Clinical Applications of the Microbiome in Obstetrics

Human microbiome refers to the genetic material of approximately 1013 microorganisms present in the human body. These microbiomes interact significantly with the physiological, metabolic, and immune systems, particularly during pregnancy. Microbiome dysbiosis in pregnant women and their fetuses is associated with obstetric complications and poor neonatal outcomes. Oral and gut microbiomes can influence the placenta, uterus, and fetus via hematogenous translocation. Through ascending translocation, vaginal microbiota can directly affect the uterine environment. Current research focuses on the presence of the placental microbiome, which is characterized by low biomass. However, more well-controlled studies are required to specifically address the contamination issues. Use of antibiotics during pregnancy and the mode of delivery, specifically cesarean section, have been linked to the establishment of the neonatal gut microbiome. Probiotic supplementation may be beneficial during pregnancy, particularly for women receiving antibiotic treatment.

Experience of Lifetime Health Maintenance Program: An Observational Study of a 30-Year Period of Outpatient Primary Care in a Tertiary Hospital / 가정의학회지

Background@#This study aimed to identify the clinical content of patients registered with the Lifetime Health Maintenance Program (LHMP) under the care of a single family physician who introduced and operated the program in Korea at a tertiary hospital for over 30 years. @*Methods@#We analyzed the electronic medical records of 745 patients who had registered for more than 3 times with the LHMP under the care of a single family physician between January 1, 2010 and December 31, 2019. We reviewed medical records from June 1989, when the hospital was established, to February 2022. The participants’ age at the time of LHMP enrollment, sex, initial consultation date, final consultation date, and consultation content were evaluated. @*Results@#Patients visited the LHMP for various reasons, including acute symptom management, chronic disease management, psychiatric consultation, counseling on health behaviors, health checkups, and vaccination. The top five diagnoses for acute symptom management were upper respiratory infection, abdominal pain, dizziness/vertigo, headache, and lower back pain, whereas those for chronic disease management were dyslipidemia, hypertension, osteoarthritis, osteoporosis/osteopenia, and diabetes. More than one in five patients received psychiatric consultation and counseling on health behaviors. As the duration of the program enrollment increased, the proportion of patients visiting the LHMP for acute symptoms, vaccinations, and health checkups also increased. Furthermore, the number of categories of consultation content increased for each patient. @*Conclusion@#The LHMP emphasized the need to systematize regular primary care physicians in Korea. Policy changes are necessary to strengthen primary care, and the LHMP serves as an intermediate step in organizing regular primary care physicians in Korea.

Tuberculosis and chest radiology

Tuberculosis is still a major public health problem, although it is decreasing worldwide. The World Health Organization is working to reduce the incidence and deaths of tuberculosis globally and aims to eradicate tuberculosis.Current Concepts: The world’s gradual eradication of tuberculosis would be virtually inconceivable without the outstanding scientific works of Robert Koch and Wilhelm Conrad Röntgen. In 1882, Koch’s discovery of the tuberculosis bacillus was the most important first step towards controlling and ending this deadly disease. In 1895, Röntgen’s discovery of the X-ray revolutionized humanity as it became the first technology used to create images of the human body. X-ray images became an essential tool in modern medicine within a short period.Discussion and Conclusion: Chest radiology plays a crucial role in tuberculosis screening, diagnosis, and management. Chest radiology has contributed to the control of tuberculosis, which has plagued humanity for a long time, and will continue to contribute to eradicating tuberculosis in the world.

Alzheimer’s Disease Prediction Using Attention Mechanism with Dual‑Phase 18 F‑Florbetaben Images / 대한핵의학회잡지

Materials and Methods@#A total of 264 patients (74 CN and 190 AD), who underwent FBB imaging test and neuropsychological tests, were retrospectively analyzed. Early- and delay-phase FBB images were spatially normalized with an in-house FBB template. The regional standard uptake value ratios were calculated with the cerebellar region as a reference region and used as independent variables that predict the diagnostic label assigned to the raw image. @*Results@#AD positivity scores estimated from dual-phase FBB showed better accuracy (ACC) and area under the receiver operating characteristic curve (AUROC) for AD detection (ACC: 0.858, AUROC: 0.831) than those from delay phase FBB imaging (ACC: 0.821, AUROC: 0.794). AD positivity score estimated by dual-phase FBB (R: −0.5412) shows a higher correlation with psychological test compared to only dFBB (R: −0.2975). In the relevance analysis, we observed that LSTM uses different time and regions of early-phase FBB for each disease group for AD detection. @*Conclusions@#These results show that the aggregated model with dual-phase FBB with long short-term memory and attention mechanism can be used to provide a more accurate AD positivity score, which shows a closer association with AD, than the prediction with only a single phase FBB.

