Inwhee Park

Introduction Hyperuricaemia is prevalent in type 2 diabetes mellitus (T2DM) and associated with adverse renal and mortality outcomes; however, existing predictive models have primarily targeted populations with diabetic nephropathy or reduced renal function, limiting their applicability to early-stage T2DM. We developed a machine learning (ML)-based model to predict incident hyperuricaemia in newly diagnosed patients with T2DM with preserved kidney function and evaluated its association with long-term cardiorenal and mortality outcomes. Research design and methods Using multicentre electronic health record databases in South Korea, ML models were developed to predict incident hyperuricaemia within 1 year of T2DM diagnosis. Model performance was externally validated across three independent databases. Based on model-derived risk stratification, 5-year risks of kidney failure, cardiovascular outcomes and all-cause mortality were evaluated. Kaplan-Meier survival analysis was used to compare cumulative incidence between risk groups in the development cohort. HRs were estimated using Cox regression and pooled using random-effects meta-analysis, with adjustment for age, sex, hypertension, insulin use and diuretic use. Results The Extreme Gradient Boosting model achieved the highest discrimination (area under the receiver operating characteristic curve: 0.769 in the development cohort (n=5263); 0.709–0.750 in external validation). In fully adjusted pooled analyses, high-risk patients exhibited significantly elevated 5-year risks of kidney failure (HR=2.47; 95% CI 1.18 to 5.18) and all-cause mortality (HR=2.56; 95% CI 1.81 to 3.62). The association with cardiovascular outcomes was attenuated after full adjustment (HR=1.12; 95% CI 0.96 to 1.30). Conclusions In newly diagnosed patients with T2DM with preserved kidney function, individuals classified as high-risk for incident hyperuricaemia by ML model were found to have higher long-term risks of kidney failure and all-cause mortality, independent of traditional risk factors. These findings suggest that model-derived hyperuricaemia risk may serve as a prognostic marker reflecting underlying renal and systemic vulnerability before overt organ damage occurs.

Peritoneal dialysis is promoted for its spatial flexibility compared to in-center hemodialysis. However, this flexibility entails a significant relocation of clinical responsibility, requiring patients to manage infection control and medical logistics within non-institutional settings. While spatial factors-including housing conditions, storage capacity, and environmental cleanliness-are critical to modality sustainability, they are often reduced to logistical metrics in clinical consultations. This study investigates the concrete mechanisms through which patients evaluate and manage their physical environments to ensure clinical safety. A qualitative study was conducted using semi-structured interviews with 43 adult patients receiving peritoneal dialysis at a tertiary university hospital in South Korea. Interviews explored how participants experienced and evaluated different spaces in relation to peritoneal dialysis. Data were analyzed inductively using thematic analysis. Participants perceived space not as a static setting but as a managed clinical site, categorized into three domains. Hospitals represented delegated safety, where clinical rigor was entrusted to professionals. Homes functioned as sites of internalized safety, where patients exercised hygienic control by reconfiguring domestic routines to accommodate medical inventories. Spaces beyond the home revealed a paradox of spatial liberation: while peritoneal dialysis theoretically enables flexibility, the unpredictability of external environments often triggered rigorous risk assessments, leading to self-imposed spatial narrowing. Across all domains, the patient's capacity for environmental control was the primary determinant of whether a space was deemed safe. This study highlights that space is not a neutral backdrop to treatment, but a central dimension of the PD experience. Understanding how patients perceive and manage their environment is essential for meaningful modality discussions, realistic education, and patient-centered communication. Without addressing these spatial dynamics, PD risks being presented as flexible in principle while remaining constraining in practice.

Objective: This study evaluated mandibular cortical thickness and morphological changes in chronic kidney disease (CKD) patients using cone beam computed tomography (CBCT) and their correlation with bone metabolism markers. Methods: CKD patients were divided into CKD-I (eGFR (estimated glomerular filtration rate) < 30) and CKD-II (eGFR ≥ 30) groups, with healthy controls for comparison. Mental index (MI), antegonial index (AI), and panoramic mandibular index (PMI) were compared using Kruskal-Wallis test. Mandibular cortical index (MCI) classifications, lamina dura loss, and soft tissue calcifications were assessed using Fisher’s test. Relationships between serum bone metabolism markers and radiomorphometric indices were analyzed by linear regression. Results: The study included 94 CKD patients (56 CKD-I, 38 CKD-II) and 88 controls. MI and AI were significantly lower in CKD-I versus controls (p < 0.05). MCI class I was less prevalent in CKD-I (5.4%) than controls (35.2%) (p < 0.001). Lamina dura loss (p = 0.006) and soft tissue calcifications (p = 0.009) occurred more frequently in CKD groups. Elevated alkaline phosphatase was associated with reduced cortical thickness (p < 0.01). Conclusions: Although findings should be interpreted considering the retrospective design’s limitations, CBCT revealed significant bone abnormalities in CKD patients, with compromised bone quality and reduced mandibular cortical thickness, especially in advanced renal impairment, suggesting its value for pre-implant bone quality assessment in CKD patients.

