The severity of chronic kidney disease (CKD) stage 5D complications increases with hemodialysis (HD) vintage, leading to elevated mortality risk. Calibrating the cumulative risk of HD patients against the baseline aging rate in the general population enables a quantitative assessment of dialysis-related accelerated aging. To develop the NephroAge framework for quantifying accelerated aging in patients on maintenance HD. The study included 5356 patients aged ≥ 40 years initiating first-time maintenance HD. Baseline hazard function was estimated using the Human Mortality Database life tables. Age-standardized expected survival was calculated using a plug-in estimator conditional on age at HD initiation. The cumulative incidence of death was estimated using the Aalen–Johansen estimator. For each patient, we calculated an equivalent age in the general population at which the cumulative hazard matched that observed on HD. NephroAge was defined as age at HD start plus HD vintage plus Δ, where Δ represents dialysis-attributable “added years” of aging. Added years showed a strongly nonlinear pattern with both HD vintage and age at initiation, reflecting the nonadditivity of their effects. Patients who started HD at very advanced ages (75–80 years) had NephroAge values close to or below their chronological age, consistent with strong survival selection in this highly resilient subgroup. NephroAge condenses age at HD initiation and treatment vintage into a single, interpretable metric of premature aging. Younger patients accumulate substantially more added years per year on HD than their older counterparts, highlighting pronounced “biological cost” of long-term dialysis in younger individuals.

Doppler ultrasound (DUS) parameters can be used to predict primary dysfunction of native AVF. In practice, this is often simplified to identifying binary thresholds of parameters that allow to classify patients as having a high or low risk of primary dysfunction. However, this approach often works poorly and does not provide sufficient power. Aim: to model the association of the most common DUS parameters with the risk of various variants of primary AVF dysfunction. A retrospective case-control study included 40 adult patients with normal AVF maturation (successful puncture 3 months after creation), 37 patients with AVF thrombosis before first use within three months after creation, and 32 patients with immaturation: AVF functioning but not available for puncture three in months after creation. The threshold of normal maturation at 3 months was defined due to local criteria. All patients received a native AVF in the lower third of the forearm of the non-dominant upper limb. To reduce the influence of other factors, we did not include patients with coagulopathy, hypotension, vasculitis, history of drug abuse, etc. DUS is routinely performed on all patients. The diameter of the cephalic vein (V_d) with compression at the shoulder, the length of its segment with a depth less than 6 mm from the skin (V_length), the diameter of the radial artery (A_d), the volume blood flow (VBF) and the resistive index in the reactive hyperemia test (RH_RI) [1] were evaluated. Modelling was performed using multinomial logistic regression with three outcomes of interest: maturation, immaturation and thrombosis. The model fitted the observed data well: Nagelkerke R² 0.75 (full vs. null model), AUC 0.93 [95%CI 0.87; 0.99] for normal maturation, AUC 0.89 [95%CI 0.82; 0.96] for thrombosis and AUC 0.88 [95%CI 0.81; 0.96] for immaturation. Within relatively favourable conditions (fixed V_d = 4 mm, V_length = 70 mm, A_d = 3 mm, VBF = 30 ml/min and RH_RI = 0.5), the reduction in vein and artery diameter is mainly associated with the risk of thrombosis, the risk of primary dysfunction is almost independent of vein extension with a depth of less than 6 mm. An increase in the resistive index greater than 0.7–0.8 significantly increases the risk of primary dysfunction, mainly by increasing the risk of immaturation—Fig. 1. In other conditions, as illustrated in Fig. 2 (V_d = 2.5 mm, V_length = 60 mm, A_d = 2 mm, VBF = 20 ml/min and RH_RI = 0.5), DUS indices are differently associated with the risk of primary dysfunction. The Figs 1 and 2 show that within different conditions, various DUS parameters have different optimal cut-offs for classifying a patient as being at high risk of primary dysfunction. Individual DUS parameters allow poor prediction of the risk of primary dysfunction (and its variants), because each parameter has different informativeness at different values of other parameters. The risk of dysfunction cannot be assessed on the basis of a single DUS parameter. Probably the decision tree based on a set of DUS parameters may be a solution.

Cardiopulmonary recirculation (CPR) is a known risk factor for heart failure (HF). Typically, the assessment is performed on the interdialytic day. Hemodialysis (HD) sessions can induce significant hemodynamic changes, which may be important for patients with HF and preserved ejection fraction (EF), in whom the risk may be underestimated. To evaluate the dynamics of CPR due to a HD session following a long interdialytic gap in patients with HF and preserved EF. The prospective cohort single-arm study included 20 adult HD patients who met the inclusion criteria: EF ≥ 50

Abstract Background and Aims Ejection fraction (EF) and chronic heart failure (HF) are often considered as criteria for the possibility of arteriovenous fistula (AVF) creation in relation to an increased risk of death, without sufficient evidence for this. There is, however, rare but compelling evidence that low EF increases the risk of AVF dysfunction. Aims: to evaluate the association between EF at the time of AVF creation and the incidence of adverse cardiovascular events, all-cause mortality, as well as AVF dysfunction Method This retrospective cohort study included 962 adult patients who had a first-time created functioning AVF. Only patients with a more than three months period after AVF creation and within a five-year period were included. The mean follow-up period was 34 ± 13 months. Four groups were identified based on EF and the presence of HF at the time of AVF creation (transthoracic echocardiogram): HF with reduced EF (rEF) <40%, with mid-range (mrEF) of 40-49%, or with preserved EF (pEF) ≥50% + HF, and a “no HF” group with EF ≥50% and no HF. Results In the univariate analysis, a reduced EF was associated with an increased risk of mortality, with the hazard ratios (HRs) of 2.706 [95% CI 1.330; 5.507], p = 0.006 for mrEF and 8.250 [95% CI 2.621; 25.97], p < 0.001 for rEF, compared to the “no HF” group (here and thereafter)—Fig. 1. However, after adjusting for age, sex, and Charlson Comorbidity Index (CCI), the EF was not significantly associated with the risk of death. Only the CCI score remained a significant factor (HR = 1.748 [95% CI 1.482; 2.063], p < 0.001). A decreased EF was associated with the incidence of AVF dysfunction both in the univariate analysis and after adjustments. In the univariate analysis, the incidence rate ratios (IRRs) of 6.88 [95% CI 3.88; 12.1], p < 0.001 for mrEF, and 19.9 [95% CI 8. 64; 41.6], p < 0.001 for rEF, were shown. After adjusting for age, sex, and CCI, the IRR for mrEF was 8.96 [95% CI 5.81; 13.7], p < 0.001, and for rEF it was 23.4 [95% CI 13.8; 38.6], p < 0.001. Even in the presence of polycystic kidney disease and diabetes mellitus in the fully adjusted model, the association between EF and the incidence of AVF dysfunction remained statistically significant: the IRR was 8.61 [95% CI 5.61; 13.1], p < 0.001 for mrEF, and 33.4 [95% CI 19.5; 56.2], p < 0.001 for rEF. The findings were confirmed in a sensitivity analysis that included adjustments for unplanned onset of dialysis and competing risks survival analysis (death—outcome of interest, conversion of HD to PD or kidney transplantation and conversion of AVF to CVC—competing events). According to our results patients with EF<40% will inevitably lose AVF function for various reasons within 3.5 years—Fig. 2. Meanwhile, this approach will give the patient additional time of HD via AVF, but not CVC, without increasing the risk of death, subject to Qa monitoring. Conclusion In patients with CKD 5 who are initiating treatment with maintenance hemodialysis, a decreased EF is associated to a greater extent with a higher risk of AVF dysfunction than with an increased risk of mortality. The burden of comorbidities, rather than a standalone assessment of EF, is one of the major risk factors determining patient survival.