The Prognosis of Post-Scabetic Itch / 대한피부과학회지

Background@#The primary goal of scabies treatment is to eliminate mites; however, but post-scabetic itch persists in many patients. Since long-standing itching can lead to the development of other comorbidities, appropriate interventions are necessary. @*Objective@#This study aimed to investigate the effects of inappropriate (continuous or prolonged) scabicide use and oral steroids on the duration of pruritus in patients with scabies. @*Methods@#The duration of pruritus, use of oral corticosteroids, total immunoglobulin E (IgE) levels, specific IgE levels for house dust mites, and eosinophil counts were evaluated. Post-scabetic itch was defined as itching that persisted for more than 3 weeks, although scabies was no longer detected; 208 participants with post-scabetic itch were included. @*Results@#We recruited 265 participants with confirmatory diagnosis of scabies and 116 with clinical diagnosis. We treated 124 participants with scabicides based on the guidelines, whereas 257 participants were not. The type of scabicide did not affect the duration of pruritus. Scabicide overuse did not shorten the duration of pruritus; however, its prolonged use lengthened the treatment period. Although oral corticosteroids did not shorten the duration of pruritus in the patients, they were effective when the patient had post-scabetic itch. In addition, a positive correlation between the total IgE level and duration of pruritus was observed. @*Conclusion@#This study investigated the effect of treatment modality on the clinical course of scabies. Our findings suggest that overuse of scabicides might be associated with post-scabetic itch, and short-term use of oral corticosteroids may be effective in reducing its duration.

Effects of a Nursing Simulation Learning Module on Clinical Reasoning Competence, Clinical Competence, Performance Confidence, and Anxiety in COVID-19 Patient-Care for Nursing Students

Purpose@#This study aimed to develop a nursing simulation learning module for coronavirus disease 2019 (COVID-19) patient-care and examine its effects on clinical reasoning competence, clinical competence, performance confidence, and anxiety in COVID-19 patient care for nursing students. @*Methods@#A non-equivalent control group pre- and post-test design was employed. The study participants included 47 nursing students (23 in the experimental group and 24 in the control group) from G City. A simulation learning module for COVID-19 patient-care was developed based on the Jeffries simulation model. The module consisted of a briefing, simulation practice, and debriefing. The effects of the simulation module were measured using clinical reasoning competence, clinical competence, performance confidence, and anxiety in COVID-19 patient-care. Data were analyzed using χ 2 -test, Fisher’s exact test, t-test, Wilcoxon signed-rank test, and Mann– Whitney U test. @*Results@#The levels of clinical reasoning competence, clinical competence, and performance confidence of the experimental group were significantly higher than that of the control group, and the level of anxiety was significantly low after simulation learning. @*Conclusion@#The nursing simulation learning module for COVID-19 patient-care is more effective than the traditional method in terms of improving students’ clinical reasoning competence, clinical competence, and performance confidence, and reducing their anxiety. The module is expected to be useful for educational and clinical environments as an effective teaching and learning strategy to empower nursing competency and contribute to nursing education and clinical changes.

Increased Healthcare Delays in Tuberculosis Patients During the First Wave of COVID-19 Pandemic in Korea: A Nationwide Cross-Sectional Study

Background@#The coronavirus disease 2019 (COVID-19) pandemic caused disruptions to healthcare systems, consequently endangering tuberculosis (TB) control. We investigated delays in TB treatment among notified patients during the first wave of the COVID-19 pandemic in Korea. @*Methods@#We systemically collected and analyzed data from the Korea TB cohort database from January to May 2020. Groups were categorized as ‘before-pandemic’ and ‘during-pandemic’ based on TB notification period. Presentation delay was defined as the period between initial onset of symptoms and the first hospital visit, and healthcare delay as the period between the first hospital visit and anti-TB treatment initiation. A multivariate logistic regression analysis was performed to evaluate factors associated with delays in TB treatment. @*Results@#Proportion of presentation delay > 14 days was not significantly different between two groups (48.3% vs. 43.7%, P = 0.067); however, proportion of healthcare delay > 5 days was significantly higher in the during-pandemic group (48.6% vs. 42.3%, P = 0.012). In multivariate analysis, the during-pandemic group was significantly associated with healthcare delay > 5 days (adjusted odds ratio = 0.884, 95% confidence interval = 0.715–1.094). @*Conclusion@#The COVID-19 pandemic was associated with healthcare delay of > 5 days in Korea. Public health interventions are necessary to minimize the pandemic’s impact on the national TB control project.

