This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Remarkably, the mortality in our cohort was lower than that previously reported 4 and similar to the general population, 5 even though some patients are still admitted. Larger studies are underway to provide robust information on the prognosis and management of kidney transplant recipients with COVID-19.

No abstract

<b><i>Introduction:</i></b> COVID-19 is a highly contagious disease that has easily spread worldwide. Outpatient maintenance hemodialysis seems to entail an increased risk of contagion, and previous reports inform of increased mortality among this population. <b><i>Methods:</i></b> We retrospectively analyzed clinical and laboratory parameters, outcomes, and management once discharged of CKD-5D patients infected with SARS-CoV-2 from our health area. <b><i>Results:</i></b> Out of the 429 CKD-5D population, 36 were diagnosed with SARS-CoV-2 infection (8%): 34 on in-center hemodialysis and 2 on peritoneal dialysis. Five were asymptomatic. The most common symptom was fever (70%), followed by dyspnea and cough. History of cardiovascular disease and elevation of LDH and C-reactive protein during admission were associated with higher mortality. Thirteen patients died (36%), 8 patients were admitted to an ICU, and survival was low (38%) among the latter. The mean time to death was 12 days. Most discharged patients got negative rRT-PCR in nasopharyngeal swabs within 26 days of diagnosis. However, there is a portion of cured patients that continue to have positive results even more than 2 months after the initial presentation. <b><i>Conclusions:</i></b> Patients on dialysis have an increased mortality risk if infected with SARS-CoV-2. Preventive measures have proven useful. Thus, proper ones, such as universal screening of the population and isolation when required, need to be generalized. Better de-isolation criteria are necessary to ensure an appropriate use of public health resources.

Introduction Given the increased COVID-19 observed in kidney transplant recipients (KTRs) and haemodialysis patients, several studies have tried to establish the efficacy of mRNA vaccines in these populations by evaluating their humoral and cellular responses. However, there is currently no information on clinical protection (deaths and hospitalizations), a gap that this study aims to fill. Methods Observational prospective study involving 1,336 KTRs and haemodialysis patients from three dialysis units affiliated to Hospital Clínic of Barcelona, Spain, vaccinated with two doses of mRNA-1273 (Moderna) or BNT162b2 (Pfizer-BioNTech) SARS-CoV-2 mRNA vaccines. The outcomes measured were SARS-CoV-2 infection diagnosed by a positive RT-PCR fourteen days after the second vaccine dose, hospital admissions derived from infection, and a severe COVID-19 composite outcome, defined as either ICU admission, invasive and non-invasive mechanical ventilation, or death. Results Six per cent (18/302) of patients on haemodialysis were infected, of whom four required hospital admission (1.3%), only one (0.3%) had severe COVID-19, and none of them died. In contrast, 4.3% (44/1034) of KTRs were infected, and presented more hospital admissions (26 patients, 2.5%), severe COVID-19 (11 patients, 1.1%) or death (4 patients, 0.4%). KTRs had a significantly higher risk of hospital admission than HD patients, and this risk increased with age and male sex (HR 3.37 and 4.74, respectively). Conclusions The study highlights the need for booster doses in KTRs. In contrast, the haemodialysis population appears to have an adequate clinical response to vaccination, at least up to four months from its administration. Graphical abstract

Blood flow (Qb) is one of the dialysis parameters most strongly influencing the performance of dialysis modalities. However, few studies have compared different dialysis modalities in patients with low Qb. We conducted a prospective, single‐center study in 21 patients. Each patient underwent four dialysis sessions with routine dialysis parameters: high‐flux hemodialysis (HD), predilution hemodiafiltration (pre‐HDF), expanded HD (HDx), and postdilution HDF (post‐HDF). The removal ratios (RR) of urea, creatinine, ß2‐microglobulin, myoglobin, prolactin, α1‐microglobulin, free kappa and lambda immunoglobulin light chains (ķFLC and λFLC), α1‐acid glycoprotein, and albumin were compared intraindividually. A proportional part of the dialysate was collected to quantify albumin loss. There were no differences in urea and creatinine RRs. The β2‐microglobulin RR was higher in pre‐HDF and post‐HDF. Myoglobin and prolactin RRs were higher with HDx and post‐HDF. The α1‐microglobulin and α1‐acid glycoprotein RRs were significantly higher with post‐HDF than with other treatments, and RRs obtained with HDx were higher than obtained with HD and pre‐HDF. Free ķFLC and λFLC RRs showed the following results in ascending order: HD, pre‐HDF, HDx, and post‐HDF, most of them with statistical significance. Albumin loss varied from 0.45 g with HD to 3.5 g with post‐HDF. The global removal score values were 41.0 ± 4.8% with HD, 44.0 ± 5.2% with pre‐HDF, 49.5 ± 4.6% with HDx, and 54.8 ± 5.3% with post‐HDF, with significant differences between all treatment modalities. In conclusion, this study confirms the superiority of post‐HDF over high‐flux HD, pre‐HDF, and HDx in patients with low Qb. HDx was the closest alternative to post‐HDF and was clearly superior to HD and pre‐HDF. Finally, pre‐HDF was also superior to HD. With this Qb, there was a higher risk of underdialysis, both diffusive and convective, especially in patients with a session duration of less than 5 h.

