A New Predictive Equation for Estimating Serum Ionized Calcium Levels in Patients on Chronic Hemodialysis.

BACKGROUND Circulating calcium mainly carries out its physiologic function in its ionized form (iCa). Clinically, iCa is usually estimated by multiplying the total calcium (TCa) level by 0.5 in the general population, but this method is not accurate when applied to patients on long-term hemodialysis (CHD). Accordingly, this study aimed to develop a predictive function for iCa in patients on CHD by incorporating TCa and other additional variables. MATERIAL AND METHODS This was a retrospective cross-sectional study consisting of 2 cross-sectional datasets: a derivation set including 469 CHD patients in June 2019, and a validation set including 446 CHD patients in September 2019. The derivation set's data were analyzed using the stepwise model selection of machine learning with 10-fold cross-validation to develop a predictive function for iCa. This predictive function was then applied to the validation set's data, and the predictive function's estimated iCa was compared with the actual laboratory iCa by using the paired-samples t test and intraclass correlation coefficient. RESULTS After analyzing the routine laboratory data parameters of patients in the derivation set, the following 5 variables were included in the predictive function of iCa: blood urea nitrogen, creatinine, phosphate, TCa, and albumin. This predictive function was applied to the validation set to yield an estimated iCa level that was not significantly different from the laboratory-measured iCa level of the validation dataset (P=0.676) with an excellent ICC of 0.905. CONCLUSIONS We developed a new predictive function that accurately measures the iCa in patients on CHD by using routine laboratory data.

Serum uric acid is associated with chronic kidney disease in elderly Chinese patients with diabetes.

BACKGROUND: The relationship between hyperuricemia and chronic kidney disease (CKD) has been investigated extensively. However, studies on elderly individuals are still limited. Moreover, there is no consensus on whether hyperuricemia or elevated serum uric acid (SUA) within the normal range is correlated with the new onset of CKD and whether there are differences between males and females. METHODS: We included 39039 elderly diabetic patients without CKD at baseline from a community-based cohort in Wuhan, China. The outcome event was the new onset of CKD (defined as an estimated glomerular filtration rate < 60 mL/min/1.73 m2). Multivariate Cox models were used to assess the adjusted hazard ratio (HR). RESULTS: During the 2-year follow-up period, 3162 (8.10%) patients with diabetes developed new-onset CKD. The optimal cutoff value of SUA for incident CKD was 347.4 µmol/L. The adjusted HRs of hyperuricemia for new-onset CKD were 1.925 (1.724-2.150) and 1.676 (1.520-1.848) for males and females, respectively. The risk of developing CKD increased across the Q4 group up to 2.242 times for their counterparts in the lowest SUA quartile, independent of age, sex, diabetes duration, obesity, hypertension, systolic blood pressure, diastolic blood pressure, smoking, drinking, dyslipidemia, triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and fasting plasma glucose. CONCLUSIONS: Hyperuricemia is an independent predictor of incident CKD. Elevated SUA was linearly correlated with CKD in elderly patients with diabetes, showing a relatively higher intensity among males compared with that among females. The optimal cutoff value of SUA for the risk of new-onset CKD in elderly patients with diabetes was 347.4 µmol/L.

Copeptin is associated with microalbuminuria and renal function in the general Japanese population.

An association between copeptin (precursor molecule of arginine vasopressin) and markers for renal function has been reported, but data on the Japanese population has been limited. In this study, we investigated whether elevated copeptin levels are associated with microalbuminuria and renal dysfunction in the general Japanese population. A total of 1,262 participants (842 female and 420 male) were enrolled. Multiple regression analysis was performed to assess the association of copeptin levels (logarithm) with estimated glomerular filtration rate (eGFR) and the urine albumin-to-creatinine ratio (UACR) after adjusting for age, BMI, and lifestyle variables. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression methods in which chronic kidney disease (CKD) was the dependent variable. The copeptin levels differed significantly with sex, but were not found to be related to age or the span of time from preceding meal to blood sampling. In female participants, copeptin level was negatively correlated with eGFR (beta = -0.100, p-value = 0.006) and positively correlated with UACR (beta = 0.099, p-value = 0.003). In male participants, a negative correlation (beta = -0.140, p-value = 0.008) was observed for eGFR. In both females and males, those with high copeptin levels had more than double the ORs of CKD (OR = 2.1-2.9) adjusted for CKD-related factors. The present study found elevated copeptin levels to be associated with renal function loss in the Japanese population and microalbuminuria in female. Moreover, it was evident that high copeptin levels are associated with CKD. These results suggest that copeptin could be considered a marker of renal function.