Baseline Clinical and Biomarker Characteristics of Biobank Innovations for Chronic Cerebrovascular Disease With Alzheimer’s Disease Study: BICWALZS

Objective@#We aimed to present the study design and baseline cross-sectional participant characteristics of biobank innovations for chronic cerebrovascular disease with Alzheimer’s disease study (BICWALZS) participants. @*Methods@#A total of 1,013 participants were enrolled in BICWALZS from October 2016 to December 2020. All participants underwent clinical assessments, basic blood tests, and standardized neuropsychological tests (n=1,013). We performed brain magnetic resonance imaging (MRI, n=817), brain amyloid positron emission tomography (PET, n=713), single nucleotide polymorphism microarray chip (K-Chip, n=949), locomotor activity assessment (actigraphy, n=200), and patient-derived dermal fibroblast sampling (n=175) on a subset of participants. @*Results@#The mean age was 72.8 years, and 658 (65.0%) were females. Based on clinical assessments, total of 168, 534, 211, 80, and 20 had subjective cognitive decline, mild cognitive impairment (MCI), Alzheimer’s dementia, vascular dementia, and other types of dementia or not otherwise specified, respectively. Based on neuroimaging biomarkers and cognition, 199, 159, 78, and 204 were cognitively normal (CN), Alzheimer’s disease (AD)-related cognitive impairment, vascular cognitive impairment, and not otherwise specified due to mixed pathology (NOS). Each group exhibited many differences in various clinical, neuropsychological, and neuroimaging results at baseline. Baseline characteristics of BICWALZS participants in the MCI, AD, and vascular dementia groups were generally acceptable and consistent with 26 worldwide dementia cohorts and another independent AD cohort in Korea. @*Conclusion@#The BICWALZS is a prospective and longitudinal study assessing various clinical and biomarker characteristics in older adults with cognitive complaints. Details of the recruitment process, methodology, and baseline assessment results are described in this paper.

Two Cases of Patients with a Rash along the Intertriginous Area without Certain Drug History / 대한피부과학회지

We report a skin rash with a sharply demarcated erythema on the flexural area. The differential diagnoses included Baboon syndrome and symmetrical drug-related intertriginous and flexural exanthema. The diagnosis can be made based on the presence of previous cutaneous sensitization and causative agents. Our cases were consistent with a diagnosis of Baboon syndrome with no drug history.

Latent Tuberculosis Cascade of Care Among Healthcare Workers:A Nationwide Cohort Analysis in Korea Between 2017 and 2018

Background@#In 2017, Korea implemented nationwide latent tuberculosis infection (LTBI) project targeting healthcare workers (HCWs). We aimed to assess its performance using the cascade of care model. @*Methods@#We included 45,503 employees of medical institutions with positive interferongamma release assay result who participated between March 2017 and December 2018. We described percentages of LTBI participants completing each step in the cascade of care.Poisson regression model was conducted to assess individual characteristics and factors associated with not-visiting clinics for further care, not-initiating LTBI treatment, and notcompleting treatment. @*Results@#Proportions of visiting clinics and initiating and completing treatment in HCWs were 54.9%, 38.5%, and 32.0%, respectively. Despite of less likelihood of visiting clinics and initiating LTBI treatment, older age ≥ 65 years were more likely to complete treatment (adjusted relative risk [aRR], 0.80; 95% confidence interval [CI], 0.64–0.99), compared to young age < 35 years. Compared to nurses, doctors were less likely to visit clinic; however, were more likely to initiate treatment (aRR, 0.88; 95% CI, 0.81–0.96). Those who visited public health centers were associated with not-initiating treatment (aRR, 1.34; 95% CI, 1.29–1.40). When treated at private hospitals, 9-month isoniazid monotherapy was less likely to complete treatment, compared to 3-month isoniazid and rifampicin combination therapy (aRR, 1.33; 95% CI, 1.16–1.53). @*Conclusion@#Among employees of medical institutions with LTBI, only one third completed treatment. Age, occupation, treatment center, and initial regimen were significantly related to LTBI treatment performance indicators. Rifampicin-based short treatment regimens were effective under standard of care.

