A Randomized Trial of the IMPACT of Ferric Citrate on Erythropoietin and Intravenous Iron Use in Patients Receiving Dialysis.

INTRODUCTION: Ferric citrate (FC) is an FDA-approved iron-based phosphate binder for adults with dialysis-dependent chronic kidney disease. This study investigated the impact of FC as the primary phosphate-lowering therapy on utilization of erythropoiesis-stimulating agents (ESAs) and intravenous (IV) iron. METHODS: In this randomized, open-label, active-controlled, multicenter study (NCT04922645), patients on dialysis and receiving ESAs were randomized to receive FC or remain on standard of care (SOC) phosphate-lowering therapy for up to 6 months. Primary endpoints were the difference in change from baseline to efficacy evaluation period (EEP) in mean monthly ESA and IV iron doses. Secondary endpoints included treatment differences in hemoglobin, phosphate, TSAT, and ferritin levels. RESULTS: 209 patients were randomized to FC and had a Day 1 Dosing Visit (n=103) or SOC (n=106). The two groups had similar baseline laboratory characteristics, however atherosclerotic CV disease, peripheral vascular disease, and congestive heart failure were more common in the SOC group. The mean treatment difference in ESA monthly dose was -30.8 µg (FC vs SOC; p=0.02). An absolute though non-statistically significant change in mean monthly IV iron dose of -37.2 mg (p=0.17) was observed with FC. Mean hemoglobin, TSAT, and ferritin all increased from baseline to the EEP with FC vs. SOC. Serious adverse events occurred in 28% of patients receiving FC vs. 37% in those receiving SOC. CONCLUSIONS: In patients receiving dialysis, treatment with FC as compared to remaining on SOC phosphate binders resulted in reductions in mean monthly ESA and IV iron dose.

SARS-CoV-2 Vaccine Antibody Response and Breakthrough Infection in Patients Receiving Dialysis.

BACKGROUND: Whether breakthrough SARS-CoV-2 infections after vaccination are related to the level of postvaccine circulating antibody is unclear. OBJECTIVE: To determine longitudinal antibody-based response and risk for breakthrough infection after SARS-CoV-2 vaccination. DESIGN: Prospective study. SETTING: Nationwide sample from dialysis facilities. PATIENTS: 4791 patients receiving dialysis. MEASUREMENTS: Remainder plasma from a laboratory processing routine monthly tests was used to measure qualitative and semiquantitative antibodies to the receptor-binding domain (RBD) of SARS-CoV-2. To evaluate whether peak or prebreakthrough RBD values were associated with breakthrough infection, a nested case-control analysis matched each breakthrough case patient to 5 control patients by age, sex, and vaccination month and adjusted for diabetes status and region of residence. RESULTS: Of the 4791 patients followed with monthly RBD assays, 2563 were vaccinated as of 14 September 2021. Among the vaccinated patients, the estimated proportion with an undetectable RBD response increased from 6.6% (95% CI, 5.5% to 7.8%) 14 to 30 days after vaccination to 20.2% (CI, 17.0% to 23.3%) 5 to 6 months after vaccination. Estimated median index values decreased from 91.9 (CI, 78.6 to 105.2) 14 to 30 days after vaccination to 8.4 (CI, 7.6 to 9.3) 5 to 6 months after vaccination. Breakthrough infections occurred in 56 patients, with samples collected a median of 21 days before breakthrough infection. Compared with prebreakthrough index RBD values of 23 or higher (equivalent to ≥506 binding antibody units per milliliter), prebreakthrough RBD values less than 10 and values from 10 to less than 23 were associated with higher odds for breakthrough infection (rate ratios, 11.6 [CI, 3.4 to 39.5] and 6.0 [CI, 1.5 to 23.6], respectively). LIMITATIONS: Single measure of vaccine response; ascertainment of COVID-19 diagnosis from electronic health records. CONCLUSION: The antibody response to SARS-CoV-2 vaccination wanes rapidly in persons receiving dialysis. In this population, the circulating antibody response is associated with risk for breakthrough infection. PRIMARY FUNDING SOURCE: Ascend Clinical Laboratory.

