Impact of obesity on renal function in elderly Korean adults: a national population-based cohort study.

Background: Obesity is a well-known risk factor for chronic kidney disease and its progression. However, the impact of obesity on the renal function of the elderly population is uncertain. We investigated the association between obesity and renal outcomes in the elderly. Methods: We analyzed 130,504 participants from the Korean National Health Insurance Service-Senior cohort. Obesity was classified according to body mass index (BMI), sex-specific waist circumference (WC), and the presence of metabolic syndrome. The primary outcome was renal function decline, defined as a decline in the estimated glomerular filtration rate (eGFR) of at least 50% from baseline or new-onset end-stage renal disease. Results: During a follow-up period of 559,531.1 person-years (median, 4.3 years), 2,486 participants (19.0%; incidence rate of 4.44 per 1,000 person-years) showed renal function decline. A multivariate Cox proportional hazards model revealed that BMI/WC was not associated with renal function decline. However, the group with metabolic syndrome had a significantly increased risk of renal function decline compared to the group without metabolic syndrome (adjusted hazard ratio [HR], 1.24; 95% confidence interval [CI], 1.13-1.36). Compared with the non-metabolic syndrome group, the adjusted HRs (95% CI) for participants with one through five components were 0.96 (0.84-1.11), 1.10 (0.96-1.27), 1.24 (1.06-1.45), 1.37 (1.12-1.66), and 1.99 (1.42-2.79), respectively (p for trend < 0.001). Conclusion: In elderly Korean adults, metabolic syndrome and the number of its components were associated with a higher risk of renal function decline, but BMI or WC was not significant.

Association between dementia diagnosis at dialysis initiation and mortality in older patients with end-stage kidney disease in South Korea.

Background: The prevalence of dementia is 2- to 7-fold higher among patients with end-stage kidney disease (ESKD) than among the general population; however, its clinical implications in this population remain unclear. Therefore, this study aimed to determine whether comorbid dementia increases mortality among older patients with ESKD undergoing newly initiated hemodialysis. Methods: We analyzed data from the Korean Society of Geriatric Nephrology retrospective cohort, which included 2,736 older ESKD patients (≥70 years old) who started hemodialysis between 2010 and 2017. Kaplan-Meier survival and Cox regression analyses were used to examine all-cause mortality between the patients with and without dementia in this cohort. Results: Of the 2,406 included patients, 8.3% had dementia at the initiation of dialysis; these patients were older (79.6 ± 6.0 years) than patients without dementia (77.7 ± 5.5 years) and included more women (male:female, 89:111). Pre-ESKD diagnosis of dementia was associated with an increased risk of overall mortality (hazard ratio, 1.503; p < 0.001), and this association remained consistent after multivariate adjustment (hazard ratio, 1.268; p = 0.009). In subgroup analysis, prevalent dementia was associated with mortality following dialysis initiation in female patients, those aged <85 years, those with no history of cerebrovascular accidents or severe behavioral disorders, those not residing in nursing facilities, and those with no or short-term hospitalization. Conclusion: A pre-ESKD diagnosis of dementia is associated with mortality following dialysis initiation in older Korean population. In older patients with ESKD, cognitive assessment at dialysis initiation is necessary.

Importance of dialysis specialists in early mortality in elderly hemodialysis patients: a multicenter retrospective cohort study.

The early mortality rate in elderly patients undergoing hemodialysis is more than twice that in young patients, requiring more specialized healthcare. We investigated whether the number of professional dialysis specialists affected early mortality in elderly patients undergoing hemodialysis. This multicenter retrospective cohort study analyzed data from 1860 patients aged ≥ 70 years who started hemodialysis between January 2010 and December 2017. Study regions included Seoul, Gyeonggi-do, Gangwon-do, Daejeon/Chungcheong-do, Daegu/Gyeongsangbuk-do, and Busan/Ulsan/Gyeongsangnam-do. The number of patients undergoing hemodialysis per dialysis specialist was calculated using registered data from each hemodialysis center. Early mortality was defined as death within 6 months of hemodialysis initiation. Gangwon-do (28.3%) and Seoul (14.5%) showed the highest and lowest early mortality rate, respectively. Similarly, Gangwon-do (64.6) and Seoul (43.9) had the highest and lowest number of patients per dialysis specialist, respectively. Relatively consistent results were observed for the regional rankings of early mortality rate and number of patients per dialysis specialist. Multivariate Cox regression analysis-adjusted for previously known significant risk factors-revealed that the number of patients per dialysis specialist was an independent risk factor for early mortality (hazard ratio: 1.031, p < 0.001). This study underscores the growing need for dialysis specialists for elderly hemodialysis patients in Korea.

