Kidney Research and Clinical Practice最新文献

Background: This study addresses the gap in knowledge regarding the long-term mortality implications of postoperative acute kidney injury (PO-AKI) utilizing advanced machine learning techniques to predict outcomes more accurately than traditional statistical models.

Methods: A retrospective cohort study was conducted using data from seven institutions between March 2009 and December 2019. Machine learning models were developed to predict all-cause mortality of PO-AKI patients using 23 preoperative variables and one postoperative variable. Model performance was compared to a traditional statistical approach with Cox regression analysis. The concordance index was used as a predictive performance metric to compare prediction capabilities among different models.

Results: Among 199,403 patients, 2,105 developed PO-AKI. During a median follow-up of 144 months (interquartile range, 99.61-170.71 months), 472 in-hospital deaths occurred. Subjects with PO-AKI had a significantly lower survival rate than those without PO-AKI (p < 0.001). For predicting mortality, the XGBoost with an accelerated failure time model had the highest concordance index (0.7521), followed by random survival forest (0.7371), multivariable Cox regression model (0.7318), survival support vector machine (0.7304), and gradient boosting (0.7277).

Conclusion: XGBoost with an accelerated failure time model was developed in this study to predict long-term mortality associated with PO-AKI. Its performance was superior to conventional models. The application of machine learning techniques may offer a promising approach to predict mortality following PO-AKI more accurately, providing a basis for developing targeted interventions and clinical guidelines to improve patient outcomes.

Alport syndrome, a rare genetic disorder affecting around 1 in 50,000 individuals, primarily presents as microscopic hematuria and chronic kidney disease (CKD) with associated extrarenal complications. The Alport syndrome results from mutations in COL4A3, COL4A4, and COL4A5 genes, disrupting the formation of the α3-α4-α5 chain in the collagen IV network. The etiology involves X chromosome-related, autosomal dominant, autosomal recessive, and digenic inheritance patterns. The disease primarily manifests as kidney involvement, featuring persistent hematuria, proteinuria, and a progressive decline in renal function. Hearing loss, ocular abnormalities, and extrarenal manifestations further contribute to its complexity. Genotype-phenotype correlations are relatively evident, with distinct presentations in X-linked, autosomal recessive, and autosomal dominant cases. Diagnosis relies on urinalysis, histologic examination, and genetic testing with advancements in next-generation sequencing aiding identification. Although no specific treatment exists, early diagnosis improves outcomes, emphasizing the importance of genetic testing for prognosis and familial screening. The purpose of this review is to advance knowledge and enhance understanding of Alport syndrome.

Background: This study investigates angiotensin II (Ang II)'s regulatory mechanism on renal outer medullary potassium channel (ROMK) activity in the distal convoluted tubule (DCT) during low potassium intake, focusing on the Janus kinase 2 (JAK2) pathway activation mediated by the Ang II type 1 receptor (AT1R).

Methods: Utilizing a low potassium diet mouse model, various methods including patch clamping, reverse transcription-quantitative polymerase chain reaction, Western blotting, and immunohistochemical staining were applied to analyze ROMK channel activity and the expression of related proteins.

Results: The findings reveal that Ang II inhibits ROMK activity in the DCT2 membrane through AT1R activation, with the JAK2 pathway playing a central role. Further, inhibiting JAK2 reverses this effect, indicating its potential in hypertension treatment.

Conclusion: This study provides novel insights into the role of Ang II in renal potassium excretion and hypertension pathophysiology.

Donor-derived cell-free DNA (dd-cfDNA) based liquid kidney biopsies have the potential to detect the chances of kidney transplant rejection. Several studies have found that dd-cfDNA can be used to determine the risk of kidney transplant rejection and may correlate with antibody-mediated rejection (ABMR), T cell-mediated rejection (TCMR), and estimated glomerular filtration rate (eGFR). A high concentration of dd-cfDNA in the body fluids may indicate possible transplant rejection since dd-cfDNA is released as a result of apoptotic and necrotic processes initiated by the recipient's immune system. dd-cfDNA assays have advantages over conventional biopsies since they are noninvasive, and therefore, have the potential to provide a safe and reliable biomarker. Different dd-cfDNA levels have been reported above a number of cutoff thresholds: ABMR at 2.45% and TCMR at 1.3%, compared with 0.44% in healthy patients; and eGFR at 2.5%, a decrease of 25% compared with healthy patients. These results indicate the levels of dd-cfDNA that may be used to signal possible kidney rejection. dd-cfDNA assay is a rapid technique, making it particularly useful in emergencies, and further research into its use in the study of kidney rejection should prove beneficial.

