Introduction: The strength of inspiratory and expiratory muscles in patients treated with peritoneal dialysis is lower than in haemodialysis patients and in those after kidney transplantation. The dialysate in the abdominal cavity increases intraab-dominal pressure and disturbs diaphragm contraction.Aim of the research: To compare the effects of inspiratory muscle training (IMT) on respiratory and functional parameters in patients undergoing peritoneal dialysis.Material and methods: A randomised, unblinded trial was conducted. Subjects were randomly assigned to perform 6 weeks of IMT at 40% of maximal inspiratory pressure. Measurements were taken at baseline and 6 weeks after the intervention. Primary outcomes included functional capacity (assessed by 6-minute walk test), maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax), and spirometry parameters.Results: Initially, a cohort of 37 peritoneal dialysis patients, with an average age of 51.3 years (95% CI: 47.1-55.5), underwent randomisation. The control group consisted of 18 participants, whereas the study group comprised 19 subjects. Owing to at-trition prior to the conclusion of the 6-week duration, the control group was subsequently reduced to 11, and the study group to 18. Patients who underwent respiratory muscle training (RMT) showed significant improvement in PImax (p < 0.0001), PEmax (p = 0.048), and 6MWT distance (p = 0.01). Increases in systolic blood pressure (SBP, p = 0.036) and heart rate (HR, p = 0.045) induced by the 6MWT were less marked in the respiratory training group.Conclusions: Respiratory muscle training appears to enhance respiratory muscle strength, potentially improving exercise tolerance. Despite the attrition, our study provides valuable insights into the effects of IMT on respiratory and functional parameters in peritoneal dialysis patients.

Systemic light chain (AL) amyloidosis is a relapsing plasma cell disorder. Therapy is limited, particularly for triple-class refractory disease. We report the use of belantamab mafodotin, a BCMA-directed drug-antibody conjugate, for relapsed AL amyloidosis, including patients traditionally excluded from clinical trials. Thirty-one patients were reviewed, with a median of three prior lines of therapy. The median follow-up was 12 months (95% CI 4-19), and a median of five doses were delivered. The best haematological overall response rate was 71%, and the complete/very good partial response was 58%. Sixty-eight percent had keratopathy and improved in all. Belantamab mafodotin has high efficacy and good tolerability in patients with relapsed AL amyloidosis.

Introduction: The aim of this study was to investigate the persistence of SARS-CoV-2 neutralizing antibodies (NAbs) one year after contracting COVID-19.Material and methods: The study included 38 patients - 34 men and 4 women - suffering from COVID-19 between March 15 and May 26, 2020. The median age in the group was 31 years, ranging from 22 to 67 years. The levels of neutralizing antibodies were measured at three timepoints - baseline, 6 months, and 12 months. The primary endpoint was a post-infection positive result for NAbs (> 15 AU/ml; Results: The median level of NAbs after 12 months was 26.5 AU/ml. At the end of observation (12 months), 21 of the 38 patients had a NAb level of >15 AU/ml (positive). The median antibody halflife was 5.8 months.Conclusions: A high percentage of the patients maintained positive levels of antibodies 6 and 12 months after COVID-19 infection. The dynamics of the antibody level decline suggests the need for booster vaccination at least once a year.

