Flow cytometric lymphocyte subset analysis (FCLSA) is essential for assessing immune status across various diseases and clinical settings. We surveyed current clinical laboratory practices related to FCLSA to establish a baseline reference for future standardization in Korea. Nine university hospitals actively performing FCLSA responded to the 22-question survey, which covered seven categories of laboratory practice. These hospitals used commercial reagent antibody kits from either Beckton Dickinson Biosciences (N = 4) or Beckman Coulter Diagnostics (N = 5). Most hospitals performed daily instrument setup and scheduled maintenance every 2–6 months. Two levels of commercial quality control materials were routinely used each day. Sample and reagent antibody volumes varied across hospitals, even when the same reagent kit was used. Acquired cell counts ranged from 5 × 10 3 to 5 × 10 4 cells, with two hospitals adjusting counts based on the cell type analyzed. Most laboratories reported percentages and general opinions; some additionally reported white blood cell and lymphocyte counts, along with lymphocyte percentages. This is the first comprehensive survey on the clinical laboratory practice of FCLSA in Korea.Standardization of FCLSA should be accelerated to ensure reliable and reproducible results.

Background: Current reference intervals for lymphocyte subpopulations are primarily based on Western populations, with limited data available for Korean children, particularly for extended subsets. We determined absolute cell counts and percentages of lymphocyte subpopulations in Korean children, according to age and sex. Methods: Samples from 92 children—stratified into two age groups, groups 1 (5–9 yrs) and 2 (10–17 yrs)—were obtained. Immunophenotyping was performed via flow cytometry using the Primary Immunodeficiency Orientation Tube (PIDOT) panel, primarily classifying the cells into T, B, and natural killer cell populations. T lymphocytes were divided into CD4+ , CD8+ , and CD4– CD8– subsets; T and B cells were further subdivided according to their maturation stage. Results: Children in group 1 exhibited higher absolute counts of total B cells, unswitched memory B cells/plasma cells, total T cells, CD4+ naïve cells, and TCRγδ+ T cells than those in group 2. In contrast, Group 2 children showed higher absolute counts of CD4+ effector memory (EM) T cells. Males had higher absolute counts of total B cells, particularly pregerminal center B cells, CD4+ EM cells, and CD8+ terminally differentiated T cells, whereas females showed higher proportions of CD4+ , CD4+ naïve, and CD8 + central memory/transitional memory T cells. Conclusions To the best of our knowledge, this study is the first to establish reference values for extended lymphocyte subsets in Korean children using the PIDOT panel. Age, sex, and laboratory-related factors influenced lymphocyte subset distributions. These findings may serve as reference data for immune disorders and immunotherapy in pediatric populations.

Purpose: To determine the correlation between electroretinography (ERG) performed using a handheld ERG device equipped with skin electrodes and postoperative best-corrected visual acuity (BCVA) in patients with vitreous hemorrhage (VH) due to proliferative diabetic retinopathy (PDR). Methods: The medical records of patients who underwent vitrectomy for diabetic VH caused by PDR at our institution between July 1, 2017, and June 30, 2023, were reviewed retrospectively. We analyzed the correlation between preoperative ERG obtained using a handheld ERG device (RETeval), RETeval skin electrodes (Sensor Strips), and postoperative BCVA. Results: We evaluated the medical records of 70 eyes of 70 patients. The BCVA, which was measured in logMAR units, improved from 1.910 ± 0.504 preoperatively to 0.287 ± 0.225 postoperatively (p < 0.001). In the group that underwent panretinal photocoagulation before VH, the amplitudes of the b-wave in photopic ERG and 30-Hz flicker ERG were negatively correlated with the postoperative BCVA. The implicit times of the b-wave in photopic ERG and 30-Hz flicker ERG were positively correlated with the postoperative BCVA (p < 0.05). Conclusions Photopic ERG recorded using a handheld retinal ERG device equipped with skin electrodes can aid in predicting the visual prognosis in patients with severe VH caused by diabetes mellitus.