Abstract Background and Aims Cardio-fistular recirculation (CFR)—ratio of cardiac output (CO) to AVF volume blood flow (Qa)—is a well-known risk factor for death and cardiovascular adverse events. Currently, there are no clear limits for this index that definitely indicate AVF cardiotoxicity. In most cases, an interval score of <20%, 20-30%, or >30% is used to denote low, medium, and high risk, respectively. Typically, the assessment is performed on the interdialysiс day. HD sessions can cause significant hemodynamic changes, which may be important for patients with chronic heart failure (CFH) and preserved ejection fraction (EF), in whom the risk may be underestimated. The aim of this prospective cohort study is to evaluate changes in heart structure and CFR in patients with СFH and preserved EF before and after an HD session. Method The study included 20 stable adult HD patients who met the inclusion criteria: CHF with preserved EF (50%), NYHA I-II, Qa ≥1 l/min, CFR < 30%, interdialysiс weight gain < 5%, eKt/V > 1.2. Non-inclusion criteria: arrhythmias (except grade I AV block), NYHA III-IV, valvular disease (except mitral regurgitation I-II), intradialytic hypo/hypertension. All patients underwent transthoracic ECHO-CG with tissue Doppler on the third day after the last HD session (Monday/Tuesday), one hour before and 2 hours after the HD session. In addition, we measured AVF volume blood flow—brachial artery Qa. Results Patient Descriptive Statistics: M/F 8/12, mean age 52.2 (SD 11.2, range 41-67) years, HD vintage 49 (11.1, 33-72) months, BMI 28.2 (3.8, 22.9-36.0) kg/m2, interdialysiс weight gain 3.2 (0.8, 1.9-4.7) kg, relative interdialysiс weight gain 4.1% (0.8, 2.9-4.9). A significant trend in ECHO-CG parameters was observed, indicating a decrease in cardiac preload (Table 1). Although there were no significant changes in EF, a pronounced decrease in CO was noted with a relatively stable Qa value. As a result, 5 out of 20 patients had a CFR value of more than 30% after HD, which assigned them to a high-risk group. As shown in Fig. 1, even patients with pre-HD CFR values less than 25% were classified as high-risk. Patients were intentionally examined after a long interdialysiс interval because this HD session is associated with the greatest hemodynamic changes. Some publications suggest that the risk of death after long interdialysic interval is significantly higher than that after short interval. Increase in CFR after HD probably has a synergistic deleterious effect with other risk factors. The severity of this influence is determined by both the maximum achieved CFR values and the rate of CO recovery. Conclusion Some patients have a significant increase in CFR after HD. However, the prognostic value of this phenomenon remains unclear. In patients with significant CHF symptoms and normal or subnormal CFR on an interdialytic day, it is recommended to perform a post-HD examination. This can serve as a “stress test” to reveal any latent hemodynamic disadvantage caused by the AVF cardiotoxic effect.

Abstract Background and Aims Heart failure (HF) with preserved / high cardiac output (CO) is a well-known syndrome in patients with high-flow AVF. However, the threshold for classifying an AVF as high-flow is currently undefined. Cardio-fistular recirculation (CFR) is often used as a criterion, with values greater than 25-30% considered cardiotoxic and associated with adverse outcomes. Additionally, CFR is one of the few easily modifiable risk factors through surgical reduction of AVF volume blood flow (Qa). The study aimed to evaluate the extent of involution of heart structural and functional changes following Qa reduction. Method A prospective cohort study included 86 adult HD patients who met the inclusion criteria: HF with preserved / high CO, CFR > 25%, eKt/V > 1.2. Non-inclusion criteria: arrhythmias (except grade I AV block), valvular disease (except mitral regurgitation I-II). Patients were divided into two groups according to the severity of symptoms: NYHA I-II (N = 39) and NYHA III-IV (N = 47). All patients underwent a thorough examination, Qa assessment and ECHO-CG with tissue Doppler on the interdialytic day immediately prior to surgery. Qa reduction was achieved by external PTFE banding, PTFE graft segment placement or aneurysmorrhaphy (in case of coexisting AVF aneurysm). Long-term results were evaluated at 6 months after surgery. As the aim was to evaluate the dynamics, patients who died during follow-up, underwent conversion of KRT, or had a change in vascular access were excluded. Results Table 1 presents the descriptive statistics of the patients prior to surgery. Both groups of patients showed a significant decrease in Qa, CO, cardiac index, end-systolic and end-diastolic volume indices, and LV myocardial mass index, while EF remained unchanged (data not shown). At the same time, there were no significant differences in the dynamics of the above parameters (group*time interaction in the mixed-effects model). Fig. 1 shows that there was a significant group*time interaction: there was a significant difference in CFR before surgery (p = 0.001), but not after (p = 0.958). In both groups, CFR was adjusted to achieve optimal values. The E/A ratio was not different before the surgery (p = 0.209), but it was different after the surgery (p < 0.001). NT-proBNP levels were higher in the NYHA III-IV group both preoperatively (p < 0.001) and postoperatively (p < 0.001). We have observed a similar pattern in the dynamics of the PASP as well (p < 0.001 at both time points). The likelihood of complete weaning from CHF therapy at 6 months after Qa reduction is almost twice as high in the NYHA I-II group (RR = 1.93 [95% CI 1.2; 3.18], p = 0.009). Conclusion Defining AVF as high-flow based solely on Qa value is not accurate. Instead, it is more appropriate to define cardiotoxicity based on both CFR and the severity of clinical symptoms. Patients in NYHA III-IV benefit less from Qa reduction than patients in NYHA I-II and are more likely to retain diastolic dysfunction and pulmonary hypertension. We recommend reducing Qa in the early stages of HF.