Background: Cyclic corticosteroid‐cyclophosphamide or cyclosporine is a well‐known membranous nephropathy (MN) treatment but has high risks of adverse drug reactions (ADRs). Rituximab has a non‐inferior effect compared to previous treatments, with fewer ADRs. However, the high cost of rituximab is a pharmacoeconomic disincentive.Methods: We conducted a cost‐minimisation analysis to evaluate the relative and absolute costs of rituximab versus corticosteroid‐cyclophosphamide or cyclosporine in patients with MN over 2 years using a decision‐tree model based on ADRs from two pivotal trials (RI‐CYCLO and MENTOR). We included costs of medication, time, transportation, and ADRs. Deterministic sensitivity analysis and threshold analysis were performed to assess the uncertainty of the model input parameters and estimate the appropriate price of rituximab.Results: The total expected cost for rituximab was $4132, and $2684 for the comparators, with an expected incremental cost of $1448. Despite a 2.8 times higher medication cost, rituximab reduced ADR costs by 96.3% ($223), time costs by 31.1% ($280), and transportation costs by 46.8% ($180). A 46.9% price reduction of rituximab would make it an economically favourable option for treating MN compared to comparators.Conclusions: If the price of rituximab is reduced, it can be a good alternative to corticosteroid‐cyclophosphamide or cyclosporine for MN in the Republic of Korea.

Purpose: The COVID-19 (coronavirus disease 2019) pandemic led to significant changes in clinical clerkships, including reduced ward rounds. We aimed to determine how the pandemic–induced changes in the clinical practice environment affect the clinical performance of medical students.Methods: We analyzed objective structured clinical examination scores of third- and fourth-year medical students from 2019–2020 and 2020–2021 across six stations by the Seoul–Gyeonggi Consortium. Clinical, communication, and ability scores were measured and analyzed using repeated-measures multivariate analysis of variance.Results: The interaction between clinical practice progress and pandemic-induced changes significantly affected physical examination and medical history scores, though the differences were not substantial. Patient-physician interaction significance varied by measurement period. Clinical communication ability also showed significant differences based on the measurement period and practical experience.Conclusion: During the pandemic, alternative learning methods, including self–learning, simulation/practice, and peer role–play, helped improve medical competency in areas such as history–taking and physical examination. However, these were less effective in improving patient–physician interactions or clinical communication efficacy. Alternative learning methods have limitations, and they cannot replace direct patient encounters in clinical practice.

Background: The global coronavirus disease 2019 (COVID-19) pandemic has placed patients with end-stage kidney disease (ESKD) at heightened risk owing to their vulnerability to infections. Our study focused on patients with ESKD, examining COVID-19 incidence, hospitalization, and mortality in relation to their renal replacement therapy (RRT) type and identifying factors influencing COVID-19 hospitalization. Methods: We conducted a retrospective cohort study using health insurance claims data from the Health Insurance Review and Assessment Service for patients with ESKD between July 2017 and June 2022. COVID-19 data for the general population were sourced from the Korea Disease Control and Prevention Agency. Results: Patients undergoing hemodialysis (HD) constituted 90.7% of the cohort, followed by kidney transplantation (KT) recipients and peritoneal dialysis (PD). After adjusting for every 10,000 individuals, KT recipients exhibited the highest COVID-19 incidence, followed by those undergoing HD and PD, whereas the general population showed a higher infection rate of 43.64. Patients undergoing HD had the highest hospitalization rates, followed by KT recipients and those undergoing PD. The mortality rate per 10,000 individuals was highest in HD, followed by PD, the general population, and KT. Multivariate analysis indicated that age, RRT duration, residence in a nursing hospital, and comorbidities were associated with COVID-19 hospitalization. Conclusion: Among RRT modalities, KT recipients displayed the highest COVID-19 incidence, whereas those undergoing HD exhibited the highest hospitalization and mortality rates. This study contributes to our understanding of infectious diseases in patients on RRT and aids in preparedness for future infectious disease outbreaks.

