Comparison of outcomes between the incremental and thrice-weekly initiation of hemodialysis: a propensity-matched study of a prospective cohort in Korea

Background

Recent reports have suggested the possible benefit of beginning hemodialysis (HD) at a rate less frequent than three times weekly and incrementally increasing the dialysis dose. However, the data regarding the benefits and safety of incremental HD are insufficient.

Methods

We analyzed 927 patients with newly initiated HD from the Clinical Research Center for End-Stage Renal Disease cohort from 2008 to 2014. The patients were classified into a thrice-weekly initiation group or an incremental initiation group (one to two sessions per week) according to the frequency of HD per week at baseline. We compared health-related quality of life (HRQOL), daily urine volume at 12 months and all-cause mortality between the groups. We matched the thrice-weekly and incremental groups at a 1:2 ratio using propensity score matching.

Results

A total of 312 patients (207 in the thrice-weekly group and 105 in the incremental group) were selected. All-cause mortality was comparable between the two groups before and after propensity score matching. The HRQOL tended to be better in the incremental group for the majority of domains of the Kidney Disease Quality of Life Short Form and Beck's Depression Inventory; however, only the symptoms and problems domain was significantly better in the incremental group at 3 months after HD. At 12 months after HD, there were no differences between the groups. The daily urine volume at 12 months after HD was similar between the two groups.

Conclusions

Incremental HD initiation showed comparable results to thrice-weekly initiation for HRQOL, residual renal function and all-cause mortality. Incremental HD may be considered an additional option for HD initiation in selected patients.

Klotho plays a protective role against glomerular hypertrophy in a cell cycle-dependent manner in diabetic nephropathy

There are few studies on the effect of klotho on podocytes in diabetic nephropathy. Thus, we tested whether klotho exerts a protective effect against glomerular injury in diabetes. Mouse podocytes were cultured in media containing 5.6 or 30 mM glucose(HG) with or without 200 pM of recombinant klotho (rKL). Additionally, 32 mice were injected intraperitoneally with either diluent( n = 16, C) or with streptozotocin ( n = 16, DM). Control and diabetic mice underwent sham operation and unilateral nephrectomy, respectively. Eight mice from each control and DM group were treated daily with 10 μg·kg^-1·day^-1 of rKL, using an osmotic minipump. Klotho was expressed in podocytes, and its expression was dependent on peroxisome proliferator-activateed receptor-γ (PPARγ). HG treatment increased the expression of cell cycle-related and apoptotic markers, and these were significantly attenuated by rKL; rKL inhibited the extracellular signal-regulated protein kinase-1/2 and p38 signaling pathways in HG-induced podocyte injury. However, siRNA against klotho gene in HG-treated podocytes failed to aggravate cell cycle arrest and apoptosis. When HG-treated podocytes were incubated in the high-klotho-conditioned medium from tubular epithelial cells, cell injury was significantly attenuated. This effect was not observed when klotho was inhibited by siRNA. In vivo, the expressions of cell cycle-related and apoptotic markers were increased in diabetic mice compared with controls, which were significantly decreased by rKL. Glomerular hypertrophy (GH) and increased profibrotic markers were significantly alleviated after rKL administration. These results showed that klotho was expressed in glomerular podocytes that and its expression was regulated by PPARγ. Additionally, administration of rKL attenuated GH via a cell cycle-dependent mechanism and decreased apoptosis.

The impact of disease severity on paradoxical association between body mass index and mortality in patients with acute kidney injury undergoing continuous renal replacement therapy

BACKGROUND

Association between high body mass index (BMI) and survival benefit is confounded by comorbid conditions such as nutritional status and inflammation. Patients with acute kidney injury (AKI), particularly those receiving continuous renal replacement therapy (CRRT), are highly catabolic and more susceptible to loss of energy. Herein, we evaluated whether disease severity can modify the relationship between BMI and mortality.