MicroRNA-21 inhibition attenuates airway inflammation and remodelling by modulating the transforming growth factor β–Smad7 pathway

Background/Aims@#Current asthma therapies remain unsatisfactory for controlling airway remodelling in asthma. MicroRNA-21 is a key player in asthma pathogenesis, but the molecular mechanisms underlying its effects on airway remodelling are not completely understood. We investigated the effects of inhibition of microRNA-21 on allergic airway inflammation and remodelling. @*Methods@#Female BALB/c mice were divided into four groups: control, ovalbumin-sensitized and -challenged for 3 months, microRNA-negative control-treated ovalbumin-treated, and microRNA-21 inhibitor-treated ovalbumin-treated groups. Parameters related to airway remodelling, cytokine production, airway inflammation, and airway hyperresponsiveness were compared between groups. Human bronchial smooth muscle cells were used in a mechanism study. @*Results@#In this asthma model, ovalbumin-sensitized and -challenged mice exhibited allergic airway inf lammation and airway remodelling. MicroRNA-21 inhibitor-treated mice had fewer inflammatory cells, lower TH2 cytokine production, and suppressed parameters related to remodelling such as goblet cell hyperplasia, collagen deposition, hydroxyproline content, and expression of smooth muscle actin. Inhibition of microRNA-21 decreased transforming growth factor β1 expression and induced Smad7 expression in lung tissue. In human bronchial smooth muscle cells stimulated with transforming growth factor β1, microRNA-21 inhibition upregulated Smad7 expression and decreased markers of airway remodelling. @*Conclusions@#Inhibition of microRNA-21 had both anti-inflammatory and anti-remodelling effects in this model of ovalbumin-induced chronic asthma. Our data suggest that the microRNA-21–transforming growth factor β1–Smad7 axis modulates the pathogenesis of ovalbumin-induced chronic asthma and in human bronchial smooth muscle cells. MicroRNA-21 inhibitors may be a novel therapeutic target in patients with allergic asthma, especially those with airway remodelling.

Verrucous Carcinoma of the Nipple, Which Is a Rare Site / 대한피부과학회지

Verrucous carcinoma is a rare, low-grade, well-differentiated variant of squamous cell carcinoma. It occurs mainly on the soles, but has also been reported in other locations, including the buttocks, hand, anus, and genitalia. A 38-year-old woman presented with an asymptomatic skin lesion of the nipple. She first noticed the lesion three months prior. A solitary, cauliflower-shaped, black polypoid mass was observed on her right nipple.Histopathological examination revealed a superficial lesion resembling verruca vulgaris. It was composed of relatively well-differentiated cells with severe epidermal proliferation, and some tumor cells were observed in the dermis. The final diagnosis was verrucous carcinoma. Complete excision of all the lesions was performed. The patient had no recurrence. We report an interesting case of verrucous carcinoma that occurred at a relatively rare site; only one previous report of verrucous carcinoma associated with the breast or nipple was found.

Diagnosis of Hypersensitivity Pneumonitis: 2020 Clinical Practice Guideline

Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) characterized by an inhaled inciting antigen that leads to the inflammation of the lung parenchyma and small airway with immunologic reactions. Over the last decades, the most effective therapeutic option for HP has been limited to antigen avoidance. The differential diagnosis of HP from other ILDs is the beginning of treatment as well as diagnosis. However, the presence of several overlapping clinical and radiologic features makes differentiating HP from other ILDs particularly challenging. In 2020, a multidisciplinary committee of experts from the American Thoracic Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax suggested a new clinical practice guideline classifying HP into nonfibrotic and fibrotic phenotypes on the basis of chest high-resolution CT (HRCT) findings. Therefore, we introduced a new diagnostic algorithm based on chest HRCT in the clinical practice guideline for the diagnosis of HP.

Radiologic Diagnosis of Nontuberculous Mycobacterial Pulmonary Disease

The incidence and prevalence of nontuberculous mycobacterial pulmonary disease (NTM-PD) is increasing worldwide, including in Korea, and the clinical importance of NTM-PD is also rapidly increasing. The diagnosis and management of NTM-PD is difficult. Radiologic evidence is mandatory to diagnose NTM-PD, and the radiologic findings may be the first evidence of the disease in many patients. Traditionally, NTM-PD demonstrates two different radiologic forms:fibrocavitary and nodular bronchiectatic. However, the disease also shows non-specific and a wide spectrum of radiologic features. Radiologists must be aware of the radiologic features of NTM-PD and should include them in the differential diagnosis. This review focuses on the epidemiology in Korea, diagnostic criteria, and radiological features of NTM-PD for radiologists.