Purpose: The male predominance in the incidence of gastric cancer (GC) is established; however, sex differences in the prognosis of GC remain controversial. As such, this study analyzed the prognosis of patients with GC based on age and sex. Materials and Methods: Data from 14,739 patients diagnosed with GC at Seoul National University Bundang Hospital between 2003 and 2023 were analyzed. Baseline characteristics, histological types of GC, overall and GC-specific survival rates (age and stage stratification), and associated risk factors were analyzed. Results: Females were significantly younger (p < 0.001) and exhibited more gastric body cancers (p < 0.001) and tumors with diffuse-type or poorly differentiated histology (p < 0.001) than males. Females exhibited an advantage over males in terms of overall survival (p=0.004), but not in GC-specific survival. However, age stratification revealed significant sex differences, that females < 50 years of age exhibited survival disadvantages (p < 0.001); however, this trend was reversed with age, and females > 60 years exhibited survival advantages (p < 0.001) for both overall and GC-specific survival. This may be explained by the lower ratio of diffuse-type GC as females age. Furthermore, in the analysis according to stage, females with stage IV disease exhibited significant survival disadvantages, with significantly younger age and a higher proportion of diffuse-type GC which exhibits aggressive features, resulting in poorer survival than in males. Conclusion Age and stage stratification revealed significant differences in survival between the sexes, which can be helpful for public health strategies.

Background: We analyzed the status of organ distribution in pediatric deceased donor liver transplantation (DDLT) in Korea. Additionally, we estimated how many pediatric patients could have avoided living donor liver transplantation (LDLT) or survived if new criteria for splittable deceased donors were adopted. Based on the findings, we advocate expanding policy to promote the universal adoption of split liver transplantation (SLT). Methods: Using the Korean Network for Organ Sharing database, we identified patients who underwent DDLT between January 2000 and December 2020. We considered “po-tential splittable donors” those with a donor-to-recipient weight ratio of ≥1.0 who met the existing SLT criteria (age 10–40 years; weight ≥50 kg). By comparing the numbersof pediatric LDLT recipients and potential splittable donors annually, we estimated how many patients might have avoided LDLT if the left lateral section of each splittable liver had been allocated to a child. Additionally, we compared the number of deaths on the DDLT waiting list with the number of potential splittable donors to estimate possibly preventable deaths. Results: Overall, we identified 640 potential splittable donors. Over the 20-year period, 1,210 pediatric patients (<19 years old) received LDLT. If potentially splittable livers had been split, this number could have been nearly halved. Furthermore, 127 patients died while on the DDLT waiting list. Using SLT with potential splittable donors, these deaths might have been prevented. Conclusions SLT could reduce avoidable deaths among pediatric patients while decreasing the economic and social burden of LDLT, without compromising survival for adult DDLT recipients.

Vaccines are highly effective, but rare or delayed adverse events following immunization (AEFIs) require post-licensure surveillance beyond clinical trials. Korea lacks a comprehensive, active, database-based framework, yet key assets exist: nationwide claims databases (National Health Insurance Service/Health Insurance Review and Assessment Service), the national immunization registry (Korea Disease Control and Prevention Agency’s Immunization Registry Information System) for National Immunization Program (NIP) and non-NIP vaccines, and increasingly standardized hospital electronic health records.We propose a federated, code to data architecture with data linkages between these data.Implementation should adopt a common data model (CDM), standardized case definitions, latency accounting, and transparent public reporting under strong privacy governance. Major challenges include multi step administrative approvals for data linkage, incomplete capture of adult non-NIP vaccinations, heterogeneous hospital data structures, and strict data protection constraints. Strategic priorities are to streamline statutory and administrative processes for public health use, mandate or enable claims-based capture of adult vaccinations, enhance CDM based interoperability, and develop secure hubs for aggregated outputs. With these measures, Korea will be well positioned to establish a scalable active surveillance system capable of detecting rare AEFIs, supporting transparent and evidence-based communication, and ensuring equitable injury compensation grounded in domestic data.

Irritable bowel syndrome (IBS) is a chronic, disabling, and functional bowel disorder that significantly affects social functioning and reduces quality of life and increases social costs. The Korean Society of Neurogastroenterology and Motility published clinical practice guidelines on the management of IBS based on a systematic review of the literature in 2017, and planned to revise these guidelines in light of new evidence on the pathophysiology, diagnosis, and management of IBS. The current revised version of the guidelines is consistent with the previous version and targets adults diagnosed with or suspected of having IBS. These guidelines were developed using a combination of de novo and adaptation methods, with analyses of existing guidelines and discussions within the committee, leading to the identification of key clinical questions. Finally, the guidelines consisted of 22 recommendations, including 3 concerning the definition and risk factors of IBS, 4 regarding diagnostic modalities and strategies, 2 regarding general management, and 13 regarding medical treatment. For each statement, the advantages, disadvantages, and precautions were thoroughly detailed. The modified Delphi method was used to achieve expert consensus to adopt the core recommendations of the guidelines. These guidelines serve as a reference for clinicians (including primary care physicians, general healthcare providers, medical students, residents, and other healthcare professionals) and patients, helping them to make informed decisions regarding IBS management.