Soluble CD14 and Osteoprotegerin Associate with Ankle-Brachial Index as a Measure of Arterial Stiffness in Patients with Mild-to-Moderate Chronic Kidney Disease in a Five-Year Prospective Study.

INTRODUCTION: Vascular lesions and arterial stiffness appear at early stages of chronic kidney disease (CKD) and follow an accelerated course with disease progression, contributing to high cardiovascular mortality. There are limited prospective data on mechanisms contributing to progression of arterial stiffness in mild-to-moderate CKD (stages 2-3). METHODS: We applied an affinity proteomics approach to identify candidates of circulating biomarkers with potential impact on vascular lesions in CKD and selected soluble cluster of differentiation 14 (sCD14), angiogenin (ANG), and osteoprotegerin (OPG) for further analysis. We studied their association with ankle-brachial index (ABI) and carotid intima-media thickness, as measures of arteriosclerosis and atherosclerosis, respectively, in 48 patients with CKD stages 2-3, who were prospectively followed and intensively treated for 5 years, and 44 healthy controls. RESULTS: Concentrations of sCD14 (p < 0.001), ANG (p < 0.001), and OPG (p < 0.05) were higher in patients with CKD 2-3 at baseline, and sCD14 (p < 0.001) and ANG (p < 0.001) remained elevated in CKD patients at follow-up. There were positive correlations between ABI and sCD14 levels (r = 0.36, p = 0.01) and between ABI and OPG (r = 0.31, p = 0.03) at 5 years. The changes in sCD14 during follow-up correlated to changes in ABI from baseline to 5 years (r = 0.41, p = 0.004). CONCLUSION: Elevated levels of circulating sCD14 and OPG in patients with CKD 2-3 were significantly associated with ABI, a measure of arterial stiffness. An increase in sCD14 over time in CKD 2-3 patients was associated with a corresponding increase in ABI. Further studies are needed to examine if early intensive multifactorial medication to align with international treatment targets may influence cardiovascular outcomes.

A potential link between fibroblast growth factor-23 and the progression of AKI to CKD.

BACKGROUND: Patients who recover from acute kidney injury (AKI) have a 25% increase in the risk of chronic kidney disease (CKD) and a 50% increase in mortality after a follow-up of approximately 10 years. Circulating FGF-23 increases significantly early in the development of AKI, is significantly elevated in patients with CKD and has become a major biomarker of poor clinical prognosis in CKD. However, the potential link between fibroblast growth factor-23 levels and the progression of AKI to CKD remains unclear. METHOD: Serum FGF-23 levels in AKI patients and ischaemia‒reperfusion injury (IRI) mice were detected with ELISA. Cultured HK2 cells were incubated with FGF-23 and PD173074, a blocker of FGFR, and then TGFß/Smad and Wnt/ß-catenin were examined with immunofluorescence and immunoblotting. Quantitative real-time polymerase chain reaction was used to detect the expression of COL1A1 and COL4A1. Histologic staining confirmed renal fibrosis. RESULTS: The level of serum FGF-23 was significantly different between AKI patients and healthy controls (P < 0.01). Moreover, serum FGF-23 levels in the CKD progression group were significantly higher than those in the non-CKD progression group of AKI patients (P < 0.01). In the AKI-CKD mouse model, serum FGF-23 levels were increased, and renal fibrosis occurred; moreover, the protein expression of ß-catenin and p-Smad3 was upregulated. PD173074 downregulated the expression of ß-catenin and p-Smad3 and reduced fibrosis in both mice and HK2 cells. CONCLUSION: The increase in FGF-23 may be associated with the progression of AKI to CKD and may mediate renal fibrosis via TGF-ß and Wnt/ß-catenin activation.

Cystatin C-Based Equation to Estimate GFR without the Inclusion of Race and Sex.