METHODS

We conducted an observational study in 1144 patients who had undergone CRRT owing to various causes of AKI between 2010 and 2014. Patients were categorized into four groups; underweight (< 18.5 kg/m²), normal (18.5-22.99 kg/m²), overweight (23.0-24.99 kg/m²), and obesity (≥25 kg/m²) according to BMI classification by the Committee of Clinical Practice Guidelines and Korean Society for the Study of Obesity. More severe disease was defined as sepsis-related organ failure assessment (SOFA) score of ≥ a median value of 12. The study endpoint was death that occurred within 30 days after the initiation of CRRT.

RESULTS

The mean age was 63.2 years and 439 (38.4%) were females. The median BMI was 23.6 (20.9-26.2) kg/m². The obese group were younger and higher SOFA score than normal BMI group. In a multivariable Cox regression analysis, we found a significant interaction between BMI and SOFA score (P <  0.001). Furthermore, obese patients were significantly associated with a lower risk of death as compared to normal BMI group after adjusting confounding factors [hazard ratio (HR), 0.81; 95% confidence interval (CI), 0.68-0.97; P = 0.03]. This association was only evident among patients with high severity (HR, 0.61; 95% CI, 0.48-0.76, P <  0.001). In contrast, in those with low severity, survival benefit of high BMI was lost, whereas underweight was associated with an increased risk of death (HR, 1.74; 95% CI, 1.16-2.60; P = 0.007).

CONCLUSION

In this study, we found a survival benefit of high BMI in AKI patients undergoing CRRT, particularly in those with more disease severity; the effect was not observed in those with less disease severity.

Phosphate is a potential biomarker of disease severity and predicts adverse outcomes in acute kidney injury patients undergoing continuous renal replacement therapy

Hyperphosphatemia is associated with mortality in patients with chronic kidney disease, and is common in critically ill patients with acute kidney injury (AKI); however, its clinical implication in these patients is unknown. We conducted an observational study in 1144 patients (mean age, 63.2 years; male, 705 [61.6%]) with AKI who received continuous renal replacement therapy (CRRT) between January 2009 and September 2016. Phosphate levels were measured before (0 h) and 24 h after CRRT initiation. We assessed disease severity using various clinical parameters. Phosphate at 0 h positively correlated with the Acute Physiology and Chronic Health Evaluation II (APACHE II; P < 0.001) and Sequential Organ Failure Assessment (SOFA; P < 0.001) scores, and inversely with mean arterial pressure (MAP; P = 0.02) and urine output (UO; P = 0.01). In a fully adjusted linear regression analysis for age, sex, Charlson comorbidity index (CCI), MAP, and estimated glomerular filtration rate (eGFR), higher 0 h phosphate level was significantly associated with high APACHE II (P < 0.001) and SOFA (P = 0.04) scores, suggesting that phosphate represents disease severity. A multivariable Cox model also showed that hyperphosphatemia was significantly associated with increased 28-day (HR 1.05, 95% CI 1.02-1.08, P = 0.001) and 90-day (HR 1.05, 95% CI 1.02-1.08, P = 0.001) mortality. Furthermore, patients with increased phosphate level during 24 h were at higher risk of death than those with stable or decreased phosphate levels. Finally, c-statistics significantly increased when phosphate was added to a model that included age, sex, CCI, body mass index, eGFR, MAP, hemoglobin, serum albumin, C-reactive protein, and APACHE II score. This study shows that phosphate is a potential biomarker that can reflect disease severity and predict mortality in critically ill patients receiving CRRT.

Changes in geriatric nutritional risk index and risk of major adverse cardiac and cerebrovascular events in incident peritoneal dialysis patients

Background

Geriatric nutritional risk index (GNRI) is a validated nutritional assessment method, and lower GNRI values are closely associated with adverse clinical outcomes in dialysis patients. This study investigated the impact of changes in GNRI during the first year of dialysis on cardiovascular outcomes in incident peritoneal dialysis (PD) patients.