Abstract Background and Aims Older adults are approximately 40% of all prevalent HD patients [ERA Annual report]. Cardiovascular disease is the leading cause of death in this cohort. It is well-known that the cardiotoxic effect of arterio-venous fistula (AVF) is fully realized when cardio-fistula recirculation (CFR) is above 20-30%. We believe that the reduction of AVF blood flow (Qa) in the elderly is often less effective than in the younger patients. Aim: to evaluate the outcomes of Qa reduction in the elder and the younger HD patients. Method The prospective cohort study included 21 patients over 60 years old and 36 patients under 60 years old: the median age was 74 years [IQR 69; 78, min-max 64-81] and 41 years [IQR 35; 45, min-max 31; 55], respectively. In all patients, GFR before reduction was more than 25%: 32.8% [IQR 29.2; 35.1, min-max 27.3; 38.9] and 33% [IQR 31; 35.125, min-max 27.1; 39.3], respectively. Qa reduction was performed by banding of the paraanastomotic AVF segment with intraoperative control (Doppler ultrasonography) until reaching Qa of 1.5 l / min or less. Results In all patients, we noted a significant (p<0.0001 in all cases) decrease in Qa as a result of the banding: in older adults from 2.1 l / min [IQR 1.9; 2.4, min-max 1.8; 2.8] to 1.2 l / min [IQR 1; 1.4, min-max 0.8; 1.5], delta Qa was -1 l / min [IQR -1.2; -0.9, min-max -1.5; -0.7], in younger patients from 2.8 l / min [IQR 2.5; 3.1, min-max 1.9; 3.5] to 1.3 l / min [IQR 1.1; 1.4, min-max 0.9; 1.5], -1.5 l / min [IQR -1.7; -1.3, min-max -2.3; -0.9], respectively. In both elder and younger patients, we noted a significant decrease in CFR - Fig. 1. However, after Qa reduction, only 5 of 21 elderly patients had CFR value less than 20%. Thus, 17 of 21 patients had CFR in the «gray zone» - 20-30%: 22.8% [IQR 21.85; 27.3, min-max 21; 29.2]. In younger patients, 25 of 36 had CFR less than 20% after Qa reduction, while 11 stayed in the «gray zone»: 21.15% [IQR 20.575; 22.3, min-max 20.3; 23.4]. The probability of reducing CFR to a safe level (less than 20%) after surgery was significantly less in the elder patients: RR = 0.3429 [95% CI 0.1495; 0.6852], p = 0.0011. We consider the lower baseline cardiac output in the elderly to be the main reason of the lower efficacy of Qa reduction: the difference between medians (older adults-younger patients before Qa reduction, Hodges-Lehmann method) was 1.9 l / min [95% CI 1.5; 2.4], p <0.0001. At the same time, Qa before reduction did not differ much between the older and the younger: 0.6 l / min [95% CI 0.4; 0.8], p <0.0001. Moreover, the reduction of Qa in elderly patients led to a decrease in the ejection fraction (EF), which was not noticed in young patients - Fig. 2. Notably, in all patients of both groups the initial value of the EF was more than 55%. We believe that this can be explained by an abrupt increase in afterload against the background of a decreased compensatory heart capability in the elderly. At the same time, decrease in the EF after Qa reduction in the elderly may indirectly indicate that conventional EF in the elderly is maintained by a presence of a high-flow AVF. Evaluation of EF against this background creates a putative picture of well-being and can mask the development of heart failure with reduced EF for a long time. Conclusion We noted a lower efficacy of Qa reduction as a method of reducing both cardio-fistula recirculation and cardiovascular risk in the elder patients compared to the younger patients on maintenance HD. Elder patients seem to require a different approach to reduce cardiovascular risk than younger patients.

BACKGROUND: There is a lack of studies providing comprehensive data on the prevalence of mineral and bone disorders (MBD) laboratory abnormalities after kidney transplantation in Russia. AIM: to obtain real-world data on the prevalence of the main mineral abnormalities among kidney transplant recipients and to revise their concomitant MBD therapy. METHOD: This cross-sectional study included 236 patients with successful kidney transplantation. Their serum intact parathyroid hormone (iPTH), total calcium (Ca), phosphorus (P), and alkaline phosphatase (ALP) levels were measured. RESULTS: Only 6.2% of our cohort had all laboratory parameters within the target range, whereas persistent HPT along with hypercalcemia was noted in almost one third of the patients (31%). Normal iPTH levels were observed in 13% cases; 84% of the patients had hyperparathyroidism. The fraction of patients with target iPTH did not differ between the groups with normal and decreased estimated glomerular filtration rate (eGFR) (p=0.118). Hypercalcemia was observed in 29% cases. The serum P level varied significantly in groups with different eGFR (p<0.0001), increasing with declining graft function. Furthermore, 40.7% of patients had ALP above the target range. While 123 patients received active vitamin D (alfacalcidol), 33 received monotherapy with inactive vitamin D (cholecalciferol). The control group consisted of 57 medication-naïve patients. The serum total Ca level varied significantly between the groups (p=0.0006), being higher in patients supplemented with cholecalciferol. The fraction of patients with normocalcemia was lowest in the cholecalciferol group (chi-square, р=0.0018). CONCLUSION: The prevalence of biochemical abnormalities after kidney transplantation is high. Alfacalcidol usage may be safer than using cholecalciferol to prevent hypercalcemia development.

АКТУАЛЬНОСТЬ АКТУАЛЬНОСТЬ. На сегодняшний день крайне мало исследований, представляющих объективные данные о распространенности минеральных и костных нарушений (МКН) у реципиентов почечного трансплантата (ПТ) в России. ЦЕЛЬ. Провести скрининг, включающий определение основных лабораторных показателей МКН у пациентов, перенесших аллотрансплантацию трупной почки (АТП), а также оценить назначение сопроводительной терапии, направленной на коррекцию МКН при хронической болезни почек (МКН-ХБП). МАТЕРИАЛЫ И МЕТОДЫ МАТЕРИАЛЫ И МЕТОДЫ. В поперечное исследование были включены 236 пациентов, перенесших успешную трансплантацию почки. У всех пациентов определяли уровень интактного паратиреоидного гормона (ПТГ), общего кальция, фосфора, щелочной фосфатазы (ЩФ) сыворотки. РЕЗУЛЬТАТЫ РЕЗУЛЬТАТЫ. Лишь у 6,2% реципиентов ПТ наблюдались целевые уровни всех исследуемых лабораторных показателей МКН, при этом повышенный уровень ПТГ в сочетании с гиперкальциемией был отмечен почти у трети пациентов (31%). Целевой уровень ПТГ наблюдался у 13% реципиентов, 84% пациентов демонстрировали гиперпаратиреоз. Доли пациентов с целевым уровнем ПТГ не различались в группах реципиентов с сохранной и сниженной расчетной скоростью клубочковой фильтрации (рСКФ) (p=0,118). Гиперкальциемия наблюдалась у 29% реципиентов. Уровни неорганического фосфора сыворотки значительно различались в группах пациентов с разной рСКФ (p<0,0001), возрастая по мере снижения функции трансплантата. У 40,7% пациентов было отмечено повышение уровня ЩФ. В качестве сопутствующей терапии 123 пациента получали активный витамин D (альфакальцидол), 33 пациента — препарат неактивной формы витамина D (колекальциферол), 57 пациентов не получали лекарственной терапии МКН-ХБП. Уровень общего кальция сыворотки статистически значимо различался в этих группах (p=0,0006), наиболее высокий его уровень отмечался в группе терапии колекальциферолом. Доля пациентов с нормокальциемией в группе лечения колекальциферолом была наиболее низкой (χ2 р=0,0018). ЗАКЛЮЧЕНИЕ ЗАКЛЮЧЕНИЕ. Распространенность МКН у реципиентов ПТ очень высока. Применение альфакальцидола по сравнению с препаратами неактивной формы витамина D может быть более безопасным в отношении развития гиперкальциемии.

