Autoimmune adverse event following COVID-19 vaccination in Seoul, South Korea.

BACKGROUND: There is growing evidence that the coronavirus disease 2019 (COVID-19) vaccination can affect the regulation of the immune system, leading to the development of autoimmune diseases. However, the autoimmune adverse events (AEs) after COVID-19 vaccination remain largely unclear. OBJECTIVE: We sought to investigate the autoimmune AEs after COVID-19 vaccination from a population-based cohort in South Korea. METHODS: A total of 4,203,887 participants, representing 50% of the population residing in Seoul, were recruited from the National Health Insurance Service database and then divided into 2 groups on the basis of COVID-19 vaccination. The cumulative incidence, hazard ratios (HRs), and 95% CIs of autoimmune AEs were assessed following COVID-19 vaccination. RESULTS: The incidence of vitiligo has been observed to be significantly higher in the vaccination group compared with the no vaccination group. The cumulative incidence of vitiligo began to show a significant difference starting 2 weeks after vaccination, and it reached 2.2% in the vaccination group and 0.6% in the no vaccination group by 3 months after COVID-19 vaccination. Vitiligo (HR, 2.714; 95% CI, 1.777-4.146) was an increased risk among autoimmune AEs. Furthermore, the risk of vitiligo was the highest for heterologous vaccination (HR, 3.890; 95% CI, 2.303-6.573) compared with using cDNA vaccine (HR, 2.861; 95% CI, 1.838-4.453) or mRNA vaccine (HR, 2.475; 95% CI, 1.607-3.813). CONCLUSIONS: Vitiligo as an autoimmune AE was noted to be substantially higher in the COVID-19-vaccinated group compared with the controls. Therefore, the occurrence of vitiligo could be considered as one of the significant AEs post-COVID-19 vaccination.

Pure laparoscopic donor hepatectomy: Experience of 556 cases at Seoul National University Hospital.

Pure laparoscopic donor hepatectomy (PLDH) has become a routine procedure at Seoul National University Hospital, and the pure laparoscopic method is now being applied to liver recipients as well. This study aimed to review the procedure and outcomes of PLDH to identify any areas that required improvement. Data from 556 donors who underwent PLDH between November 2015 and December 2021 and their recipients were retrospectively reviewed. Among these, 541 patients underwent pure laparoscopic donor right hepatectomy (PLDRH). The mean hospital stay of the donor was 7.2 days, and the rate of grade I, II, IIIa, and IIIb complications was 2.2%, 2.7%, 1.3%, and 0.9%, respectively, without any irreversible disabilities or mortalities. The most common early and late major complications in the recipient were intraabdominal bleeding (n = 47, 8.5%) and biliary problems (n = 198, 35.6%), respectively. Analysis of the PLDRH procedure showed that operative time, liver removal time, warm ischemic time, Δhemoglobin%, Δtotal bilirubin%, and postoperative hospital stay decreased significantly as the number of cases accumulated. In conclusion, the operative outcomes of PLDRH improved as the number of cases increased. However, continuous caution is needed because major complications still occur in donors and recipients even after hundreds of cases.

Impact of ambient temperature on respiratory disease: a case-crossover study in Seoul.

