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Background Dialysis patients have been maintaining a high rate of cardiovascular morbidity and mortality. For this reason, it is to introduce necessary new technical advances in clinical practice. There is a relation between toxins retention and inflammation, mortality and morbidity. Medium cut-off (MCO) membranes are a new generation of membranes that allow the removal of a greater number of medium-sized molecules compared with high-flux hemodialysis (HF-HD), but retaining albumin. MCO membranes have an increased permeability and the presence of internal filtration. Because of these special properties, MCO generated a new concept of therapy called expanded HD (HDx). Until now, online hemodiafiltration (OL-HDF) has demonstrated its superiority, in terms of survival, compared with HF-HD. However, the comparison between OL-HDF and HDx remains an unsolved question. Methods The MOTheR HDx study trial (NCT03714386) is an open-label, multicenter, prospective, 1:1 randomized, parallel-group trial designed to evaluate the efficacy and safety of HDx compared with OL-HDF in patients treated for dialysis in Spain for up to 36 months. The main endpoint is to determinate whether HDx is non inferior to OL-HDF at reducing the combined outcome of all-cause death and stroke (ischemic or hemorrhagic), acute coronary syndrome (angina and myocardial infarction), peripheral arterial disease (amputation or revascularization) and ischemic colitis (mesenteric thrombosis). Results The trial has already started. [ABSTRACT FROM AUTHOR]

Background There is scarce evidence on the fourth dose of severe acute respiratory syndrome coronavirus 2 vaccines in chronic kidney disease (CKD) patients. We evaluated the humoral response and effectivity of the fourth dose in the CKD spectrum: non-dialysis CKD (ND-CKD), haemodialysis (HD), peritoneal dialysis (PD) and kidney transplant (KT) recipients. Methods This is a prespecified analysis of the prospective, observational, multicentric SENCOVAC study. In patients with CKD who had received a complete initial vaccination and one or two boosters and had anti-Spike antibody determinations 6 and 12 months after the initial vaccination, we analysed factors associated with persistent negative humoral response and higher anti-Spike antibody titres as well as the efficacy of vaccination on coronavirus disease 2019 (COVID-19) severity. Results Of 2186 patients (18% KT, 8% PD, 69% HD and 5% ND-CKD), 30% had received a fourth dose. The fourth dose increased anti-Spike antibody titres in HD (P  = .001) and ND-CKD (P  = .014) patients and seroconverted 72% of previously negative patients. Higher anti-Spike antibody titres at 12 months were independently associated with repeated exposure to antigen (fourth dose, previous breakthrough infections), previous anti-Spike antibody titres and not being a KT recipient. Breakthrough COVID-19 was registered in 137 (6%) patients, 5% of whom required admission. Admitted patients had prior titres <620 UI/ml and median values were lower (P  = .020) than in non-admitted patients. Conclusions A fourth vaccine dose increased anti-Spike antibody titres or seroconverted many CKD patients, but those with the highest need for a vaccine booster (i.e. those with lower pre-booster antibody titres or KT recipients) derived the least benefit in terms of antibody titres. Admission for breakthrough COVID-19 was associated with low anti-Spike antibody titres. [ABSTRACT FROM AUTHOR]

Cardiorenal syndromes (CRS) are broadly defined as disorders of the heart and kidneys whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction of the other. CRS are currently classified into five categories, mostly based on disease-initiating events and their acuity or chronicity. CRS types 3 and 4 (also called renocardiac syndromes) refer to acute and chronic kidney dysfunction resulting in acute and chronic heart dysfunction, respectively. The notion of renocardiac syndromes has broadened interest in kidney–heart interactions but uncertainty remains in the nephrological community's understanding of the clinical diversity, pathophysiological mechanisms and optimal management approaches of these syndromes. This triple challenge that renocardiac syndromes (and likely other cardiorenal syndromes) pose to the nephrologist can only be faced through a specific and demanding training plan to enhance his/her cardiological scientific knowledge and through an appropriate clinical environment to develop his/her cardiological clinical skills. The first must be the objective of the subspecialty of cardionephrology (or nephrocardiology) and the second must be the result of collaboration with cardiologists (and other specialists) in cardiorenal care units. This review will first consider various aspects of the challenge s that renocardiac syndromes pose to nephrologists and, then, will discuss those aspects of cardionephrology and cardiorenal units that can facilitate an effective response to the challenges. [ABSTRACT FROM AUTHOR]