Abstract BACKGROUND AND AIMS We aimed to analyze the outcomes of HD patients with COVID-19 hospitalized in the Moscow region, Russia, and to compare it with those in the general population. METHOD Data were obtained retrospectively from the Moscow region COVID-19 register database, which comprises all hospitalizations with suspected or confirmed COVID-19 between February 2020 and November 2021. A total of 384 327 patients were included; 1 435 of them were ESRD patients. RESULTS Among ESRD patients there were 1386 HD patients and 49 kidney graft recipients. Thus, during the specified period, 48.5% of all prevalent HD patients of the Moscow region and only 7.8% of the graft recipients required hospitalization. Due to a few number of hospital admissions among kidney recipients they were excluded from the further analyses. We observed typical 4 waves of hospital admissions in the general population, but not in HD patients. In these patients, we noted a peak in December 2020 with a subsequent decrease in February, 2021; then the number of hospitalizations remained stable. The proportion of HD patients was approximately 0.5% of all patients with COVID-19 admitted to hospital. Almost all HD patients with COVID-19 were hospitalized regardless of disease severity. The mean age of hospitalized HD patients was significantly more than that in the general population: 68.95 ± 13.69 years versus 59.18 ± 17.11 years, P < 0.001. Of note, the mean age of HD patients in Russia is 56.3 ± 11.7 years. The proportion of men among hospitalized HD patients with COVID-19 reached 50.4% versus 43.5% in the general population. HD was associated with a significant increase in the risk of critical but stable and extremely critical (+ worsened: terminal and clinical death) condition at admission (Figure 1A): RR = 3.36 [95% confidence interval (95% CI) 3.12–3.59], P < 0.001 and RR = 4.83 (95% CI 3.93–5.92), P < 0.001, respectively. HD patients were significantly more likely to need for any kind of respiratory support (oxygen mask and mechanical ventilation (MV)) or MV alone (Figure 1B): RR = 1.72 (95% CI 1.63–1.81), P < 0.001 and RR = 4.67 (95% CI 4.18–5.21), P < 0.001, respectively. HD was associated with a significant increase in the risk of death (Figure 1C): RR = 3.48 (95% CI 3.24–3.72), P < 0.001. HD significantly increased the risk of death in patients without oxygen support and in patients with need for an oxygen mask (Figure 2A): RR = 3.56 (95% CI 2.97–4.25), P < 0.001 and RR = 2.47 (95% CI 2.18–2.78), P < 0.001, respectively. For patients requiring MV, mortality was >95% in both cohorts: RR = 0.999 (95% CI 0.955–1.01), P = 0.309. Deceased patients were older than survivors both in HD patients [73 (IQR 65–82) versus 69 (IQR 59–78) years; P < 0.001] and in the general population [72 (IQR 63–82) versus 60 (IQR 48–69) years; P < 0.001], however, the difference between medians was significantly greater in the general population: 13 (95% CI 12–14) versus 5 (95% CI 3–6) years. Heart and lung diseases increased the risk of death. In the general population concomitant heart diseases worsened the prognosis to a greater extent compared with lung diseases: RR = 2.69 (95% CI 2.64–2.74), P < 0.001 and RR = 1.3 (95% CI 1.26–1.35), P < 0.001, respectively. In HD patients pre-existing lung diseases had a greater impact on the risk of death than heart diseases: RR = 2.02 (95% CI 1.71–2.41), P < 0.001 and RR = 3.05 (95% CI 2.73–3.41), P < 0.001, respectively. In the multivariate model, significant predictors of death in HD patients were need for MV (OR = 9.81, 95% CI 8.48–17.8; P < 0.001) and lung diseases (OR = 2.92, 95% CI 1.92–5.42; P < 0.001], but not heart diseases, age and gender. CONCLUSION HD patients with COVID-19 have a significantly worse prognosis compared with the general population. The main risk factors for death are need for respiratory support and pre-existing lung diseases.

Abstract BACKGROUND AND AIMS Cardiopulmonary recirculation (CRP) is one of the most informative instrumental parameters, widely used to predict adverse cardiovascular events in patients on maintenance hemodialysis (HD). CRP calculation is based on two indirectly measured estimates: AVF volume blood flow (Qa) and cardiac output (CO). Large CRP variability may cause underestimation of cardiovascular risk in many HD patients. We aimed to study the inter- and inner-observer agreement of Qa and CO. As a second step, we studied the changes in Qa, CO and CPR before and after HD. METHOD The prospective study included 88 patients with native AVF. At the first step, we evaluated the inter- and inner-observer agreement of Qa measurement with color duplex ultrasound (Bland–Altman plots, Figure 1A–D). Two specialists with 5–7 years of experience measured Qa twice on brachial artery, twice on fistula vein. To estimate the maximum relative error in paired measurements we calculated the mean and the absolute mean difference for each pair. Then, the absolute mean difference was divided by mean; the greatest deviations from the average are given in %. After that, they measured CO twice before HD and once after HD. Ultrafiltration during HD was 1.6 ± 0.34 L. RESULTS We observed a good concordance between Qa measurements on brachial artery by one specialist (Figure 1A) and by two specialists (Figure. 1B): deviations were [–13.9%; 13.1%] and [–18.3%; 16.4%], respectively. There was a poor concordance between assessments on brachial artery and fistula vein (Figure 1C), and Qa measurement on fistula vein alone (Figure 1 D). In the latter case, the variance was very high even if measurements were performed by one specialist: deviations were [–37.9%; 39.6%] and [–59.3%; 93.6%], respectively. In all cases, the systematic bias was low, but the deviations were significantly different between measurement methods. The variance of bias increased along with increasing of Qa. We observed a good concordance between CO assessments made by one specialist and between specialists: deviations were [–12.4%; 12.3%] and [–10.5%; 9.1%], respectively. The main pitfall of CPR-based cardiovascular risk stratification is that CO changes significantly after HD (Fig. 2A), while Qa values remain relatively stable (Figure 2B): although Qa difference before and after HD is statistically significant, it seems to be modest. Median CO decrease after HD was 13.4% (26.6% max), while median of Qa decrease was 1.7% (6.1% max). This leads to a significant increase of CPR value after HD, which can reach 40%(! ) in some patients (absolute increase of 0.11) (Figure. 2C). CPR value more than 30% is considered to be an indication for Qa reduction. In our cohort, 17% of the patients had CPR >30% before HD and 42% after HD. CONCLUSION Qa assessment should be performed only on brachial artery. There is a significant decrease in CO after HD even if ultrafiltration was moderate, whereas Qa remains relatively stable. This leads to a significant increase of CPR value in some patients after HD. CPR assessment before HD may lead to underestimation of cardiovascular risk. The decision on Qa reduction to decrease CPR should be based on CPR assessment after HD session.

