Mendelian randomization (MR) uses genetic variation as a natural experiment to investigate the causal effects of modifiable risk factors (exposures) on outcomes. Two-sample Mendelian randomization (2SMR) is widely used to measure causal effects between exposures and outcomes via genome-wide association studies. 2SMR can increase statistical power by utilizing summary statistics from large consortia such as the UK Biobank. However, the first-order term approximation of standard error is commonly used when applying 2SMR. This approximation can underestimate the variance of causal effects in MR, which can lead to an increased false-positive rate. An alternative is to use the second-order approximation of the standard error, which can considerably correct for the deviation of the first-order approximation. In this study, we simulated MR to show the degree to which the first-order approximation underestimates the variance. We show that depending on the specific situation, the first-order approximation can underestimate the variance almost by half when compared to the true variance, whereas the second-order approximation is robust and accurate.

OBJECTIVES: This study was conducted to estimate the socioeconomic cost of injuries in South Korea. METHODS: We matched claims data from national health insurance, automobile insurance and industrial accident compensation insurance (IACI), and mortality data obtained from the national statistical office from 2001 to 2003 by patients' unique identifier. Socioeconomic cost included both direct cost and indirect cost: the direct cost was injury-related medical expenditure and the indirect cost included loss of productivity due to healthcare utilization and premature death. RESULTS: The socioeconomic cost of injuries in Korea was approximately 1.9% of the GDP from 2001 to 2003. That is, 12.1 trillion KRW (Korean Won) in 2001, 12.3 trillion KRW in 2002, and 13.7 trillion KRW in 2003. In 2003, direct medical costs were 24.6% (3.4 trillion KRW), the costs for loss of productivity by healthcare utilization were 13.0% (1.8 trillion KRW), and the costs for loss of productivity by premature death were 62.4% (8.6 trillion KRW). CONCLUSIONS: In this study, the socioeconomic cost of injuries in Korea between 2001 and 2003 was estimated by using not only health insurance claims data, but also automobile insurance, IACI claims and mortality data. We conclude that social efforts are required to reduce the socioeconomic cost of injuries in Korea, which represented approximately 1.9% of the GDP for the time period specified.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; *Cost of Illness ; Efficiency ; Female ; *Health Care Costs ; Humans ; Infant ; Infant, Newborn ; Inpatients ; Korea ; Length of Stay ; Male ; Middle Aged ; Outpatients ; Socioeconomic Factors ; Wounds and Injuries/*economics/mortality

BACKGROUND: This study aimed to estimate risk adjusted mortality rate in the ICUs (Intensive care units) by APACHE (Acute Physiology And Chronic Health Evaluation) III for revealing the performance variation in ICUs. METHODS: This study focused on 1,090 patients in the ICUs of 18 hospitals. For establishing risk adjusted mortality predictive model, logistic regression analysis was performed. APACHE III, surgery experience, admission route, and major disease categories were used as independent variables. The performance of each model was evaluated by c-statistic and goodness-of-fit test of Hosmer-Lemeshow. Using this predictive model, the performance of each ICU was tested as ratio of predictive mortality rate and observed mortality rate. RESULTS: The average observed mortality rate was 24.1%. The model including APACHE III score, admission route, and major disease categories was signified as the fittest one. After risk adjustment, the ratio of predictive mortality rate and observed mortality rate was distributed from 0.49 to 1.55. CONCLUSIONS: The variation in risk adjusted mortality among ICUs was wide. The effort to reduce this quality difference is needed.
APACHE ; Humans ; Critical Care ; Intensive Care Units ; Logistic Models ; Risk Adjustment