Methods

We reviewed medical records in 133 incident PD patients to determine GNRI at the start of PD and after 12 months. Patients were categorized into improved (delta GNRI > 0) and worsening/stationary (delta GNRI ≤ 0) groups. The primary outcome was major adverse cardiac and cerebrovascular events (MACCEs).

Results

During a mean follow-up of 51.1 months, the primary outcome was observed in 42 patients (31.6%). The baseline GNRI at PD initiation was not significantly associated with MACCEs (log-rank test, P = 0.40). However, the cumulative event-free rate was significantly lower in the worsening or stationary GNRI group than in the improved group (log-rank test, P = 0.004). Multivariate Cox analysis revealed that a worsening or stationary GNRI was independently associated with higher risk for MACCEs (hazard ratio, 2.47; 95% confidence interval, 1.15–5.29; P = 0.02). In subgroup analysis, patients with worsening or stationary GNRI were at significantly greater risk for MACCEs in both the lower (P = 0.04) and higher (P = 0.01) baseline GNRI groups.

Conclusion

Baseline GNRI was not associated with MACCEs, but patients with deteriorating or stationary nutritional status were at significantly greater risk for MACCEs, suggesting that serial monitoring of nutritional status is important to stratify cardiovascular risk in incident PD patients.

Baseline Chloride Levels are Associated with the Incidence of Contrast-Associated Acute Kidney Injury

Although hypo- and hyperchloremia have been associated with worsening renal outcomes, there has been no study that correlates hypo- and hyperchloremia and the incidence of contrast-associated acute kidney injury (CA-AKI). A total of 13,088 patients with less than 2.0 mg/dL of serum creatinine (Cr) who underwent contrast-enhanced abdominal CT (CECT) were included. Patients were divided into 3 groups based on Cl (the hypo-, normo- and hyperchloremia groups). Patients were also classified by baseline Cr (<1.2; the ‘Normal Cr group’ and 1.2–2.0 mg/dL; the ‘Slightly increased Cr group’). Multivariate logistic regression analysis was used to reveal the association between Cl and CA-AKI. Among patients, 2,525 (19.3%) and 241 (1.8%) patients were classified in the hypo- and hyperchloremia group. The incidence of CA-AKI was significantly lower in the normochloremia group (4.0%) compared to the hypo- (5.4%) and hyperchloremia groups (9.5%). On multivariate logistic regression, hypochloremia was significantly associated with the incidence of CA-AKI compared with normochloremia (1.382, P = 0.002). Moreover, hypochloremia was still significantly associated with the incidence of CA-AKI in ‘Normal Cr group’ compared with normochloremia (1.314, P = 0.015), while hyperchloremia did not show significant association with CA-AKI incidence. In conclusion, hypochloremia might be associated with the incidence of CA-AKI even in patients who have normal-range Cr levels.

High and low sodium intakes are associated with incident chronic kidney disease in patients with normal renal function and hypertension

The association between salt intake and renal outcome in subjects with preserved kidney function remains unclear. Here we evaluated the effect of sodium intake on the development of chronic kidney disease (CKD) in a prospective cohort of people with normal renal function. Data were obtained from the Korean Genome and Epidemiology Study, a prospective community-based cohort study while sodium intake was estimated by a 24-hour dietary recall Food Frequency Questionnaire. A total of 3,106 individuals with and 4,871 patients without hypertension were analyzed with a primary end point of CKD development [a composite of estimated glomerular filtration rate (eGFR) under 60 mL/min/1.73 m² and/or development of proteinuria during follow-up]. The median ages were 55 and 47 years, the proportions of males 50.9% and 46.3%, and the median eGFR 92 and 96 mL/min/1.73 m² in individuals with and without hypertension, respectively. During a median follow-up of 123 months in individuals with hypertension and 140 months in those without hypertension, CKD developed in 27.8% and 16.5%, respectively. After adjusting for confounders, multiple Cox models indicated that the risk of CKD development was significantly higher in people with hypertension who consumed less than 2.08 g/day or over 4.03 g/day sodium than in those who consumed between 2.93-4.03 g/day sodium. However, there was no significant difference in the incident CKD risk among each quartile of people without hypertension. Thus, both high and low sodium intakes were associated with increased risk for CKD, but this relationship was only observed in people with hypertension.