BACKGROUND: Respiratory diseases contribute to global morbidity and mortality, and temperature is a significant factor. We investigated the association between ambient temperature and emergency department (ED) visits for various respiratory diseases in Seoul, South Korea. METHODS: Using data from the National Emergency Department Information System (2008-2017), we analysed 1,616,644 ED visits for respiratory diseases, categorised according to the Korean Standard Classification of Diseases 7th revision codes (J00-J99). Using a time-stratified case-crossover design and a distributed lag nonlinear model, we investigated the effect of temperature exposure on ED visits for respiratory diseases, calculating the relative risk (RR) for the maximum risk temperature (MaxRT) of both cold and hot extremes compared to the minimum risk temperature (MinRT). RESULTS: Cold temperatures (MaxRT: -9.0 °C) resulted in a 2.68-fold increase (RR = 2.68, 95% CI = 2.26-3.14) in ED visits for total respiratory diseases, while hot temperatures (MaxRT: 29.4 °C) led to a 1.26-fold increase (RR = 1.26, 95% CI = 1.11-1.42) compared to the MinRT (24.8 °C). Cold temperatures increased the risk of most respiratory diseases, except interstitial lung disease, whereas hot temperatures increased ED visits for acute upper respiratory infections and influenza. Cold temperatures increased ED visits for all age groups, especially those aged 18-64 (RR = 3.54, 95% CI = 2.90-4.33), while hot temperatures significantly affected those < 18 (RR = 1.45, 95% CI = 1.27-1.66). The risk levels were similar in both males and females, regardless of hot and cold temperatures. CONCLUSION: Our findings underscore the significant impact of both cold and heat exposure on ED visits for respiratory diseases, with varying intensities and risk profiles across different population groups.

Arthrobacter horti sp. nov., isolated from mountain soil.

Gram-stain-positive, aerobic, rod-shaped strains, YJM1T and YJM12S, were isolated from Maebong Mountain, Dogok-dong, Gangnam-gu, Seoul, Republic of Korea. Strains YJM1T and YJM12S exhibited growth at 5-35 °C (optimum, 20-30 °C) and pH 6-9 (optimum, pH 7) and in 0-4 % (w/v) NaCl. Strains YJM1T and YJM12S showed highest 16S rRNA gene sequence similarity to the following members of the genus Arthrobacter: A. nanjingensis A33T (98.3 %/98.2 % similarity), A. woluwensis NBRC 107840T (98.2 %/98.1 %), A. humicola KV-653T (97.3 %), A. oryzae KV-651T (97.3 %), and A. globiformis NBRC 12137T (97.2 %). The strains grew well on Reasoner's 2A, nutrient, Mueller-Hinton, yeast-dextrose, and glucose-peptone-meat extract agars. The major polar lipids of strain YJM1T were phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylinositol. The primary respiratory quinone of strain YJM1T was MK-9(H2), and the major fatty acids of strains YJM1T and YJM12S were anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0, and iso-C16 : 0. The DNA G+C content, based on the whole genome sequence of strain YJM1T, was 68.3 mol%. Average nucleotide identity values and digital DNA-DNA hybridization values between strain YJM1T and the reference strains ranged from 75.0 to 92.7 % and from 21.0 to 65.3 %, respectively. Strain YJM1T exhibited antimicrobial activity against Bacillus subtilis and Escherichia coli. Considering the chemotaxonomic, phenotypic, genotypic, and phylogenetic results, we propose the strain YJM1T represents a novel species in the genus Arthrobacter and suggest the name Arthrobacter horti sp. nov. (type strain YJM1T=KACC 23300T=JCM 36483T).

Surge of acute gastroenteritis outbreaks due to rising norovirus GII.4 transmission in Seoul childcare centers and kindergartens in 2022 compared to 2019-2021.

Noroviruses are the most common cause of acute gastroenteritis (AGE) outbreaks in childcare centers and kindergartens. Their high transmissibility is partly due to their genetic diversity. AGE outbreaks that occurred in Seoul childcare centers and kindergartens from 2019 to 2022 were investigated, and 68 epidemiological reports prepared by public health centers in Seoul were used for data collection. In the three quarters of 2022, there were 40 outbreaks of AGE in Seoul childcare centers and kindergartens, which exceeded the 35 total outbreaks that occurred during the previous three years. The proportion of childcare centers and kindergartens with AGE outbreaks among all facilities in Seoul increased from 12.6% in 2019 to 58.8% in 2022. Noroviruses were the most common pathogens responsible for AGE outbreaks in these cases. From 2019 to 2021, norovirus GII.2 was the predominant genotype, and GII.4 was detected in about 25% of cases. However, in 2022, GII.4 became predominant and was detected in about 79% of cases. The attack rate and infection source of AGE outbreaks from 2019 to 2021 were not significantly different from those in 2022. In conclusion, the number of AGE outbreaks in Seoul childcare centers and kindergartens increased significantly, primarily because of increased norovirus GII.4 transmission in 2022.

