Association of severe preeclampsia and vascular damage assessed by noninvasive markers of arterial stiffness

BACKGROUND

Preeclampsia (PE) is a hypertensive disorder of pregnancy associated with high maternal and fetal morbidity and mortality and increased future risk of cardiovascular complications.

OBJECTIVE

To analyze whether women who have had PE with severe features in their pregnancy have higher arterial stiffness (AS) parameters than those whose PE course was without signs of severity.

METHODS

Sixty-five women who developed PE during their gestation were evaluated, divided into two groups: PE group without severe features or non-severe PE (n=30) and PE group with severe features or severe PE (n=35). Carotid-femoral pulse wave velocity (cfPWV), central augmentation index corrected to a heart rate of 75 beats per minute (AIxc75) and central augmentation pressure (cAP) were determined one month and six months postpartum. Comparison of proportions was carried out using the chi-square test, comparison of means between groups using the Student's t-test or the Mann-Whitney test, and comparison of means of the same group at different evolutionary moments, using the t-test or the Wilcoxon test. Correlation, with and between hemodynamic parameters, was carried out with Spearman's correlation coefficient and the association between demographic variables, personal history and hemodynamic parameters, and altered arterial stiffness parameters was carried out using linear and logistic regression models.

RESULTS

Women with severe PE presented, both at 1 and 6 months postpartum, higher values of blood pressure, both central and peripheral, as well as AR and pulse amplification parameters, than those women whose PE was not severe. Central augmentation index (cAIx) values at 1 month and 6 months postpartum were higher, although not significantly, in the severe PE group compared to the non-severe PE group (24.0 (16.5-34.3) vs. 19.0% (14-29) and 24.0 (14.0-30.0) vs. 20.0% (12.3-26.8), respectively). Carotid-femoral pulse wave velocity (cfPWV) was significantly higher at both 1 and 6 months postpartum in the severe PE group compared to the non-severe PE group (10.2 (8.8-10.7) vs. 8.8m/s (8.3-9.6) and 10.0 (8.8-10.6) vs. 8.8m/s (8.3-9.3), respectively). Central systolic pressure and central pulse pressure amplification were also higher, although not significantly, in the severe PE group in comparison with the non-severe PE group.

CONCLUSIONS

Women who have had severe PE have more pronounced arterial stiffness parameters than those in whom PE was not particularly severe. The determination of cAIx and cfPWV, as a strategy for the assessment of cardiovascular risk, should be evaluated among women who have had PE.

Non-HLA Antibodies and Their Role in Highly Sensitized Patients

BACKGROUND

The role of non-HLA antibody is gaining special attention in solid-organ transplantation and in highly sensitized (HS) patients because of its potential involvement in graft loss (GL) and/or antibody-mediated rejection (ABMR). The identification of non-HLA antibodies while listed may provide deeper information about the increased immunologic risk prior to transplant. We aimed to identify non-HLA antibodies pretransplant that could involve GL in HS patients.

METHODS

Nineteen pretransplant samples from HS patients who underwent transplant at the Marqués de Valdecilla University Hospital were studied for both HLA antibodies and a panel of 39 non-HLA antigens analyzed based on Luminex platform.

RESULTS

Eleven patient (57.9%) maintained the graft (KT group), whereas 8 (42.1%) had a GL within a median of 30 days. The median fluorescent intensity (MFI) of the 39 non-HLA antigens were compared within the groups, obtaining a statistically significant differences in protein tyrosine phosphatase receptor type N (P < .04) with a MFI mean of 1408 vs 4931 for KT and GL groups, respectively. However, no significant differences were observed in non-HLA MFI between ABMR and non-ABMR KT recipients.

CONCLUSIONS

The presence of non-HLA antibodies in HS is high. The levels of anti-protein tyrosine phosphatase receptor type N before transplant could indicate a potential risk of GL, although longitudinal studies with large number of cases are needed to define anti-non-HLA profiles of risk of ABMR.