Effect of low-density lipoprotein level and mortality in older incident statin-naïve hemodialysis patients.

BACKGROUND: This study aimed to analyze low-density lipoprotein cholesterol (LDL-C) levels and their relationship with mortality in order to identify the appropriate lipid profile for older Korean hemodialysis patients. METHODS: We enrolled a total of 2,732 incident hemodialysis patients aged > 70 years from a retrospective cohort of the Korean Society of Geriatric Nephrology from 2010 Jan to 2017 Dec, which included 17 academic hospitals in South Korea. Of these patients, 1,709 were statin-naïve, and 1,014 were analyzed after excluding those with missing LDL-C level data. We used multivariate Cox regression analysis to select risk factors from 20 clinical variables among the LDL-C groups. RESULTS: The mean age of the entire patient population was 78 years, with no significant differences in age between quartiles Q1 to Q4. However, the proportion of males decreased as the quartiles progressed towards Q4 (p < 0.001). The multivariate Cox regression analysis, which included all participants, showed that low LDL-C levels were associated with all-cause mortality. In the final model, compared to Q1, the hazard ratios (95% confidence interval) were 0.77 (0.620-0.972; p = 0.027), 0.85 (0.676-1.069; p = 0.166), and 0.65 (0.519-0.824; p < 0.001) for Q2, Q3, and Q4, respectively, after adjusting for covariates, such as conventional and age-specific risk factors. The final model demonstrated that all-cause mortality increased as LDL-C levels decreased, as confirmed by a restrictive cubic spline plot. CONCLUSIONS: In older hemodialysis patients who had not previously received dyslipidemia treatment, elevated LDL-C levels were not associated with increased all-cause mortality. Intriguingly, lower LDL-C levels appear to be associated with an unfavorable effect on all-cause mortality among high-risk hemodialysis patients.

Clinical characteristics of acute kidney injury in patients with glyphosate surfactant herbicide poisoning.

BACKGROUND: In this study, we investigated the clinical characteristics of acute kidney injury (AKI) in patients with glyphosate surfactant herbicide (GSH) poisoning. METHODS: This study was performed between 2008 and 2021 and included 184 patients categorized into the AKI (n = 82) and nonAKI (n = 102) groups. The incidence, clinical characteristics, and severity of AKI were compared between the groups based on the Risk of renal dysfunction, Injury to the kidney, Failure or Loss of kidney function, and End-stage kidney disease (RIFLE) classification. RESULTS: The incidence of AKI was 44.5%, of which 25.0%, 6.5%, and 13.0% of patients were classified into the Risk, Injury, and Failure categories, respectively. Patients in the AKI group were older (63.3 ± 16.2 years vs. 57.4 ± 17.5 years, p = 0.02) than those in the non-AKI group. The length of hospitalization was longer (10.7 ± 12.1 days vs. 6.5 ± 8.1 days, p = 0.004) and hypotensive episodes occurred more frequently in the AKI group (45.1% vs. 8.8%, p < 0.001). Electrocardiographic (ECG) abnormalities on admission were more frequently observed in the AKI group than in the non-AKI group (80.5% vs. 47.1%, p < 0.001). Patients in the AKI group had poorer renal function (estimated glomerular filtration rate at the time of admission, 62.2 ± 22.9 mL/min/1.73 m2 vs. 88.9 ± 26.1 mL/min/1.73 m2 , p < 0.001) on admission. The mortality rate was higher in the AKI group than in the non-AKI group (18.3% vs. 1.0%, p < 0.001). Multiple logistic regression analysis showed that hypotension and ECG abnormalities upon admission were significant predictors of AKI in patients with GSH poisoning. CONCLUSION: The presence of hypotension on admission may be a useful predictor of AKI in patients with GSH intoxication.

Association between physical activity and risk of renal function decline and mortality in community-dwelling older adults: a nationwide population-based cohort study.