Latent Tuberculosis Infection Screening and Treatment in Congregate Settings (TB FREE COREA):Demographic Profiles of InterferonGamma Release Assay Cohort

In 2017, the Korean government launched an unprecedentedly large-scaled latent tuberculosis infection (LTBI) screening project which covered more than a million individuals in congregate settings. A total of 1,047,689 participants of source population (n = 2,336,157) underwent LTBI testing from 2017 to 2018. The overall LTBI test uptake rate during this project was 44.8%. Workers in daycare centers (83.5%) and kindergartens (78.9%) showed high participation rate. A total of 1,012,206 individuals with valid results of interferongamma release assay (IGRA) were selected to constitute the IGRA cohort. Most of the enrolled participants in the IGRA cohort were in their working age. Approximately, threequarters of total enrolled population were female. Investigating the LTBI prevalence, stages of LTBI care cascade, natural history of LTBI, efficacy of LTBI treatment and cost-effectiveness of LTBI screening are feasible within this IGRA cohort.

Epidemiological Features and Economic Burden of Guillain-Barré Syndrome in South Korea:A Nationwide Population-Based Study

Background@#and Purpose Guillain-Barré syndrome (GBS) is rare, but its symptoms are severe and they occasionally lead to long-term disability. Country-specific epidemiological evidence is useful for detecting potential problems at the population level. This study investigated the epidemiological and economic characteristics of GBS in South Korea. @*Methods@#The Korean National Health Insurance Service claims data from 2010 to 2016 were used to identify incident cases as newly hospitalized patients with a primary diagnosis of GBS (the 10th revision of the International Classification Disease code of G61.0). New cases were defined as patients not having claim records for GBS within one year prior to the hospital admission for GBS. @*Results@#The incidence rate increased by 45.6% between 2010 and 2016, from 1.28 to 1.82 per 100,000 population. All age groups other than <20 years showed increasing trends. The incidence rate was highest in those aged 65 years to 74 years. Approximately 72% of the incident GBS cases had antecedent infection within 42 days before GBS was diagnosed. Children younger than 10 years constituted the highest proportion of antecedent infections (93.7%).The average length of stay per GBS hospitalization was 33.5 days. Patients had an average of 7.48 outpatient visits for GBS treatment per year. The economic burden from a societal perspective of treating GBS during the first year was USD 16,428. @*Conclusions@#The increasing incidence trend and substantial economic burden of GBS strongly advocate the development of effective strategies for preventing and managing GBS.

Targeting Hypoxia Using Evofosfamide and Companion Hypoxia Imaging of FMISO-PET in Advanced Biliary Tract Cancer / Journal of the Korean Cancer Association, 대한암학회지

Purpose@#Hypoxia is widely known as one of the mechanisms of chemoresistance and as an environmental condition which triggers invasion and metastasis of cancer. Evofosfamide is a hypoxia-activated prodrug of the cytotoxin bromo-isophosphoramide mustard conjugated with 2-nitroimidazole. Biliary tract cancer (BTC) is known to contain large hypoxic area. This study evaluated the efficacy and safety of evofosfamide as a second-line treatment of advanced BTC. @*Materials and Methods@#Patients received evofosfamide at a dose of 340 mg/m2 on days 1, 8, and 15 of every 28-day cycle. Primary end-point was progression-free survival (PFS) rate at 4-months (4m-PFSR). Secondary end-points included overall survival (OS), PFS, disease control rate (DCR), metabolic response by 18F-fluorodeoxyglucose positron emission tomography (PET), hypoxic parameters evaluated by 18F-fluoromisonidazole (FMISO) PET and toxicity. @*Results@#Twenty patients were treated with evofosfamide, with 16 response-evaluable patients. There was no objective response; stable disease was observed in nine patients, with a DCR of 56.25%. 4m-PFSR was 40.6%. Median PFS was 3.60 months (95% confidence interval [CI], 1.68 to 5.52). Median OS was 6.37 months (95% CI, 3.94 to 8.79). Reduction of tumor metabolic activity was observed in eight of 15 patients (53.3%). High baseline hypoxic parameters were associated with poor PFS. Change of hypoxic parameters between pretreatment and post-treatment reflected hypoxic-activated drug response. There was no treatment-related death. @*Conclusion@#Evofosfamide as second-line treatment of advanced BTC showed acceptable safety and comparable efficacy to other agents. Changes in volumetric parameters measured with FMISO PET, showing the degree of tumor hypoxia, reflected the response to evofosfamide based on the mode of action.