Background: Cardiovascular disease is an important risk factor for mortality among kidney transplant recipients. In this study, we aimed to investigate the association between cardiovascular risk score at kidney transplantation and long-term outcomes of patients.

Methods: In this prospective, observational cohort study, we enrolled kidney transplant recipients who participated in the Korean Organ Transplantation Registry and underwent transplantation between April 2014 and December 2019. The cardiovascular risk status of kidney transplant recipients was assessed using the Framingham risk score. All-cause mortality, major adverse cardiovascular events, allograft failure, estimated glomerular filtration rates (eGFRs), and composite outcomes were evaluated after kidney transplantation.

Results: Of the 4,682 kidney transplant recipients, 96 died during 30.7 ± 19.1 months of follow-up. The Kaplan-Meier survival analysis results showed that high Framingham risk scores were associated with all-cause mortality, major adverse cardiovascular events, and composite outcomes. According to the multivariable Cox analysis, high Framingham risk scores were associated with an increased risk of mortality (hazard ratio [HR], 3.20; 95% confidence interval [CI], 1.30-7.91), major adverse cardiovascular events (HR, 8.43; 95% CI, 2.41-29.52), and composite outcomes (HR, 2.05; 95% CI, 1.19-3.46). The eGFRs after transplantation were significantly higher among patients in the low Framingham risk score group (p < 0.001). However, Framingham risk scores were not associated with graft loss or rapid decline in eGFRs.

Conclusion: The Framingham risk score is a useful indicator of cardiovascular events, mortality, and kidney function after kidney transplantation.

Background: Immunoglobulin A nephropathy (IgAN) is a major cause of end-stage kidney disease (ESKD). The International IgA Nephropathy Prediction Tool (IIgAN-PT) predicts IgAN prognosis, but improvement in the prediction performance using machine learning (ML)-based methods is needed.

Methods: We analyzed 4,425 biopsy-confirmed patients with IgAN and ≥6 months of follow-up from nine tertiary university hospitals in Korea. The study population was divided into development and validation cohorts. Using the collected 87 clinicodemographic and pathological variables, ML-based prediction models for ESKD or estimated glomerular filtration rate were constructed: 1) the conventional CatBoost model, 2) the optimized CatBoost model with Cox proportional hazards, 3) the deep Cox proportional hazards model, and 4) the deep Cox mixture model. The area under the curve (AUC) and calibration plots were used to investigate the discriminative and calibration performance of the models, which were then compared with those of the IIgAN-PT full model.

Results: The full model showed excellent performance (AUC [95% confidence interval] for 5-year outcome, 0.896 [0.8530.940]), with acceptable calibration results. The ML-based models showed good performance in predicting adverse kidney outcomes and revealed acceptable discrimination performance in the external validation (AUC [95% confidence interval] for the 5-year outcome: 1) 0.829 [0.791-0.866]; 2) 0.847 [0.804-0.890]; 3) 0.823 [0.784-0.862]; and 4) 0.832 [0.794-0.870]), although they underestimated the external validation cohort risks. With the validation data, the overall performance of the IIgAN-PT was non-inferior to that of the ML-based model. Conclusions: Our ML-based models showed good performance in predicting adverse kidney outcomes in patients with IgAN but they did not outperform the IIgAN-PT.

Background: Tolvaptan, a selective vasopressin V2 receptor antagonist, was first approved by the Korean Ministry of Food and Drug Safety in 2015 as a treatment option for autosomal dominant polycystic kidney disease (ADPKD). To prescribe tolvaptan safely and effectively, we designed the phase 4 clinical trial among Korean ADPKD patients with chronic kidney disease stages 1 to 3.

Methods: A total of 117 Korean patients aged 19 to 50 years with rapidly progressing ADPKD were enrolled in the study. Tolvaptan was prescribed for 24 months with the maximum tolerable dose up to 120 mg/day. The primary outcome was the incidence of treatment-emergent adverse events (TEAEs) including hepatic adverse events. The secondary outcomes were the annual mean percent change of total kidney volume (TKV) and the annual mean change of estimated glomerular filtration rate (eGFR).

Results: A total of 489 TEAEs occurred in 106 patients (90.6%). A total of 17 cases of hepatic adverse events (14.5%) occurred during the study period and mostly within the first 18-month period. However, liver enzymes were normalized after drug discontinuation. Although it was not statistically significant, patients with a previous history of liver disease as well as those with mild elevation of liver enzyme showed a higher frequency of hepatic adverse events. Compared with the predicted value from the calculation, tolvaptan attenuated both TKV growth and eGFR decline rate.