Surviving the cold: Assessing long-term outcomes among Korean CKD patients exposed to low perceived temperature during winter.

Perceived temperature (PT), which encompasses meteorological factors such as wind speed, cloud cover, and humidity, reflects the actual effect of temperature on the human body. However, limited data exist on the health implications of prolonged exposure to low temperatures during winter in individuals with chronic kidney disease (CKD). We investigated the association between winter PT and long-term outcomes among CKD patients. A total of 32,870 CKD patients from three tertiary hospitals in Seoul were enrolled in this retrospective study (2001-2018). PT was calculated using Staiger's equation, integrating temperature data from 29 automated weather stations across Seoul, along with dew point temperature, wind velocity, and cloud cover data. Kriging interpolation was utilized to estimate PT values at the patients' locations. Overall mortality and major adverse cardiovascular events (MACEs) were assessed using a time-varying Cox proportional hazards model. Additionally, the Cox regression model evaluated PT corresponding to temperature thresholds for cold surge watches or warnings. Over a median follow-up of 6.14 ± 3.96 years, 6147 deaths (18.7%) were recorded. We found that as the average or minimum PT and Ta decreased by 1 °C, the risk of overall mortality significantly increased. In multivariable analyses, the hazard ratio (HR) for the average PT was 1.049 (95% confidence interval [CI] 1.028-1.071), and that for the minimum PT was 1.038 (CI 1.027-1.052). Furthermore, a cold surge warning at a PT of -25.63 °C indicated an HR of 1.837 (CI 1.764-1.914) and a C-index of 0.792. The increased risk of mortality was more pronounced in patients with low or middle socioeconomic statuses. For MACEs, lower average and minimum PT and Ta were associated with an increased risk, following a similar trend to overall mortality, although not all results reached statistical significance. These findings emphasize the importance of targeted public health policies to mitigate risks among vulnerable CKD patients.

Ambient volatile organic compounds in the Seoul metropolitan area of South Korea: Chemical reactivity, risks and source apportionment.

The chemical reactivity, contribution of emission sources, and risk assessment of volatile organic compounds (VOCs) in the atmosphere of the Seoul metropolitan area (SMA) were analyzed. Datasets collected from 6 photochemical assessment monitoring stations (PAMS) of SMA from 2018 to 2021 were used. Alkenes and aromatics contributed significantly to ozone formation relative to the emission concentrations, and aromatics accounted for most of the secondary organic aerosols (SOA) formation in the SMA. The contributions of ozone and SOA formation were found to be notably higher at measurement stations in residential areas such as Guwol (GW) and Sosabon (SS) compared to other measurement stations. From the results of an emission source analysis, it was confirmed that anthropogenic sources such as combustion sources, vehicle exhaust, fuel evaporation, and solvent use had a significant effect at all measurement stations. Assessing the health risk, non-carcinogenic compounds were at acceptable level at all measurement stations. On the other hand, carcinogenic compounds were approaching risk level (10-4), thereby demanding immediate attention. The level of exposure to carcinogenic compounds increased by age group, and male was more vulnerable than female. It was found that SS had the highest level of exposure to carcinogens in the atmosphere of the population ages 60 or older. The health threat of the SMA population is expected due to direct exposure from inhalation of ambient toxic compounds and indirect exposure from ozone and PM2.5 formations through oxidation of VOCs. This study emphasizes the importance of addressing specific emission sources within the metropolitan area and developing comprehensive regional strategies to mitigate VOCs.

Analysis of PM2.5 inorganic and organic constituents to resolve contributing sources in Seoul, South Korea and Beijing, China and their possible associations with cytokine IL-8.