Abstract BACKGROUND AND AIMS Patients on HD are known to have many various adverse events associated with past COVID-19. In this cross-sectional study, we assessed the incidence of vascular access (VA) dysfunction (primary end point) and probability of successful reconstruction of preexisting permanent VA (AVF/AVG) in a case of its dysfunction (secondary end point) within two months after discharge from COVID hospital. METHOD Data were obtained from Moscow region COVID-19 register database. The study includes the results of treatment of 1386 HD patients who were admitted to hospital with suspected or confirmed COVID-19 between February 2020 and November 2021. All COVID-19 positive patients were hospitalized regardless of disease severity to prevent further spread of the infection in dialysis units. The main analysis included 934 patients with known sustainable VA: AVF (N = 804, 86.3%), AVG (N = 54, 5.8%) or CVC (N = 74, 7.9%). Median duration of HD was 34 (IQR 21–69) months (from 6 to 98). RESULTS Hospital mortality among HD patients was 32.3%. The AVF/AVG/CVC ratio in recovered (N = 632) and deceased (N = 302) patients was 89.2%/5.7%/5% and 80.1%/6%/13.9%, respectively. HD via CVC was associated with an increased risk of death: RR = 1.877 (95% CI 1.472–2.302); P < 0.0001. Most of the recovered patients with AVFs (Figure 1, left) and AVGs (Figure 1, right) needed interventions due the VA dysfunction. Even if AVF patency was successfully restored, it led to the reduction of its functional segment. In contrast, most of the recovered patients with CVCs did not receive interventions for VA dysfunction (Figure 2). Thus, only 45.4% (287 of 632) of recovered patients did not receive interventions for VA dysfunction; the rest 54.6% showed dysfunction of VA. 23.6% (N = 149) underwent successful AVF/AVG reconstruction and retained function of the preexisting VA. In 15.3% (N = 97) patients, AVF/AVG function was completely lost and a new AVF/AVG was created. Conversion from functional AVF/AVG into CVC was performed in 14.1% (N = 89) patients. Thus, the incidence of complete loss of preexisting permanent VA function was 29.4% (N = 186). Conversion into better vascular access was performed in only 1.7% (N = 11) patients: conversion from AVG into AVF or from CVC into AVF/AVG. Among patients who underwent successful reconstruction of preexisting AVF, the probability of successful restore of its function within the first month was 55.3% (95% CI 48.3–62.2), during the second month—only 31.1% (95% CI 22.9–40.4). For AVG, the probability of maintaining of existing access during the first and second months was 23.8% (95% CI 9.3–45.2] and 18.2% (95% CI 3.2–48.3), respectively. Thus, reconstruction of permanent VA within the second month after discharge from COVID hospital increases the risk of complete loss of its function: RR = 1.469 (95% CI 1.22–1.762). Only 6.6% (N = 37) of patients received AVF/AVG reconstruction in COVID hospital. Compared with 2019, in 2021 the rate of reconstructive surgeries in the Moscow region decreased from 2.771 (95% CI 2.426–3.15) to 1.375 (95% CI 1.114–1.68) per 10 patient-years (only prevalent HD patients; P < 0.0001). The number of tertiary care centers for VA creation and maintaining in the region decreased from eight to five during the pandemic. At the same time, the rate of CVC implantations increased (outside of COVID hospitals) from 1.498 (95% CI 1.248–1.784) to 2.908 (95% CI 2.522–3.337) per 10 patient-years; P < 0.0001. CONCLUSION COVID-19 is associated with high incidence of VA dysfunction and complete loss of VA function. The delay in reconstruction of existing VA significantly increases the risk of its loss. This may be caused by a decrease in the number of reconstructive VA surgeries due to reducing the number of specialized centers and personnel. As a result, we observe an increase in CVC usage. Thus, over the next few years, we can expect increased prevalence of central vein stenoses and deterioration of treatment outcomes of HD patients.

Abstract BACKGROUND AND AIMS Older adults are approximately 40% of all prevalent HD patients (ERA-EDTA Annual report, 2019). Cardiovascular disease is the leading cause of death in this cohort. It is well-known that the cardiotoxic effect of arterio-venous fistula (AVF) is fully realized when cardio-fistula recirculation (CFR) is above 20–30%. We believe that the reduction of AVF blood flow (Qa) in the elderly is often less effective than in younger patients. To evaluate the outcomes of Qa reduction in the elder and the younger HD patients. METHOD The prospective cohort study included 21 patients ˃ 60 years and 36 patients ˂60 years: the median age was 74 years [interquartile range (IQR) 69; 78, min-max 64–81] and 41 years (IQR 35; 45, min-max 31; 55), respectively. In all patients, glomerular filtration rate (GFR) before reduction was more than 25%: 32.8% (IQR 29.2; 35.1, min-max 27.3; 38.9) and 33% (IQR 31; 35.125, min-max 27.1; 39.3), respectively. Qa reduction was performed by banding of the para-anastomotic AVF segment with intraoperative control (Doppler ultrasonography) until reaching Qa of 1.5 L/min or less. RESULTS In all patients, we noted a significant (P < 0.0001 in all cases) decrease in Qa as a result of the banding: in older adults from 2.1 L/min (IQR 1.9; 2.4, min-max 1.8; 2.8) to 1.2 L/min (IQR 1; 1.4, min-max 0.8; 1.5), delta Qa was −1 L/min (IQR −1.2; −0.9, min-max −1.5; −0.7), in younger patients from 2.8 L/min (IQR 2.5; 3.1, min-max 1.9; 3.5) to 1.3 L/min (IQR 1.1; 1.4, min-max 0.9; 1.5), −1.5 L/min (IQR −1.7; −1.3, min-max −2.3; −0.9], respectively. In both elder and younger patients, we noted a significant decrease in CFR—Figure 1. However, after Qa reduction, only 5/21 elderly patients had CFR value less than 20%. Thus, 17/21 patients had CFR in the ‘gray zone’ —20–30%: 22.8% (IQR 21.85; 27.3, min-max 21; 29.2). In younger patients, 25/36 had CFR ˂ 20% after Qa reduction, while 11 stayed in the ‘gray zone’: 21.15% (IQR 20.575; 22.3, min-max 20.3; 23.4). The probability of reducing CFR to a safe level (˂ 20%) after surgery was significantly less in the elder patients: RR = 0.3429 [95% confidence interval (95%CI) 0.1495; 0.6852], P = 0.0011. We consider the lower baseline cardiac output in the elderly to be the main reason for the lower efficacy of Qa reduction: the difference between medians (older adults-younger patients before Qa reduction, Hodges–Lehmann method) was 1.9 L/min (95% CI 1.5; 2.4), P < 0.0001. At the same time, Qa before reduction did not differ much between the older and the younger: 0.6 L/min (95% CI 0.4; 0.8), P < 0.0001. Moreover, the reduction of Qa in elderly patients led to a decrease in the ejection fraction (EF), which was not noticed in young patients—Figure 2. Notably, in all patients of both groups, the initial value of the EF was more than 55%. We believe that this can be explained by an abrupt increase in afterload against the background of a decreased compensatory heart capability in the elderly. At the same time, a decrease in the EF after Qa reduction in the elderly may indirectly indicate that conventional EF in the elderly is maintained by a presence of a high-flow AVF. Evaluation of EF against this background creates a putative picture of well-being and can mask the development of heart failure with reduced EF for a long time. CONCLUSION We noted a lower efficacy of Qa reduction as a method of reducing both cardio-fistula recirculation and cardiovascular risk in the elder patients compared to the younger patients on maintenance HD. Elder patients seem to require a different approach to reduce cardiovascular risk than younger patients.