SARS-CoV-2 Infection during the Omicron Surge among Patients Receiving Dialysis: The Role of Circulating Receptor-Binding Domain Antibodies and Vaccine Doses.

BACKGROUND: It is unclear whether circulating antibody levels conferred protection against SARS-CoV-2 infection among patients receiving dialysis during the Omicron-dominant period. METHODS: We followed monthly semiquantitative SARS-CoV-2 RBD IgG index values in a randomly selected nationwide cohort of patients receiving dialysis and ascertained SARS-CoV-2 infection during the Omicron-dominant period of December 25, 2021 to January 31, 2022 using electronic health records. We estimated the relative risk for documented SARS-CoV-2 infection by vaccination status and by circulating RBD IgG using a log-binomial model accounting for age, sex, and prior COVID-19. RESULTS: Among 3576 patients receiving dialysis, 901 (25%) received a third mRNA vaccine dose as of December 24, 2021. Early antibody responses to third doses were robust (median peak index IgG value at assay limit of 150). During the Omicron-dominant period, SARS-CoV-2 infection was documented in 340 (7%) patients. Risk for infection was higher among patients without vaccination and with one to two doses (RR, 2.1; 95% CI, 1.6 to 2.8, and RR, 1.3; 95% CI, 1.0 to 1.8 versus three doses, respectively). Irrespective of the number of vaccine doses, risk for infection was higher among patients with circulating RBD IgG <23 (506 BAU/ml) (RR range, 2.1 to 3.2, 95% CI, 1.3 to 3.4 and 95% CI, 2.2 to 4.5, respectively) compared with RBD IgG ≥23. CONCLUSIONS: Among patients receiving dialysis, a third mRNA vaccine dose enhanced protection against SARS-CoV-2 infection during the Omicron-dominant period, but a low circulating RBD antibody response was associated with risk for infection independent of the number of vaccine doses. Measuring circulating antibody levels in this high-risk group could inform optimal timing of vaccination and other measures to reduce risk of SARS-CoV-2 infection.

SARS-CoV-2 Vaccine Acceptability in Patients on Hemodialysis: A Nationwide Survey.

BACKGROUND: Patients on dialysis are at increased risk for COVID-19-related complications. However, a substantial fraction of patients on dialysis belong to groups more likely to be hesitant about vaccination. METHODS: With the goal of identifying strategies to increase COVID-19 vaccine uptake among patients on hemodialysis, we conducted a nationwide vaccine acceptability survey, partnering with a dialysis network to distribute an anonymized English and Spanish language online survey in 150 randomly selected facilities in the United States. We used logistic regression to evaluate characteristics of vaccine-hesitant persons. RESULTS: A total of 1515 (14% of eligible) patients responded; 20% of all responders, 29% of patients aged 18-44 years, and 29% of Black responders reported being hesitant to seek the COVID-19 vaccine, even if the vaccine was considered safe for the general population. Odds of vaccine hesitancy were higher among patients aged 18-44 years versus those 45-64 years (odds ratio [OR], 1.5; 95% confidence interval [95% CI], 1.0 to 2.3), Black patients versus non-Hispanic White patients (OR, 1.9; 95% CI, 1.3 to 2.7), Native Americans or Pacific Islanders versus non-Hispanic White patients (OR, 2.0; 95% CI, 1.1 to 3.7), and women versus men (OR, 1.6; 95% CI, 1.2 to 2.0). About half (53%) of patients who were vaccine hesitant expressed concerns about side effects. Responders' main information sources about COVID-19 vaccines were television news and dialysis staff (68% and 38%, respectively). CONCLUSIONS: A substantial proportion of patients receiving in-center hemodialysis in the United States are hesitant about seeking COVID-19 vaccination. Facilitating uptake requires outreach to younger patients, women, and Black, Native American, or Pacific Islander patients, and addressing concerns about side effects. PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/JASN/2021_07_07_JASN2021010104.mp3.

SARS-CoV-2 infection during the Omicron surge among patients receiving dialysis: the role of circulating receptor-binding domain antibodies and vaccine doses.