Purpose: The model for end-stage liver disease (MELD) 3.0 has recently been suggested for determining liver allocation. We aimed to apply MELD 3.0 to a Korean population and to discover differences between patients with and without hepatocellular carcinoma (HCC). Materials and Methods: This study is a retrospective study of 2203 patients diagnosed with liver cirrhosis at Severance Hospital between 2016–2022. Harrell’s concordance index was used to validate the ability of MELD scores to predict 90-day survival. Results: During a mean follow-up of 12.9 months, 90-day survival was 61.9% in all patients, 50.4% in the HCC patients, and 74.8% in the non-HCC patients. Within the HCC patients, the concordance index for patients on the waitlist was 0.653 using MELD, which increased to 0.753 using MELD 3.0. Among waitlisted patients, the 90-day survival of HCC patients was worse than that of non-HCC patients with MELD scores of 31–37 only (69.7% vs. 30.0%, p=0.001). Applying MELD 3.0, the 90-day survival of HCC patients was worse than that of non-HCC patients across a wider range of MELD 3.0 scores, compared to MELD, with MELD 3.0 scores of 21–30 and 31–37 (82.0% vs. 72.5% and 72.3% vs. 24.3%, p=0.02 and p<0.001, respectively). Conclusion MELD 3.0 predicted 90-day survival of the HCC patients more accurately than original MELD score; however, the disparity between HCC and non-HCC patients increased, particularly in patients with MELD scores of 21–30. Therefore, a novel exception score is needed or the current exception score system should be modified.

OBJECTIVES: We compared the viral cycle threshold (Ct) values of infected patients to better understand viral kinetics by vaccination status during different periods of variant predominance in Gyeonggi Province, Korea. METHODS: We obtained case-specific data from the coronavirus disease 2019 (COVID-19) surveillance system, Gyeonggi in-depth epidemiological report system, and Health Insurance Review & Assessment Service from January 2020 to January 2022. We defined periods of variant predominance and explored Ct values by analyzing viral sequencing test results. Using a generalized additive model, we performed a nonlinear regression analysis to determine viral kinetics over time. RESULTS: Cases in the Delta variant’s period of predominance had higher viral shedding patterns than cases in other periods. The temporal change of viral shedding did not vary by vaccination status in the Omicron-predominant period, but viral shedding decreased in patients who had completed their third vaccination in the Delta-predominant period. During the Delta-predominant and Omicron-predominant periods, the time from symptom onset to peak viral shedding based on the E gene was approximately 2.4 days (95% confidence interval [CI], 2.2 to 2.5) and 2.1 days (95% CI, 2.0 to 2.1), respectively. CONCLUSIONS In one-time tests conducted to diagnose COVID-19 in a large population, although no adjustment for individual characteristics was conducted, it was confirmed that viral shedding differed by the predominant strain and vaccination history. These results show the value of utilizing hundreds of thousands of test data produced at COVID-19 screening test centers.

PURPOSE: The purpose of this study was to evaluate the experiences of patients who used emergency department services and to analyze the factors which influenced their willingness to use them again. METHODS: The survey was carried out at 17 emergency medical centers for one days, and 509 patients and caregivers answered the questions. The questionnaire was developed through literature review and consultation with professionals. The survey questions addressed the following: duration of residence in ED (emergency department), waiting times, fairness of waiting times, respectfulness from medical staff, explanation of treatment plan, explanation of medical test, explanation of drug prescription, explanation of discharge, ease of asking about treatment, response times to requests for help, respect for privacy, existence of threatening situations and cleanliness of ED. RESULTS: The major factors which influenced patients' willingness to return were duration of residence in ED, fairness of waiting times, respectfulness from medical staff, explanation of drug prescription, ease of asking about treatment, existence of threatening situations and cleanliness of ED. Only education among all demographic and socio-economic factors and clinical outcomes had a bearing on willingness to return. CONCLUSION: The evaluation of patients' experiences is a useful method for gauging the quality of emergency department services. Moreover, specifically focused questions about patients' experiences can greatly contribute to improving the quality of emergency department services.
Caregivers ; Drug Prescriptions ; Emergencies ; Emergency Medical Services ; Humans ; Medical Staff ; Morphinans ; Privacy ; Surveys and Questionnaires ; Reaction Time ; Ursidae

OBJECTIVES: To investigate the patterns of unintentional home injuries in Korea. METHODS: The study population was 12,382,088 people who utilized National Health Insurance services due to injuries (main diagnosis codes S00 to T28) during 2006. Stratified samples(n=459,501) were randomly selected by sex, age group and severity of injury. A questionnaire was developed based on the International Classification of External Causes of Injury and 18,000 cases surveyed by telephone were analyzed after being projected into population proportionately according to the response rates of their strata. Domestic injury cases were finally included. RESULTS: Domestic injuries (n=3,804) comprised 21.1% of total daily life injuries during 2006. Women were vulnerable to home injuries, with the elderly and those of lower income (medical-aid users) tending to suffer more severe injuries. Injury occurred most often due to a slipping fall (33.9%), overexertion (15.3%), falling (9.5%) and stumbling (9.4%), with severe injury most often resulting from slipping falls, falls and stumbles. Increasing age correlated with domestic injury-related disability. CONCLUSIONS: The present findings provide basic information for development of home injury prevention strategies, with focus on the elderly.