Abstract Background and Aims The prevalence of central vein stenosis (CVS) in patients on hemodialysis (HD) is difficult to be assessed directly. This is mainly caused by the variety of clinical signs and the high frequency of asymptomatic CVS. Aim: to assess the frequency of occurrence of various CVS forms in HD patients. Method The retrospective observational study is based on the results of treatment of 1865 HD patients who underwent diagnostic and therapeutic procedures on vascular access in our center. In case of vascular access dysfunction, patients were examined according to a local protocol: ultrasound of the peripheral (to exclude lesion of peripheral AVF segments) and central veins (over the available length), followed with CT-angiography or percutaneous angiography, if necessary. Results AVF/AVG dysfunction was observed in 29.4% of patients (549 of 1865). 211 patients were diagnosed with CVS. The prevalence of CVS was 11.3% (211 of 1865) among all HD patients and 38.4% (211 of 549) in patients with AVF dysfunction. Among patients with CVS, 37% (78 of 211) had vein lesions without clinical symptoms or with minimal manifestations (a tendency to decrease KT/V). The prevalence of asymptomatic CVS was 4.2% (78 of 1865) in the general population of HD patients and 14.2% (78 of 549) in patients with AVF dysfunction. In case of asymptomatic CVS it was detected by an ultrasound examination during CVC implantation (N=38), during unsuccessful attempts to implant CVC (N=29), in the case of recurrent AVF thrombosis without underlying peripheral segments lesion (N=9) or during echocardiography (N=2). The prevalence of asymptomatic CVS among patients without AVF dysfunction was 5.9% (78 of 1316). True prevalence of subclinical CVS among HD patients without obvious signs of AVF dysfunction may vary widely. A total of 48.8% (103 of 211) of all CVS cases were treated. At the same time, in 10.7% (11 of 103) of cases, patients did not present symptoms of CVS, and surgery was performed due to recurrent AVF thrombosis without damage of the peripheral parts of AVF. Patients with clinically manifest CVS who received endovascular interventions had a significantly higher risk of AVF loss compared to patients with asymptomatic CVS: HR=2.566 [95% CI 1.706; 3.86], log rank p<0.0001. However, patients with an asymptomatic CVS had a higher risk of AVF function loss compared to the general HD population (HR=2,051 [95% CI 1,243; 3,384], log rank p= 0.0004) – fig. 1. The use of CVC is a known risk factor of CVS development. We analyzed the relationship of CVS risk with multiply CVC placements and catheter dwell time using the Cox proportional hazards regression model (fig. 2). In the univariate model, a greater No of CVCs as well as longer time in place increased the risk of CVS. In the multivariate model (χ2=105.516, df=2, p<0.0001), catheter dwell time was no longer associated with an increased risk of CVC, while the mean number of inserted catheters remained an important risk factor. Conclusion The prevalence of both symptomatic and asymptomatic forms of CVS in HD patients is high. Patients with vascular access dysfunction should be carefully examined to identify the asymptomatic CVS. The mean No of catheterizations is a more important risk factor of CVS than longer catheter dwell time.

Abstract Background and Aims Percutaneous renal biopsy is essential tool in nephrology but it is invasive procedure that can lead to complications, including gross hematuria, clinical significant haematoma and infection. The aim of the study was to determine the nature and incidence of PRB complications and the impact of biopsy results on treatment strategy. Method 82 patients (male – 42, female – 40) with a median age of 43.5 (Q1; Q3 – 34;71) years, BMI 26.4 (22.9; 30.6) were included in retrospective study of all native kidney biopsies performed at our institute from January 1, 2016 to December 31, 2019. An informed consent was mandatory in all patients. The indications for biopsies were nephrotic syndrome, 24-hour proteinuria ≥ 1g, nephritic syndrome, renal failure of unknown origin. The median duration of kidney disease was 9.5 (3.0; 26.6) months, serum creatinine level - 135 (87; 197) μmol/l, eGFR (CKD-EPI formula) – 52.9 (26.6; 83.7) ml/min/1.73 m2, 24-hour proteinuria – 2.8 (1.2; 5.4) g. All biopsies were percutaneous, ultrasound-guided and were performed under local anesthesia in prone position with a 16G needle. Medications that may increase bleeding risk (anticoagulants, antiplatelet agents, and nonsteroidal anti–inflammatory drugs) was stopped before PRB. Immediately after the biopsy, bed rest and vital signs monitoring was prescribed for 12 hours. In the absence of complications, a control kidneys ultrasound was performed 24 hours after biopsy; if complications were suspected, regarding to the local protocol. We prescribed prophylactic antibiotics to the patients with a hematoma volume > 100 ml. All biopsy specimens were sent to tertiary laboratory of renal pathology and evaluated by light and immunofluorescence (IF) microscopy; electron microscopy was not used in our study. Biopsy samples were considered satisfactory for diagnosis if they contained five or more glomeruli. Results Post-biopsy complications included gross hematuria – 19 of 82 (23.5%) patients, haematomas ≤ 100 ml – 17 (20.7%), haematomas > 100 ml – 8 (20.7%), pain in the puncture site requiring the administration of analgesics – 2 (2.4%). No death, infections, bladder obstruction or nephrectomy due to biopsy complications was registered. One (1.2%) patient required blood transfusion. We identified renal arteriovenous fistula which did not require special treatment in one (1.2%) patient 2 months after PRB. We found no differences in the incidence of post-biopsy haematomas by gender, age, or BMI. Haematomas were significantly more common in patients with higher mean blood pressure and serum creatinine levels (Fig.1, A, B). In one case (1.2%) the biopsy was inadequate. The results of PRB were varied, including unexpected findings. IgA nephropathy was found in 23 of 81 (28.4%) patients, focal segmental glomerulosclerosis – in 21 (25.9%), membranous nephropathy – in 9 (11.1%), pauci-immune crescentic glomerulonephritis – in 6 (7,4%), lupus nephritis – in 2 (2.4%), membranoproliferative glomerulonephritis – in 2 (2.4%) - one with polyclonal Ig+/C3+ on IF and one - with monoclonal IgG kappa+, C3 nephropathy – in 1 (1.2%), AL-amyloidosis – in 2 (2.4%), light chain deposit disease – in 1 (1.2%), hypertensive nephropathy – in 1 (1.2%), diabetic nephropathy – in 3 (3.7%), tubulointerstitial nephritis – 5 (6.2%), thrombotic microangiopathy – in 2 (2.4%), diffuse nephrosclerosis – in 2 (2.4%), renal tuberculosis – in 1 (1.2%). According to the results of the biopsy, pathogenetic treatment was first prescribed to 43 of 81 (53.1%) patients, changed – in 17 (21%), treatment remained unchanged – in 8 (9.9%) cases. Thirteen (16%) patients were referred for additional examination by a hematologist and rheumatologist. Conclusion Biopsy of native kidney is a high diagnostic value and safe procedure with a low risk of major complications. Treatment was changed significantly after biopsy in 74% of patients in our study.