Normal body mass index with central obesity has increased risk of coronary artery calcification in Korean patients with chronic kidney disease

In chronic kidney disease (CKD), overweight and mild obesity have shown the lowest cardiovascular (CV) risk. However, central obesity has been directly associated with CV risk in these patients. This bidirectional relationship of body mass index (BMI) and central obesity prompted us to evaluate CV risk based on a combination of BMI and waist-to-hip ratio (WHR) in nondialysis CKD patients. We included 1078 patients with CKD stage 2 through 5 (nondialysis) enrolled in a nationwide prospective cohort of Korea. Patients were divided into 3 groups by BMI (normal BMI, 18.5-22.9; overweight, 23.0-27.4; and obese, 27.5 and over kg/m²) and were dichotomized by a sex-specific median WHR (0.92 in males and 0.88 in females). Coronary artery calcification (CAC) was determined by multislice computed tomography. CAC (score above 10 Agatston units) was found in 477 patients. Multivariate logistic regression analysis indicated that BMI was not independently associated with CAC. However, WHR showed an independent linear and significant association with CAC (odds ratio, 1.036; 95% confidence interval, 1.007-1.065 per 0.01 increase). Furthermore, when patients were categorized into 6 groups according to a combination of BMI and WHR, normal BMI but higher WHR had the highest risk of CAC compared with the normal BMI with lower WHR group (2.104; 1.074-4.121). Thus, a normal BMI with central obesity was associated with the highest risk of CAC, suggesting that considering BMI and WHR, 2 surrogates of obesity, can help to discriminate CV risk in Korean nondialysis CKD patients.

Determination of the optimal target level of proteinuria in the management of patients with glomerular diseases by using different definitions of proteinuria

Proteinuria is a major determinant of adverse renal outcome, and its reduction slows renal progression in glomerular diseases. However, the optimal target of proteinuria in glomerular diseases is unclear, and discrepancies in the definition of proteinuria produce ambiguous findings. Here we investigated the optimal target of proteinuria by using different definitions of proteinuria. We analyzed 574 IgA nephropathy (IgAN), 175 membranous nephropathy (MGN), and 177 focal segmental glomerulosclerosis (FSGS) cases from 3 Korean kidney centers. We evaluated the impact of proteinuria on renal outcome with 2 definitions: time-average proteinuria (TAP) and time-varying proteinuria (TVP). The endpoint was renal progression, defined as a 50% decline in glomerular filtration rate or end-stage renal disease. During a median follow-up of 57.3 months, the primary outcome occurred in 54 patients with IgAN, 26 with MGN, and 30 with FSGS. Multivariate Cox regression using TAP indicated that there was a linear association between proteinuria and risk of renal progression in IgAN. However, moderate proteinuria was not associated with an increased risk of renal progression in MGN and FSGS. In contrast, the analysis by TVP showed that the risk significantly increased in proportion to proteinuria during follow-up in all 3 diseases. Our findings suggest that TVP-based model can delineate association between proteinuria and risk of renal progression better than TAP-based model, considering that TVP reflects the dynamic change of proteinuria over time. Thus, proteinuria reduction to the lowest possible level is required to improve renal outcomes in patients with glomerular diseases.

The locally activated renin-angiotensin system is involved in albumin permeability in glomerular endothelial cells under high glucose conditions

Background

Although the diabetic milieu per se , hemodynamic changes, oxidative stress and local growth factors such as angiotensin II (AII) are considered to be mediators in the pathogenesis of diabetic nephropathy, the underlying pathways mediating the changes in glomerular endothelial cells (GECs) are not well understood. Therefore, we investigated changes in the renin-angiotensin system (RAS) components in high glucose (HG)-stimulated GECs and the role of the local RAS in morphological and functional changes in GECs under diabetic conditions.