MO371: Should We Systematically Look for Urine Alterations in all Patients With Monoclonal Gammopathy of Undetermined Significance?

BACKGROUND AND AIMS

Monoclonal gammopathy of undetermined significance (MGUS) has a high prevalence in the elderly population, being as high as 9% in subjects over 85 years. Population aging leads to an increase in the number of patients with MGUS. In 2012, monoclonal gammopathy of renal significance (MGRS) was described to identify MGUS patients with renal alterations but without overt hematological disorders. Despite an increasing number of cases and case series being reported, the prevalence and natural history of MGRS are not known with precision, in part because a systematic search for kidney damage is not standardized in all patients in whom MGUS is diagnosed. Our objective was to analyze in how many MGUS patients urine has been systematically analyzed and in how many of them any alterations suggestive of MGRS were detected.

METHOD

A retrospective observational study was carried out in our center of all patients in whom a paraprotein had been detected in the blood during the first trimester of 2018 and who did not present a known underlying hematological disorder. Glomerular filtration rate (GFR) was estimated using the CKD-EPI equation. The percentage of patients with a urine test using dipstick and urine sediment was analyzed, as well as the presence or any alteration suggestive of MGRS in them.

RESULTS

Three hundred and sixty patients were recorded, 44% females and with a mean age of 74 ± 12 years. Mean GFR was 69 ± 22 mL/min/1.73 m2 being 32% below 60 mL/min/1.73 m2. Urine dipstick and urine sediment were performed in only 42% and 24% of patients, respectively. Urine dipstick was more frequently performed in patients with worse GFR (72 ± 20 versus 64 ± 24 mL/min/1.73 m2P = 0.001) and in older patients (73 ± 13 versus 76 ± 11, P = 0.027). Similarly, urine sediment was more frequently performed in patients with worse GFR (72 ± 20 versus 59 ± 25 mL/min/1.73 m2 P &lt; 0.001). Significant hemoglobinuria was found in 38% and dipstick albuminuria in 29% of them. Among those patients with urine sediment analysis, significant hematuria was detected in 56% and leukocyturia in 52%. Patients with significant dipstick hemoglobinuria (70 ± 21 versus 55 ± 26 mL/min/1.73 m2 P &lt; 0.001) and albuminuria (68 ± 21 versus 54 ± 28 mL/min/1.73 m2 P = 0.005) showed worse GFR (figure 1).

CONCLUSION

Despite the risk of suffering some pathologic renal conditions included in the term MGRS, in most of our patients with MGUS, a urine dipstick or sediment analysis is not performed. MGUS patients with urine alterations show worse renal function. We advocate that all MGUS patients should have a dipstick and sediment urinalysis to rule out any possible associated kidney damage.

MO1013: What is the Best Measure of Time in the Therapeutic Range of Tacrolimus for Kidney Transplantation?

BACKGROUND AND AIMS

Tacrolimus is the main immunosuppressive drug in the vast majority of kidney transplants, but it is a drug with a narrow therapeutic margin. Each centre must establish therapeutic ranges to optimize its efficacy and minimize its toxic effects. Maintaining levels in the appropriate range is difficult due to its inherent inter- and intra-patient variability. In the monitoring of transplants, in addition to assessing the drug levels at each visit, the measurement of time in therapeutic range (TTR) allows us to measure how long the patient has been exposed to the appropriate doses. Currently, it is not known which are the optimal ranges of time or of blood levels that are better related to the subsequent evolution of kidney transplantation.

METHOD

We performed a single centre, observational study of 215 consecutive kidney transplant recipients performed in our centre from October/2014 to January/2020 who received uninterrupted treatment with tacrolimus during the first year, excluding hypersensitized recipients. TTR was calculated using the Rosendaal method between months 3 and 12 (TTR-M3-12) or 6 and 12 (TTR-M6-12) with a target for blood levels &gt;6 ng/mL (TTR-M3-12-T &gt; 6, TTR-M6-12-T &gt; 6) or between 6 and 10 ng/mL (TTR-M3-12-T6-10, TTR-M6-12-T6-10).