China and South Korea are the most polluted countries in East Asia due to significant urbanization and extensive industrial activities. As neighboring countries, collaborative management plans to maximize public health in both countries can be helpful in reducing transboundary air pollution. To support such planning, PM2.5 inorganic and organic species were determined in simultaneously collected PM2.5 integrated filters. The resulting data were used as inputs to positive matrix factorization, which identified nine sources at the ambient air monitoring sites in both sites. Secondary nitrate, secondary sulfate/oil combustion, soil, mobile, incinerator, biomass burning, and secondary organic carbon (SOC) were found to be sources at both sampling sites. Industry I and II were only identified in Seoul, whereas combustion and road dust sources were only identified in Beijing. A subset of samples was selected for exposure assessment. The expression levels of IL-8 were significantly higher in Beijing (167.7 pg/mL) than in Seoul (72.7 pg/mL). The associations between the PM2.5 chemical constituents and its contributing sources with PM2.5-induced inflammatory cytokine (interleukin-8, IL-8) levels in human bronchial epithelial cells were investigated. For Seoul, the soil followed by the secondary nitrate and the biomass burning showed increase with IL-8 production. However, for the Beijing, the secondary nitrate exhibited the highest association with IL-8 production and SOC and biomass burning showed modest increase with IL-8. As one of the highest contributing sources in both cities, secondary nitrate showed an association with IL-8 production. The soil source having the strongest association with IL-8 production was found only for Seoul, whereas SOC showed a modest association only for Beijing. This study can provide the scientific basis for identifying the sources to be prioritized for control to provide effective mitigation of particulate air pollution in each city and thereby improve public health.

Effect of COVID-19 response work experience on turnover intention among employees of dedicated COVID-19 hospitals in Seoul.

BACKGROUND: According to previous studies, stress and job burnout among medical personnel increased during the COVID-19 pandemic. This study analyzed the effect of the experience of COVID-19 response work on the intention of municipal hospital staffs to leave their workplaces during the pandemic. METHODS: The 3556 employees who had worked for more than 1 year at one of the eight Seoul Municipal Hospitals that either provided inpatient treatment for quarantined COVID-19 patients or operated as screening clinics were taken as the study population. In total, 1227 employees completed a web or mobile survey between October 21 and November 18, 2020. A chi-squared test was performed to confirm the difference in the distribution of turnover intention depending on whether the employees performed COVID-19 response tasks. Multiple logistic regression analyses were performed to determine the factors that affected the intention to leave. RESULTS: Of the 1227 respondents, 761 (62.0%) were frontline workers who were the first line of response to COVID-19. Experience with COVID-19 response tasks (OR = 1.59, p = 0.003) was significantly associated with the intention to leave. Additionally, the probability of turnover intention was significantly higher among workers aged 20-29 years (OR = 2.11, p = 0.038) and 40-49 years (OR = 1.57, p = 0.048), unmarried individuals (OR = 1.66, p = 0.005), doctors (OR = 2.41, p = 0.010), nurses (OR = 1.59, p = 0.036), and technical staff members (OR = 2.22, p = 0.009). High turnover intention was found among those who experienced high levels of burnout (OR = 2.03, p < 0.001) and those working in non-directly managed municipal hospitals (OR = 1.87, p = 0.018). CONCLUSION: Employees directly involved in COVID-19 response work displayed higher turnover intention. Various personal, job, and organizational factors significantly influenced employees' intentions to leave their positions in dedicated COVID-19 hospitals. These findings suggest the necessity of introducing management programs to aid workers who have experienced sudden changes in their duties and loss of autonomy while performing COVID-19 response tasks.

The factors related to depressive symptoms in urban older adults in South Korea: a study based on the Seoul Aging Survey.