Introduction Chronic comorbidities that are common in the elderly population can have a significant impact on the clinical course, the choice of treatment, and survival of myelodysplastic syndromes (MDS) patients. No studies have focused on the coexistence of two diseases that are common in the elderly population, chronic kidney disease (CKD) and MDS, so the epidemiological data and clinical implications of both diseases occurring together are unknown. Aims Primary objective: to assess the prevalence of CKD in patients with MDS in comparison to the age-adjusted general population. Secondary objective: to evaluate the impact of CKD on clinical course in MDS patients. Methods This was a prospective analysis using clinical and laboratory data from MDS patients who were registered in the Polish Adult Leukemia Group (PALG) Registry from 2010 to 2023. Data have been provided by 28 hematologic centers. CKD was defined as an eGFR < 60 mL/min/1.73m², disregarding albuminuria since urinalysis results were not recorded in the database. The stages of CKD were classified based on eGFR according to the NKF KDOQI National Kidney Foundation Kidney Disease Outcome Quality Initiative guidelines, and eGFR was calculated using CKD-EPI equation. For comparison of the prevalence of CKD in MDS subjects aged ≥60 years to the general population, we used data from the PolSenior 2 study (covering the years 2018-2019). Data were age and sex standardized using demographic tables from Statistics Poland (https:// demografia.stat.gov.pl/bazademografia/Tables.aspx). Median survival time was calculated using Kaplan-Meier estimator. Multivariate analysis was performed using Cox regression. Results Overall, data (including eGFR) were available for 1813 MDS patients. Median age at diagnosis was 71 years [IQR 64 - 78]. and 55.3% patients were male. Sixty percent of the patients were diagnosed as IPPS lower risk. At the time of MDS diagnosis, CKD was detected in 479 patients (26.4%). Among patients aged ≥ 60, the crude rate of CKD was 30.3%. The standardized rate of CKD in the general population aged ≥ 60 years was significantly lower than in the similarly aged MDS group, with rates of 13.2% [CI 12.3-14.1] and 25.5% [CI 22.9-28.4]; p<0.001, respectively. (Figure 1) Patients with CKD were significantly older (median 78 yo) than those without CKD (median 68 yo; p<0.001), and more likely to have diabetes (33.2% vs 19.7%; p<0.001), and to have coincidence of another malignancy (21.6%) than those without CKD (14.9%; p=0.001). Median hemoglobin concentration was significantly lower in the CKD group (8.9 g/dL) than in the non-CKD group (9.4 g/dL; p < 0.05). Subjects with decreased eGFR were more likely to be dependent on RBC transfusion (56.5%) than subjects with eGFR ≥ 60 ml/min per 1.73m 2 (48.9%; p=0.0008). Median survival of patients with eGFR ≥ 60 ml/min per 1.73m 2 was 2.5 y [CI 1.0-6.1] vs 1.4 y [CI 0.6-4.2] for CKD. In multivariate analysis we found that CKD stage, age ≥ 65, higher IPSS score, high-risk IPSS cytogenetics and ECOG >1 were independent predictors of shorter survival. (Figure 2). Conclusions Myelodysplastic syndrome (MDS) subjects are more likely to have chronic kidney disease (CKD) than the general population. The presence of CKD in MDS patients is associated with worse overall survival and higher RBC transfusion requirement.

This article reviews studies on SARS-CoV-2 antibodies, including neutralizing antibodies (NAbs) and post-vaccination response. The SARS-CoV-2 virus is closely related to SARS-CoV and MERS-CoV, sharing 79% and 50% of its genome sequence with them, respectively. Antibodies are crucial in identifying and destroying pathogens such as viruses, and understanding virus-specific antibodies can help end pandemics quickly. The SARS-CoV-2 virus uses the spike protein to enter human cells via the angiotensin-converting enzyme 2 receptor (ACE2). The immune response to the virus involves various components, including dendritic cells, T cells, B cells, and NAbs. Seroconversion, antibody kinetics, and immune response after COVID-19 vaccination are essential factors in understanding the virus and developing treatments. Neutralizing antibody therapies have been explored as potential treatments, but the emergence of viral variants challenges their long-term development. Lessons learned from antibody-based therapies can influence future strategies for treating emerging infectious diseases.