Conclusion: Although the incidence of hepatic adverse events was higher in Korean ADPKD patients compared to the previous studies, tolvaptan can be prescribed safely and effectively using meticulous titration and 1-month interval monitoring.

Background: In-depth investigation is imperative to scrutinize medical costs associated with the periods before and after biopsies for diverse kidney diseases in South Korea. Long-term epidemiological data, including follow-up information, is essential for comparing risks linked to various kidney diseases and their adverse outcomes.

Methods: Patients diagnosed with glomerulonephritis (GN), tubulointerstitial nephritis (TIN), and acute tubular necrosis (ATN) at Seoul National University Hospital between 2012 and 2018 were included. We linked the prospective cohort data of biopsy-confirmed kidney disease patients (KORNERSTONE) from our study hospital to the national claims database of Korea, covering both medical events and insured costs. We analyzed medical costs during the periods before and after kidney biopsies, categorized by specific diagnoses, and delved into adverse prognostic outcomes.

Results: Our study involved 1,390 patients with biopsy-confirmed GN, TIN, and ATN. After diagnosis, monthly average medical costs increased for most kidney diseases, excluding membranous nephropathy, Henoch-Schönlein purpura, and amyloidosis. The most substantial yearly average medical cost increase was observed in the ATN, acute TIN (ATIN), and chronic TIN (CTIN) groups. Costs rose for most kidney disease categories, except for amyloidosis. Higher myocardial infarction, stroke, and death rates were noted in CTIN, ATIN, and ATN compared to other types, with lupus nephritis displaying the highest end-stage kidney disease progression rate.

Conclusion: In South Korea, medical costs for the majority of GN, TIN, and ATN patients increased following kidney biopsy diagnosis. This current data provides valuable epidemiological insights into the medical costs and prognosis of various kidney diseases in the country.

Background: The aim of this study is to investigate the impact of sex on the clinical outcomes of spousal donor kidney transplantation.

Methods: We analyzed 456 spousal donor kidney transplantation recipients and categorized them into standard or high immunological risk groups according to panel-reactive antibody ≥50% or less. There were 366 recipients in the standard-risk group and 89 recipients in the high-risk group.

Results: When comparing biopsy-proven allograft rejection within 1 year from kidney transplantation, husband-to-wife recipients showed significantly higher incidence than wife-to-husband recipients in the high-risk group. By contrast, there was no significant difference between wife-to-husband and husband-to-wife recipients in the standard-risk group. Allograft function recovery was better in husband-to-wife recipients than in wife-to-husband recipients in each group, while husband-to-wife recipients in the high-risk group showed a more rapid decline than other recipients. The long-term patient and allograft survival rates showed no difference between husband-to-wife recipients and wife-to-husband recipients within the same groups.

Conclusion: The husband-to-wife recipients with high immunological risk showed a higher risk of biopsy-proven allograft rejection compared to wife-to-husband recipients, so careful monitoring and management may be required.

Background: Left ventricular hypertrophy (LVH) is a vital risk factor for mortality of dialysis patients. The association of the geometry and severity of LVH with cardiovascular and all-cause mortality in hemodialysis (HD) patients remains unknown. This study investigated clinical outcomes among HD patients with different LVH geometric patterns and severity.

Methods: The monocentric retrospective cohort study enrolled chronic HD patients who underwent echocardiography for the assessment of LVH. The patients with LVH were divided into concentric and eccentric groups and then subdivided into four groups based on LVH severity: mild-to-moderate eccentric, mild-to-moderate concentric, severe eccentric, and severe concentric LVH. The risks of cardiovascular and all-cause mortality between groups were evaluated using Cox proportional hazard analysis.

Results: Of the 237 patients on HD with LVH, 131 had concentric LVH, and 106 had eccentric LVH, with 33, 44, 73, and 87 having mild-to-moderate eccentric, mild-to-moderate concentric, severe eccentric, and severe concentric LVH, respectively. Compared with eccentric LVH, the crude hazard ratio (cHR) of cardiovascular mortality of concentric LVH was 2.03 (95% confidence interval [CI], 1.13-3.65). Severe concentric LVH was a significant risk factor for all-cause and cardiovascular mortality compared with mild-to-moderate eccentric LVH (cHR: 2.58 [95% CI, 1.00-6.65] and 3.73 [95% CI, 1.13-12.33], respectively). After adjustment for all variables, concentric LVH and severe concentric LVH remained significant risk factors for cardiovascular mortality (adjusted HR: 2.13 [95% CI, 1.13-4.01] and 3.71 [95% CI, 1.07-12.82], respectively).

Conclusion: Concentric LVH, especially severe concentric LVH, was associated with a high risk of cardiovascular mortality among patients with chronic HD.