PURPOSE: This study aims to comprehensively examine the determinants of depression among urban older adults in Seoul, utilizing the social-ecological model to address multifaceted influences. METHODS: A comprehensive analysis was conducted using data from the 2022 Seoul Aging Survey, which surveyed 2,914 individuals aged 65 and above. A multiple logistic regression analysis was performed to identify factors contributing to depressive symptoms, including socio-demographic characteristics, health behaviors and status, research accessibility, social support, and environmental influences. RESULTS: This study revealed that poor subjective health (OR = 1.47) and the presence of multiple chronic diseases (OR = 1.59) significantly increased the risk of depressive symptoms among urban older adults. From a social support standpoint, living alone was associated with a higher risk of depression (OR = 1.66), low food security (OR = 2.56), and low digital competency (OR = 2.70) were all significant predictors of depressive symptoms. Additionally, a lack of engagement with cultural facilities (OR = 2.15) was identified as a critical environmental factor contributing to depression. CONCLUSIONS: The findings underscore the need for comprehensive policy and practical interventions aimed at preventing chronic disease, enhancing social support networks, improving digital literacy, ensuring food security, and expanding access to healthcare and cultural facilities. Such measures are crucial in mitigating depression among urban older adults, thereby enhancing their overall well-being and quality of life.

Psychological Distress Trends and Effect of Media Exposure Among Community Residents After the Seoul Halloween Crowd Crush.

BACKGROUND: It is unclear how exposure to and perception of community trauma creates a mental health burden. This study aimed to examine the psychological distress trends among community residents in acute stress reaction, acute stress disorder, and post-traumatic stress disorder phases following the Seoul Halloween crowd crush. METHODS: A three-wave repeated cross-sectional survey was conducted with participants after the incident. Analysis of covariance (ANCOVA) with post hoc Bonferroni test was adopted to examine temporal changes in psychological distress and psychological outcomes resulting from media impacts. A two-way ANCOVA was adopted to examine the interaction effects of time and relevance to victims on psychological distress. RESULTS: A total of 807, 1,703, and 2,220 individuals participated in the three waves. Anxiety (estimated mean [standard error of the mean]: 2.28 [0.03] vs. 2.12 [0.02] vs. 2.03 [0.02]; P < 0.001), depression (2.22 [0.03] vs. 2.01 [0.02] vs. 1.90 [0.02]; P < 0.001), and anger (2.70 [0.03] vs. 2.66 [0.02] vs. 2.49 [0.02]; P < 0.001) gradually improved. However, sense of safety initially worsened and did not recover well (2.96 [0.03] vs. 2.75 [0.02] vs. 2.77 [0.02]; P < 0.001). The interaction effect of time and relevance to the victim were significant in depression (P for interaction = 0.049), anger (P for interaction = 0.016), and sense of safety (P for interaction = 0.004). Among participants unrelated to the victim, those exposed to graphics exhibited higher levels of anxiety (2.09 [0.02] vs. 1.87 [0.07]; P = 0.002), depression (1.99 [0.02] vs. 1.83 [0.07]; P = 0.020), and anger (2.71 [0.03] vs. 2.47 [0.08]; P = 0.003) at W2 and higher anger (2.49 [0.02] vs. 2.31 [0.06]; P = 0.005) at W3. CONCLUSION: Community residents indirectly exposed to trauma also experienced psychological distress in the early stages after the incident. A significant impact of media which might have served as a conduit for unfiltered graphics and rumors was also indicated.

Association of ambient temperature with intentional self-harm and suicide death in Seoul: a case-crossover design with a distributed lag nonlinear model.