RESULTS

The mean follow-up time was 4.1 ± 2.0 years. The TTR that had a greater capacity to discriminate the risk of rejection {TTR-M3-12-T &gt; 6: AUC-ROC 0.614, [95% confidence interval (95% CI) 0.513–0.714]; P = .018; TTR-M6-12-T &gt; 6: AUC-ROC 0.607, 95% CI 0.502–0.713, P = .029; TTR-M3-12-T6-10: AUC-ROC 0.610, 95% CI 0.516–0.703, P = .023; TTR-M6-12-T6-10; AUC-ROC 0.596, 95% CI 0.495–0.696, P = .051} during the first year and of having a glomerular filtration rate of &lt;30 mL/min/1.73 m2 at the first year (TTR-M3-12-T &gt; 6: AUC-ROC 0.676, 95% CI 0.542–0.811; P = .014; TTR-M6-12-T &gt; 6: AUC-ROC 0.623, 95% CI 0.511–0.795; P = .037; TTR-M3-12-T6-10: AUC-ROC 0.566, 95% CI 0.429–0.703; P = .358; TTR-M6-12-T6-10: AUC-ROC 0.575, 95% CI 0.446–0.703; P = .310) was TTR-M3-12-T &gt; 6. By Cox regression, the TTR that was significantly related to death censored graft loss of the kidney graft censoring for death was TTR-M3-12-T &gt; 6 (TTR-M3-12-T &gt; 6: HR = 0.972, 95% CI 0.949–0.995; P = .079; TTR-M6-12-T &gt; 6: HR = 0.980, 95% CI 0.961–0.998; P = .033; TTR-M3-12-T6-10: HR = 0.985, 95% CI 0.962–1.009; P = .230; TTR-M6-12-T6-10: HR = 0.987, 95% CI 0.968–1.007; P = .199). By multivariate Cox regression analysis, patients in the lower tertile of TTR (HR = 10.027, 95% CI 1.244–81.447; P = .031) had worse survival than those in the upper tertiles, regardless of kidney function in the first year (Fig. 1).

CONCLUSION

The measurement of TTR after kidney transplantation makes possible to easily estimate the time of exposure to adequate levels of tacrolimus, relating it to the risk of acute rejection, kidney function in the first year, and death-censored graft survival. Among the possible TTR measures, the one that is best related to post-transplant outcome is taking into account tacrolimus blood levels between month 3 and 12 and those &gt;6 ng/mL (TTR-M3-12-T &gt; 6).

Safety and immediate humoral response of COVID-19 vaccines in chronic kidney disease patients: the SENCOVAC study

Background

Chronic kidney disease (CKD) patients are at high-risk for severe Covid-19. The multicentric, observational and prospective SENCOVAC study aims to describe the humoral response and safety of SARS-CoV-2 vaccines in CKD patients. Safety and immediate humoral response results are reported here.

Methods

Four cohorts of patients were included: kidney transplant (KT) recipients, haemodialysis (HD), peritoneal dialysis (PD) and non-dialysis CKD patients from 50 Spanish centres. Adverse events after vaccine doses were recorded. At baseline and on day 28 after the last vaccine dose, anti-Spike antibodies were measured and compared between cohorts. Factors associated with development of anti-Spike antibodies were analyzed.

Results

1746 participants were recruited: 1116 HD, 171 PD, 176 non-dialysis CKD patients and 283 KT recipients. Most patients (98%) received mRNA vaccines. At least one vaccine reaction developed after the first dose in 763 (53.5%) and after the second dose in 741 (54.5%) of patients. Anti-Spike antibodies were measured in the first 301 patients. At 28 days, 95% of patients had developed antibodies: 79% of KT, 98% of HD, 99% of PD and 100% of non-dialysis CKD patients (p<0.001). In a multivariate adjusted analysis, absence of an antibody response was independently associated to KT (OR 20.56, p = 0.001) and to BNT162b2 vaccine (OR 6.03, p = 0.023).