Background: It is unclear whether a third dose of mRNA platform vaccines, or antibody response to prior infection or vaccination confer protection from the Omicron variant among patients receiving dialysis. Methods: Monthly since February 2021, we tested plasma from 4,697 patients receiving dialysis for antibodies to the receptor-binding domain (RBD) of SARS-CoV-2. We assessed semiquantitative median IgG index values over time among patients vaccinated with at least one dose of the two mRNA vaccines. We ascertained documented COVID-19 diagnoses after December 25, 2021 and up to January 31, 2022. We estimated the relative risk for documented SARS-CoV-2 infection by vaccination status using a log-binomial model accounting for age, sex, and prior clinical COVID-19. Among patients with RBD IgG index value available during December 1-December 24, 2021, we also evaluated the association between the circulating RBD IgG titer and risk for Omicron variant SARS-CoV-2 infection. Results: Of the 4,697 patients we followed with monthly RBD assays, 3576 are included in the main analysis cohort; among these, 852 (24%) were unvaccinated. Antibody response to third doses was robust (median peak index IgG value at assay limit of 150, equivalent to 3270 binding antibody units/mL). Between December 25-January 31, 2022, SARS-CoV-2 infection was documented 340 patients (7%), 115 (36%) of whom were hospitalized. The final doses of vaccines were given a median of 272 (25 th , 75 th percentile, 245-303) days and 58 (25 th , 75 th percentile, 51-95) days prior to infection for the 1-2 dose and 3 dose vaccine groups respectively. Relative risks for infection were higher among patients without vaccination (RR 2.1 [95%CI 1.6, 2.8]), and patients with 1-2 doses (RR 1.3 [95%CI 1.0, 1.8]), compared with patients with three doses of the mRNA vaccines. Relative risks for infection were higher among patients with RBD index values < 23 (506 BAU/mL), compared with RBD index value ≥ 23 (RR 2.4 [95%CI 1.9, 3.0]). The higher risk for infection among patients with RBD index values < 23 was present among patients who received three doses (RR 2.1 [95%CI 1.3, 3.4]). Conclusions: Among patients receiving hemodialysis, patients unvaccinated, without a third mRNA vaccine dose, or those lacking robust circulating antibody response are at higher risk for Omicron variant infection. Low circulating antibodies could identify the subgroup needing intensified surveillance, prophylaxis or treatment in this patient population.

SARS-CoV-2 vaccine antibody response and breakthrough infection in dialysis.

BACKGROUND: Patients receiving dialysis are a sentinel population for groups at high risk for death and disability from COVID-19. Understanding correlates of protection post-vaccination can inform immunization and mitigation strategies. METHODS: Monthly since January 2021, we tested plasma from 4791 patients receiving dialysis for antibodies to the receptor-binding domain (RBD) of SARS-CoV-2 using a high-throughput assay. We qualitatively assessed the proportion without a detectable RBD response and among those with a response, semiquantitative median IgG index values. Using a nested case-control design, we matched each breakthrough case to five controls by age, sex, and vaccination-month to determine whether peak and pre-breakthrough RBD IgG index values were associated with risk for infection post-vaccination. RESULTS: Among 2563 vaccinated patients, the proportion without a detectable RBD response increased from 6.6% [95% CI 5.5-8.1] in 14-30 days post-vaccination to 20.2% [95% CI 17.1-23.8], and median index values declined from 92.7 (95% CI 77.8-107.5) to 3.7 (95% CI 3.1-4.3) after 5 months. Persons with SARS-CoV-2 infection prior-to-vaccination had higher peak index values than persons without prior infection, but values equalized by 5 months (p=0.230). Breakthrough infections occurred in 56 patients, with samples collected a median of 21 days pre-breakthrough. Peak and pre-breakthrough RBD values <23 (equivalent to <506 WHO BAU/mL) were associated with higher odds for breakthrough infection (OR: 3.7 [95% CI 2.0-6.8] and 9.8 [95% CI 2.9-32.8], respectively). CONCLUSIONS: The antibody response to SARS-CoV-2 vaccination wanes rapidly, and in persons receiving dialysis, the persisting antibody response is associated with risk for breakthrough infection.

Estimated SARS-CoV-2 Seroprevalence in US Patients Receiving Dialysis 1 Year After the Beginning of the COVID-19 Pandemic.