BACKGROUND: Physical activity (PA) is an important risk factor associated with health outcomes. However, the relationship between PA and kidney function decline in older adults remains unclear. We examined the influence of PA on kidney function decline and mortality in community-dwelling older adults. METHODS: Adults aged ≥ 65 years with an estimated glomerular filtration rate (eGFR) > 60 mL/min/1.73 m2 who had available health checkup data from 2009 to 2010 were included. The cohort was followed annually through December 2015 for anthropometric, sociodemographic, and medical information including outcomes and biennially for laboratory information from the health checkup. We divided these patients into three groups according to self-reported PA (Inactive group: no leisure-time PA, Active group: vigorous activity for at least 80 min/week or a sum of moderate-intensity activity and walking for at least 300 min/week, Low-active group: level of PA between the definitions of the other two groups). Associations between the intensity of PA and death, cardiovascular death, and ≥ 50% eGFR decline were investigated. RESULTS: Among 102,353 subjects, 32,984 (32.23%), 54,267 (53.02%), and 15,102 (14.75%) were classified into the inactive, low-active, and active groups, respectively. The active group was younger, contained a higher proportion of men, and had higher frequencies of hypertension, diabetes mellitus, drinking, and smoking than the other groups. The active group had significantly lower incidence rates of mortality, cardiovascular mortality, and kidney function decline than the other groups (all p < 0.001). The active group also showed lower all-cause (hazard ratio [HR], 0.76; 95% confidence interval [CI], 0.70-0.82) and cardiovascular mortality (HR, 0.64; 95% CI, 0.53-0.78) and protection against ≥ 50% eGFR decline (HR, 0.81; 95% CI, 0.68-0.97) compared with the inactive group in the fully adjusted Cox proportional hazards regression model. CONCLUSIONS: High PA was an independent modifiable lifestyle factor for reducing mortality and protecting against declines in kidney function in older adults.

New Genotypes and Diversity of Orientia tsutsugamushi DNA samples from Patients with Scrub Typhus in South Korea as Determined by Multilocus Sequence Typing.

Orientia tsutsugamushi, an obligate intracellular organism, is the causative agent of scrub typhus. Multilocus sequence typing (MLST) is a genetic typing method that provides a unified bacterial isolate characterization approach. However, there are no comparative studies in South Korea on the genotypic properties of O. tsutsugamushi based on MLST. To conduct a comparative analysis with previous data collected from Thailand, Laos, and Japan, we investigated the genetic diversity of O. tsutsugamushi from 51 patients with scrub typhus in South Korea by using MLST. The MLST analysis revealed 10 new alleles in the housekeeping genes: gpsA, n = 2; mdh, n = 1; nrdB, n = 1; nuoF, n = 1; ppdK, n = 1; sucB, n = 2; and sucD, n = 2. These novel alleles led to the assignment of six new sequence types (STs) (ST93-98). The 51 samples corresponded to seven different STs (ST48 and ST93-98), with ST48 accounting for the largest proportion (49.0%) of O. tsutsugamushi STs in South Korea. Interestingly, O. tsutsugamushi from patients with scrub typhus in South Korea were clustered in two different clades, and the five Korean STs (ST48, ST93, ST94, ST95, and ST98) were close genetically to ST80, which was isolated from Laos. The remaining two STs (ST96 and ST97) were close genetically to ST49 (Ikeda, Japan). Overall, our results suggest that the relative genetic stability and the clonal populations of O. tsutsugamushi strains in South Korea have remained mostly conserved.

Circulating miRNAs in extracellular vesicles related to treatment response in patients with idiopathic membranous nephropathy.