Toray has created a new generation of dialyzers, the polysulphone (TS) UL series, and polymethylmethacrylate (PMMA) NF‐U series, which offer enhanced efficacy over the previous TS‐S series and NF‐H series. The aim of this study was to evaluate the safety and efficacy of these dialyzer series versus contrasted expanded hemodialysis (HDx) and postdilution hemodiafiltration (HDF). We conducted a prospective study in 12 patients. Each patient underwent six dialysis sessions: FX80 Cordiax in HD, Toraysulfone TS‐1.8 UL in HD, Theranova 400 in HDx, polymethylmethacrylate (PMMA) NF‐2.1 U in HDF, Toraysulfone TS‐2.1 UL in HDF, and FX80 Cordiax in HDF. The removal ratios (RRs) of urea, creatinine, ß2‐microglobulin, myoglobin, prolactin, α1‐microglobulin, α1‐acid glycoprotein, and albumin were compared intraindividually. Dialysate albumin loss was also measured. The RRs for β2‐microglobulin, myoglobin, prolactin, α1‐microglobulin, and α1‐acid glycoprotein were higher with the TS‐2.1 UL and FX80 Cordiax dialyzers in HDF than those obtained with HD treatments and NF‐2.1 U in HDF. The β2‐microglobulin, myoglobin, and prolactin RRs were also higher with HDx than those obtained with HD treatments. The myoglobin and prolactin RRs were higher with TS‐1.8 UL in HD than those obtained with helixone dialyzers in HD. Dialysate albumin loss was less than 3 g in all situations except in TS‐2.1 UL in HDF. The highest global removal score values were obtained with the TS‐2.1 UL and helixone dialyzers in HDF. Significant differences were found between all study situations. In conclusion, the new generation dialyzers, Toraysulfone TS Series UL and PMMA NF‐U series, show excellent behaviour and tolerance in HD and HDF, representing an upgrade versus their predecessor series. The higher permeability of the TS UL series has been proven with higher efficiency in HD and maximum performance in HDF. The new PMMA NF‐U series allows the use of HDF with good efficiency and complete safety.

Background Metabolic acidosis is a common problem in haemodialysis patients, but acidosis overcorrection has been associated with higher mortality. There is no clear definition of the optimal serum bicarbonate target or dialysate bicarbonate. This study analysed the impact of reducing dialysate bicarbonate from 35 to 32 mEq/L on plasma bicarbonate levels in a cohort of patients treated with online haemodiafiltration (OL-HDF). Methods We performed a prospective cohort study with patients in a stable chronic OL-HDF programme for at least 12 months in the Hospital Clinic of Barcelona. We analysed pre- and post-dialysis total carbon dioxide(TCO2) before and after dialysate bicarbonate reduction from 35 to 32 mEq/L, as well as the number of patients with a pre- and post-dialysis TCO2 within 19–25 and ≤29 mEq/L, respectively, after the bicarbonate modification. Changes in serum sodium, potassium, calcium, phosphorous and parathyroid hormone (PTH) were also assessed. Results We included 84 patients with a 6-month follow-up. At 6 months, pre- and post-dialysis TCO2 significantly decreased (26.78 ± 1.26 at baseline to 23.69 ± 1.92 mEq/L and 31.91 ± 0.91 to 27.58 ± 1.36 mEq/L, respectively). The number of patients with a pre-dialysis TCO2 &gt;25 mEq/L was significantly reduced from 80 (90.5%) to 17 (20.2%) and for post-dialysis TCO2  &gt;29 mEq/L this number was reduced from 83 (98.8%) to 9 (10.7%). PTH significantly decreased from 226.09 (range 172–296) to 182.50 (125–239)  pg/mL at 6 months (P &lt; 0.05) and post-dialysis potassium decreased from 3.16 ± 0.30 to 2.95 ± 0.48 mEq/L at 6 months (P &lt; 0.05). Sodium, pre-dialysis potassium, calcium and phosphorous did not change significantly. Conclusions Reducing dialysate bicarbonate concentration by 3 mEq/L significantly and safely decreased pre- and post-dialysis TCO2, avoiding acidosis overcorrection and improving secondary hyperparathyroidism control. An individualized bicarbonate prescription (a key factor in the adequate control of acidosis) according to pre-dialysis TCO2 is suggested based on these results.