Previous epidemiological studies have reported a short-term association between ambient temperature and suicide risk. To gain a clearer understanding of this association, it is essential to differentiate the risk factors for intentional self-harm (ISH) from those specifically associated with suicide deaths. Therefore, this study aims to examine whether the association between daily temperature and ISH or suicide deaths differs by age and sex. Between 2014 and 2019, cases of emergency room visits related to ISH and suicide deaths in Seoul were identified. A time-stratified case-crossover design was used to adjust for temporal trends and seasonal variation. A distributed lag nonlinear model was used to analyze the nonlinear and time-delayed effect of ambient temperature on ISH and suicide deaths. Positive associations were observed between temperature and both ISH and suicide deaths. For ISH, the relative risk (RR) was high at 1.17 (95% confidence interval (CI): 1.03, 1.34) for a temperature of 25.7 °C compared with 14.8 °C. The RR for suicide death was higher than those for ISH, at 1.43 (95% CI: 1.03, 2.00) for a temperature of 33.7 °C. These associations varied by age and sex, with males and females aged 35-64 years showing increased susceptibility to suicide deaths. This study provides detailed evidence that unusually high temperatures, both anomalous and out of season, may trigger suicidal behaviors, including both ISH and suicide deaths.

Role of Seaports and Imported Rats in Seoul Hantavirus Circulation, Africa.

Seoul orthohantavirus (SEOV) is not considered a major public health threat on the continent of Africa. However, Africa is exposed to rodentborne SEOV introduction events through maritime traffic after exponential growth of trade with the rest of the world. Serologic studies have already detected hantavirus antibodies in human populations, and recent investigations have confirmed circulation of hantavirus, including SEOV, in rat populations. Thus, SEOV is a possible emerging zoonotic risk in Africa. Moreover, the range of SEOV could rapidly expand, and transmission to humans could increase because of host switching from the usual brown rat (Rattus norvegicus) species, which is currently invading Africa, to the more widely installed black rat (R. rattus) species. Because of rapid economic development, environmental and climatic changes, and increased international trade, strengthened surveillance is urgently needed to prevent SEOV dissemination among humans in Africa.

Modified susceptible-exposed-infectious-recovered model for assessing the effectiveness of non-pharmaceutical interventions during the COVID-19 pandemic in Seoul.

Susceptible-exposed-infectious-recovered (SEIR) models were applied to assess the effectiveness of non-pharmaceutical interventions (NPIs) and to study the dynamic behavior of the COVID-19 pandemic. Recently, SEIR models have evolved to address the change of human mobility by some NPIs for predicting the new confirmed cases. However, the models have serious limitations when applied to Seoul. Seoul has two representative quarantine policies, i.e. social distancing and the ban on gatherings. Effects of the two policies need to be reflected in different functional forms in the model because changes in human mobility do not fully reflect the ban on gatherings. Thus we propose a modified SEIR model to assess the effectiveness of social distancing, ban on gatherings and vaccination strategies. The application of the modified SEIR model was illustrated by comparing the model output with real data.

The buffering effect of social capital for daily mental stress in an unequal society: a lesson from Seoul.

This study attempted to illustrate whether mental health deterioration could be alleviated by high social capital in an environment with high economic inequality. Daily mental stress was employed as a mental health factor when analyzing the association with economic inequality in the Seoul Survey data. Regarding social capital, community trust and altruism were included as cognitive dimensions, and participation and cooperation were included as structural dimensions in each model. The first finding showed a significantly positive relationship between economic inequality and daily stress, meaning that, like other mental health problems, daily mental stress is also high in regions with high economic inequality. Second, the slope of the daily stress increased in respondents with high social trust and participation was alleviated in an economically unequal environment. This indicates that social trust and participation have a buffering effect by moderating the slope of daily stress in societies with high inequality. Third, the buffering effect differs depending on the social capital factor. The buffering effect of trust and participation showed in an unequal environment, while the buffering effect of cooperation showed regardless of the unequal environment. In summary, social capital factors showed the effect of relieving daily mental stress in the relationship with economic inequality. Also, the buffering effect of social capital on mental health may show different aspects for each element.

Dosimetric assessment in the brain for downlink EMF exposure in Korean mobile communication networks.