Conclusion

The rate of anti-Spike antibody development after vaccination in KT patients was low but in other CKD patients it approached 100%; suggesting that KT patients require persistent isolation measures and booster doses of a Covid-19 vaccine. Potential differences between Covid-19 vaccines should be explored in prospective controlled studies.

RICORS2040: the need for collaborative research in chronic kidney disease

Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still confuse CKD with chronic kidney insufficiency or failure. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is ‘solved’ by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated ageing and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal coronavirus disease 2019 (COVID-19) and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality that is 10- to 100-fold higher than similar-age peers, and life expectancy is shortened by ~40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth greatest global cause of death by 2040 and the second greatest cause of death in Spain before the end of the century, a time when one in four Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded Centres for Biomedical Research (CIBER) network structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020–2030 was launched by the American Association of Kidney Patients and the European Kidney Health Alliance. Leading Spanish kidney researchers grouped in the kidney collaborative research network Red de Investigación Renal have now applied for the Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) call for collaborative research in Spain with the support of the Spanish Society of Nephrology, Federación Nacional de Asociaciones para la Lucha Contra las Enfermedades del Riñón and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true.

MO924GROWTH DIFFERENTIATION FACTOR 15 PREDICTOR VALUE IS SUPERIOR TO TROPONIN I IN THE EVALUATION OF KIDNEY TRANSPLANT CANDIDATES

Background and Aims

Elevation of cardiac troponin has been shown to be a marker of myocardial ischemia and other cardiovascular pathologies frequently present in patients with CKD. Pretransplant cardiac troponin I (cTNI) has demonstrated its predictor value of survival after kidney transplant in previous studies. Growth differentiation factor 15 (GDF-15) is a biomarker induced by oxidative stress currently studied as a predictor of mortality and cardiovascular events (CVE) in multiple scenarios, including patients with chronic kidney disease. The aim of this study is to compare the utility of cTNI and GDF-15 to predict posttransplant mortality and CVE in a cohort of kidney transplant recipients.

Method

We included 359 kidney transplants performed between 2005 and 2015. cTNI and GDF-15 were measured on stored serum samples obtained pretransplant. Information about patients was extracted from the prospectively maintained database of renal transplant recipients at our center.

Results

Receptors had a median age of 54.1 and were 67.4% male. 22% were diabetic before the transplant, whereas 9.5% and 8.1% had prior history of coronary and peripheral artery disease. 16.5% transplants were performed preemptively. Median GDF-15 was 5346.4 (IQR= 4071.83-6786.32) pg/ml and median cTNI was 5.6 (IQR= 3.11-10.67) ng/l. After follow up, 77 (21.45%) patients died. During this period, incidence of cerebrovascular accident, acute coronary syndrome and mayor adverse cardiovascular events (MACE) was 6.38%, 12.68% and 20.56% respectively. Patients were stratified in tertiles according to GDF-15 and cTNT levels. In the univariate analysis, higher levels of GDF-15 significantly related to overall mortality, cardiovascular mortality, cerebrovascular accident, acute coronary syndrome and major adverse cardiovascular events. Higher cTNI related to cardiovascular mortality, acute coronary syndrome and MACE, but not overall mortality (Log Rank p=0.4). (Fig 1).

By multivariate cox regression analysis, including both biomarkers and clinical characteristics (age, diabetes, prior coronary and peripheral artery disease and pretransplant renal replacement therapy), the relation between overall survival and GDF-15 remained significant for the highest tertile (HR 2.2 CI95% (1.2-4.1), p = 0.01). Similarly, GDF-15 relation with cerebrovascular accidents and MACE remained significant after the adjustment by these characteristics [HR 9.7 CI95% (2.2-43.1), p = 0.003 and HR 2.7 CI95% (1.4-5.1), p = 0.002] for the highest risk tertile. On the contrary, posttransplant acute coronary syndrome was only related to cTNI tertiles and previous coronary artery disease in the multivariate model [HR 3.2 CI95% (1.5-7.3), p = 0.003 for the highest cTNI tertile].

