BACKGROUND/OBJECTIVES: This study aimed to use plasma metabolites to identify clusters of breast cancer survivors and to compare their dietary characteristics and health-related factors across the clusters using unsupervised machine learning. SUBJECTS/METHODS: A total of 419 breast cancer survivors were included in this crosssectional study. We considered 30 plasma metabolites, quantified by high-throughput nuclear magnetic resonance metabolomics. Clusters were obtained based on metabolites using 4 different unsupervised clustering methods: k-means (KM), partitioning around medoids (PAM), self-organizing maps (SOM), and hierarchical agglomerative clustering (HAC). The t-test, χ2 test, and Fisher’s exact test were used to compare sociodemographic, lifestyle, clinical, and dietary characteristics across the clusters. P-values were adjusted through a false discovery rate (FDR). RESULTS: Two clusters were identified using the 4 methods. Participants in cluster 2 had lower concentrations of apolipoprotein A1 and large high-density lipoprotein (HDL) particles and smaller HDL particle sizes, but higher concentrations of chylomicrons and extremely large very-low-density-lipoprotein (VLDL) particles and glycoprotein acetyls, a higher ratio of monounsaturated fatty acids to total fatty acids, and larger VLDL particle sizes compared with cluster 1. Body mass index was significantly higher in cluster 2 compared with cluster 1 (FDR adjusted-PKM < 0.001; PPAM = 0.001; PSOM < 0.001; and PHAC = 0.043). CONCLUSION The breast cancer survivors clustered on the basis of plasma metabolites had distinct characteristics. Further prospective studies are needed to investigate the associations between metabolites, obesity, dietary factors, and breast cancer prognosis.

Pulmonary hypertension is more common in preterm infants compared to term infants, and the incidence increases as gestational age decreases. In preterm infants, pulmonary hypertension is a risk factor that increases mortality. Inhaled nitric oxide (iNO) is an approved treatment for pulmonary hypertension in preterm infants in Korea. Since January 2021, iNO has been used for hypoxic respira tory failure associated with early acute persistent pulmonary hypertension of the newborn (PPHN) in preterm infants. Although studies suggest that iNO improves oxygenation and reduces mortality in preterm infants with pulmonary hypertension, there are concerns about its effectiveness and potential adverse effects. In addition, there are several challenges in administering iNO therapy to pre­term infants in Korea that need to be addressed. The current therapeutic indications in Korea allow iNO therapy to be administered only if treatment is started within 14 days of life, so it cannot be used for late pulmonary hypertension. Additionally, iNO therapy requires meeting the criteria for hypoxic respiratory failure, which includes calculating the oxygenation index (OI) using PaO 2 values obtained from arterial blood gas analysis (ABGA). To evaluate treatment response, PaO 2 values from ABGA are also necessary. However, invasive arterial blood sampling is a particularly challenging procedure in preterm infants. Therefore, alternative criteria beyond OI are needed. Furthermore, echocardiographic findings are essential to determine the therapeutic indication for PPHN in iNO therapy. However, not all neonatal intensive care units have consistent access to echocardiography. These issues must be addressed and resolved through further research and evidence.

Background/Aims: Portal vein thrombosis (PVT) frequently occurs in patients with inflammatory bowel disease (IBD), particularly when influenced by factors such as abdominal infections, IBD flare-ups, or surgical procedures. The implications of PVT range from immediate issues such as intestinal ischemia to long-term concerns including portal hypertension and its complications. However, there is a notable gap in comprehensive studies on PVT in IBD, especially with the increasing incidence of IBD in Asia. This research aimed to evaluate the clinical features and outcomes of PVT in patients with IBD at a leading hospital in South Korea. Methods: This retrospective analysis reviewed adult patients diagnosed with both IBD and PVT from 1989 to 2021 at a renowned South Korean medical center. The study focused on patient characteristics, specifics of PVT, administered treatments, and outcomes, all confirmed through enhanced CT scans. Results: A total of 78 patients met the study’s criteria. Notably, only 20.5% (16/78) were treated with oral anticoagulants; however, a vast majority (96.2%; 75/78) achieved complete radiographic resolution (CRR). When comparing patients receiving anticoagulants to those who did not, a significant preference for anticoagulant use was observed in cases where the main portal vein was affected, as opposed to just the left or right veins (p = 0.006). However, multivariable analysis indicated that neither anticoagulant use nor previous surgeries significantly impacted CRR. Conclusions Patients with IBD and PVT generally had favorable outcomes, regardless of anticoagulant use.