Methods

We stimulated GECs with 5.6 mM glucose or 30 mM glucose with or without an angiotensin II type I receptor blocker (ARB) in vitro and also performed experiments with Sprague-Dawley rats injected with diluent ( n = 16) or streptozotocin [ n = 16, diabetes (DM)]. Eight rats from each group were treated with ARB for 3 months in vivo . Real-time polymerase chain reaction, western blot analysis, enzyme-linked immunosorbent assay and immunofluorescent staining using cultured GECs were performed. The permeability of GECs to macromolecules was assessed by measuring the passage of fluorescein isothiocyanate-labeled bovine serum albumin. Morphological changes were also evaluated by scanning and transmission electron microscopy.

Results

There were significant increases in angiotensinogen expression in HG-stimulated GECs along with significant increases in AI and AII levels. Moreover, the expression of heparan sulfate glycosaminoglycans (HS-GAG) assessed by immunofluorescent staining was significantly lower and the permeability to albumin was significantly higher in GECs exposed to HG medium, and ARB treatment significantly abrogated these changes. Upon electron microscopy examination, the mean size of the GEC fenestrae was significantly greater in HG-stimulated GECs and DM rats, and these increases were significantly ameliorated by ARB.

Conclusions

The local RAS within GECs was activated under HG conditions, and this activation may be associated with both an alteration in GEC fenestration and a decrease in HS-GAG, resulting in the development of albuminuria in diabetic nephropathy.

Selective tubular activation of hypoxia-inducible factor-2α has dual effects on renal fibrosis

Hypoxia-inducible factor (HIF) is a key transcriptional factor in the response to hypoxia. Although the effect of HIF activation in chronic kidney disease (CKD) has been widely evaluated, the results have been inconsistent until now. This study aimed to investigate the effects of HIF-2α activation on renal fibrosis according to the activation timing in inducible tubule-specific transgenic mice with non-diabetic CKD. HIF-2α activation in renal tubular cells upregulated mRNA and protein expressions of fibronectin and type 1 collagen associated with the activation of p38 mitogen-activated protein kinase. In CKD mice, activation of HIF-2α at the beginning of CKD significantly aggravated renal fibrosis, whereas it did not lead to renal dysfunction. However, activation at a late-stage of CKD abrogated both renal dysfunction and fibrosis, which was associated with restoration of renal vasculature and amelioration of hypoxia through increased renal tubular expression of VEGF and its isoforms. As with tubular cells with HIF-2α activation, those under hypoxia also upregulated VEGF, fibronectin, and type 1 collagen expressions associated with HIF-1α activation. In conclusion, late-stage renal tubular HIF-2α activation has protective effects on renal fibrosis and the resultant renal dysfunction, thus it could represent a therapeutic target in late stage of CKD.

Characteristics and Clinical Outcomes of End-Stage Renal Disease Patients on Peritoneal Dialysis for over 15 Years: A Single-Center Experience

Background

Maintaining peritoneal dialysis (PD) for a long time is problematic owing to a number of factors. This study aimed to clarify the characteristics and examine the clinical outcomes of patients who received PD as a long-term dialysis modality.

Methods

All end-stage renal disease (ESRD) patients who initiated PD at Yonsei University Health System between 1987 and 2000 were screened. Patients who maintained PD for over 15 years were classified as the long-term PD group and those who were treated with PD for less than 5 years were included in the short-term PD group. Demographic and biochemical data and clinical outcomes were compared between the groups. Independent factors associated with long-term PD maintenance were ascertained using multivariate logistic regression analysis.