Abstract Background and Aims Post-transplant hypercalcemia is common after successful kidney transplantation in patients with chronic kidney disease (CKD) and can be partially explained by the side effects of concomitant therapy. We aimed to evaluate the prevalence of hypercalcemia among recipients of kidney transplant and its relationship with vitamin D supplementation. Method We performed a cross-sectional study of 236 patients underwent successful kidney transplantation in our clinic. Median age was 49 [Q1-Q3: 39; 58] years, mean estimated glomerular filtration rate (eGFR) was 51,1±21,8 ml/min/1,73 m2. Most of the patients received hemo- or peritoneal dialysis treatment, pre-emptive transplantation was performed in 6% cases. For those previously received dialysis, median duration of any type of dialysis was 21 [Q1-Q3: 11; 36] months. Median time after transplantation reached 42 [Q1-Q3: 19; 75] months. Target range for total serum Ca was defined according to National guidelines on CKD-MBD as 2,1 - 2,5 mmol/l. Results In our cohort median serum total Ca level was 2,41 [Q1-Q3: 2,36; 2,56] mmol/l. Hypercalcemia was encountered in 21% (7 of 33) cases during the first year after transplantation and in 30% (61 of 203) – after first year. Serum total Ca weakly correlated with iPTH (ρ= 0,282 [95%CI: 0,15; 0,4], р<0,0001), alkaline phosphatase (ρ=0,181 [95%CI: 0,05; 0,31], р=0,006) and total duration of renal replacement therapy (dialysis + transplantation) - ρ=0,2 [95%CI: 0,07; 0,32], р=0,002. We did not observe statistically significant correlations between serum total Ca and eGFR (p=0,132), total Ca level and time after transplantation (p=0,06). Total Ca levels did not differ in groups with different eGFR (p=0,04 in Kruskall-Wallis test, but no statistically significant differences after correction for multiply comparisons). Data on concomitant therapy were available for 230 patients. 173 of 230 recipients received any therapy of CKD-MBD. Of them, 123 patients took only active vitamin D (alfacalcidol), 33 patients received monotherapy with inactive vitamin D (cholecalciferol). 57 patients not taking any medications were the control group. Serum total Ca level varied significantly between groups (p=0,0006, Kruskall-Wallis test), being higher in patients supplemented with cholecalciferol - fig.1. Meanwhile, iPHT (p=0,171), serum phosphorus (p=0,563) and alkaline phosphatase levels did not differ in these three groups. Fraction of patients with normocalcemia was the lowest in cholecalciferol group (χ2, р=0,0018) - fig. 2. Conclusion We observed a high prevalence of hypercalcemia in kidney transplant patients, that was not associated with transplant function or time after transplantation. Our data suggest usage of active vitamin D to be safer than cholecalciferol to prevent hypercalcemia development in renal allograft recipients.

Purpose. To evaluate the potential option of selecting donor–recipient pairs by using the number of epitopemismatches.Materials and methods. An observational cohort study was carried out, which included 824 adult recipients of ABO compatible deceased donor kidneys. The end point was a transplant loss. If a recipient with a functioning graft died, the observation was censored. The number of epitope mismatches (EpMM) was calculated using open source information on the population frequency of haplotypes and the repertoire of epitopes with confirmed immunogenicity. All possible combinations of the donor and recipient genotypes were compiled, and the probability of each combination was calculated. After that, the number of donor epitopes absent in the recipient was calculated for each combination with a non-zero probability, whereupon the weighted mean EpMM was calculated, where the weight coefficient was the normalized probability of occurrence of each combination.Results. All of the donor – recipient pairs had HLA-mismatches (HLA MM): 1.9% of recipients had 1 HLA MM, 6.7% had 2 HLA MM, 29.9% had 3 HLA MM, 38.5% had 4 HLA MM, 18.1% had 5 HLA MM, and 4.9% had 6 HLA MM. The HLA MM impacted graft survival was determined: log-rank test p < 0.0001, Breslow test p < 0.0001. The median values and the interquartile ranges of EpMM were 6 [4; 7], 12 [7.74; 17.25], 18 [14; 22], 24 [20; 30], 30.5 [25; 37] and 36 [26.5; 44.5] for the cases of 1, 2, 3, 4, 5 and 6 HLA MMs, respectively. An increase in HLA MM resulted in a higher risk of developing donor-specific anti-HLA antibodies (DSA). Hazard ratio (HR) = 1.21 [95% confidence interval (CI): 0.7; 1.9], 1.71 [95% CI: 1.22; 2.36], 2.04 [95% CI: 1.42; 2.73], 2.25 [95% CI: 1.63; 2.96], 2.59 [95% CI: 2.03; 3.29] for 2, 3, 4, 5, and 6 HLA MM, respectively, versus HLA MM = 1. An increase in EpMM also resulted in a higher risk of developing DSA. HR = 1.66 [95% CI: 1.09; 2.47], 2.1 [95% CI: 1.46; 2.91], 2.41 [95% CI: 1.86; 3.03], 2.61 [95% CI: 2.12; 3.12], 2.77 [95% CI: 2.26; 3.33] for 10–19, 20–29, 30–39, 40–49 and > 50 EpMM, respectively, versus EpMM < 10. An increase in HLA MM was associated with an increased risk of transplant loss. HR = 1.24 [95% CI 0.7; 2.15], 1.48 [95% CI 0.86; 2.33], 1.88 [95% CI 1.32; 2.52], 2.41 [95% CI 2; 2.93], 2, 98 [95% CI 2.59; 3.46] at 2, 3, 4, 5, and 6 HLA MM, respectively, versus HLA MM = 1. An increase in EpMM also was associated with an increased risk of transplant loss. HR = 1.71 [95% CI 1.1; 2.49], 2.11 [95% CI 1.59; 2.68], 2.4 [95% CI 1.96; 2.86], 2.59 [95% CI 2.17; 3.04], 2.71 [95% CI 2.31; 3.15] at 10–19, 20–29, 30–39, 40–49 and > 50 EpMM, respectively, versus EpMM < 10. In order to demonstrate the effectiveness of EpMM accounting, we analyzed graft survival among the patients with 4 HLA MM. With the number of EpMM in the range from 10 to 24 and from 25 to 43 the difference in survival rates was statistically significant, but only at the late stages of the post-transplant period: log-rank test p = 0.0067, Breslow test p = 0.0982. The median survival for EpMM 10–24 was 10.33 [95% CI 9.05; 11.61] years, for EpMM 22–43 – 8.67 [95% CI 7.68; 9.66] years, HR 1537 [95% CI 1.114; 2.12]. At the same time, it was not the median of survival that increased, but the proportion of patients with a functioning graft: at 10-24 EpMM after 15 years, 18.28% [95% CI 8.2; 31.67] grafts functioned, while at 25–43 EpMM only 4.75% [95% CI 0.94; 13.64] functioned.Conclusion. In the routine practice of a transplantation center with a short waiting list of its own, it might be possible to improve the kidney transplant survival as a result of considering epitope mismatches, thus reducing the risk of developing donor-specific anti-HLA antibodies and ensuring a higher graft survival rate. This method can be used for additional ranking of transplantation candidates depending on the number of epitope mismatches within the fixed number of HLA-mismatches and thus select the optimal one. Besides, it is theoretically possible to use this method as an alternative to the traditional donor/recipient histocompatibility evaluation. Additional research is required.