Introduction: Systemic AL amyloidosis, a rare incurable plasma cell disorder, has no approved treatments at relapse. Belantamab mafodotin is an antibody-drug conjugate which targets BCMA antigen approved for relapsed refractory myeloma. We report our results using belantamab mafodotin monotherapy for the treatment of patients with relapsed refractory AL amyloidosis including those traditionally excluded from clinical trials (eGFR<30 ml/min/1.73m 2 and cardiac Mayo stage IIIb disease). Methods: All patients treated with belantamab mafodotin monotherapy at standard dose (2.5 mg/kg) or dose reduction between April 2021 - July 2023. Standardised assessments including measurement of cardiac biomarkers, clonal parameters and imaging were performed and disease assessment was reported as per International Society of Amyloidosis consensus criteria. Results: Twenty-seven patients were included. The median age at was 65 years (range 41-76) and eight (30%) patients were aged >70 years. Eighteen (67%) had λ AL-type and nine (33%) κ AL-type. A median of two organs were involved at baseline (range 1-4) with renal and cardiac involvement in 20 (74%) and 15 (56%) respectively (3 each for Mayo stage IIIa and stage IIIb). The median time from AL amyloidosis diagnosis to first administration of belantamab mafodotin was 69 (range 5-174) months (~6 years) with a median of 3 prior lines of treatment (range 2-6). Prior drug class exposure included proteasome inhibitors (100%), immunomodulatory drugs (81%) and anti-CD38 antibody (81%) therapy. Ten patients (37%) had undergone prior melphalan-conditioned autologous stem cell transplantation. At the time of first belantamab mafodotin dose, the median involved free light chain concentration was 118mg/l (range 31-1778), eGFR was 40 ml/min (range 7 - 120) and a third (9/27) with an eGFR <30 ml/min/1.73m 2. NT-proBNP was 845 ng/l (range 99-70,000). At data cut-off, a median of 5 (range 1-11) doses of belantamab mafodotin were delivered. Of those with evaluable disease, best haematological overall response rate (partial response or better) was 80% (20/25) at a median time to best haematological response of 2 months (95% CI 1-4, range 1-17). Complete response (CR) or very good partial response (VGPR) was achieved in 64% (16/25). Two patients have only had 1 cycle and too early to perform response assessment. Reasons for treatment discontinuation (n=12) were: inadequate response/progression (n=7), keratopathy (n=1), grade 3 thrombocytopenia (n=1), physician choice (n=3: discontinued due to treatment for unrelated metastatic squamous cell carcinoma but remains in CR; facilitation of renal transplant; prior to BCMA-directed CAR-T in VGPR). At a median follow-up of 13 months follow-up (95% CI 4-18, range 1-27) from belantamab mafodotin initiation, 15 patients (56%) remain on therapy. Two patients died (1 due to progressive disease, 1 unrelated) and seven patients progressed and had subsequent line of therapy at a median time of 6 months (95% CI 2-4) in those that had a next line of therapy. Median treatment-free survival or death was 27 months (10-NR), and 1-year treatment-free survival/death was 69% (95% CI 41-86). Median overall survival (OS) is not reached. 1-year OS is 88% (95% CI 59-97). Bilateral microcystic corneal keratopathy, the most frequent adverse event, was seen in 19 (70%) patients (5%; 1/19 grade 4).Ocular adverse events improved in all patients after treatment delay. Only one patient required treatment cessation due to ocular toxicity (despite achieving PR after one dose). Thrombocytopenia was reported in 3 (11%) (grade 3: 1; grade 2: 1). Only two patients remained on the standard dose of 2.5mg/kg for >3 cycles. Nine patients had eGFR <30ml/min and 6/9 started at a dose of 1.25mg/kg with no unexpected side effects (1 patient had grade 3 keratopathy). One patient post-renal transplantation (on tacrolimus and mycophenolate) had no significant toxicity and achieved a CR after cycle 3. No treatment-related deaths, cardiac or renal toxicities observed in our cohort. Conclusion: Belantamab mafadotin has high efficacy and good tolerability in multiply relapsed AL amyloidosis including efficacy in patients otherwise excluded from clinical trials. Treatment-emergent adverse events (especially keratopathy) do not preclude delivery of drug with appropriate dose reductions.

Book Citations: Authors, Title, HemaSphere, 2022;6:(S3):pages. The individual abstract DOIs can be found at https://journals.lww.com/hemasphere/pages/default.aspx. Disclaimer: Articles published in the journal HemaSphere exclusively reflect the opinions of the authors. The authors are responsible for all content in their abstracts including accuracy of the facts, statements, citing resources, etc.