Importance: Seroprevalence studies complement data on detected cases and attributed deaths in assessing the cumulative spread of the SARS-CoV-2 virus. Objective: To estimate seroprevalence of SARS-CoV-2 antibodies in patients receiving dialysis and adults in the US in January 2021 before the widespread introduction of COVID-19 vaccines. Design, Setting, and Participants: This cross-sectional study used data from the third largest US dialysis organization (US Renal Care), which has facilities located nationwide, to estimate SARS-CoV-2 seroprevalence among US patients receiving dialysis. Remainder plasma (ie, plasma that would have otherwise been discarded) of all patients receiving dialysis at US Renal Care facilities from January 1 to 31, 2021, was tested for SARS-CoV-2 antibodies. Patients were excluded if they had a documented dose of SARS-CoV-2 vaccination or if a residence zip code was missing from electronic medical records. Crude seroprevalence estimates from this sample (January 2021) were standardized to the US adult population using the 2018 American Community Survey 1-year estimates and stratified by age group, sex, self-reported race/ethnicity, neighborhood race/ethnicity composition, neighborhood income level, and urban or rural status. These data and case detection rates were then compared with data from a July 2020 subsample of patients who received dialysis at the same facilities. Exposures: Age, sex, race/ethnicity, and region of residence as well as neighborhood race/ethnicity composition, poverty, population density, and urban or rural status. Main Outcomes and Measures: The spike protein receptor-binding domain total antibody assay (Siemens Healthineers; manufacturer-reported sensitivity of 100% and specificity of 99.8%) was used to estimate crude SARS-CoV-2 seroprevalence in the unweighted sample, and then the estimated seroprevalence rates for the US dialysis and adult populations were calculated, adjusting for age, sex, and region. Results: A total of 21 464 patients (mean [SD] age, 63.1 [14.2] years; 12 265 men [57%]) were included in the unweighted sample from January 2021. The patients were disproportionately older (aged 65-79 years, 7847 [37%]; aged ≥80 years, 2668 [12%]) and members of racial/ethnic minority groups (Hispanic patients, 2945 [18%]; non-Hispanic Black patients, 4875 [29%]). Seroprevalence of SARS-CoV-2 antibodies was 18.9% (95% CI, 18.3%-19.5%) in the sample, with a seroprevalence of 18.7% (95% CI, 18.1%-19.2%) standardized to the US dialysis population, and 21.3% (95% CI, 20.3%-22.3%) standardized to the US adult population. In the unweighted sample, younger persons (aged 18-44 years, 25.9%; 95% CI, 24.1%-27.8%), those who self-identified as Hispanic or living in Hispanic neighborhoods (25.1%; 95% CI, 23.6%-26.4%), and those living in the lowest-income neighborhoods (24.8%; 95% CI, 23.2%-26.5%) were among the subgroups with the highest seroprevalence. Little variability was observed in seroprevalence by geographic region, population density, and urban or rural status in the January 2021 sample (largest regional difference, 1.2 [95% CI, 1.1-1.3] higher odds of seroprevalence in residents of the Northeast vs West). Conclusions and Relevance: In this cross-sectional study of patients receiving dialysis in the US, fewer than 1 in 4 patients had evidence of SARS-CoV-2 antibodies 1 year after the first case of SARS-CoV-2 infection was detected in the US. Results standardized to the US population indicate similar prevalence of antibodies among US adults. Vaccine introduction to younger individuals, those living in neighborhoods with a large population of racial/ethnic minority residents, and those living in low-income neighborhoods may be critical to disrupting the spread of infection.

Antibody Response to COVID-19 vaccination in Patients Receiving Dialysis.