Abstract Background and Aims Mineral and bone disorders (MBD) are common after successful kidney transplantation in patients with chronic kidney disease (CKD). We aimed to evaluate the prevalence of biochemical abnormalities among recipients of kidney transplant. Method We performed a cross-sectional study of 236 patients underwent successful kidney transplantation in our clinic between 2007 and 2019. Median age was 49 [Q1-Q3: 39; 58] years, mean estimated glomerular filtration rate (eGFR) was 51,1±21,8 ml/min/1,73 m2. Most of the patients received hemo- or peritoneal dialysis treatment, pre-emptive transplantation was performed in 6% cases. For those previously received dialysis, median duration of any type of dialysis was 21 [Q1-Q3: 11; 36] months. Median time after transplantation reached 42 [Q1-Q3: 19; 75] months. We evaluated serum intact parathyroid hormone (iPTH), total calcium (Ca), phosphorus (P) and alkaline phosphatase (AP) levels. Target ranges were defined according to National guidelines on CKD-MBD as follows: 2,1 - 2,5 mmol/l for total Ca, 0,87 – 1,49 mmol/l for P; normal AP level is defined considering a gender (53-128 Е/l for men, 42-98 Е/l for women). Target iPTH level for optimal and slightly decreased transplant function (corresponding chronic kidney diasease (CKD) stage 3T) was defined as 35-70 pg/ml, for eGFR corresponding CKD 4T – as 70-110 pg/ml, for CKD 5T – as 70-150 pg/ml. Results In our cohort normal iPTH level was observed only in 13% cases, whereas 84% of the patients had hyperparathyroidism. iPTH inversely correlated with eGFR (ρ= -0,454 [95%CI: -0,55; -0,34], р<0,0001 – fig.1) and its level differed significantly between groups with different CKD stage (р<0,0001, Kruskall-Wallis test) – fig.2. However, fraction of patients with target iPTH did not differ in recipient groups with normal and decreased eGFR (p=0,118). Hypercalcaemia was observed in 29% cases; there was a weak correlation of serum total Ca level with iPTH (ρ= 0,282 [95%CI: 0,15; 0,4], р<0,0001) and AP (ρ=0,181 [95%CI: 0,05; 0,31], р=0,006) – fig.3. Hypophosphatemia was seen much more frequently during the first year after transplantation than in long-term period (30,3% vs 6,4% respectively, р=0,0002). Serum P level varied significantly in groups with different eGFR (p<0,0001, Kruskall-Wallis test), increasing in parallel with declining of transplant function – fig.4. The percentage of patients within a target range of AP amounted to 54%, above the target range – 40,7%. In total, only 6,8% of our cohort had all laboratory parameters within the target range. Conclusion We observed a high prevalence of biochemical abnormalities in kidney transplant patients confirming that transplantation itself does not cure mineral and bone disorders in CKD patients.

Abstract Background and Aims According to the current KDIGO guidelines, angioplasty should be preferred procedure for treatment of CVS instead of the bare metal stents or self-expanding stent-grafts placement. However, bare stents are still significantly more affordable than stent grafts. Aim: comparative analysis of the results of isolated balloon angioplasty (BA) and combined technique (BA with a stent placement in HD patients with central vein stenosis (CVS). Method A retrospective study included 62 patients with functional AVF and confirmed CVS: subclavian, brachiocephalic veins, vena cava inferior, or multiple lesions. In 39 patients, stents were not used; isolated balloon angioplasty (BA) was performed. In 23 patients we used bare metal stents during the first endovascular treatment. Results The use of stents leads to increase of primary patency (the time interval between the first and second endovascular interventions) – fig. 1A; HR (BA only vs. stenting) 2.064 [95% CI 1.252; 3.404], p = 0.0017. The use of stents allows to increase secondary patency (the time interval between the first endovascular intervention and the complete cessation of the use of AVF): HR=2.03 [95% CI 1.232; 3.347], p = 0.0021; fig 1B. Total need for surgical interventions did not differ: BA only 1.511 [95% CI 1.225; 1.843] and BA+stenting 1.277 [95% CI 0.997; 1.611] per 10 patient-months, incidence rate ratio 1.183 [95% CI 0.872; 1.612] p=0.2822. The second isolated BA allowed to increase patency compared to the first (HR of AVF function loss or relapse 0.512 [95% CI 0.32; 0.818], log rank p=0.001), and the third compared to the second isolated BA (HR=0.607 [95% CI 0.384; 0.959], log rank p=0.0157). The fourth isolated BA also showed a slight increase in AVF patency, but in this case we observed no significant difference with the previous intervention (HR= 0.783 [95% CI 0.501; 1.225], log rank p=0.2433). In the case of BA+stenting, the second intervention, which was consisted of stent recanalization, allowed to increase patency of the AVF (HR= 0.433 [95% CI 0.231; 0.813], log rank p= 0.0014), but the third intervention was no longer accompanied by a significant increase in patency (HR= 0.873 [95% CI 0.489; 1.558], log rank p= 0.629) and AVF function was completely lost. Conclusion The use of stents leads to a moderate increase in the median patency of AVF and a significant increase in the proportion of patients with functional AVF in the long-term period. However, repeated surgeries are significantly less effective than in a case of isolated BA. Therefore, we consider isolated BA to be the optimal treatment strategy, and stenting should be used only if the isolated BA does not result in clinical improvement. Multiple endovascular interventions can extend the duration of AVF functioning, however, in our study, AVF function was completely lost up to 52 months after the clinical manifestation of CVS in all patients. Thus, isolated BA and BA combined with a bare metal stent placement cannot be considered as a definitive treatment of CVS. Endovascular interventions provide only the necessary amount of time to create vascular access on the contralateral side or for shift of modality of renal replacement therapy.