Background Chronic kidney disease (CKD) patients are at high-risk for severe coronavirus disease 2019 (COVID-19). The multicentric, observational and prospective SENCOVAC study aims to describe the humoral response and safety of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in CKD patients. Safety and immediate humoral response results are reported here. Methods Four cohorts of patients were included: kidney transplant (KT) recipients, and haemodialysis (HD), peritoneal dialysis (PD) and non-dialysis CKD patients from 50 Spanish centres. Adverse events after vaccine doses were recorded. At baseline and on Day 28 after the last vaccine dose, anti-Spike antibodies were measured and compared between cohorts. Factors associated with development of anti-Spike antibodies were analysed. Results A total of 1746 participants were recruited: 1116 HD, 171 PD, 176 non-dialysis CKD patients and 283 KT recipients. Most patients (98%) received mRNA vaccines. At least one vaccine reaction developed after the first dose in 763 (53.5%) and after the second dose in 741 (54.5%) of patients. Anti-Spike antibodies were measured in the first 301 patients. At 28 days, 95% of patients had developed antibodies: 79% of KT, 98% of HD, 99% of PD and 100% of non-dialysis CKD patients (P < 0.001). In a multivariate adjusted analysis, absence of an antibody response was independently associated with KT (odds ratio 20.56, P = 0.001) and with BNT162b2 vaccine (odds ratio 6.03, P = 0.023). Conclusion The rate of anti-Spike antibody development after vaccination in KT patients was low but in other CKD patients it approached 100%, suggesting that KT patients require persistent isolation measures and booster doses of a COVID-19 vaccine. Potential differences between COVID-19 vaccines should be explored in prospective controlled studies. [ABSTRACT FROM AUTHOR]

Background Kidney replacement therapy (KRT) conferred a high risk for coronavirus disease 2019 (COVID-19) related mortality early in the pandemic. We evaluate the presentation, treatment and outcomes of COVID-19 in patients on KRT over time during the pandemic. Methods This registry-based study involved 6080 dialysis and kidney transplant (KT) patients with COVID-19, representing roughly 10% of total Spanish KRT patients. Epidemiology, comorbidity, infection, vaccine status and treatment data were recorded, and predictors of hospital admission, intensive care unit (ICU) admission and mortality were evaluated. Results Vaccine introduction decreased the number of COVID-19 cases from 1747 to 280 per wave. Of 3856 (64%) COVID-19 KRT patients admitted to the hospital, 1481/3856 (38%) were admitted during the first of six waves. Independent predictors for admission included KT and the first wave. During follow-up, 1207 patients (21%) died, 500/1207 (41%) during the first wave. Among vaccinated patients, mortality was 19%, mostly affecting KT recipients. Overall, independent predictors for mortality were older age, disease severity (lymphopaenia, pneumonia) and ICU rejection. Among patient factors, older age, male sex, diabetes, KT and no angiotensin receptor blockers (ARB) were independent predictors of death. In KT recipients, individual immunosuppressants were independent predictors of death. Over time, patient characteristics evolved and in later pandemic waves, COVID-19 was mainly diagnosed in vaccinated KT recipients; in the few unvaccinated dialysis patients, ICU admissions increased and mortality decreased (28% for the first wave and 16–22% thereafter). Conclusions The clinical presentation and outcomes of COVID-19 during the first wave no longer represent COVID-19 in KRT patients, as the pandemic has become centred around vaccinated KT recipients. Vaccines lowered the incidence of diagnosed COVID-19 and mortality. However, mortality remains high despite increased access to ICU care. [ABSTRACT FROM AUTHOR]