Adjuvant oxaliplatin-based chemotherapy effect after treatment of colorectal hepatic metastasis

Purpose@#We aimed to investigate whether adjuvant oxaliplatin-based chemotherapy after treatment for hepatic metastasis affects recurrence or survival and to determine the risk factors for recurrence or survival. @*Methods@#Forty-six patients who underwent curative treatment for hepatic metastasis from colorectal cancer between July 2009 and December 2017 were included from a retrospectively collected patient database. Curative resection included hepatic resection, radiofrequency ablation (RFA), or a combination of both, followed by adjuvant chemotherapy with oxaliplatin-based chemotherapy. @*Results@#Thirty-seven patients (80.4%) had colon cancer and 9 (19.6%) had rectal cancer. Twenty-six patients (56.5%) underwent hepatic resection, 7 (15.2%) RFA, and 13 (28.3%) hepatic resection and RFA. Thirty-two patients (69.6%) underwent chemotherapy after hepatic treatment. The recurrence incidence was 50% in the non-chemotherapy group and 46.9% in the chemotherapy group (P > 0.999). The incidence of death was 7.1% in the non-chemotherapy group and 18.8% in the chemotherapy group (P = 0.657). The recurrence risk factors were N stage (N0 vs. N2; P = 0.013, P = 0.005) and bilobed hepatic metastasis (P = 0.027, P = 0.009) in the univariate and multivariate analyses, respectively. However, chemotherapy after hepatic treatment was not a risk factor for disease-free survival (DFS) or overall survival (OS) in the univariate and multivariate analyses (P = 0.656 and P = 0.414, respectively; P = 0.510 and P = 0.459, respectively). @*Conclusion@#Oxaliplatin-based adjuvant chemotherapy after colorectal hepatic metastasis treatment did not affect the DFS or OS. The N stage of the primary tumor and bilobed hepatic metastasis are risk factors for recurrence and death.

Upper Extremity Deep Vein Thrombosis After Botulinum Toxin Injection: A Case Report

Botulinum toxin (BoNT) injection is widely used to improve spasticity. However, after the treatment, the patient may experience pain, inflammation, swelling and redness at the injection site. In this case, we addressed deep vein thrombosis (DVT) after BoNT treatment of the upper limb. A male aged 37 years had spasticity and dystonia in his left upper extremity. BoNT-A 100 U was injected into the left biceps brachii and an equal amount into the brachialis to relieve spasticity. After three days, he developed redness and painful swelling in the left upper arm and the next day, through the upper extremity computed tomography venography, DVT was identified in the left cephalic vein. The thrombus resolved after the anticoagulation therapy with rivaroxaban (Xarelto). We hypothesized the role of mainly three mechanisms in the development of DVT in this case: repetitive strenuous activity, relative stasis due to reduced muscle tone, and possible direct mechanical damage to the vessel wall.

Analysis of the Impact of the Coronavirus Disease Epidemic on the Emergency Medical System in South Korea Using the Korean Triage and Acuity Scale

Purpose@#Severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19), has spread worldwide. Global health systems, including emergency medical systems, are suffering from a lack of medical resources. Using a method for classifying patients visiting the emergency department (ED), we aimed to investigate trends in emergency medical system usage during the COVID-19 epidemic in Korea. @*Materials and Methods@#This retrospective observational study included patients who visited emergency medical institutions registered with the National Emergency Department Information System database from January 1, 2017 to May 31, 2020. The primary outcome was identification of changes in the distribution of patients visiting the ED according to the type of emergency medical institution. The secondary outcome was a detailed comparison of Korean Triage and Acuity Scale (KTAS) levels and patient distributions before and during the infectious disaster crisis period. @*Results@#Severe patients visited regional emergency centers (RECs) and local emergency centers (LECs) more frequently during the COVID-19 period, and disposition status warranting admission to the intensive care unit or resulting in death was more common in RECs and LECs during the COVID-19 period [RECs, before COVID-19: 300686 (6.3%), during COVID-19: 33548 (8.0%) (p<0.001); LECs, before COVID-19: 373593 (3.7%), during COVID-19: 38873 (4.5%) (p<0.001)]. @*Conclusion@#During the COVID-19 period, severe patients were shifted to advanced emergency medical institutions, and the KTAS better reflected severe patients. Patient distribution according to the stage of emergency medical institution improved, and validation of the KTAS triage increased more in RECs.