Background: Systemic AL amyloidosis is an incurable relapsing plasma cell disorder. Despite therapeutic advances, there are no approved treatments for relapse disease. Treatment is often challenging due to underlying organ dysfunction. Belantamab mafodotin is an antibody-drug conjugate targeting B-cell maturation antigen with approval for relapsed refractory myeloma. In multiply pre-treated myeloma, the DREAMM-2 phase II trial showed an overall response rate of 32% for those with 2.5 mg/kg dose administered every three weeks with 2/3rd patients reporting keratopathy. A small case series of 6 patients with relapsed AL amyloidosis (Zhang et al, ASH 2021) was recently reported and a phase 2 trial is recruiting for patients with refractory amyloidosis (NCT04617925). Aims: We report our initial results using Belantamab monotherapy for the treatment of patients with AL amyloidosis with relapsed disease. Methods: Data for consecutive patients who were administered Belantamab at a specialist referral centre, National Amyloidosis Centre, University College London, was analysed. Results: Eleven patients were included 8 male, 3 female. Median age at Belantamab initiation was 65 (range 42-74) years. Eight patients had λ AL-type and three κ AL-type. At diagnosis, median involved free light-chain concentration was 534 (range 73-7181) mg/l. A median of two organs involved at baseline (range 1-3): 4 had cardiac involvement (half Mayo stage 2; half Mayo stage 3a) and 8 had renal involvement. The median prior lines of therapy was 3 (range 2-5) with all exposed to prior immunomodulatory drugs, proteasome inhibitors and 73% to anti-CD38 antibody treatments. Thirty-six percent had relapsed after melphalan-conditioned autologous stem cell transplantation. A median of 3 cycles of belantamab were delivered (range 1-8). The most frequent adverse event was ocular toxicity which was experienced in 8 patients (grade 1-3), necessitating dose modification of the three-weekly schedule. One patient developed transient grade 1 dyspnoea and liver dysfunction. No patients developed cytopenias, unlike previous reports (Zhang et al, 2021), nor infections beyond COVID (2 patients mild with no hospital admissions). The majority of the cohort required dose reduction either at initiation (patient 4, due to end stage renal failure; patient 11, post-renal transplant) or during therapy (n=5; three to 1.9mg/kg, two to 1.25mg/kg) due to ocular toxicity. Only one patient remained on the standard dose of 2.5mg/kg for ≥3 cycles. Ocular toxicity improved after treatment interruption (drug intervals 4-6 weeks) and no patients required complete treatment cessation. One patient is too early to assess response. Haematological responses (PR or better) were seen in 7 patients with 3 complete responses and two very good partial responses (VGPR) which are ongoing. Both renal patients (patients 4 and 11) commenced a dose of 1.25mg/kg and sustained a VGPR with no additional toxicity. Patient 3 had a 42% reduction in sFLC after two doses but then a prolonged gap due to keratopathy and has lost the response. There were no cardiac or renal toxicities observed. Image:Summary/Conclusion: Belantamab mafodotin demonstrates significant activity in patients with heavily pre-treated AL amyloidosis with 70% achieving a ≥PR. Apart from keratopathy requiring dose modification, no other substantial toxicity was observed. Two patients with renal impairment (stage V CKD and ESRD) and one patient post-renal transplant tolerated treatment with no additional toxicity. Belantamab mafodotin shows promise in treatment of relapsed AL and needs further prospective trials.

ABSTRACT Background Coronavirus disease 2019 (COVID-19)-related short-term mortality is high in dialysis patients, but longer-term outcomes are largely unknown. We therefore assessed patient recovery in a large cohort of dialysis patients 3 months after their COVID-19 diagnosis. Methods We analyzed data on dialysis patients diagnosed with COVID-19 from 1 February 2020 to 31 March 2021 from the European Renal Association COVID-19 Database (ERACODA). The outcomes studied were patient survival, residence and functional and mental health status (estimated by their treating physician) 3 months after COVID-19 diagnosis. Complete follow-up data were available for 854 surviving patients. Patient characteristics associated with recovery were analyzed using logistic regression. Results In 2449 hemodialysis patients (mean ± SD age 67.5 ± 14.4 years, 62% male), survival probabilities at 3 months after COVID-19 diagnosis were 90% for nonhospitalized patients (n = 1087), 73% for patients admitted to the hospital but not to an intensive care unit (ICU) (n = 1165) and 40% for those admitted to an ICU (n = 197). Patient survival hardly decreased between 28 days and 3 months after COVID-19 diagnosis. At 3 months, 87% functioned at their pre-existent functional and 94% at their pre-existent mental level. Only few of the surviving patients were still admitted to the hospital (0.8–6.3%) or a nursing home (∼5%). A higher age and frailty score at presentation and ICU admission were associated with worse functional outcome. Conclusions Mortality between 28 days and 3 months after COVID-19 diagnosis was low and the majority of patients who survived COVID-19 recovered to their pre-existent functional and mental health level at 3 months after diagnosis.