Results

Among 1,116 study patients, 87 (7.8%) were included in the long-term group and 293 (26.3%) were included in the short-term group. In the long-term group, the mean patient age at PD initiation was 39.6 ± 11.5 years, 35 patients (40.2%) were male, and the mean PD duration was 205.3 ± 32.7 months. Patients were younger, body weight was lower, the proportion of patients with diabetes or cardiovascular diseases was lower, and the proportion of low to low-average transporters was higher in the long-term group than in the short-term group ( p < 0.001). Multiple logistic regression analysis revealed that age, body mass index (BMI), serum creatinine, type of PD solution, and diabetes were significant independent factors associated with long-term PD maintenance.

Conclusion

Peritoneal dialysis can be considered as a long-term renal replacement therapy option, especially in non-diabetic, not overweight, and young ESRD patients.

Periostin-binding DNA aptamer treatment attenuates renal fibrosis under diabetic conditions

Diabetic nephropathy, the major cause of chronic kidney disease, is associated with progressive renal fibrosis. Recently, accumulation of periostin, an extracellular matrix protein, was shown to augment renal fibrosis. Aptamers have higher binding affinities without developing the common side effects of antibodies. Thus, we evaluated the effect of periostin inhibition by an aptamer-based inhibitor on renal fibrosis under diabetic conditions. In vitro, transforming growth factor-β1 (TGF-β1) treatment significantly upregulated periostin, fibronectin, and type I collagen mRNA and protein expressions in inner medullary collecting duct (IMCD) cells. These increases were attenuated significantly in periostin-binding DNA aptamer (PA)-treated IMCD cells exposed to TGF-β1. In vivo, PA treatment attenuated the increased blood urea nitrogen levels in the diabetic mice significantly. Fibronectin and type I collagen mRNA and protein expressions increased significantly in the kidneys of diabetic mice: PA administration abrogated these increases significantly. Immunohistochemistry and Sirius Red staining also revealed that fibronectin expression was significantly higher and tubulointersititial fibrosis was significantly worse in diabetic mice kidneys compared with control mice. These changes were ameliorated by PA treatment. These findings suggested that inhibition of periostin using a DNA aptamer could be a potential therapeutic strategy against renal fibrosis in diabetic nephropathy.

PGC-1α Protects from Notch-Induced Kidney Fibrosis Development

Kidney fibrosis is the histologic manifestation of CKD. Sustained activation of developmental pathways, such as Notch, in tubule epithelial cells has been shown to have a key role in fibrosis development. The molecular mechanism of Notch-induced fibrosis, however, remains poorly understood. Here, we show that, that expression of peroxisomal proliferation g-coactivator (PGC-1α) and fatty acid oxidation-related genes are lower in mice expressing active Notch1 in tubular epithelial cells (Pax8-rtTA/ICN1) compared to littermate controls. Chromatin immunoprecipitation assays revealed that the Notch target gene Hes1 directly binds to the regulatory region of PGC-1α Compared with Pax8-rtTA/ICN1 transgenic animals, Pax8-rtTA/ICN1/Ppargc1a transgenic mice showed improvement of renal structural alterations (on histology) and molecular defect (expression of profibrotic genes). Overexpression of PGC-1α restored mitochondrial content and reversed the fatty acid oxidation defect induced by Notch overexpression in vitro in tubule cells. Furthermore, compared with Pax8-rtTA/ICN1 mice, Pax8-rtTA/ICN1/Ppargc1a mice exhibited improvement in renal fatty acid oxidation gene expression and apoptosis. Our results show that metabolic dysregulation has a key role in kidney fibrosis induced by sustained activation of the Notch developmental pathway and can be ameliorated by PGC-1α.

Structure of spin excitations in heavily electron-doped Li0.8Fe0.2ODFeSe superconductors

Heavily electron-doped iron-selenide high-transition-temperature (high-T_c) superconductors, which have no hole Fermi pockets, but have a notably high T_c, have challenged the prevailing s_± pairing scenario originally proposed for iron pnictides containing both electron and hole pockets. The microscopic mechanism underlying the enhanced superconductivity in heavily electron-doped iron-selenide remains unclear. Here, we used neutron scattering to study the spin excitations of the heavily electron-doped iron-selenide material Li_0.8Fe_0.2ODFeSe (T_c = 41 K). Our data revealed nearly ring-shaped magnetic resonant excitations surrounding (π, π) at ∼21 meV. As the energy increased, the spin excitations assumed a diamond shape, and they dispersed outward until the energy reached ∼60 meV and then inward at higher energies. The observed energy-dependent momentum structure and twisted dispersion of spin excitations near (π, π) are analogous to those of hole-doped cuprates in several aspects, thus implying that such spin excitations are essential for the remarkably high T_c in these materials.