BACKGROUND: The accuracy of estimation of kidney function with the use of routine metabolic tests, such as measurement of the serum creatinine level, has been controversial. The European Kidney Function Consortium (EKFC) developed a creatinine-based equation (EKFC eGFRcr) to estimate the glomerular filtration rate (GFR) with a rescaled serum creatinine level (i.e., the serum creatinine level is divided by the median serum creatinine level among healthy persons to control for variation related to differences in age, sex, or race). Whether a cystatin C-based EKFC equation would increase the accuracy of estimated GFR is unknown. METHODS: We used data from patients in Sweden to estimate the rescaling factor for the cystatin C level in adults. We then replaced rescaled serum creatinine in the EKFC eGFRcr equation with rescaled cystatin C, and we validated the resulting EKFC eGFRcys equation in cohorts of White patients and Black patients in Europe, the United States, and Africa, according to measured GFR, levels of serum creatinine and cystatin C, age, and sex. RESULTS: On the basis of data from 227,643 patients in Sweden, the rescaling factor for cystatin C was estimated at 0.83 for men and women younger than 50 years of age and 0.83 + 0.005 × (age - 50) for those 50 years of age or older. The EKFC eGFRcys equation was unbiased, had accuracy that was similar to that of the EKFC eGFRcr equation in both White patients and Black patients (11,231 patients from Europe, 1093 from the United States, and 508 from Africa), and was more accurate than the Chronic Kidney Disease Epidemiology Collaboration eGFRcys equation recommended by Kidney Disease: Improving Global Outcomes. The arithmetic mean of EKFC eGFRcr and EKFC eGFRcys further improved the accuracy of estimated GFR over estimates from either biomarker equation alone. CONCLUSIONS: The EKFC eGFRcys equation had the same mathematical form as the EKFC eGFRcr equation, but it had a scaling factor for cystatin C that did not differ according to race or sex. In cohorts from Europe, the United States, and Africa, this equation improved the accuracy of GFR assessment over that of commonly used equations. (Funded by the Swedish Research Council.).

Serum Phosphate Levels Modify the Impact of FGF23 Levels on Hemoglobin in Chronic Kidney Disease.

Anemia is a complication of chronic kidney disease (CKD). Phosphate and fibroblast growth factor-23 (FGF23) have a close relationship, as both are related to the pathogenesis of anemia. However, the possible interplay between them regarding their effect on anemia has not been evaluated. This was a cross-sectional study of 896 participants from the NEFRONA study (273 CKD3, 246 CKD4-5, 282 dialysis and 95 controls). The levels of 25(OH) and 1,25(OH)2 vitamin D, intact FGF23 (iFGF23) and soluble Klotho were measured, together with standard blood biochemistries. Anemia was defined as hemoglobin levels < 13 g/dL in men and <12 g/dL in women. Patients with anemia (407, 45.4%) were younger, mostly men and diabetic; were in advanced CKD stages; had lower calcium, 1,25(OH)2 vitamin D and albumin levels; and had higher ferritin, phosphate, intact PTH, and iFGF23. An inverse correlation was observed between hemoglobin and both iFGF23 and phosphate. The multivariate logistic regression analyses showed that the adjusted risk of anemia was independently associated with higher serum phosphate and LogiFGF23 levels (ORs (95% CIs) of 4.33 (2.11−8.90) and 8.75 (3.17−24.2), respectively (p < 0.001)). A significant interaction between phosphate and iFGF23 (OR of 0.66 (0.53−0.83), p < 0.001) showed that the rise in the adjusted predicted risk of anemia with the increase in iFGF23 was steeper when phosphate levels were low. Phosphate levels acted as modifiers of the effect of iFGF23 concentration on anemia. Thus, the effect of the increase in iFGF23 levels was stronger when phosphate levels were low.

Utilidad de la fórmula HUGE para el diagnóstico de enfermedad renal crónica en el anciano / Usefulness of the HUGE formula for the diagnosis of chronic kidney disease in the elderly