Conclusion

Our study highlights the potential utility of GDF-15 as a predictor of mortality and cardiovascular events after kidney transplant and its superiority compared to cTNI. In our study, cardiac troponin showed a stronger relation with acute coronary events, probably due to its specific production in myocardial tissue. Altogether, these two molecules could be used in conjunction with clinical characteristics to create prognostic models to better stratify patient’s risk prior organ allocation, predict mortality and cardiovascular adverse events after transplant and ideally find strategies to minimize them. Large-scale, multicenter validation using these biomarkers would be the next step to prove its utility among kidney transplant candidates.

Advanced Chronic Kidney Disease Units in Spain: a national survey on standards of structure, resources, results and patient safety

BACKGROUND AND OBJECTIVE

Recently, the Advanced Chronic Kidney Disease Units (UERCA, in Spanish) have been developed in Spain to offer a better quality of life to patients with advanced chronic kidney disease (ACKD), improving their survival and reducing morbidity in this phase of the disease. Nowadays, there is not much evidence in the Spanish and international literature regarding the structure and how to achieve these objectives in the UERCA. From the ERCA working group of the Spanish Society of Nephrology (SEN), this project is promoted to improve care for ERCA patients through the definition of quality standards for the operation of the UERCA.

MATERIAL AND METHODS

An initial proposal for quality standards concerning the operation of the UERCA was configured through consultation with the main sources of references and the advice of an expert working group through face-to-face and telematic meetings. Base on this initial proposal of standards, a survey was conducted and sent it via email to 121 nephrology specialist and nursing professionals with experience in Spanish UERCA to find out, among others, the suitability of each standards, that is, its mandatory nature or recommendation as standards. The access to the survey was allowed between July 16^th, 2018, until September 26^th, 2018.

RESULTS

A total of 95 (78.5%) professionals participated out of the 121 who were invited to participate. Of these, 80 of the participants were nephrology specialists and 15 nursing professionals, obtaining a varied representation of professionals from the Spanish geography. After analyzing the opinions of these participants, the standards were defined to a total of 68, 37 of them (54.4%) mandatory and 31 of them (45.5%) recommended. Besides, it was observed that the volume of patients attended in the UERCA is usually above 100 patients, and the referral criteria is generally below 25-29 mL/min/1.73 m² of glomerular filtration.

CONCLUSIONS

This work constitutes a first proposal of quality standards for the operation of UERCA in Spain. The definition of these standards has made it possible to establish the bases for the standardization of the organization of UERCA, and to subsequently work on the configuration of a standards manual for the accreditation of ERCA Units.

P1739IMMUNOSUPPRESSION WITH CALCINEURIN INHIBITOR AFTER RENAL TRANSPLANT FAILURE PREVENTS ALLOSENSITIZATION

Background and Aims

Retransplantation is an important option to consider in patients who return to dialysis after graft failure since it reduces mortality. HLA allosensitization hinders retransplantation, and immunosuppression withdrawal after graft failure seems to favor sensitization. There are no established protocols on the immunosuppressive treatment that should be maintained after transplant failure in order to reduce the development of anti-HLA antibodies. The aim of the study is to evaluate the effect of immunosuppression withdrawal on the development of anti-HLA antibodies after graft loss.