Because the position and direction of the human body is not fixed in an actual environment, the incidence direction of the electromagnetic field (EMF) from mobile communication base stations, WiFi access points, broadcasting towers, and other far-field sources is arbitrary. To analyze the overall health effects of radio frequency EMF exposure, the dosimetric assessment for such environmental exposures created from an unspecified number of sources in daily life, along with exposures from specific EMF sources, must be quantified. This study is aimed at numerically evaluating the time-averaged specific absorption rate (SAR) of the human brain for environmental EMF exposure in the frequency range of 50-5800 MHz. Whole-body exposure to EMFs that are evenly incident spatially is considered. By comparing the results of several incidence directions and the number of polarizations, an optimal calculation condition has been derived. Finally, based on the results measured in Seoul at the end of 2021, the SAR and daily specific energy absorption (SA) in the brains of both a child and an adult for downlink exposures from 3G to 5G base stations are reported. Comparison results of the daily brain SA for exposure to DL EMF in all 3G to 5G mobile networks and exposure to a 10-min voice call (uplink EMF) using a mobile phone connected to a 4G network show that the SA from the downlinks is much higher than that from the uplinks.

Machine learning based estimation of urban on-road CO2 concentration in Seoul.

The urban on-road CO2 emissions will continue to increase, it is therefore essential to manage urban on-road CO2 concentrations for effective urban CO2 mitigation. However, limited observations of on-road CO2 concentrations prevents a full understanding of its variation. Therefore, in this study, a machine learning-based model that predicts on-road CO2 concentration (CO2traffic) was developed for Seoul, South Korea. This model predicts hourly CO2traffic with high precision (R2 = 0.8 and RMSE = 22.9 ppm) by utilizing CO2 observations, traffic volume, traffic speed, and wind speed as the main factors. High spatiotemporal inhomogeneity of hourly CO2traffic over Seoul, with 14.3 ppm by time-of-day and 345.1 ppm by road, was apparent in the CO2traffic data predicted by the model. The large spatiotemporal variability of CO2traffic was related to different road types (major arterial roads, minor arterial roads, and urban highways) and land-use types (residential, commercial, bare ground, and urban vegetation). The cause of the increase in CO2traffic differed by road type, and the diurnal variation of CO2traffic differed according to land-use type. Our results demonstrate that high spatiotemporal on-road CO2 monitoring is required to manage urban on-road CO2 concentrations with high variability. In addition, this study demonstrated that a model using machine learning techniques can be an alternative for monitoring CO2 concentrations on all roads without conducting observations. Applying the machine learning techniques developed in this study to cities around the world with limited observation infrastructure will enable effective urban on-road CO2 emissions management.

Increasing the accuracy of the asthma diagnosis using an operational definition for asthma and a machine learning method.

INTRODUCTION: Analysis of the National Health Insurance data has been actively carried out for the purpose of academic research and establishing scientific evidences for health care service policy in asthma. However, there has been a limitation for the accuracy of the data extracted through conventional operational definition. In this study, we verified the accuracy of conventional operational definition of asthma, by applying it to a real hospital setting. And by using a machine learning technique, we established an appropriate operational definition that predicts asthma more accurately. METHODS: We extracted asthma patients using the conventional operational definition of asthma at Seoul St. Mary's hospital and St. Paul's hospital at the Catholic University of Korea between January 2017 and January 2018. Among these extracted patients of asthma, 10% of patients were randomly sampled. We verified the accuracy of the conventional operational definition for asthma by matching actual diagnosis through medical chart review. And then we operated machine learning approaches to predict asthma more accurately. RESULTS: A total of 4,235 patients with asthma were identified using a conventional asthma definition during the study period. Of these, 353 patients were collected. The patients of asthma were 56% of study population, 44% of patients were not asthma. The use of machine learning techniques improved the overall accuracy. The XGBoost prediction model for asthma diagnosis showed an accuracy of 87.1%, an AUC of 93.0%, sensitivity of 82.5%, and specificity of 97.9%. Major explanatory variable were ICS/LABA,LAMA and LTRA for proper diagnosis of asthma. CONCLUSIONS: The conventional operational definition of asthma has limitation to extract true asthma patients in real world. Therefore, it is necessary to establish an accurate standardized operational definition of asthma. In this study, machine learning approach could be a good option for building a relevant operational definition in research using claims data.