INTRODUCCIÓN: La enfermedad renal crónica se encuentra en ascenso.Prevenir o retardar su progresión mediante la aplicación de estrategias dirigidas al diagnóstico precoz es esencial. OBJETIVO: Evaluar la utilidad de la fórmula HUGE para el diagnóstico de Enfermedad Renal Crónica en el anciano. MATERIAL Y MÉTODO: Se realizó un estudio observacional descriptivo prospectivo y de corte longitudinal en 260 adultos mayores que ingresaron en los servicios de Geriatría y Medicina Interna del Hospital Clínico Quirúrgico "Hermanos Ameijeiras" en el período enero de 2019 y junio de 2020. RESULTADOS: El 58,5% de la muestra de estudio fueron mujeres. La edad promedio fue de 77,1 ± 7,3 años. La enfermedad renal crónica estuvo presente en el 64,2% de los pacientes. Se observó mayor frecuencia de pacientes con daño renal (32,7%) al emplear la formula CKD­ EPI en comparación con los identificados al emplear la fórmula HUGE (25,0%). Al estimar la concordancia entre ambas fórmulas se observó un estadístico kappa (k) de 0,814 (IC de 95%:0,7370 - 0,8909; p < 0,001). La sensibilidad de la fórmula de HUGE fue de un 76,5% (IC de 95%: 66,9% - 86,1%) y la especificidad de un 100% (99,7% - 100%). El valor predictivo positivo fue de 100 % (IC de 95%: 99,2% - 100%) y el negativo de 89,7% (85,2% - 94,2%). CONCLUSIONES: La fórmula CKD-EPI identifica daño renal en mayor porcentaje, en estadios precoces. Por el contrario, la fórmula de HUGE, detecta el daño renal en un porcentaje mayor en estadios más avanzados.La concordancia para diagnosticar daño renal entre la fórmula CKD-EPI y HUGE fue muy buena. La fórmula HUGE es útil, sensible y específica para evaluar la enfermedad renal crónica en los adultos mayores.

INTRODUCTION: Chronic kidney disease is on the rise. Preventing or delaying its progression through the application of strategies aimed at early diagnosis is essential. OBJECTIVE: To evaluate the usefulness of the HUGE formula for the diagnosis of Chronic Kidney Disease in the elderly. MATERIAL AND METHOD: A prospective, descriptive and longitudinal observational study was carried out in 260 older adults who were admitted to the Geriatrics and Internal Medicine services of the "Hermanos Ameijeiras" Surgical Clinical Hospital between January 2019 and June 2020. RESULTS: 58.5% of the study sample was women. The mean age was 77.1 ± 7.3 years. CKD was present in 64.2% of the patients. A higher frequency of patients with kidney damage (32.7%) was observed when using the CKD ­ EPI formula compared to those identified when using the HUGE (25.0%). When estimating the concordance between both formulas, a kappa statistic (k) of 0.814 (95% CI: 0.7370 - 0.8909; p < 0.001) was observed. The sensitivity of the HUGE formula was 76.5% (95% CI: 66.9% - 86.1%) and the specificity was 100% (99.7% - 100%). The positive predictive value was 100% (95% CI: 99.2% - 100%) and the negative predictive value was 89.7% (85.2% - 94.2%). CONCLUSIONS: The CKD-EPI formula identifies kidney damage in a higher percentage, in early stages. On the contrary, the HUGE formula detects kidney damage in a higher percentage in more advanced stages. The concordance to diagnose kidney damage between the CKD-EPI and HUGE formula was very good. The HUGE formula is useful, sensitive, and specific for evaluating chronic kidney disease in older adults.

The role of renal damage markers in the diagnosis of early stages of kidney injury in patients with latent autoimmune diabetes in adults.

Serum creatinine level begins to increase after a decrease in glomerular filtration rate (GFR) by 50% and more, so the question emerged about a more accurate method of determining GFR. The study aimed to determine the role of renal damage markers in the diagnosis of early-stage renal disease in patients with latent autoimmune diabetes in adults (LADA). We included 84 patients with diabetes mellitus (DM) and chronic kidney disease (CKD) caused by diabetic kidney disease (DKD), as well as 25 representatives of the control group. Patients were divided into three groups - 43 people with LADA, 21 with type 1 diabetes mellitus (T1DM), and 20 patients with type 2 diabetes mellitus (T2DM). GFR was assessed using six formulas after establishing the category of GFR and albuminuria. The GFR rate estimated by the CKD-EPI formula in patients with LADA and DKD did not significantly differ from that of CKD-EPI cysC, slightly different from MDRD GFR (10.6% higher, respectively) but 21.9% lower compared to CG formula. In patients with LADA and T1DM, GFR was higher in cases with existing albuminuria, regardless of the formulas used. Thus, the non albuminuria phenotype is accompanied by a greater degree of renal impairment, which indicates the need to determine serum cystatin C in the early stages of LADA. Cystatin C levels are the most accurate, early, and independent predictor of the development and progression of CKD in patients with DM, including LADA.