This article aims to identify the reasons why patients with major depressive episode (MDE) do not seek treatment for their mental disorder. 89 out of 208 persons screened were diagnosed with major depressive episode using the Mini-International Neuropsychiatric Interview. 85 individuals with untreated depression filled out the following questionnaires: Beck Depression Inventory, List of Explanations of Well-Being (LEWB), Brief Measure to Assess Perception of Self-Influence on the Course of the Disease, Coping Inventory for Stressful Situations, Brief Method of Evaluating Coping with Disease, and Metacognitions Questionnaire. There were 43 women (50.6%) and 42 men (49.4%), aged 24 to 93 years (Mean (M) = 68.26 years; Standard Deviation (SD) = 14.19 years), with dialysis vintage ranging from 1 month to 33 years (M = 70.63 months; SD = 75.26 months). Among study patients, 70.6% declared that depression was the cause of their poor well-being, 75.3% attributed their depressive symptoms to kidney failure, and 49.4%, more specifically, to hemodialysis. A total of 64.7% of patients had a low perception of self-influence on the course of their kidney disease, and 58.5% presented a coping style focused on emotions. The most frequent dysfunctional metacognitive beliefs were negative beliefs about not controlling one's own thoughts. This attitude was related to the low perception of self-influence on the course of the disease, maladaptive coping styles, and dysfunctional metacognitive beliefs.

Objective: This study aimed to investigate the efficacy and safety of convalescent plasma (CP) transfusion in a group of high-risk COVID-19 patients. Methods: This prospective study included 204 patients from a single tertiary-care hospital, hospitalized with COVID-19, of whom 102 were treated with CP administration and standard care (PG) and 102 others who received standard care only (CG). The CG was selected from 336 hospitalized patients using the propensity-score matching (PSM) technique using age, MEWS score, and comorbidities. The primary outcome was mortality rate; secondary outcomes were the requirement of a ventilator, length of ventilator need, length of intensive care unit (ICU) stay, and length of overall hospital confinement. Additionally, parameters predicting death in COVID-19 patients were identified. Results: Findings confirmed a significantly lower mortality rate in the PG versus the CG (13.7% vs. 34.3 %, p = 0.001) and a significant difference in the cumulative incidence of death between the two groups (p < 0.001). CP treatment was associated with lower risk of death (OR = 0.25 CI95 [0.06; 0.91], p = 0.041). There were no significant differences in ICU stay, ventilator time, and hospitalization time between the two groups. Conclusions: A significantly lower mortality rate was observed in the group of patients treated with CP. Age, presence of cardiac insufficiency, active cancer, a ventilator requirement, and length of hospitalization significantly increased the risk of death in both groups. Our study shows that CP affords better outcomes when administrated in the earlier stage of high-risk COVID-19 disease.

The mitochondria play a pivotal role in regulating glucose-induced insulin secretion in the pancreatic beta cell. We have recently demonstrated that glutamate derived from mitochondria participates directly in the stimulation of insulin exocytosis. In the present study, mitochondria isolated from the beta cell line INS-1E generated glutamate when incubated with the tricarboxylic acid cycle intermediate succinate. The generation of glutamate correlated with stimulated mitochondrial activity monitored as oxygen consumption and was inhibited by the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Glutamate is formed by the mitochondrial enzyme glutamate dehydrogenase from alpha-ketoglutarate. Transient overexpression of glutamate dehydrogenase in INS-1E cells resulted in potentiation of glucose-stimulated hormone secretion without affecting basal release. These results further point to glutamate as an intracellular messenger playing a key role in the control of insulin exocytosis.