Regional Disparities in the Infant Mortality Rate in Korea Between 2001 and 2021.

BACKGROUND: The infant mortality rate (IMR) has been considered an important indicator of the overall public health level. Despite improvements in recent decades, regional inequalities in the IMR have been reported worldwide. However, there are no Korean epidemiological studies on regional disparities in the IMR. METHODS: We extracted causes of death data from the Statistics Korea through the Korean Statistical Information Service database between 2001 and 2021. The total and regional IMRs were calculated to determine regional disparities. Based on causes of death and using Seoul as a reference, the excess infant deaths and population attributable fractions (PAFs) were calculated for 15 other metropolitan cities and provinces. The average annual percent changes by region from 2001 to 2021 were obtained using a joinpoint regression program. To assess inequities in IMR trends, the rate ratios (RRs) and rate differences (RDs) of the 15 regions were calculated by dividing the study period into period 1 (2001-2007), period 2 (2008-2014), and period 3 (2015-2021). RESULTS: The overall IMR in Korea was 3.64 per 1,000 live births, and the IMRs in the 14 regions were relatively higher than that in Seoul, with RRs ranging from 1.15 (95% confidence interval [CI], 1.04, 1.27) in Jeju-do to 1.62 (95% CI, 1.54, 1.71) in Daegu, over the total study period. Significant differences in infant deaths by region were observed for all causes of death, with PAFs ranging from 2.2% (95% CI, 1.7, 2.6) in Gyeonggi-do to 38.4% (95% CI, 38.1, 38.6) in Daegu. The leading cause of excess infant deaths was perinatal problems. The IMR disparities in the relative and absolute measures decreased from 1.44 (1.34, 1.54) to 1.21 (1.10, 1.31) for RRs and from 0.79 (0.63, 0.96) to 0.30 (0.15, 0.45) for RDs between periods 1 and 2, followed by an increase from 1.21 (1.10, 1.31) to 1.36 (1.21, 1.53) for RRs and from 0.30 (0.15, 0.45) to 0.51(0.36, 0.67) for RDs between period 2 and 3. CONCLUSION: Infant death is associated with place of residence and regional gaps have recently widened again in Korea. An in-depth investigation of the causes of regional disparities in infant mortality is required for effective governmental policies to achieve equality in infant health.

Reliability and Validity of the Korean Version of the Ask Suicide-Screening Questions (ASQ).

BACKGROUND: The Ask Suicide-Screening Questions (ASQ) tool is a simple suicide screening tool developed to screen patient suicide risk (SR). The purpose of this study was to verify the reliability and validity of the ASQ tool in hospitalized patients. METHODS: The internal consistency and test-retest reliability of the South Korean version of the ASQ tool were verified in 99 hospitalized patients admitted to a tertiary medical institution in Seoul. To verify the correlations and validity of each convergence with other scales, the Mini-International Neuropsychiatric Interview (MINI), Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), and Satisfaction with Life Scale (SWLS) were also conducted to determine convergent and discriminant validity. Then, the receiver operating characteristic (ROC) curve diagnosis values for suicide and depression levels with the highest correlations were analyzed. RESULTS: As a result, Cronbach's alpha was 0.826, and when each item was removed sequentially, Cronbach's alpha ranged from 0.736-0.840, showing stable internal consistency. Most of the corrected item-total correlation were over 0.500; however, a relatively low correlation was shown for the fourth and fifth questions, which had values of 0.429 and 0.410, respectively. The test-retest reliability was 0.830, and the MINI and PHQ-9 showed high values of 0.872 and 0.672, respectively. The area under the curve (AUC) according to the ASQ diagnosis value was also the highest for the MINI (0.936). CONCLUSION: The validity and reliability of the South Korean version of the ASQ tool were demonstrated. Through this validation, the ASQ tool can be used for simple suicide risk screening (SRS) in hospitalized patients.