Can plasma TWEAK levels predict coronary slow flow in patients with chronic kidney disease?

BACKGROUND: The tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is one of the inflammatory mediators contributing to the atherosclerotic process. TWEAK has been studied in patients with chronic kidney disease (CKD), and it has demonstrated that its level declines as estimated glomerular filtration rate (eGFR) decreases. Most studies have found that the decreased TWEAK levels were seen in atherosclerosis and associated with plaque calcification. The objective of this prospective study was to clarify any relationship between coronary slow-flow (CSF) and TWEAK levels in patients with CKD under conservative treatment. METHODS: This prospective study included 93 consecutive patients with CKD (mean creatinine level was 1.8±0.4 mg/dL) undergoing invasive coronary angiography (ICA) for any reason except for acute coronary syndromes from May 2019 to March 2020. A total of 93 patients were divided into two groups concerning having CSF (n=35) or no-CSF (n=58). RESULTS: Patients with CSF had higher TWEAK levels than those without CSF (695.2± 225.2 vs. 465.8±157.6, p<0.001). As the number of coronary arteries with slow flow increased, TWEAK levels increased statistically significantly (r:0.635/ p<0.001). Receiver operating characteristic (ROC) analysis showed that TWEAK levels of 516 pg/mL could predict CSF in patients with CKD. CONCLUSIONS: Our study has shown that plasma TWEAK levels were an independent predictor for CSF in patients with CKD. In addition, our study has found that elevated TWEAK levels may not reflect the healthy arteries as it was hypothesized in the past.

Factors associated with 1-year changes in serum fibroblast growth factor 23 levels in pediatric patients with chronic kidney disease.

BACKGROUND: Fibroblast growth factor 23 (FGF23) levels increase as kidney function decreases and are associated with increased mortality in patients with chronic kidney disease (CKD). Inflammation has also been shown to increase FGF23 production in adults; however, this has not been validated in pediatric patients with CKD. Furthermore, previous studies on children involved a single measurement of FGF23 without a follow-up, and a few studies have examined changes in FGF23 levels. METHODS: We measured the levels of serum intact FGF23, tumor necrosis factor-α (TNF-α), and interleukin-6 as parameters of inflammation and other variables related to bone metabolism at baseline and after 1 year in 62 pediatric patients with CKD (stages 2-5D, 1-16 years old). Factors related to changes in FGF23 levels were investigated. RESULTS: The median age of patients at the evaluation was 10.5 years (interquartile range 6.0-14.0), and the estimated glomerular filtration rate (eGFR) was 59.0 mL/min/1.73 m2 (45.1-69.3). Primary diseases included congenital anomalies of the kidney and urinary tract, ischemic kidney, and glomerulonephritis. The baseline value of FGF23 was 66.5 pg/mL (48.3-96.4), and percent change in FGF23 levels after 1 year was 8.5% (- 29.9-74.7). The percent change in FGF23 levels showed a negative correlation with that in eGFR (P = 0.010), and a positive correlation with that in TNF-α levels (P = 0.035). A multivariate linear regression analysis identified TNF-α as an independent factor increasing FGF23 levels. CONCLUSIONS: An increase in TNF-α levels is associated with elevation of FGF23 levels in pediatric patients with CKD.

Serum osteocalcin concentration as an independent biomarker of osteoporosis in patients with chronic kidney disease.