BACKGROUND: Extracellular vesicle (EV)-microRNAs (miRNAs) are potential biomarkers for various renal diseases. This study attempted to identify the circulating EV-miRNA signature not only for discriminating idiopathic membranous nephropathy (IMN) from idiopathic nephrotic syndrome (INS), but also to predict the treatment response of patients with IMN. METHODS: We prospectively enrolled 60 participants, including those with IMN (n = 19) and INS (n = 21) and healthy volunteers (HVs; n = 20) in this study. Using RNA sequencing, we assessed the serum EV-miRNA profiles of all participants. To identify the EV-miRNAs predictive of treatment response in IMN, we also analyzed EV-miRNAs among patients with IMN with and without clinical remission. RESULTS: The expression levels of 3 miRNAs differed between IMN patients, INS patients and HVs. In addition, compared to HVs, RNA sequencing revealed differential expression of 77 and 44 EV-miRNAs in patients with IMN without and with remission, respectively. We also identified statistically significant (|fold change ≥ 2, p < 0.05) differences in the expression levels of 23 miRNAs in IMN without remission. Biological pathway analysis of miRNAs in IMN without remission indicated that they are likely involved in various pathways, including renal fibrosis. CONCLUSION: Our study identified EV-miRNAs associated with IMN as well as those associations with therapeutic response. Therefore, these circulating EV-miRNAs may be used as potential markers for the diagnosis and prediction of treatment response in patients with IMN.

Unusual Ovarian Vein Thrombosis Associated with Urinary Tract Infection: A Case Report.

Teaching Point: Radiologists need to be familiar with that ovarian vein thrombosis can occur as a complication of urinary tract infection. Ovarian vein thrombosis is a rare disease in which a majority of cases occur during the postpartum period. There are few case reports for ovarian vein thrombosis associated with urinary tract infection in non-postpartum women. We report a case of ovarian vein thrombosis incidentally diagnosed on computed tomography in a patient with symptoms of urinary tract infection.

A Rare Case of Spinal Epidural Abscess Following Urinary Tract Infection Caused by Escherichia coli in a Patient with Pre-existing Stress Fractures of the Lumbar Spine.

Spinal epidural abscess (SEA) caused by Escherichia coli is an uncommon condition. It usually occurs secondary to urinary tract infection (UTI), following hematogenous propagation. Disruption of spinal anatomic barriers increases susceptibility to SEA. Although rarely, such disruption can take the form of lumbar spine stress fractures, which can result from even innocuous activity. Here, we describe a case of SEA secondary to UTI in a patient with pre-existing stress fractures of the lumbar spine, following use of an automated massage chair. Successful treatment of SEA consisted of surgical debridement and a six-month course of antibiotic therapy.

Effect of shared decision-making education on physicians' perceptions and practices of end-of-life care in Korea.

BACKGROUND: Evidence of the ethical appropriateness and clinical benefits of shared decision-making (SDM) are accumulating. This study aimed to not only identify physicians' perspectives on SDM, and practices related to end-of-life care in particular, but also to gauge the effect of SDM education on physicians in Korea. METHODS: A 14-item questionnaire survey using a modified Delphi process was delivered to nephrologists and internal medicine trainees at 17 university hospitals. RESULTS: A total of 309 physicians completed the survey. Although respondents reported that 69.9% of their practical decisions were made using SDM, 59.9% reported that it is not being applied appropriately. Only 12.3% of respondents had received education on SDM as part of their training. The main obstacles to appropriate SDM were identified as lack of time (46.0%), educational materials and tools (29.4%), and education on SDM (24.3%). Although only a few respondents had received training on SDM, the proportion of those who thought they were using SDM appropriately in actual practice was high; the proportion of those who chose lack of time and education as factors that hindered the proper application of SDM was low. CONCLUSION: The majority of respondents believed that SDM was not being implemented properly in Korea, despite its use in actual practice. To improve the effectiveness of SDM in the Korean medical system, appropriate training programs and supplemental policies that guarantee sufficient application time are required.

Clinical significance of hypoalbuminemia in patients with scrub typhus complicated by acute kidney injury.

