Background/Aims: Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. Methods: This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. Results: A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. Conclusions The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19.

Background: This study aimed to identify the clinical characteristics of multidrug-resistant/ rifampicin-resistant tuberculosis (MDR/RR-TB) in the Republic of Korea. Methods: Data of notified people with tuberculosis between July 2018 and December 2021 were retrieved from the Korea Tuberculosis Cohort database. MDR/RR-TB was further categorized according to isoniazid susceptibility as follows: multidrug-resistant tuberculosis (MDR-TB), rifampicin-monoresistant tuberculosis (RMR-TB), and RR-TB if susceptibility to isoniazid was unknown. Multivariable logistic regression analysis was conducted to identify the factors associated with MDR/RR-TB. Results: Between 2018 and 2021, the proportion of MDR/RR-TB cases among all TB cases and TB cases with known drug susceptibility test results was 2.1% (502/24,447). The proportions of MDR/RR-TB and MDR-TB cases among TB cases with known drug susceptibility test results were 3.3% (502/15,071) and 1.9% (292/15,071), respectively. Among all cases of rifampicin resistance, 31.7% (159/502) were RMR-TB and 10.2% (51/502) were RR-TB. Multivariable logistic regression analyses revealed that younger age, foreigners, and prior tuberculosis history were significantly associated with MDR/ RR-TB. Conclusion Rapid identification of rifampicin resistance targeting the high-risk populations, such as younger generations, foreign-born individuals, and previously treated patients are necessary for patient-centered care.

Background/Aims: Fexuprazan, a novel potassium-competitive acid blocker, was developed for treating acid-related disorders. Pharmacokinetic and pharmacodynamic properties of fexuprazan, unlike those of proton pump inhibitors, are independent of food effect. This study aims to evaluate differences in efficacy and safety of fexuprazan in patients with erosive esophagitis (EE) according to the timing of dosing. Methods: In this multicenter, open-label noninferiority study, patients who had typical reflux symptoms with endoscopically confirmed EE were randomized 1:1 to receive fexuprazan 40 mg daily 30 minutes before or after meal. Treatment was completed after 2 weeks or 4 weeks when healing was endoscopically confirmed. The primary endpoint was the proportion of patients with healed EE confirmed by endoscopy up to week 4. Safety endpoints included treatment-emergent adverse events (TEAEs). Results: In the prior-to-meal group (n = 89) and after-meal group (n = 86), 4-week EE healing rates were 98.77% and 100.00% (difference, 0.01%; 95% CI, –0.01% to 0.04%) and 2-week EE healing rates were 95.77% and 97.14% (difference, 0.01%; 95% CI, –0.05% to 0.07%), respectively. TEAEs were 9.78% and 8.70% in the prior-to-meal group and the after-meal group, respectively. Conclusions Non-inferiority analysis revealed that taking fexuprazan after meal was non-inferior to taking fexuprazan before meals in patients with EE. The frequency of adverse events was similar between the 2 study groups. The drug is safe and effective for healing EE regardless of the timing of dosing.

Background/Aims: Post-infectious irritable bowel syndrome (PI-IBS) is characterized by chronic gastrointestinal symptoms that arise following an episode of infectious enteritis. The incidence rates vary, ranging from 5% to 32% and the risk factors are not well known. We aim to investigate the incidence and risk factors of PI-IBS in enteritis patients admitted to university hospitals in Korea. Methods: This multi-center prospective study was conducted in patients hospitalized for infectious enteritis. Each patient underwent 1 outpatient visit and 3 telephone surveys during the first year after discharge to determine if PI-IBS occurred within the follow-up period. Results: In the 3-month survey, 7 out of 354 patients (2%) were diagnosed with PI-IBS, and after 1 year, only 1 patient met the criteria for IBS.No statistically significant difference was found between the PI-IBS group and the non-PI-IBS group in terms of age, sex, underlying diseases, medication history, gastrointestinal symptoms, enteritis location, causative strain, hospitalization and treatment periods, and laboratory findings. Female sex (P = 0.003), enteropathogenic Escherichia coli (EPEC) infection (P = 0.044), and a longer total treatment period (P = 0.018) were independent risk factors for diarrhea lasting ≥ 3 months after enteritis. Conclusions The incidence of PI-IBS in Korea was relatively low, and most cases improved over time. No risk factors associated with the development of PI-IBS were found. However, persistent diarrhea after enteritis was associated with female sex, EPEC infection, and severe or long-lasting enteritis. IBS symptoms may persist after severe enteritis but usually improve with time.