The microscopic mechanism underlying an enhanced superconductivity in electron-doped iron selenide superconductor remains unclear. Here, Pan et al. report the spin excitations of Li_0.8Fe_0.2ODFeSe, revealing analogous momentum structure and dispersion to hole-doped cuprates.

High dietary phosphorus density is a risk factor for incident chronic kidney disease development in diabetic subjects: a community-based prospective cohort study

Background: High serum phosphorus concentrations are associated with an increased risk of cardiovascular disease and progression of chronic kidney disease (CKD). However, the relation between dietary phosphorus intake and CKD development has not been well evaluated.Objective: In this study, we investigated the impact of dietary phosphorus density on the development of incident CKD in a cohort of subjects with normal renal function.Design: Data were retrieved from the Korean Genome and Epidemiology Study, a prospective community-based cohort study. The study cohort consisted of subjects aged 40-69 y, who were followed up biennially from 2001 to 2014. A total of 873 subjects with diabetes mellitus (DM) and 5846 subjects without DM (non-DM) were included in the final analysis. The primary endpoint was incident CKD, defined as a composite of estimated glomerular filtration rate <60 mL · min^-1 · 1.73 m^-2 and/or the development of proteinuria.Results: In the DM and non-DM groups, the mean ages of the participants were 55.6 ± 8.7 and 51.4 ± 8.6 y, the numbers of male subjects were 454 (52.0%) and 2784 (47.6%), and the mean estimated glomerular filtration rates were 91.6 ± 14.0 and 94.5 ± 14.0 mL · min^-1 · 1.73 m^-2, respectively. The mean values of dietary phosphorus density, defined as the ratio of a single-day dietary phosphorus amount to the total daily calorie intake, were 0.51 ± 0.08 mg/kcal in the DM group and 0.51 ± 0.07 mg/kcal in the non-DM group. During the follow-up, CKD newly developed in 283 (32.4%) and 792 subjects (13.5%) in the DM and non-DM groups, respectively. When the subjects were divided into quartiles according to the dietary phosphorus density in each group, the highest quartile was significantly associated with the development of incident CKD by multiple Cox proportional hazard analysis in the DM group (P = 0.02) but not in the non-DM group (P = 0.72).Conclusions: High dietary phosphorus density is associated with an increased risk of CKD development in DM patients with normal renal function. The causality in this association needs to be tested in a randomized controlled trial.

The pattern of choosing dialysis modality and related mortality outcomes in Korea: a national population-based study

BACKGROUND/AIMS

Since comorbidities are major determinants of modality choice, and also interact with dialysis modality on mortality outcomes, we examined the pattern of modality choice according to comorbidities and then evaluated how such choices affected mortality in incident dialysis patients.

METHODS

We analyzed 32,280 incident dialysis patients in Korea. Patterns in initial dialysis choice were assessed by multivariate logistic regression analyses. Multivariate Poisson regression analyses were performed to evaluate the effects of interactions between comorbidities and dialysis modality on mortality and to quantify these interactions using the synergy factor.

RESULTS

Prior histories of myocardial infarction (p = 0.031), diabetes (p = 0.001), and congestive heart failure (p = 0.003) were independent factors favoring the initiation with peritoneal dialysis (PD), but were associated with increased mortality with PD. In contrast, a history of cerebrovascular disease and 1-year increase in age favored initiation with hemodialysis (HD) and were related to a survival benefit with HD (p < 0.001, both). While favoring initiation with HD, having Medical Aid (p = 0.001) and male gender (p = 0.047) were related to increased mortality with HD. Furthermore, although the severity of comorbidities did not inf luence dialysis modality choice, mortality in incident PD patients was significantly higher compared to that in HD patients as the severity of comorbidities increased (p for trend < 0.001).