Background: Growth arrest and DNA damage 45G (GADD45G) is a family of proteins involved in DNA damage response and cell growth arrest. In this study, we show evidence that urinary GADD45G protein is associated with the progression of IgA nephropathy. Methods: Patients diagnosed with IgA nephropathy without reversible acute kidney injury at study initiation and with at least one subsequent serum creatinine (SCr) measurement were included. A 50% or greater increase in SCr level was used as an endpoint for the deterioration of renal function. Enzyme-linked immunosorbent assay (ELISA) was performed using a Human GADD45G ELISA kit. Renal biopsy tissues were stained with a monoclonal mouse anti-GADD45G antibody. Results: Forty-five patients whose renal biopsy revealed IgA nephropathy were enrolled. Urinary GADD45G and urinary protein concentrations were 1.26 [0.69–2.20] μg/g creatinine and 0.65 [0.24–1.60] g/g creatinine, respectively. Urinary GADD45G showed significant positive correlations with SCr-slopes and urinary protein. The SCr-slope of the highest tertile group of urinary GADD45G (above 1.95 μg/g creatinine) was significantly higher than that of the lowest tertile group (below 0.90 μg/g). Univariate Cox regression analysis showed that urinary GADD45G was significantly associated with deterioration of renal function. A Kaplan–Meier test showed a significant difference in event-free survival for deterioration of renal function between the highest urinary GADD45G tertile group and other tertile groups. The area under the receiver operating characteristics (ROC) curve indicated urinary GADD45G had a good performance in predicting renal outcome (cut-off point 1.67 μg/g, positive predictive value 36.8%, negative predictive value 100%). Immunohistochemistry showed that GADD45G was expressed across all pathologic grades of IgA nephropathy and mainly detected in the cytoplasm of renal tubules, whereas no staining was noted in normal tissues. Conclusions: Urinary GADD45G excretion was significantly associated with kidney disease progression in patients with IgA nephropathy.

We present a unique case of concurrent Fabry disease (FD) and IgA nephropathy (IgAN) in a 27‐year‐old female with a 10‐year history of Crohn's disease (CD). The patient presented to the nephrology clinic with microscopic haematuria and proteinuria on routine tests. A kidney biopsy revealed mesangial matrix widening, mesangial cell proliferation, and podocyte enlargement with prominent lacy and clear cytoplasm, as observed with haematoxylin and eosin staining. Immunofluorescence staining demonstrated diffuse immunoglobulin A deposits in the mesangium. Electron microscopy identified myelin‐like figures in the cytoplasm of podocytes and electron‐dense deposits in the mesangium, confirming IgAN and suggesting FD. Subsequent testing showed low alpha‐galactosidase A (α‐gal) enzyme activity in the patient's white blood cells, confirming the FD diagnosis. Enzyme replacement therapy was initiated following the diagnosis. To our knowledge, this is the first reported case of the coexistence of FD, IgAN, and CD in a single patient. This case highlights the importance of considering FD in patients with proteinuria, emphasising the need for comprehensive diagnostic evaluations in complex cases.

Background/Aims: The corona virus disease 2019 posed a major risk for end-stage kidney disease (ESKD) cases. Our study aimed to assess changes in kidney replacement therapy (KRT) trends and healthcare access for these patients during the pandemic.Methods: We retrospectively analyzed nationwide data from July 2017 to June 2022 to assess changes in KRT and ESKD incidence. KRT modalities included peritoneal dialysis (PD), hemodialysis (HD), and kidney transplantation (KT). We utilized the interrupted time series (ITS) method to compare changes in KRT modality before and after the incidence of the COVID-19 pandemic.Results: ESKD incidence remained stable from 2018 to April 2022. The ITS analysis confirmed that the pandemic did not significant impact overall KRT incidence. PD cases decreased (5.7% to 1.3%), while HD cases increased (81.6% to 85%), and KT recipient remained relatively stable (12.7% to 17.3%). The hospitalization and hospital stay decreased in nursing hospital (165.01 days to 147.77 days) and general hospital (61.34 days to 55.58 days) during the pandemic, however, remained unchanged for PD and KT.Conclusions: Our findings indicate no significant changes in ESKD incidence in South Korea during the pandemic. However, there were shifts in modality distribution, with decreased PD and increased HD cases. Notably, HD cases showed a significant reduction in hospital admissions and length of stay. The healthcare system demonstrated stability during the pandemic, with minimal disruptions in ESKD care.

Objective Contrast agents used for radiological examinations are an important cause of acute kidney injury (AKI). We developed and validated a machine learning and clinical scoring prediction model to stratify the risk of contrast-induced nephropathy, considering the limitations of current classical and machine learning models. Methods This retrospective study included 38,481 percutaneous coronary intervention cases from 23,703 patients in a tertiary hospital. We divided the cases into development and internal test sets (8:2). Using the development set, we trained a gradient boosting machine prediction model (complex model). We then developed a simple model using seven variables based on variable importance. We validated the performance of the models using an internal test set and tested them externally in two other hospitals. Results The complex model had the best area under the receiver operating characteristic (AUROC) curve at 0.885 (95% confidence interval (CI) 0.876-0.894) in the internal test set and 0.837 (95% CI 0.819-0.854) and 0.850 (95% CI 0.781-0.918) in two different external validation sets. The simple model showed an AUROC of 0.795 (95% CI 0.781-0.808) in the internal test set and 0.766 (95% CI 0.744-0.789) and 0.782 (95% CI 0.687-0.877) in the two different external validation sets. This was higher than the value in the well-known scoring system (Mehran criteria, AUROC=0.67). The seven precatheterization variables selected for the simple model were age, known chronic kidney disease, hematocrit, troponin I, blood urea nitrogen, base excess, and N-terminal pro-brain natriuretic peptide. The simple model is available at http://52.78.230.235:8081/. Conclusions We developed an AKI prediction machine learning model with reliable performance. This can aid in bedside clinical decision making.