OBJECTIVES: Osteocalcin, an osteoblast-derived hormone, is associated with the development of osteoporosis and arteriosclerosis in the general population. However, its role on the pathogenesis of osteoporosis and vascular calcification in patients with chronic kidney disease (CKD) is unclear. Here, we investigated the connection between osteocalcin, bone mineral density (BMD), and abdominal aortic calcification (AAC) in CKD patients. MATERIALS AND METHODS: In total, 95 patients with stage 2 to stage 5 CKD were enrolled. Serum osteocalcin levels were measured using an electrochemiluminescence immunoassay. BMD was determined by dual-energy X-ray absorptiometry, and AAC scores were generated from lateral lumbar radiograph findings. RESULTS: 95 patients were assigned into normal bone density (30.5%, n = 29), osteopenia (45.3%, n = 43), and osteoporosis (24.2%, n = 23) groups. The osteoporosis group was characterized by older age, higher female-to-male ratio, phosphorous levels, calcification scores, osteocalcin levels, and intact parathyroid hormone (PTH) levels, while with lower hemoglobin levels as compared to normal and osteopenia groups. Multivariate multinominal regression analysis showed age, female sex, intact PTH, and serum osteocalcin level were independent determinants of osteoporosis severity in CKD patients. Furthermore, serum osteocalcin level is positively correlated to intact PTH in multivariate linear regression model, indicating that osteocalcin might be a bone turnover marker in patients with CKD. Multivariate stepwise linear regression analysis revealed that age, diabetes mellitus, poorer renal function, rather than osteocalcin, have independent associations with AAC score. CONCLUSION: Elevated serum osteocalcin levels could be considered as a marker of osteoporosis rather than that of vascular calcification in patients with CKD.

Expression of whole blood miR-126-3p, -30a-5p, -1299, -182-5p and -30e-3p in chronic kidney disease in a South African community-based sample.

The burden of chronic kidney disease (CKD) in Africa remains poorly characterized, due partly to the lack of appropriate diagnostic strategies. Although in recent years the diagnostic and prognostic utility of microRNAs (miRNAs) have gained prominence in the context of CKD, its value has not been evaluated in African populations. We investigated the expression of whole blood miRNAs (miR-126-3p, -30a-5p, -1299, -182-5p and -30e-3p) in a total sample of 1449 comprising of 13.3% individuals with CKD (stage 1-5) and 26.4% male participants, as well as the association of these miRNAs with prevalent CKD, in a community-based sample of South African adults. We used Reverse Transcription Quantitative Real-Time PCR (RT-qPCR) to analyze miRNA expression. There was an increased expression in whole blood miR-126-3p, -30a-5p, -1299 and -182-5p in individuals with CKD, compared to those without (all p ≤ 0.036), whereas miR-30e-3p showed no significant difference between the groups (p = 0.482). Only miR-126-3p, -182-5p and -30e-3p were independently associated with increased risk of CKD (all p ≤ 0.022). This study showed for the first time that there is a dysregulation of whole blood miR-126-3p, -30a-5p, -1299 and -182-5p in South Africans of mixed-ancestry with CKD. More research is needed to ascertain their role in CKD risk screening in African populations.

Serum thymus and activation-regulated chemokine level is associated with the severity of chronic kidney disease-associated pruritus in patients undergoing peritoneal dialysis.

BACKGROUND: Thymus and activation-regulated chemokine (TARC), which induces a Th2-dominated inflammation, is a well-known biomarker that reflects the severity of atopic dermatitis. The present study aimed to evaluate TARC as a Th2-associated marker with chronic kidney disease-associated pruritus (CKD-aP) in patients with peritoneal dialysis (PD). METHODS: This single-centre cross-sectional study included patients who underwent PD in our hospital between August 2020 and July 2021. The severity and impaired quality of life (QOL) of CKD-aP were assessed using the visual analogue scale (VAS) and Japanese version of the 5-D itch scale (5D-J), respectively. RESULTS: A total of 48 patients with PD were included in the present study. Age and dialysis vintage were (mean ± SD) 64.8 ± 12.0 year and (median (IQR)) 38.5 (11.5-91.5) month, respectively. VAS and 5D-J scores were 3.3 ± 2.0 and 10.5 (9.0-12.0), respectively. Serum TARC level was 481.5 (278.9-603.4) pg/mL (upper limits of normal 450 pg/mL) and significantly correlated with VAS (r = 0.39, p = 0.006) and 5D-J score (r = 0.37, p = 0.009). Multivariate linear analysis revealed that higher serum TARC level was significantly associated with VAS (p < 0.001) and 5D-J score (p < 0.001). Furthermore, the serum brain natriuretic peptide level tended to be associated with VAS (p = 0.060) and 5D-J score (p = 0.029). CONCLUSION: Serum TARC level is an independent predictor of the severity and impaired QOL of CKD-aP in patients with PD, and TARC might be involved in the pathogenesis of CKD-aP.

Circulating Cystatin C Is an Independent Risk Marker for Cardiovascular Outcomes, Development of Renal Impairment, and Long-Term Mortality in Patients With Stable Coronary Heart Disease: The LIPID Study.