Despite the high prevalence of chronic kidney disease (CKD) and its high cardiovascular risk, patients with CKD, especially those with advanced CKD (stages 4–5 and patients on kidney replacement therapy), are excluded from most cardiovascular clinical trials. It is particularly relevant in patients with advanced CKD and heart failure (HF) who have been underrepresented in many pivotal randomized trials that have modified the management of HF. For this reason, there is little or no direct evidence for HF therapies in patients with advanced CKD and treatment is extrapolated from patients without CKD or patients with earlier CKD stages. The major consequence of the lack of direct evidence is the under-prescription of HF drugs to this patient population. As patients with advanced CKD and HF represent probably the highest cardiovascular risk population, the exclusion of these patients from HF trials is a serious deontological fault that must be solved. There is an urgent need to generate evidence on how to treat HF in patients with advanced CKD. This article briefly reviews the management challenges posed by HF in patients with CKD and proposes a road map to address them. [ABSTRACT FROM AUTHOR]

Background Hemodialysis (HD) patients are commonly prescribed phosphate binders (PBs) to manage serum phosphorus levels, as hyperphosphatemia is strongly associated with poorer survival. Nonadherence with the PB prescription is associated with elevated serum phosphorus levels. We studied associations between patient satisfaction with their PB and serum phosphorus levels and mortality rates. Methods Adult HD patients in Germany, Italy, Spain and the UK in the Dialysis Outcomes and Practice Patterns Study were administered a survey instrument in late 2017. Patients were asked about their satisfaction with their PBs, as measured through three questions (difficulty, inconvenience and dissatisfaction) on a 5-point Likert scale, with each dichotomized into average worst versus good responses. These were used as predictors in linear regression models of continuous serum phosphorus levels and in Cox proportional hazards models of mortality, with adjustments for demographics, comorbidities and laboratory values. Results Patients having greater difficulty, inconvenience and dissatisfaction with their PB had higher serum phosphorus levels in adjusted models {+0.21 mg/dL [95% confidence interval (CI) ±0.23], +0.30 (±0.21) and 0.36 (±0.22), respectively}, and higher odds of having serum phosphorus levels ≥6.0 mg/dL. Measures of dissatisfaction were also associated with an elevated risk of mortality, with adjusted hazard ratios of 2.2 (95% CI 1.3–3.6), 1.6 (1.0–2.6) and 1.7 (1.1–2.7), respectively; this association was not strongly affected by adjustment for baseline serum phosphorous level. Conclusions Self-reported difficulty, inconvenience and dissatisfaction in taking one's prescribed PBs were associated with elevated serum phosphorus levels and serum phosphorus levels above clinically meaningful thresholds. While the mechanism for the association with mortality is unclear, patient-reported satisfaction should be considered when attempting to manage patient serum phosphorus levels. [ABSTRACT FROM AUTHOR]

Background Hyperkalemia is common among hemodialysis (HD) patients and has been associated with adverse clinical outcomes. Previous studies considered a single serum potassium (K) measurement or time-averaged values, but serum K excursions out of the target range may be more reflective of true hyperkalemia events. We assessed whether hyperkalemia excursions lead to an elevated risk of adverse clinical outcomes. Methods Using data from 21 countries in Phases 4–6 (2009–18) of the Dialysis Outcomes and Practice Patterns Study (DOPPS), we investigated the associations between peak serum K level, measured monthly predialysis, over a 4-month period ('peak K') and clinical outcomes over the subsequent 4 months using Cox regression, adjusted for potential confounders. Results The analysis included 62 070 patients contributing a median of 3 (interquartile range 2–6) 4-month periods. The prevalence of hyperkalemia based on peak K was 58% for >5.0, 30% for >5.5 and 12% for >6.0 mEq/L. The all-cause mortality hazard ratio for peak K (reference ≤5.0 mEq/L) was 1.15 [95% confidence interval (CI) 1.09, 1.21] for 5.1–5.5 mEq/L, 1.19 (1.12, 1.26) for 5.6–6.0 mEq/L and 1.33 (1.23, 1.43) for >6.0 mEq/L. Results were qualitatively consistent when analyzing hospitalizations and a cardiovascular composite outcome. Conclusions Among HD patients, we identified a lower K threshold (peak K 5.1–5.5 mEq/L) than previously reported for increased risk of hospitalization and mortality, with the implication that a greater proportion (>50%) of the HD population may be at risk. A reassessment of hyperkalemia severity ranges is needed, as well as an exploration of new strategies for effective management of chronic hyperkalemia. [ABSTRACT FROM AUTHOR]