Purpose: Central venous catheter (CVC) insertion is a fundamental skill required for trainees to become proficient. Simulation-based training (SBT) has been shown to improve trainees’ CVC insertion performance effectively. However, implementing a CVC curriculum requires substantial costs and resources. Currently, there is a lack of validated CVC curricula that institutions can adopt as frameworks. This study aimed to evaluate the effectiveness of our institution’s CVC simulation curriculum in improving residents’ confidence and comfort with CVC insertion and management. Materials and Methods: First-year residents (n=118) participated in SBT between 2017 and 2023. Among them, 57 (48%) participants completed surveys before training and 6 months post-training to assess changes in comfort levels across various aspects of CVC insertion. Survey responses were analyzed to evaluate the overall changes in comfort by year and items. Results: Overall comfort increased from 42.1% before training to 81.3% after training (P<0.01), with notable improvements in nonprocedural aspects. Comfort with performing the unsupervised procedure increased by 16.7% (P<0.05) but remained low post-training (29.6%). Conclusion These findings suggest that the curriculum effectively enhances residents’ comfort, particularly in nonprocedural aspects, but only partially prepares them for unsupervised CVC insertions. This indicates a gap in procedural skill acquisition despite the overall positive trends. Implementing a similar CVC curriculum may help institutions reduce CVC insertion-associated complications.

Background: This study aimed to analyze the medical expenses covered by the Korean National Health Insurance Service (KNHIS) according to body mass index (BMI) in Korean adults. Methods: We included 1,170,464 adults (623,498 men and 546,966 women) aged ≥19 years from the KNHISNational Sample Cohort database (2016 to 2019) after excluding individuals with cancer. Average annual medical expenses per person and average annual medical expenses (Korean won [KRW], 1 United States dollar=1,292 KRW) by BMI classification were assessed according to age and sex. Medical expenses comprised those for medication and combined outpatient department (OPD) and hospitalization services. Means and 95% confidence intervals were analyzed using a two-part model. Results: Average annual medical expenses increased in higher BMI quintile groups (P for trend <0.001). Average annual medical expenses per person increased significantly as BMI increased in women but not in men. Average annual medical expenses were highest in the highest quintile of BMI among women and in all age groups.While BMI showed a U-shape association with medical expenses for OPD and hospitalization in young individuals, medical expenses for medication in all age groups and those for OPD and hospitalization in middle-aged individuals increased sharply in the highest BMI quintile. Conclusion All types of average annual medical expenses increased in higher BMI groups in Korean adults, particularly in women. Individuals with the highest BMI quintile incurred the greatest medical expenses among women and across all age groups. Strategies for preventing and managing obesity are warranted to reduce the burden of obesity-related medical expenses.

Background and Objectives: This study aimed to investigate the potential impact of earphone use on the occurrence of otitis externa (OE) by conducting a survey. Subjects and Methods: This study included 517 participants. The questionnaire comprised 22 items divided into three categories; general information, earphone use, and OE. The questionnaire was designed using Google Forms and distributed through a notice posted on a hospital bulletin board. This notice included a QR code that enabled any interested individual to participate, and the responses were collected automatically. Results: The proportion of respondents who had experienced OE at least once was 21%. Among them, 33.7% experienced OE within the preceding month. For “adhering to the recommendation usage time,” individuals who responded “likely” had a 0.440 (odds ratio=0.440, 95% confidence interval=0.195-0.993) times higher likelihood; they were at lower risk of experiencing OE compared to those who responded “very unlikely.” Conclusions Our findings suggest that proper earphone use can reduce the risk of OE. Despite the lack of a significant relationship between earphone type, physical activity, and cleaning practices, continued adherence to these factors is recommended to prevent OE.

Background and Objectives: This study aimed to investigate the effects of hearing aids (HAs) on reducing symptoms of dizziness in patients with hearing loss (HL) and dizziness. Subjects and Methods: A pre- and post-intervention study was conducted between February 2022 and July 2022 at the outpatient clinic of a tertiary hospital in Seoul, South Korea. Ten participants (four males and six females) with HL and dizziness were recruited. Participants were screened using pure-tone audiometry and visual analog scale scores at baseline. Selected participants underwent the Modified Clinical Test of Sensory Interaction on Balance (mCTSIB) and Korean Dizziness Handicap Inventory (K-DHI) in the unaided state. Thereafter, participants were provided HAs and instructed to use them for at least 6 hours every day. At the 1-month follow-up, all participants were assessed in the aided state using the same tests as at baseline. All tests were performed bilaterally. Results: In the mCTSIB, a significant difference was observed in the foam surface-eyes closed score before (median=2.35) and after (median=2.2) HA use (p=0.049). No significant differences were observed in the K-DHI scores before and after HA use. Conclusions HA use may improve the static and subjective perception of balance in patients with HL and dizziness. Future research should explore the benefits of HAs under various balance conditions such as dynamic balance and gait.