Background Elevated plasma cystatin C levels reflect reduced renal function and increased cardiovascular risk. Less is known about whether the increased risk persists long-term or is independent of renal function and other important biomarkers. Methods and Results Cystatin C and other biomarkers were measured at baseline (in 7863 patients) and 1 year later (in 6106 patients) in participants in the LIPID (Long-Term Intervention with Pravastatin in Ischemic Disease) study, who had a previous acute coronary syndrome. Outcomes were ascertained during the study (median follow-up, 6 years) and long-term (median follow-up, 16 years). Glomerular filtration rate (GFR) was estimated using Chronic Kidney Disease Epidemiology Collaboration equations (first GFR-creatinine, then GFR-creatinine-cystatin C). Over 6 years, in fully adjusted multivariable time-to-event models, with respect to the primary end point of coronary heart disease mortality or nonfatal myocardial infarction, for comparison of Quartile 4 versus 1 of baseline cystatin C, the hazard ratio was 1.37 (95% CI, 1.07-1.74; P=0.01), and for major cardiovascular events was 1.47 (95% CI, 1.19-1.82; P<0.001). Over 16 years, the association of baseline cystatin C with coronary heart disease, cardiovascular, and all-cause mortality persisted (each P<0.001) and remained significant after adjustment for estimated GFR-creatinine-cystatin C. Cystatin C also predicted the development of chronic kidney disease for 6 years (odds ratio, 6.61; 95% CI, 4.28-10.20) independently of estimated GFR-creatinine and other risk factors. However, this association was no longer significant after adjustment for estimated GFR-creatinine-cystatin C. Conclusions Cystatin C independently predicted major cardiovascular events, development of chronic kidney disease, and cardiovascular and all-cause mortality. Prediction of long-term mortality was independent of improved estimation of GFR. Registration URL: https://anzctr.org.au; Unique identifier: ACTRN12616000535471.

Effects of veverimer on serum bicarbonate and physical function in women with chronic kidney disease and metabolic acidosis: a subgroup analysis from a randomised, controlled trial.

BACKGROUND: Globally, the prevalence of chronic kidney disease (CKD) is higher in women than in men; however, women have been historically under-represented in nephrology clinical trials. Metabolic acidosis increases risk of progressive loss of kidney function, causes bone demineralization and muscle protein catabolism, and may be more consequential in women given their lower bone and muscle mass. Veverimer, an investigational, non-absorbed polymer that binds and removes gastrointestinal hydrochloric acid, is being developed as treatment for metabolic acidosis. METHODS: This was a Phase 3, multicenter, randomised, blinded, placebo-controlled trial in 196 patients with CKD (eGFR: 20-40 mL/min/1.73 m2) and metabolic acidosis who were treated for up to 1 year with veverimer or placebo. We present the findings from a pre-specified subgroup analysis evaluating the effects of veverimer on metabolic acidosis and physical function among women (N = 77) enrolled in this trial. RESULTS: At week 52, women treated with veverimer had a greater increase in mean (± standard error) serum bicarbonate than the placebo group (5.4 [0.5] vs. 2.2 [0.6] mmol/L; P < 0.0001). Physical Function reported by patients on the Kidney Disease and Quality of Life - Physical Function Domain, a measure that includes items related to walking, stair climbing, carrying groceries and other activities improved significantly in women randomized to veverimer vs placebo (+ 13.2 vs. -5.2, respectively, P < 0.0031). Objectively measured performance time on the repeated chair stand test also improved significantly in the veverimer group vs. placebo (P = 0.0002). CONCLUSIONS: Veverimer was effective in treating metabolic acidosis in women with CKD, and significantly improved how they felt and functioned. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03390842 . Registered on January 4, 2018.

Serum uric acid level and all-cause and cardiovascular mortality in peritoneal dialysis patients: A systematic review and dose-response meta-analysis of cohort studies.