OBJECTIVES: This study was conducted to estimate the cumulative incidence rate (CIR) of unintentional injuries in Korean daily life and to describe the pattern of unintentional injuries. METHODS: The study population was the people who used the National Health Insurance because of injuries (ICD code: S00~T98) during 2006. The stratified sample according to gender, age and the severity of injury (NISS, New Injury Severity Score) was randomly selected. The questions on the questionnaire were developed as a reference for an international classification tool (ICECI, International Classification of External Causes of Injury). The questions included the locations of injury, the mechanisms of injury and the results of injury. Moreover, we used age, gender, region and income variables for analysis. RESULTS: The CIR of unintentional injuries that occurred in daily life for 1 year per 100,000 persons was 17,606, and the CIR of severe injuries was 286. Many injuries were occurred at home (29.6%), public places (19.0%), school (13.7%) and near home (12.0%). The major mechanisms of injuries were slipping (48.8%), contact (14.0%), physical over-exertion (13.8%), and fall (6.6%). Infants and old aged people were vulnerable to injuries, and those who lived rural area and who were in a low income level were vulnerable too. CONCLUSIONS: We signified the risk groups and risk settings of unintentional injuries in Korean daily life. These results could contribute to establishing strategies for injury prevention and implementing these strategies.
Accidents/*statistics & numerical data ; Adolescent ; Adult ; Age Factors ; Aged ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Infant, Newborn ; Korea/epidemiology ; Male ; Middle Aged ; Residence Characteristics ; Sex Factors ; Socioeconomic Factors ; Trauma Severity Indices ; Wounds and Injuries/classification/*epidemiology

Background/Aims: To investigate a reported outbreak of presumed hepatitis E virus (HEV) infection in a Korean food manufacturing facility and to explore the association between anti-HEV immunoglobulin M (IgM) positivity and coronavirus disease 2019 (COVID-19) infection or vaccination. Methods: Twenty-four cases of anti-HEV IgM positivity were reported among 646 workers at the facility in 2022. An epidemiological investigation was conducted, comprising HEV-RNA testing of blood and environmental samples, analysis of group meal records, and an association between anti-HEV IgM positivity and confirmed COVID-19 infection or vaccination. Results: All 24 patients were asymptomatic, with cases spread sporadically across the facility. HEV RNA was not detected in the serum or environmental samples. Four out of 340 meals (1.2%) showed a significantly higher proportion of anti-HEV positivity in each meal intake group than in the non-intake group on certain days. Although the cumulative rate of COVID-19 infection showed no difference, the anti-HEV IgM positive group showed significantly higher proportions of >2 doses of COVID-19 vaccination (83.3% vs 48.7%, p=0.021), vaccination within 90 days (45.8% vs 19.7%, p=0.008), and having the Moderna vaccine administered as the last vaccine (75.0% vs 14.5%, p<0.001) than those of the anti-HEV negative group. In four multivariable models, three or more COVID-19 vaccinations and the Moderna vaccine as the last vaccine were consistently associated with anti-HEV IgM positivity, while the specific day group meal intake was also a significant factor. Conclusions This epidemiological investigation showed that anti-HEV IgM positivity may occur as a false-positive result related to COVID-vaccination over three times and use of the Moderna vaccine, although a portion of true HEV infection may not be excluded.

In November 2021, 14 international travel-related severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 (omicron) variant of concern (VOC) patients were detected in South Korea. Epidemiologic investigation revealed community transmission of the omicron VOC. A total of 80 SARS-CoV-2 omicron VOC-positive patients were identified until December 10, 2021 and 66 of them reported no relation to the international travel.There may be more transmissions with this VOC in Korea than reported.