Background: Since the emergence of hypervirulent strains of Clostridioides difficile, the incidence of C. difficile infections (CDI) has increased significantly. Methods: To assess the incidence of CDI in Korea, we conducted a prospective multicentre observational study from October 2020 to October 2021. Additionally, we calculated the incidence of CDI from mass data obtained from the Health Insurance Review and Assessment Service (HIRA) from 2008 to 2020. Results: In the prospective study with active surveillance, 30,212 patients had diarrhoea and 907 patients were diagnosed with CDI over 1,288,571 patient-days and 193,264 admissions in 18 participating hospitals during 3 months of study period; the CDI per 10,000 patientdays was 7.04 and the CDI per 1,000 admission was 4.69. The incidence of CDI was higher in general hospitals than in tertiary hospitals: 6.38 per 10,000 patient-days (range: 3.25–12.05) and 4.18 per 1,000 admissions (range: 1.92–8.59) in 11 tertiary hospitals, vs. 9.45 per 10,000 patient-days (range: 5.68–13.90) and 6.73 per 1,000 admissions (range: 3.18–15.85) in seven general hospitals. With regard to HIRA data, the incidence of CDI in all hospitals has been increasing over the 13-year-period: from 0.3 to 1.8 per 10,000 patient-days, 0.3 to 1.6 per 1,000 admissions, and 6.9 to 56.9 per 100,000 population, respectively. Conclusion The incidence of CDI in Korea has been gradually increasing, and its recent value is as high as that in the United State and Europe. CDI is underestimated, particularly in general hospitals in Korea.

Objective: To evaluate the added value of diffusion-weighted imaging (DWI)-based quantitative parameters to distinguish uterine sarcomas from atypical leiomyomas on preoperative magnetic resonance imaging (MRI). Materials and Methods: A total of 138 patients (age, 43.7 ± 10.3 years) with uterine sarcoma (n = 44) and atypical leiomyoma (n = 94) were retrospectively collected from four institutions. The cohort was randomly divided into training (84/138, 60.0%) and validation (54/138, 40.0%) sets. Two independent readers evaluated six qualitative MRI features and two DWI-based quantitative parameters for each index tumor. Multivariable logistic regression was used to identify the relevant qualitative MRI features. Diagnostic classifiers based on qualitative MRI features alone and in combination with DWI-based quantitative parameters were developed using a logistic regression algorithm. The diagnostic performance of the classifiers was evaluated using a cross-table analysis and calculation of the area under the receiver operating characteristic curve (AUC). Results: Mean apparent diffusion coefficient value of uterine sarcoma was lower than that of atypical leiomyoma (mean ± standard deviation, 0.94 ± 0.30 10-3 mm2 /s vs. 1.23 ± 0.25 10-3 mm2 /s; P < 0.001), and the relative contrast ratio was higher in the uterine sarcoma (8.16 ± 2.94 vs. 4.19 ± 2.66; P < 0.001). Selected qualitative MRI features included ill-defined margin (adjusted odds ratio [aOR], 17.9; 95% confidence interval [CI], 1.41–503, P = 0.040), intratumoral hemorrhage (aOR, 27.3; 95% CI, 3.74–596, P = 0.006), and absence of T2 dark area (aOR, 83.5; 95% CI, 12.4–1916, P < 0.001). The classifier that combined qualitative MRI features and DWI-based quantitative parameters showed significantly better performance than without DWI-based parameters in the validation set (AUC, 0.92 vs. 0.78; P < 0.001). Conclusion The addition of DWI-based quantitative parameters to qualitative MRI features improved the diagnostic performance of the logistic regression classifier in differentiating uterine sarcomas from atypical leiomyomas on preoperative MRI.