Background: ANCA-associated vasculitides (AAV) is a group of rare disorders where inflammation and damage of the small blood vessels lead to dysfunction of the supplied organs. In severe flares of the disease patients may require intensive care unit (ICU) admission and treatment. The study aims to characterize Polish patients with AAV who were admitted to the ICU and compare them to the others. Methods: An observational, retrospective study based on the POLVAS - registry of Polish adult patients with AAV was carried out. Patients admitted to the ICU (ICU group) were identified and compared with the patients who did not require ICU admission (non-ICU group). Characteristics and comparison between groups were made using standard statistic descriptive methods. Results: 30 patients admitted to the ICU were identified among 573 cases included in the registry. All patients in the ICU group with available data were ANCA positive. The clinical manifestations related to the ICU admission were respiratory, renal and central nervous system involvement. The treatment regimen for remission induction was similar in both groups. Almost half of the patients in the ICU-group (48.3%) required dialysis, whereas in the non-ICU group it was 21.8% (P = 0.01). Infections were also more frequent in the ICU group (72.4% vs. 36.9% P < 0.001). The mortality rate among patients who needed ICU treatment was significantly higher when compared to the rest of the patients (53.6% vs. 7.8%; P < 0.001). Conclusions: In the Polish AAV cohort one in twenty patients required ICU admission. This group was characterized by multiple organ involvement and high mortality.

Methods Search strategy A systematic search for articles on the use of ECMO in patients with COVID-19 was performed in the PubMed database on April 19, 2020 (Supplementary material).Only studies that reported the number of deaths were included.The identified studies were additionally analyzed by citation tracking to look for further eligible articles.Statistical analysis Categorical variables were presented as frequency and percentages.Patient informed consent to participate was not required for this study.Results and discussion A 36-year -old Caucasian man was admitted to the Department of Internal Medicine, Nephrology and Transplantation Medicine because of fever, dyspnea, malaise, nonproductive cough that started 6 days earlier, and 1-day diarrhea.He reported close contact with a person who later tested positive for severe acute respiratory syndrome coronavirus 2 (SARS -CoV-2) that occurred 12 days before presentation.Due to high fever, he was taking over the counter drugs including metamizole, acetaminophen, and ibuprofen.The patient was a professional driver and a bodybuilder, but he denied using anabolic

‐2 in kidney patients 463 while bronchoalveolar lavage yielded 93% positivity. Thus, we may face the problem with false test results, both positive and negative. Therefore, the European Center for Disease Control and Prevention in their latest 9th update discussed tests performance criteria and validation.6 Every coin has two sides, the former is diagnosis of infection, the latter is its resolution. Recovery from coronavirus disease 2019 (COVID-19) is defined as absence of fever for more than 3 days, resolution of symptoms and radiologic improvement, and 2 negative PCR tests taken 24 hours apart.7 Kidney disease, in particular, requiring renal replacement therapy is associated with profound alterations in the immune system.8 Infections are the second leading cause of death among hemodialysis patients, mainly due to the impairment of both innate and acquired immunity.8 The accumulation of uremic toxins is believed to be the main cause of immune deficiency observed in advanced kidney disease.8 On the basis of the published literature, we present a patient with acute kidney injury who recovered from COVID-19 pneumonia and transiently tested positive as well as results of 6 hemodialyzed patients also transiently tested positive. We discuss the clinical relevance of these findings. A 35-year-old man with paranoidal schizophrenia was admitted on February 28, 2020 to a regional hospital due to ethylene glycol ingestion (0.75 l of radiator coolant) in a suicide attempt, who developed acute kidney injury requiring renal replacement therapy. He developed pneumonia induced by SARS-CoV-2 infection and was transferred on March 26, 2020 to the Central Clinical Hospital of Ministry of the Interior and Administration in Warsaw (CSK MSWiA). Data from the regional hospital were very scarce and details unavailable. During the hospitalization in the CSK MSWiA, he was in a stable clinical condition, without dyspnea and with normal oxygen saturation. High-resolution computed tomography performed on April 4, 2020 showed a picture of To the editor A novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA, detected by reverse transcription–polymerase chain reaction (RT-PCR) was identified as the cause of a cluster of pneumonia cases in Wuhan, China.1 It spreaded rapidly, at first in China and then resulting in an epidemic in other countries around the world.1 In a recent publication by Flisiak et al,2 the diagnostic workup for the infection is discussed, with RT-PCR being the basis for the diagnosis of active SARS-CoV-2 infection. The role of serological methods is briefly presented in the paper, and more extensive discussion is provided by Tomasik et al.3 In the course of an epidemic, mass serological testing with rapid tests “on request,” especially for detecting IgM class antibodies, can be used to identify asymptomatic infections once other means of reducing the epidemic have been used. Detection of IgG or IgM/IgG antibodies can be useful in epidemiological studies as suggested by Flisiak et al.2 With these tests, it is possible to estimate the number of people who have been in contact with the virus and developed antibodies and in the population-based studies. Even though rapid antibody tests are simple, easy to use, fast, and cheap, they have important limitations as reported previously.3 They missed the infection in the early and even mid-phase. They yielded a substantial number of false-negative results, as shown in some countries including Poland.4 Moreover, to definitively rule out or confirm SARS-CoV-2 infection, the test must be performed with the use of RT-PCR molecular diagnostics. Rapid molecular tests recently registered by the Food and Drug Administration (FDA) may offer a possible fast-track diagnostic workup of SARS-CoV-2 infection in emergency departments. It should be emphasized that typically RT-PCR of nasopharyngeal swabs has been used to confirm the clinical diagnosis of SARS-CoV-2 infection. Wang et al5 showed that only 32% of pharyngeal swabs and 63% of nasal swabs were positive, LETTER TO THE EDITOR

