbuminuria test, and eye examination), and intermediate outcome (blood pressure control, and low-density lipoprotein control). Crude and age-standardized proportions were calculated for each 252 districts in Korea. RESULTS: All quality indicators failed to achieve the recommended level. Only about 3% and 15% of the patients underwent eye examination and microalbuminuria test, respectively. Other indicators ranged from 48% to 68%. Wide variation in the quality existed among districts and indicators. Eye examination and microalbuminuria test varied the most showing tenfold (0.9%-9.2%) and fourfold (6.3%-28.9%) variation by districts, respectively. There were 32.4 and 42.7 percentage point gap between the best and the worst districts in hemoglobin A1c test and blood pressure control, respectively. CONCLUSION: Considerable proportion of T2DM patients were not adequately managed and quality of care varied substantially district to district. To improve the quality of diabetes care, it is necessary to identify the poor performance areas and establish a well-coordinated care system tailored to the need of the district.

Psoriasis increases the risk of concurrent inflammatory bowel disease: A population-based nationwide study in Korea.

BACKGROUND: The epidemiology of the association between psoriasis and inflammatory bowel disease is poorly defined and remains controversial. AIM: To evaluate the prevalence of inflammatory bowel disease in patients with psoriasis compared with the general population. METHODS: We searched the nationwide health claims database between 2011 and 2015 and evaluated the prevalence of inflammatory bowel disease, including Crohn's disease and ulcerative colitis. RESULTS: Prevalence of inflammatory bowel disease, Crohn's disease and ulcerative colitis in patients with psoriasis vs the general population in 2011 were 0.16, 0.05 and 0.12% vs 0.08, 0.03 and 0.06%, respectively, which increased significantly with time between 2011 and 2015. Patients with psoriasis consistently revealed higher standardized prevalence (age and sex adjusted) of inflammatory bowel disease, Crohn's disease and ulcerative colitis compared with the general population. Subgroup analysis revealed the highest risk of prevalent inflammatory bowel disease in patients younger than 19 years (crude odds ratio 5.33, 95% confidence interval 3.74-7.59). Severe psoriasis demonstrated higher odds of inflammatory bowel disease (odds ratio 2.96, 95% confidence interval 2.54-3.45) than mild psoriasis (odds ratio 1.68, 95% confidence interval 1.51-1.88). LIMITATIONS: Limited data for doing adjustment and cross-sectional study design. CONCLUSIONS: Psoriasis patients revealed higher risk of inflammatory bowel disease. In particular, young patients and those with severe psoriasis may require closer monitoring and comprehensive management.

Geographical Correlations between Indoor Radon Concentration and Risks of Lung Cancer, Non-Hodgkin's Lymphoma, and Leukemia during 1999-2008 in Korea.

Indoor radon is the second most important risk factor for lung cancer and may also be a risk factor for hematopoietic cancers, particularly in children and adolescents. The present study measured indoor radon concentration nationwide at 5553 points during 1989-2009 and spatially interpolated using lognormal kriging. The incidences of lung cancer, non-Hodgkin's lymphoma (NHL), and leukemia, stratified by sex and five-year age groups in each of the 234 administrative regions in the country during 1999-2008, were obtained from the National Cancer Registry and used to calculate the standardized incidence ratios. After considering regional deprivation index values and smoking rates by sex in each region as confounding variables, the cancer risks were estimated based on Bayesian hierarchical modeling. We found that a 10 Bq/m³ increase in indoor radon concentration was associated with a 1% increase in the incidence of lung cancer in male and a 7% increase in NHL in female children and adolescents in Korea aged less than 20 years. Leukemia was not associated with indoor radon concentration. The increase in NHL risk among young women requires confirmation in future studies, and the radon control program should consider children and adolescents.

Evaluation of Geographic Indices Describing Health Care Utilization.

OBJECTIVES: The accurate measurement of geographic patterns of health care utilization is a prerequisite for the study of geographic variations in health care utilization. While several measures have been developed to measure how accurately geographic units reflect the health care utilization patterns of residents, they have been only applied to hospitalization and need further evaluation. This study aimed to evaluate geographic indices describing health care utilization. METHODS: We measured the utilization rate and four health care utilization indices (localization index, outflow index, inflow index, and net patient flow) for eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee replacement surgery, caesarean sections, hysterectomy, computed tomography scans, and magnetic resonance imaging scans) according to three levels of geographic units in Korea. Data were obtained from the National Health Insurance database in Korea. We evaluated the associations among the health care utilization indices and the utilization rates. RESULTS: In higher-level geographic units, the localization index tended to be high, while the inflow index and outflow index were lower. The indices showed different patterns depending on the procedure. A strong negative correlation between the localization index and the outflow index was observed for all procedures. Net patient flow showed a moderate positive correlation with the localization index and the inflow index. CONCLUSIONS: Health care utilization indices can be used as a proxy to describe the utilization pattern of a procedure in a geographic unit.

The Effect of Geographic Units of Analysis on Measuring Geographic Variation in Medical Services Utilization.

OBJECTIVES: We aimed to evaluate the effect of geographic units of analysis on measuring geographic variation in medical services utilization. For this purpose, we compared geographic variations in the rates of eight major procedures in administrative units (districts) and new areal units organized based on the actual health care use of the population in Korea. METHODS: To compare geographic variation in geographic units of analysis, we calculated the age-sex standardized rates of eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee-replacement surgery, caesarean section, hysterectomy, computed tomography scan, and magnetic resonance imaging scan) from the National Health Insurance database in Korea for the 2013 period. Using the coefficient of variation, the extremal quotient, and the systematic component of variation, we measured geographic variation for these eight procedures in districts and new areal units. RESULTS: Compared with districts, new areal units showed a reduction in geographic variation. Extremal quotients and inter-decile ratios for the eight procedures were lower in new areal units. While the coefficient of variation was lower for most procedures in new areal units, the pattern of change of the systematic component of variation between districts and new areal units differed among procedures. CONCLUSIONS: Geographic variation in medical service utilization could vary according to the geographic unit of analysis. To determine how geographic characteristics such as population size and number of geographic units affect geographic variation, further studies are needed.