Background: Alpha-toxin (AT), a major virulence factor of Staphylococcus aureus, is an important immunotherapeutic target to prevent or treat invasive S. aureus infections. Previous studies have suggested that anti-AT antibodies (Abs) may have a protective role against S. aureus bacteremia (SAB), but their function remains unclear. Therefore, we aimed to investigate the association between serum anti-AT Ab levels and clinical outcomes of SAB. Methods: Patients from a prospective SAB cohort at a tertiary-care medical center (n = 51) were enrolled in the study from July 2016 to January 2019. Patients without symptoms or signs of infection were enrolled as controls (n = 100). Blood samples were collected before the onset of SAB and at 2- and 4-weeks post-bacteremia. Anti-AT immunoglobin G (IgG) levels were measured using an enzyme-linked immunosorbent assay. All clinical S. aureus isolates were tested for the presence of hla using polymerase chain reaction. Results: Anti-AT IgG levels in patients with SAB before the onset of bacteremia did not differ significantly from those in non-infectious controls. Pre-bacteremic anti-AT IgG levels tended to be lower in patients with worse clinical outcomes (7-day mortality, persistent bacteremia, metastatic infection, septic shock), although the differences were not statistically significant. Patients who needed intensive care unit care had significantly lower anti-AT IgG levels at 2 weeks post-bacteremia (P = 0.020). Conclusion The study findings suggest that lower anti-AT Ab responses before and during SAB, reflective of immune dysfunction, are associated with more severe clinical presentations of infection.

Isolated extramedullary relapse (EMR) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in acute myeloid leukemia (AML) is relatively rare and the clinical significance is still not well characterized, particularly in children. During or after chemotherapy, an uncommon event termed lineage switch, in which the lineage at onset of leukemia converts to another lineage at a later time, is observed in a subset of leukemia patients, but it is a rare event. We report a 10-year-old boy with isolated mediastinal EMR after allo-HSCT for AML who subsequently experienced BM relapse with the cell lineage switching from AML to T-cell acute lymphoblastic leukemia.

Subclinical hypothyroidism (SCH), characterized by elevated serum thyroid-stimulating hormone (TSH) levels and normal free thyroxine levels, usually presents without symptoms, and is often discovered incidentally during routine blood test. The Task Force of the Korean Thyroid Association Committee of Clinical Practice Guidelines has established a guideline to evaluate and manage SCH; the guideline emphasizes the implementation of diagnostic criteria based on the TSH reference range for Koreans and focuses on the proven health benefits of levothyroxine (LT4) treatment. Based on the Korea National Health and Nutrition Examination Survey (2013-2015), serum TSH level of 6.8 mIU/L is considered the reference value for SCH. SCH can be categorized as mild (TSH 6.8-10.0 mIU/L) or severe (TSH ＞10.0 mIU/L), and patients are classified as adults (age ＜70 years) or elderly patients (age ≥70years) depending on the health effects of LT4 treatment. An initial increase in serum TSH levels should be reassessed with a subsequent measurement, along with the thyroid peroxidase antibody test, preferably 2-3 months after the initial evaluation. Usually, LT4 treatment is not recommended for mild SCH in adults; however, treatment is necessary for severe SCH in patients with underlying coronary artery disease or heart failure and can be considered for coexisting dyslipidemia. LT4 treatment is not recommended for mild or even severe SCH in elderly patients, in general. Patients with SCH who receive LT4 treatment, the LT4 dosage should be personalized, and serum TSH levels should be monitored to ensure optimal LT4 dosage (dosage that is neither excessive nor insufficient). Patients with SCH who do not receive LT4 treatment require periodic follow-up at appropriate testing intervals determined by disease severity. The guideline also provides several educational points applicable in clinical settings.

Objective: Emergency medicine residents are expected to exhibit a poor health status due to excessive working hours and high stress. Because much of patient care depends on them, their health conditions will have a significant impact on patient outcomes. Our study was designed to analyze the health status of emergency medicine residents and the affecting factors using the 2019 Korean Emergency Medicine Residents Survey (KEMRS) results. Methods: The study evaluated the self-rated health-defined percentage of responders who thought they were in good health. Based on this response, the influencing factors were categorized statistically. These factors included personal characteristics, lifestyle (drinking, smoking, eating, sleeping, and exercise), and emotional stress. Results: Of a total of 384 respondents, 176 (46%) thought they were in good health. Participants who perceived themselves to be unhealthy included residents who were married, female, and those in the 3rd grade. Drinking and smoking were not perceived to affect health status, but regular exercise and proper eating patterns were seen to be positive influencing factors. Daytime sleepiness, depressive moods, and personal well-being were correlated with health status. Conclusion While personal characteristics and emotional problems cannot be changed easily, lifestyle changes can be made for better health. The health conditions of emergency residents have not been considered a matter of importance thus far. To overcome their health problems, responsible improvements in schedules and a program of long-term follow-ups need to be implemented, followed by training programs.