Background: Patients receiving dialysis may mount impaired responses to COVID19 vaccination. Methods: We report antibody response to vaccination from 1140 patients without, and 493 patients with pre-vaccination SARS-CoV-2 RBD antibody. We used commercially available assays (Siemens) to test remainder plasma monthly in association with vaccination date and type, and assess prevalence of absent total receptor binding antibody, and absent or attenuated (index value < 10) semiquantitative receptor binding domain IgG index values. We used Poisson regression to evaluate risk factors for absent or attenuated response to vaccination. Results: Among patients who were seronegative versus seropositive before vaccination, 62% and 56% were ≥65 years old, 20% and 24% were Hispanic, and 22% and 23% were Black. Median IgG index values rose steadily over time, and were higher among the seropositive than in the seronegative patients after completing vaccination (150 [25th, 75th percentile 23.2, 150.0] versus 41.6 [11.3, 150.0]). Among 610 patients who completed vaccination (assessed ≥14 days later, median 29 days later), the prevalence of absent total RBD response, and absent and attenuated semiquantitative IgG response was 4.4% (95% CI 3.1, 6.4%), 3.4% (2.4, 5.2%), and 14.3% (11.7, 17.3%) respectively. Risk factors for absent or attenuated response included longer vintage of end-stage kidney disease, and lower pre-vaccination serum albumin. Conclusions: More than one in five patients receiving dialysis had evidence of an attenuated immune response to COVID19 vaccination.

Transdermal androgen therapy to augment EPO in the treatment of anemia of chronic renal disease.

BACKGROUND: Hypogonadism and anemia are common comorbid conditions in dialysis patients. Testosterone replacement may improve such clinical parameters as anemia, sarcopenia, and low libido. Additionally, by increasing hemoglobin levels, testosterone replacement may allow for a dose reduction in recombinant human erythropoietin (rHuEPO), thereby reducing cost. METHODS: This phase IV, single-center, placebo-controlled, double-blind study assessed the effect of transdermal testosterone on serum testosterone levels, rHuEPO dose required to maintain hemoglobin level, bone mineral content, lean body mass and fat content, cholesterol level, sexual function, and mood. Forty hypogonadal male hemodialysis patients who were administered rHuEPO were randomly assigned to 100 mg of topical 1% testosterone gel (Testim; Auxilium Pharmaceuticals, Norristown, PA) or placebo, applied daily for 6 months. RESULTS: Forty men with a mean age of 56 years and baseline serum testosterone level less than 300 ng/dL (< 10.4 nmol/L) participated in this trial. In men assigned to administration of transdermal testosterone, there was an increase beyond that in the placebo group in mean serum testosterone (77.1 ng/dL [2.7 nmol/L]), dihydrotestosterone (DHT; 0.8 nmol/L), and estradiol levels (6.3 pg/mL [23.0 pmol/L]) and a decrease in mean serum luteinizing hormone levels (-3.1 IU/L). Compared with subjects administered placebo, participants on testosterone replacement therapy did not show an appreciable change in rHuEPO dose (mean difference adjusted for baseline values, 12.6 U/kg/wk; P = 0.73), bone mineral density, lean body mass or fat content, cholesterol level, sexual function, or mood. CONCLUSION: Daily administration of 100 mg of topical 1% testosterone gel for 6 months failed to significantly increase serum testosterone or DHT levels in hypogonadal men with end-stage renal disease. Treatment with transdermal testosterone did not impact on rHuEPO requirement or clinical parameters in this small placebo-controlled study. Greater serum testosterone levels may be required to show clinical benefit in men with end-stage renal disease.

Cell cycle control in glomerular disease.

The sequential activation of the cyclin-dependent kinases by their partner cyclins underlies the progression of the cell cycle from quiescence through growth to cell division. More recently a role for these proteins and their inhibitors has been appreciated in several diverse renal and non-renal cell processes, including proliferation, development, differentiation, hypertrophy and apoptosis. The glomerulus represents a unique micro-environment in which to study the cellular outcome following injury, as each of the three resident cell types undergoes a specific and distinct response to a given stimulus. The mesangial cell is capable of marked proliferation, often accompanied by the deposition of extracellular matrix. In contrast, the podocyte has previously been considered a relatively inert cell, and the reparative proliferation of glomerular endothelial cells following injury has recently been described. There is currently increasing awareness of the need to prevent, control and ameliorate the progression of renal diseases. Knowledge of the cell cycle and an understanding of how this may be beneficially manipulated may be crucial to improving the outlook for patients with both diabetic and non-diabetic glomerular disease.