Background The use of dialysis fluids (DFs) during haemodialysis has been associated with increased oxidative stress and reduced serum magnesium (Mg) levels, contributing to chronic inflammation. Since the role of Mg in modulating immune function and reducing oxidative stress has been demonstrated, the aim of this study was to characterize in vitro whether increasing the Mg concentration in DFs could protect immune cells from oxidative stress and damage. Methods The effect of citrate [citrate dialysis fluid (CDF), 1 mM] or acetate [acetate dialysis fluid (ADF), 3 mM] dialysates with low (0.5 mM; routinely used) or high (1 mM, 1.25 mM and 2 mM) Mg concentrations was assessed in THP-1 human monocytes. The levels of reactive oxygen species (ROS), malondialdehyde (MDA) and oxidized/reduced (GSSG/GSH) glutathione were quantified under basal and inflammatory conditions (stimulation with lipopolysaccharide, LPS). Results The increase of Mg in CDF resulted in a significant reduction of ROS production under basal and inflammatory conditions (extremely marked in 2 mM Mg; P  <  0.001). These effects were not observed in ADF. Interestingly, in a dose-dependent manner, high Mg doses in CDF reduced oxidative stress in monocytes under both basal and inflammatory conditions. In fact, 2 mM Mg significantly decreased the levels of GSH, GSSG and MDA and the GSSG/GSH ratio in relation to 0.5 mM Mg. Conclusions CDF produces lower oxidative stress than ADF. The increase of Mg content in DFs, especially in CDF, could have a positive and protective effect in reducing oxidative stress and damage in immune cells, especially under inflammatory conditions. [ABSTRACT FROM AUTHOR]

Background Healthcare workers have been overexposed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the current pandemic, but there is little information on the impact of SARS-CoV-2 on nephrologists. The aim of this study was to assess SARS-CoV-2 infections in nephrologists in the first and second pandemic waves, describing risk factors and clinical features. Methods This national survey was sent to Spanish nephrologists. Epidemiological data, comorbidities and medications were collected and compared between infected and non-infected nephrologists. Symptoms, prescribed treatments and outcomes are described for infected nephrologists. Results Three hundred and twenty-seven nephrologists (66% female, age 46 ± 11 years) completed the survey. Of them, 62 (19%) were infected by SARS-CoV-2. Infection was detected by real-time reverse transcription-polymerase chain reaction in the 37 symptomatic patients (62%) and by serological tests in 25 (38%) asymptomatic individuals. Five (8%) of the infected nephrologists were hospitalized. Contrary to the general population, most infections occurred during the first pandemic wave and, specifically, during the first month, when personal protective equipment (PPE) shortages were more severe. Factors associated with infection in univariate analysis were younger age (P = 0.004), work in non-nephrology departments (P = 0.045), higher exposure to coronavirus disease 2019 patients (P < 0.001), lack of appropriate PPE (P < 0.001) and non-O ABO blood group. In an adjusted multivariate model, only lack of appropriate PPE remained predictive of infection [hazard ratio 3.5 (95% confidence interval 1.9–6.8), P < 0.0001]. Conclusions SARS-CoV-2 infection was frequent among nephrologists, was frequently diagnosed late and was associated with working conditions. [ABSTRACT FROM AUTHOR]