Method

A retrospective analysis including 77 patients who lost their first renal graft between 1/1/2006-12/31/2015 was performed. 22 patients with preemptive second kidney transplant were included. Maintenance immunosuppression was collected in months 1, 3 and 6 after graft failure. Patients were divided into two groups according to the presence or not of calcineurin inhibitor (CNI) as maintenance treatment. Two sera were analyzed per patient, one immediately prior to graft loss and another one after graft failure (Luminex®, Single Antigen). In patients in whom transplantectomy was performed, the selected serum after transplant failure was already after graft nephrectomy. PRA was calculated (cPRA) in each serum and the development of de novo donor-specific antibodies (dnDSA) was evaluated.

Results

Selected sera were extracted 1.0 month before graft failure (interquartile range 0.3-2.0) and 7.6 months after transplant failure (interquartile range 6.0-12.2). By multivariate logistic regression analysis, graft nephrectomy was an independent risk factor for cPRA&gt;75% after transplant failure (OR 4.9, CI 95% 1.0-22.2, p=0.038). Similarly, the absence of CNI at 6 months after graft failure was significantly related to cPRA&gt;75% in the multivariate analysis (OR 4.8, CI 95% 1.5-15.0, p=0.006). It was possible to analyze dnDSA formation in 73 patients. The absence of CNI at 6 months after graft loss was an independent risk factor for dnDSA development (OR 23.2, CI 95% 5.3-100.6, p &lt;0.001). There were no differences in the management of other immunosuppressive drugs.

Conclusion

The absence of maintenance treatment with CNI at the sixth month after graft loss is a risk factor for sensitization. Therefore, immunosuppressive maintenance treatment based on CNI after transplant failure should be considered, since it seems to prevent HLA allosensitization.

P1691URINARY CXCL10 AT SIX AND TWELVE MONTH PREDICTS SUBCLINICAL ANTIBODY MEDIATED REJECTION AT 1 YEAR

Background and Aims

Despite the improvement in renal transplant results, the rate of graft loss from the first year has improved poorly, antibody-mediated rejection (AbMR) being the first cause of renal graft loss. Renal transplantation is usually monitored by measuring creatinine, proteinuria, immunosuppressive blood levels and, recently, donor specific antibodies and polyomavirus load. However, currently the only way to detect the alloimmune graft damage is to perform a surveillance o by indication renal biopsy. Non-invasive monitoring of the alloimmune response could contribute to improving renal transplant results. Previous studies have shown that urinary CXCL10 relates to both clinical and subclinical allograft rejection and graft loss. Our aim was to analyze the relationship between urinary CXCL10 and the biopsy findings of 1-year surveillance biopsies.

Method

From Dec/2013 to Nov/2017 90 surveillance biopsies were performed in our center at 1 year after kidney transplantation. Urine were prospectively collected at 6 and 12 month and urine samples were frozen at -70º. CXCL10 was measured by using human CXCL10/IP-10 DuoSet ELISA kits (R&D Systems) according to the protocols recommended by the company. Biopsies were classified according to Banff criteria.

Results

Median values of CXCL10 were 51.2 pg/ml (IQR 38.5 – 98.9 pg/ml) at 6 month and 62.8 pg/ml (IQR 42.7 – 99.4 pg/ml) at 12 month after transplantation. Both values were statistically related (r = 0.400, p = 0.012), and there were no significant statistical differences between both (Wilcoxon`s test p = 0.063). CXCL10 did not relate to serum creatinine, glomerular filtration rate, albuminuria, tacrolimus blood levels or prednisone dose at 1 year. Some 16.7% allograft biopsies showed subclinical cellular rejection, 26.7% showed antibody mediated rejection and 20.0% transplant glomerulopathy. Patients with antibody mediated rejection (AbMR) had higher levels of 1-year urinary CXCL10 [55.4 pg/ml (IQR 39.3) vs. 97.4 pg/ml (IQR 103.9), p = 0.021], lower GFR [68.0 ml/min/1.73m2 (IQR 33.5) vs. 43.5 ml/min/1.73m2 (IQR 22.8), p &lt; 0.001] and similar albuminuria (p = 0.079). According to ROC curve, 1-year urinary CXCL10 could discriminate patients with subclinical AbMR (AUC-ROC 0.660, 95%CI 0.511-0.809, p = 0.021). After adjusting by GFR and albuminuria, 1-year urinary CXCL10 in a logarithmic scale was able to predict subclinical AbMR (OR 2.254, 95%CI 1.012-5.021, p = 0.047) by logistic regression analysis. Similarly, patients with subclinical AbMR at 1 year had higher levels of 6-month urinary CXCL10 [45.9 pg/ml (IQR 41.4) vs. 102.3 pg/ml (IQR 1935), p = 0.026]. Moreover, 6-month urinary CXCL10 could discriminate those patients who were going to show subclinical AbMR at 1-year (see figure; AUC-ROC 0.731, 95%CI 0.545-0.916, p = 0.027). After logistic regression, each tertil of 6-month urinary CXCL10 increased the risk of suffering subclinical AbMR more than thrice (OR 3.346, 95%CI 1.184-9.456, p = 0.023).