Background: and Purpose The Treat Stroke to Target (TST) was a randomized clinical trial involving French and Korean patients demonstrating that a lower low-density lipoprotein cholesterol (LDL-C, <70 mg/dL) target group (LT) experienced fewer cerebro-cardiovascular events than a higher target (90–110 mg/dL) group (HT). However, whether these results can be applied to Asian patients with different ischemic stroke subtypes remains unclear. Methods: Patients from 14 South Korean centers were analyzed separately. Patients with ischemic stroke or transient ischemic attack with evidence of atherosclerosis were randomized into LT and HT groups. The primary endpoint was a composite of ischemic stroke, myocardial infarction, coronary or cerebral revascularization, and cardiovascular death. Results: Among 712 enrolled patients, the mean LDL-C level was 71.0 mg/dL in 357 LT patients and 86.1 mg/dL in 355 HT patients. The primary endpoint occurred in 24 (6.7%) of LT and in 31 (8.7%) of HT group patients (adjusted hazard ratio [HR]=0.78; 95% confidence interval [CI]=0.45–1.33, P=0.353). Cardiovascular events alone occurred significantly less frequently in the LT than in the HT group (HR 0.26, 95% CI 0.09–0.80, P=0.019), whereas there were no significant differences in ischemic stroke events (HR 1.12, 95% CI 0.60–2.10, P=0.712). The benefit of LT was less apparent in patients with small vessel disease and intracranial atherosclerosis than in those with extracranial atherosclerosis. Conclusion In contrast to the French TST, the outcomes in Korean patients were neutral. Although LT was more effective in preventing cardiovascular diseases, it was not so in stroke prevention, probably attributed to the differences in stroke subtypes. Further studies are needed to elucidate the efficacy of statins and appropriate LDL-C targets in Asian patients with stroke.

Background and Objectives: The Korean Organ Transplant Registry (KOTRY) provided data for this third official report on adult heart transplantation (HT), including information from 709 recipients. Methods: Data from HTs performed at seven major centers in Korea between March 2014 and December 2020 were analyzed, focusing on immunosuppression, acute rejection, cardiac allograft vasculopathy (CAV), post-transplant survival, and mechanical circulatory support (MCS) usage. Results: The median ages of the recipients and donors were 56.0 and 43.0 years, respectively.Cardiomyopathy and ischemic heart disease were the most common preceding conditions for HT. A significant portion of patients underwent HT at waiting list status 1 and 0. In the multivariate analysis, a predicted heart mass mismatch was associated with a higher risk of 1-year mortality. Patients over 70 years old had a significantly increased risk of 6-year mortality. The risk of CAV was higher for male donors and donors older than 45 years. Acute rejection was more likely in patients with panel reactive antibody levels above 80%, while statin use was associated with a reduced risk. The employment of left ventricular assist device as a bridge to transplantation increased from 2.17% to 22.4%. Pre-transplant extra-corporeal membrane oxygenation was associated with worse post-transplant survival. Conclusions In this third KOTRY report, we analyzed changes in the characteristics of adult HT recipients and donors and their impact on post-transplant outcomes. The most notable discovery was the increased use of MCS before HT and their impact on post-transplant outcomes.

Background and Objectives: Among various emerging catheter-based treatments for severe tricuspid regurgitation (TR), the spacer device can reduce the regurgitation orifice without manipulating the valve leaflet. However, its clinical application has been hampered by traumatic anchoring to the myocardium and the coaxial alignment of the balloon resulting in insufficient TR reduction. This study aimed to evaluate the early-stage safety, technical feasibility, and preliminary efficacy of the novel atraumatic vertical spacer in patients with isolated severe TR. Methods: All procedures were guided by fluoroscopy and transthoracic echocardiography.The maximum device placement time with an inflated balloon was 24 hours. Changes in the amount of TR, right ventricular function, and patient hemodynamics were measured during balloon deployment. Results: A total of 7 patients (median age 74), underwent successful device implantation without procedure-related complications. During balloon inflation (median 25 minutes), there were no symptoms or signs indicative of TR intolerance. TR was reduced by 1 grade or greater in all patients, with 2 patients exhibiting a reduction of 3 grades, from torrential TR to a moderate degree. Mild TR after balloon inflation was achieved in 3 patients with baseline severe TR. The TR reduction observed during initial balloon deployment was sustained during the subsequent balloon maintenance period. Conclusions The Pivot-balloon procedure was safe, technically feasible, and effective in reducing TR in patients with severe TR. No periprocedural complications or adverse cardiovascular events were reported during device placement with TR reduction observed in all patients. However, longer-term follow-up is needed to confirm safety and treatment effect.

Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) represents a devastating and growing global threat, calling for new antibiotic treatments. In Korea, the challenge of treating CRAB is compounded by high nosocomial acquisition rates and limited availability of novel antibiotics. Minocycline, a semisynthetic tetracycline derivative, has been proposed as a therapeutic option for CRAB infections. Nonsusceptibility to minocycline may occur through the efflux pump, TetB. The prevalence of tetB in A. baumannii has increased, along with higher minocycline minimum inhibitory concentrations (MICs). We aimed to evaluate minocycline susceptibility rates in clinical strains of CRAB, and the association between tetB carriage and minocycline susceptibility across different genotypes. Materials and Methods: Representative CRAB blood isolates were collected from Asan Medical Center, Seoul.Minocycline susceptibility was assessed using the Clinical and Laboratory Standards Institute (CLSI) breakpoint (≤4 mg/L) and the proposed pharmacokinetics (PK)/pharmacodynamics (PD) breakpoint (≤1 mg/L). Tigecycline was used as a comparator, and its susceptibility breakpoint for Enterobacterales defined by EUCAST was applied (≤0.5 mg/L).The presence of tetB was detected by PCR, and multilocus sequence typing (MLST) was performed using seven housekeeping genes. Results: Of the 160 CRAB blood isolates, 83.8% were susceptible to minocycline by the CLSI criteria, and 50.6% were PK-PD susceptible by the PK-PD criteria. The minocycline minimum inhibitory concentration (MIC)50 /MIC90 was 1/8 mg/L. tetB was present in 49% of isolates and was associated with a higher minocycline MIC (MIC50/90 2/8 mg/L vs. 1/2 mg/L). No clear correlation was observed between tetB positivity and tigecycline MIC. Nine MLSTs were identified, with significant differences in tetB carriage rates between the major sequence types. Notably, ST191, associated with non-tetB carriage and greater susceptibility to minocycline, declined over the study period (P=0.004), while ST451, associated with tetB carriage, increased. Conclusion tetB was present in 49% of CRAB isolates and was associated with higher MICs and non-susceptibility by both CLSI and PK-PD criteria. However, absence of tetB was not a reliable predictor of minocycline PK-PD susceptibility. Additionally, shifts over time towards genotypes with reduced minocycline susceptibility were observed. Further research is needed to correlate these findings with clinical outcomes and identify additional resistance mechanisms.

Background: F-18-fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography (CT) can be used to measure bone mineral density (BMD), cross-sectional muscle area (CSMA), Hounsfield units (HU) of liver and muscle, subcutaneous adipose tissue (SAT), abdominal visceral adipose tissue (VAT), and glucose metabolism. The present study aimed to identify age-related changes in body composition and glucose metabolism in Korean using opportunistic FDG-PET/CT imaging. Methods: We analyzed FDG-PET/CT, clinical history, and laboratory data abstracted from the medical records of patients who underwent health screening at a single institute between 2017 and 2022. Results: In total, 278 patients were included in the analysis (male:female=140:138). Age and body mass index were positively correlated in female, but negatively correlated in male. BMD decreased with age more in female, and CSMA decreased with age more in male. Muscle HU decreased with age for both sexes. In female, SAT and VAT increased with age; and in male, SAT decreased slightly while VAT remained stable. Muscle glucose metabolism showed no association with age in male but increased with age in female. CSMA correlated positively with BMD overall; and positively correlated with VAT and SAT in male only. In female only, both SAT and VAT showed negative correlations with glucose metabolism and correlated positively with muscle glucose metabolism. Liver HU values were inversely correlated with VAT, especially in female; and positively correlated with muscle glucose metabolism in female only. Conclusion FDG-PET/CT demonstrated distinct patterns of age-related changes in body composition and glucose metabolism, with significant differences between sexes.

Background: Given the association between nonalcoholic fatty liver disease and metabolic risks, a new term, metabolic dysfunction- associated steatotic liver disease (MASLD) has been proposed. We aimed to explore the association between MASLD and all-cause, cause-specific mortalities. Methods: We included individuals with steatotic liver disease (SLD) from the Korean National Health Insurance Service. Moreover, SLD was defined as a fatty liver index ≥30. Furthermore, MASLD, metabolic alcohol-associated liver disease (MetALD), and alcoholic liver disease (ALD) with metabolic dysfunction (MD) were categorized based on alcohol consumption and MD. We also analyzed all-cause, liver-, cancer-, hepatocellular carcinoma (HCC)- and cardiovascular (CV)-related mortalities. Results: This retrospective nationwide cohort study included 1,298,993 individuals aged 40 to 79 years for a mean follow-up duration of 9.04 years. The prevalence of MASLD, MetALD, and ALD with MD was 33.11%, 3.93%, and 1.00%, respectively. Relative to the “no SLD” group, multivariable analysis identified that MASLD (adjusted hazard ratio [aHR], 1.28; 95% confidence interval [CI], 1.26 to 1.31), MetALD (aHR, 1.38; 95% CI, 1.32 to 1.44), and ALD with MD group (aHR, 1.80; 95% CI, 1.68 to 1.93) have a significantly higher risk of all-cause mortality. Furthermore, MASLD, MetALD, ALD with MD groups showed higher liver-, cancer- and HCC-related mortality than “no SLD” group. While all-cause specific mortalities increase from MASLD to MetALD to ALD with MD, the MetALD group shows a lower risk of CV-related mortality compared to MASLD. However, ALD with MD group still have a higher risk of CV-related mortality compared to MASLD. Conclusion SLD is associated with an increased risk of all-cause, liver-, cancer-, HCC-, and CV-related mortalities.