BACKGROUND: The association between serum uric acid (SUA) and all-cause and cardiovascular disease (CVD) mortality in peritoneal dialysis (PD) patients is controversial. Therefore, we aimed to determine the relationship between SUA and all-cause and CVD mortality in PD patients. METHOD: Web of Science, EMBASE, PubMed and the Cochrane Library databases were searched from their inception to 7 April 2021. Effect estimates were presented as hazard ratios (HRs) with 95% confidence intervals (95% CIs) and pooled using random effects model. RESULT: Thirteen cohort studies with 22418 patients were included in this systematic review, of which 9 were included in the meta-analysis. Before switching the reference group, pooled result for the highest SUA category was significantly greater than the median for all-cause mortality (HR = 2.41, 95% CI: 1.37-4.26). After switching the reference group, the highest SUA category did not demonstrate an increased all-cause (HR = 1.40, 95% CI: 0.95-2.05) or CVD (HR = 1.30, 95% CI: 0.72-2.34) mortality compared with the lowest SUA category. Dose-response analysis suggested a nonlinear association between SUA and all-cause mortality risk (Pnonlinearity = 0.002). CONCLUSION: This meta-analysis didn't find the relationship between SUA levels and all-cause and CVD mortality risk in PD patients. More rigorously designed studies are warranted in the future.

Estimated Glomerular Filtration Rate in Chronic Kidney Disease: A Critical Review of Estimate-Based Predictions of Individual Outcomes in Kidney Disease.

Chronic kidney disease (CKD) is generally regarded as a final common pathway of several renal diseases, often leading to end-stage kidney disease (ESKD) and a need for renal replacement therapy. Estimated GFR (eGFR) has been used to predict this outcome recognizing its robust association with renal disease progression and the eventual need for dialysis in large, mainly cross-sectional epidemiological studies. However, GFR is implicitly limited as follows: (1) GFR reflects only one of the many physiological functions of the kidney; (2) it is dependent on several non-renal factors; (3) it has intrinsic variability that is a function of dietary intake, fluid and cardiovascular status, and blood pressure especially with impaired autoregulation or medication use; (4) it has been shown to change with age with a unique non-linear pattern; and (5) eGFR may not correlate with GFR in certain conditions and disease states. Yet, many clinicians, especially our non-nephrologist colleagues, tend to regard eGFR obtained from a simple laboratory test as both a valid reflection of renal function and a reliable diagnostic tool in establishing the diagnosis of CKD. What is the validity of these beliefs? This review will critically reassess the limitations of such single-focused attention, with a particular focus on inter-individual variability. What does science actually tell us about the usefulness of eGFR in diagnosing CKD?

Evidence-Based Medical Therapy in Patients With Heart Failure With Reduced Ejection Fraction and Chronic Kidney Disease.

Chronic kidney disease (CKD) as identified by a reduced estimated glomerular filtration rate (eGFR) is a common comorbidity in patients with heart failure with reduced ejection fraction (HFrEF). The presence of CKD is associated with more severe heart failure, and CKD itself is a strong independent risk factor of poor cardiovascular outcome. Furthermore, the presence of CKD often influences the decision to start, uptitrate, or discontinue possible life-saving HFrEF therapies. Because pivotal HFrEF randomized clinical trials have historically excluded patients with stage 4 and 5 CKD (eGFR <30 mL/min/1.73 m2), information on the efficacy and tolerability of HFrEF therapies in these patients is limited. However, more recent HFrEF trials with novel classes of drugs included patients with more severe CKD. In this review on medical therapy in patients with HFrEF and CKD, we show that for both all-cause mortality and the combined end point of cardiovascular death or heart failure hospitalization, most drug classes are safe and effective up to CKD stage 3B (eGFR minimum 30 mL/min/1.73 m2). For more severe CKD (stage 4), there is evidence of safety and efficacy of sodium glucose cotransporter 2 inhibitors, and to a lesser extent, angiotensin-converting enzyme inhibitors, vericiguat, digoxin and omecamtiv mecarbil, although this evidence is restricted to improvement of cardiovascular death/heart failure hospitalization. Data are lacking on the safety and efficacy for any HFrEF therapies in CKD stage 5 (eGFR < 15 mL/min/1.73 m2 or dialysis) for either end point. Last, although an initial decline in eGFR is observed on initiation of several HFrEF drug classes (angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers/mineralocorticoid receptor antagonists/angiotensin receptor blocker neprilysin inhibitors/sodium glucose cotransporter 2 inhibitors), renal function often stabilizes over time, and the drugs maintain their clinical efficacy. A decline in eGFR in the context of a stable or improving clinical condition should therefore not be cause for concern and should not lead to discontinuation of life-saving HFrEF therapies.