RESEARCH LETTER COVID -19 in hemodialysis patients 809Lombardy, Italy, 4 versus no COVID -19 -related mortality in Wuhan, China. 5, That is why we aimed to describe demographic characteristics, the clinical course of COVID -19, laboratory and imaging findings, and outcomes in this unique patient population. Patients and methods Study population and data collectionWe included only the dialyzed patients transferred to our Dialysis Unit who had a confirmed diagnosis of COVID -19.A confirmed diagnosis was defined as a positive result of reverse transcriptase-polymerase chain reaction assay test (gene targets: RdRp, E, and N) for SARS -CoV -2 performed using the patient's nasopharyngeal swab.Twenty -three adults (at the age of 18 years or older) were identified from 6 different hemodialysis clinics in the Masovian region.We included 19 maintenance hemodialysis patients in the analysis (for a follow -up longer than 14 days and / or until an endpoint in treatment was reached, ie, virus elimination or the patient's death).Three patients in whom the follow -up was shorter than 14 days and a single dialysis -dependent patient with acute kidney injury due to ethylene glycol ingestion were excluded.Medical records were obtained from each institution and included information on patients' demographics and comorbidities.Laboratory and radiologic data were retrieved from patients' electronic records.Additional tests and imaging were left at the discretion of the treating physician.Introduction Severe acute respiratory syndrome coronavirus 2 (SARS -CoV -2) is a novel coronavirus causing coronavirus disease 2019 (COVID -19).Its spread started when multiple cases of pneumonia of unknown origin occurred in Wuhan, China, and were first reported to the World Health Organization Country Office in China on December 31, 2019.The infection spread rapidly to other parts of the world and was declared a pandemic on March 11, 2020, when the number of cases hit 118 000 in 114 countries of the world. 1 The first case in Poland was reported on March 4, 2020.Local transmission of SARS -CoV -2 was reported to the World Health Organization on March 10, 2020. 2 On March 13, 2020, the Central Clinical Hospital of the Ministry of the Interior and Administration in Warsaw was one of the 19 hospitals in Poland repurposed into a designated hospital adapted to take care of patients with COVID -19 only.The hemodialysis facility was also turned into a dialysis clinic for COVID--19 -positive patients in order to serve hemodialysis patients from Warsaw and the Masovian region (5.403 million people and 2713 chronic hemodialysis patients).Between March 20 and April 18, 2020, 23 maintenance hemodialysis patients and a single patient on hemodialysis due to acute kidney injury, all with confirmed COVID -19, were under our care.Reports on hemodialysis patients with SARS -CoV -2 infection are limited, with conflicting data on mortality: 15.2% mortality in the United Kingdom Renal Registry, 3 24% mortality in