Purpose: The Korean Renal Cancer Study Group (KRoCS) provides consensus recommendations on the role of cytoreductive nephrectomy (CRN) in patients with metastatic renal cell carcinoma (mRCC). Materials and Methods: A group of mRCC experts from the Korean Urological Oncology Society convened at the 2021 KRoCS meeting on CRN for mRCC. Results: The consensus document was developed to address 4 questions related that were judged to be the most relevant to patient care: (1) Is there a role for CRN in patients planning targeted therapy? (2) Is there a role for CRN in patients planning immuno-oncology agents? (3) When is the optimal time of CRN in patients planning systemic treatment? (4) What is the ideal patient selection for CRN? The panelists have come up with following consensus. For mRCC patients, CRN should be considered only in those with IMDC (International Metastatic Renal Cell Carcinoma Database Consortium) favorable and intermediate risk disease, regardless of the systemic treatment plans. Timing of CRN should consider the risk group as well as the number of risk factors, but is generally recommended for after assessing the degree of response to initial systemic treatment. Patients with good performance status, limited metastatic burden on top of resectable primary tumor are candidates recommended for CRN with or without metastasectomy with priority. Conclusions In conclusion, there is still a role for CRN in the multimodality treatment of mRCC. Careful patient selection is of paramount importance. As the treatment landscape of mRCC continues to change, the role of CRN in the current immuno-oncology era will require more exploration.

Background/Aims: The adenoma detection rate (ADR) does not reflect the complete detection of every adenoma during colonoscopy; thus, many surrogate indicators have been suggested.This study investigated whether the ADR and surrogate quality indicators reflect the adenoma miss rate (AMR) when performing qualified colonoscopy. Methods: We performed a prospective, multicenter, cross-sectional study of asymptomatic examinees aged 50 to 75 years who underwent back-to-back screening colonoscopies by eight endoscopists. The ADR and surrogate quality indicators, including polyp detection rate, total number of adenomas per colonoscopy, additional adenomas found after the first adenoma per colonoscopy (ADR-Plus), and total number of adenomas per positive participant, were calculated for the prediction of AMR. Results: A total of 371 back-to-back colonoscopies were performed. There was a significant difference in ADRs (range, 44% to 75.4%; p=0.024), polyp detection rates (range, 56% to 86.9%; p=0.008) and adenomas per positive participants (range, 1.19 to 2.30; p=0.038), and a tendency of a difference in adenomas per colonoscopy (range, 0.62 to 1.31; p=0.051) and ADR-Plus (range, 0.13 to 0.70; p=0.054) among the endoscopists. The overall AMR was 20.1%, and AMRs were not different (range, 13.9 to 28.6; p>0.05) among the endoscopists. No quality indicators were significantly correlated with AMR. The number of adenomas found during the first colonoscopy was an independent factor for increased AMR (odds ratio, 1.79; p<0.001). Conclusions The colonoscopy quality indicators were significantly different among high-ADR endoscopists, and none of the quality indicators reflected the AMR of good quality colonoscopy performances. The only factor influencing AMR was the number of adenomas detected during colonoscopy.

Background: This systematic review was conducted to identify and summarize key factors, including economic methods, topics, results, and indicators, within relevant economic evaluation research on thyroid cancer. Materials and Methods: A literature search on the economic evaluation of thyroid cancer treatment was conducted using the MEDLINE database up to May 2021. Data on population, intervention, comparison, outcome, time, setting, and study design were extracted from each study. The economic evaluation method in each study was re-classified according to the theoretical criteria defined by the international economic evaluation guidelines. Results: A total of 49 studies were included, involving cost analysis (CA, n=9), cost-minimization analysis (CMA, n=3), cost-effectiveness analysis (CEA, n=29), and cost-utility analysis (CUA, n=8). When CEA and CUA were classified as one method, the consistency between the methods of the reviewers based on the theoretical criteria and those from the original studies was 77% (95% confidence interval, 0.63-0.92). Most studies dealt with specific period-related controversial issues including comparison between treatment strategies, and cost-effectiveness of the prophylactic central neck dissection, molecular testing, and rhTSH. Contrasting results have been obtained when different economic evaluation methods were applied for the same topic (e.g., total thyroidectomy [TT] was more dominant than hemithyroidectomy [HT] in CEA, but HT was more dominant than TT in CUA), and different clinical and economic inputs were applied. All studies included direct medical costs, which were mostly derived from Medicare and input probabilities in each economic model, and utility scores for outcomes were mostly based on literature reviews.Few studies included non-medical direct costs and indirect costs. Conclusion Our systematic review provides information on how to design and proceed to overcome the limitations of existing studies and ensure validity.