BACKGROUND: This study aimed to investigate the clinical significance of hypoalbuminemia (HA) in patients with scrub typhus complicated by acute kidney injury (AKI). METHODS: From 2009 to 2018, 611 patients were diagnosed with scrub typhus. We divided the patients into two groups [normoalbuminemia (NA) vs. HA] based on the serum albumin level of 3.0 g/dL and compared the incidence, clinical characteristics, and severity of AKI based on the RIFLE classification between the two groups. RESULTS: Of the total 611 patients, 78 (12.8%) were categorized into the HA group. Compared to patients in the NA group, patients in the HA group were older (73 ± 9 vs. 62 ± 14 years, P<0.001). The HA group had a significantly longer hospital stay (9.6 ± 6.2 vs 6.2 ± 3.1 days, p<0.001) and a higher incidence of complications in respiratory and cardiovascular systems. Furthermore, AKI developed significantly more in patients in the HA group (58% vs. 18%, p<0.001) as compared to the NA group. The overall incidence of AKI was 23.1%; of which, 14.9%, 7.0%, and 1.2% of cases were classified as Risk, Injury, and Failure, respectively. The serum albumin level correlated with AKI severity (3.4 ± 0.5 vs 3.0 ± 0.5 vs 2.6 ± 0.3, p<0.05). In a multivariate logistic regression analysis for predicting AKI, age, presence of co-morbidities such as chronic kidney disease, total bilirubin, leukocytosis, and hypoalbuminemia were significant predictors for AKI. CONCLUSION: Serum albumin level is helpful to predict the development and severity of scrub typhus-associated AKI.

Urinary Exosomal microRNA-21 as a Marker for Scrub Typhus-Associated Acute Kidney Injury.

Background: Urinary microRNA (miRNA)-21 is a biomarker for acute kidney injury (AKI). We conducted this study to determine if a urinary exosomal analysis for this biomarker could serve as a novel diagnostic approach for detecting kidney disease. Materials and Methods: We investigated the clinical significance of urinary exosomal miRNA-21 levels for AKI in scrub typhus patients. We collected 138 urine samples from scrub typhus patients at the time of admission. Urinary exosomal miRNA-21 was assessed in 25 age- and sex-matched scrub typhus patients with and without AKI. Results: The total leukocyte count was higher in AKI patients than in non-AKI patients (10.40 × 103/mL vs. 6.40 × 103/mL, p < 0.01). Urinary exosomal miRNA-21 levels were higher in the AKI group than in the non-AKI group (20.1 ± 1.2 vs. 17.8 ± 1.8 ΔCt value of miRNA-21, p < 0.01). Additionally, the miRNA-21 levels correlated directly with the total leukocyte counts and inversely with the estimated glomerular filtration rate. A receiver operating characteristic curve analysis demonstrated good discriminative power for the diagnosis of scrub typhus-associated AKI, with an area under the curve value of 0.907. Conclusion: Urinary exosomal miRNA-21 could be a surrogate marker for scrub typhus-associated AKI diagnosis.

Extracellular vesicles: a novel window into kidney function and disease.

PURPOSE OF REVIEW: There has been an increasing interest in extracellular vesicles as potential diagnostic, prognostic or therapeutic biomarkers for various kidney diseases, as extracellular vesicles mediate cell-cell or intercellular communication. This review explores the current state of knowledge regarding extracellular vesicles as a tool for examining kidney physiology and disease. RECENT FINDINGS: Urinary extracellular vesicles may be useful as biomarkers to detect abnormal function in renal endothelial and tubular cells as well as podocytes. Recent studies suggest that urinary extracellular vesicles may facilitate early diagnosis and/or monitoring in acute kidney injury, glomerular disease, autosomal dominanat polycyst kidney disease and urinary tract malignancies. Circulating extracellular vesicles may serve as biomarkers to assess cardiovascular disease. SUMMARY: Urinary and circulating extracellular vesicles have gained significant interest as potential biomarkers of renal diseases. Analysis of extracellular vesicles may serve as a logical diagnostic approach for nephrologists as well as provide information about disease pathophysiology.

Urinary Extracellular Vesicles as Biomarkers of Kidney Disease: From Diagnostics to Therapeutics.

Cell-derived extracellular vesicles (EVs) can be isolated from various body fluids, including urine. Urinary EVs have gained important recognition as potential diagnostic biomarkers in renal disease since their cargo includes nucleic acids, proteins, and other cellular components, which likely mirror the physiological and possibly pathophysiological state of cells along the nephron. Accumulating evidence highlights the feasibility of using EVs as biomarkers for diagnostic, prognostic, and therapeutic purposes in several forms of renal disease, such as acute kidney injury, glomerulonephritis, and renal transplantation. Additionally, exogenous delivery of EVs released in vitro by cells in culture may have salutary benefits for renal diseases. In this review, we introduce recent studies that attempt to identify urinary EVs as candidate biomarkers for human kidney diseases and consider their potential implication as a therapeutic option in key kidney diseases.