Age and chronic kidney disease have been described as mortality risk factors for coronavirus disease 2019 (COVID-19). Currently, an important percentage of patients in haemodialysis are elderly. Herein, we investigated the impact of age on mortality among haemodialysis patients with COVID-19. Data was obtained from the Spanish COVID-19 chronic kidney disease (CKD) Working Group Registry. From 18 March 2020 to 27 August 2020, 930 patients on haemodialysis affected by COVID-19 were included in the Registry. A total of 254 patients were under 65 years old and 676 were 65 years or older (elderly group). Mortality was 25.1% higher (95% CI: 22.2–28.0%) in the elderly as compared to the non-elderly group. Death from COVID-19 was increased 6.2-fold in haemodialysis patients as compared to the mortality in the general population in a similar time frame. In the multivariate Cox regression analysis, age (hazard ratio (HR) 1.59, 95% CI: 1.31–1.93), dyspnea at presentation (HR 1.51, 95% CI: 1.11–2.04), pneumonia (HR 1.74, 95% CI: 1.10–2.73) and admission to hospital (HR 4.00, 95% CI: 1.83–8.70) were identified as independent mortality risk factors in the elderly haemodialysis population. Treatment with glucocorticoids reduced the risk of death (HR 0.68, 95% CI: 0.48–0.96). In conclusion, mortality is dramatically increased in elderly haemodialysis patients with COVID-19. Our results suggest that this high risk population should be prioritized in terms of protection and vaccination. [ABSTRACT FROM AUTHOR]

Age and chronic kidney disease have been described as mortality risk factors for coronavirus disease 2019 (COVID-19). Currently, an important percentage of patients in haemodialysis are elderly. Herein, we investigated the impact of age on mortality among haemodialysis patients with COVID-19. Data was obtained from the Spanish COVID-19 chronic kidney disease (CKD) Working Group Registry. From 18 March 2020 to 27 August 2020, 930 patients on haemodialysis affected by COVID-19 were included in the Registry. A total of 254 patients were under 65 years old and 676 were 65 years or older (elderly group). Mortality was 25.1% higher (95% CI: 22.2-28.0%) in the elderly as compared to the non-elderly group. Death from COVID-19 was increased 6.2-fold in haemodialysis patients as compared to the mortality in the general population in a similar time frame. In the multivariate Cox regression analysis, age (hazard ratio (HR) 1.59, 95% CI: 1.31-1.93), dyspnea at presentation (HR 1.51, 95% CI: 1.11-2.04), pneumonia (HR 1.74, 95% CI: 1.10-2.73) and admission to hospital (HR 4.00, 95% CI: 1.83-8.70) were identified as independent mortality risk factors in the elderly haemodialysis population. Treatment with glucocorticoids reduced the risk of death (HR 0.68, 95% CI: 0.48-0.96). In conclusion, mortality is dramatically increased in elderly haemodialysis patients with COVID-19. Our results suggest that this high risk population should be prioritized in terms of protection and vaccination.

Oxidative stress is exacerbated in hemodialysis patients by several factors, including the uremic environment and the use of dialysis fluids (DFs) . Since magnesium (Mg) plays a key role in modulating immune function and in reducing oxidative stress, we aimed to evaluate whether increasing the Mg concentration in different DFs could protect against oxidative stress in immunocompetent cells in vitro. Effect of ADF (acetate 3 mM), CDF (citrate 1 mM), and ACDF (citrate 0.8 mM + acetate 0.3 mM) dialysates with Mg at standard (0.5 mM) or higher (1, 1.25, and 2 mM) concentrations were assessed in THP-1 monocyte cultures. Reactive oxygen species (ROS) and malondialdehyde (MDA) levels were quantified under basal and uremic conditions (indoxyl sulfate (IS) treatment). Under uremic conditions, the three DFs with 0.5 mM Mg promoted higher ROS production and lipid damage than the control solution. However, CDF and ACDF induced lower levels of ROS and MDA, compared to that induced by ADF. High Mg concentration (1.25 and/or 2 mM) in CDF and ACDF protected against oxidative stress, indicated by reduced ROS and MDA levels compared to respective DFs with standard concentration of Mg. Increasing Mg concentrations in ADF promoted high ROS production and MDA content. Thus, an increase in Mg content in DFs has differential effects on the oxidative stress in IS-treated THP-1 cells depending on the dialysate used., Competing Interests: P.d.S. received a grant from Baxter, as well as honoraria for participation as a speaker at the meetings of Baxter and sponsorships of scientific congresses by Nipro and Baxter. The other authors declare no conflicts of interest.