CONCLUSIONS

Some comorbidities exerted independent effects on initial choice of dialysis modality, but this choice did not always lead to the best results. Further analyses of the pattern of choosing dialysis modality according to baseline comorbid conditions and related consequent mortality outcomes are needed.

Circulating CD89-IgA complex does not predict deterioration of kidney function in Korean patients with IgA nephropathy

Background:

Soluble CD89 (sCD89)-IgA complex plays a key role in the pathogenesis of IgA nephropathy (IgAN). However, there is a lack of evidence supporting this complex as a good biomarker for disease progression. This study aimed to evaluate the usefulness of sCD89-IgA complex for risk stratification of IgAN.

Methods:

A total of 326 patients with biopsy-proven IgAN were included. sCD89-IgA complex was measured by sandwich-enzyme-linked immunosorbent assay. The study endpoints were a 30% decline in estimated glomerular filtration rate (eGFR).

Results:

sCD89-IgA complex levels were inversely and weakly associated with eGFR at the time of biopsy (r=−0.12, p=0.03). However, the significance between the two factors was lost in the multivariate linear regression after adjustment of clinical factors (β=0.35, p=0.75). In a multivariate Cox model, the highest (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.35–1.61; p=0.45) and middle (HR, 0.93; 95% CI, 0.46–1.89; p=0.84) tertiles of sCD89-IgA complex levels were not associated with an increased risk of developing a 30% decrease in eGFR. Furthermore, the decline rates in eGFR did not differ between groups and C-statistics revealed that the sCD89-IgA complex were not superior to clinical factors in predicting disease progression.

Conclusions:

This study found no association between sCD89-IgA complex levels and disease progression in IgAN. Although sCD89 can contribute to the formation of immune complexes, our findings suggest that the sCD89-IgA level is not a good predictor of adverse outcomes and has limited clinical utility as a biomarker for risk stratification in IgAN.

Association of serum lipid levels over time with survival in incident peritoneal dialysis patients

BACKGROUND

The association of dyslipidemia with mortality has not been fully evaluated in patients on peritoneal dialysis (PD). Moreover, changes in lipids levels over time and associated death risk have not yet been studied in this population.

OBJECTIVE

We studied the association of time-updated serum lipid concentrations with all-cause and cardiovascular (CV) mortalities in a 10-year cohort of 749 incident PD patients.

METHODS

Association was assessed using time-varying Cox proportional hazard regression models with adjustment for multiple variables including statin therapy.

RESULTS

During a median follow-up of 36 (interquartile range, 21-61) months, 273 all-cause and 107 CV deaths occurred. Compared with those with total cholesterol (TC) of 180 to <210 or low-density lipoprotein cholesterol (LDL-C) of 100 to <130 mg/dL, hazard ratios (95% confidence interval) of the lowest TC (<150 mg/dL) and LDL-C (<70 mg/dL) were 2.32 (1.61-3.35) and 2.02 (1.45-2.83) for all-cause mortality and 1.87 (1.04-3.37) and 1.92 (1.13-3.26) for CV mortality, respectively. Lower triglyceride (<100 mg/dL) and high-density lipoprotein cholesterol (<30 mg/dL) levels were associated with higher all-cause mortality (1.66 [1.11-2.47] and 1.57 [1.08-2.29]) but not with CV mortality.

CONCLUSIONS

Contrary to the general population, lower TC and LDL-C levels over time were significantly associated with both worse survival and increased CV mortality in incident PD patients. Although lower triglyceride and high-density lipoprotein cholesterol concentrations were associated with significantly higher all-cause mortality, they failed to show any clear association with CV mortality. The underlying mechanisms responsible for this apparent paradox await further investigations.