Conclusion

Both 6- and 12-month urinary CXCL10 relate to the diagnosis of subclinical AbMR by 1-year surveillance biopsies independently of other variables such as renal function and albuminuria. Of interest, by a non-invasive monitoring of urinary CXCL10 as early as at 6 months we can predict some subclinical histologic findings at 1 year, such as AbMR, that can have a strong impact on the transplant outcome.

P1622GROWTH DIFFERENTIATION FACTOR 15: A BIOMARKER WITH HIGH CLINICAL POTENTIAL IN THE EVALUATION OF KIDNEY TRANSPLANT CANDIDATES

Background and Aims

Kidney transplantation results a significant improvement in patient survival. Nevertheless, mortality the first years after transplant remains relatively high, being mostly related to cardiovascular (CV) events. The selection of patients for kidney transplantation includes a general assessment focused on CV status. In spite of that, due to the complexity and heterogeneity of mechanisms leading to vascular disease in this population (not exclusively related to traditional CV risk factors and pathogenesis), this evaluation remains insufficient and not particularly effective. During the last years different strategies have been studied to stratify potential receptors better and optimize organ allocation, including the development of clinical prognostic scores and novel biomarkers.

Growth differentiation factor 15 (GDF-15) is a stress-responsive member of the TGF-β family. Although its mechanism of action is not completely understood, it acts as a cytokine with effects in regulation of inflammation, metabolism and senescence. In the recent years, interest has arisen regarding its use as a biomarker for diagnosis, prognosis and risk stratification in multiple scenarios. Encouraging results have shown its utility as a biomarker of mortality (all cause and CV), heart failure and acute coronary syndrome in different populations. The aim of this work is to assess the utility of GDF-15 to predict survival in kidney transplant candidates.

Method

395 kidney transplant recipients between 2005 and 2015 were included. GDF-15 measurements were performed from stored serum samples obtained pretransplant. The concentration of GDF-15 was analyzed using an enzyme-linked immunosorbent assay (Quantikine, R&D Systems).

Results

Patient characteristics are shown in Table 1. The median GDF-15 was 5331.3 (50.49-16242.3) pg/ml. After a mean of 90.6 ± 41.5 months of follow up 82 (20.8%) patients died. Patients were stratified in tertiles according to GDF-15 levels: low (GDF-15 ≤ 4612.1 pg/ml), medium (GDF-15 4612.1-6296.5 pg/ml) and high risk tertile (GDF-15 &gt; 6296.5 pg/ml). Higher GDF-15 concentrations were significantly associated with mortality: HR 2.16 95%CI (1.14-1.44), p = 0.018 for medium tertile and HR 3.28 95%CI (1.79-6.1), p &lt;0.001 for high risk tertile (Figure 1). After adjusting for age, diabetes, coronary artery disease, peripheral vascular disease, non-renal solid organ transplant and dialysis at the time of transplant, the relation between survival and GDF-15 was significant (HR 2.24 95%CI (1.2-4.16), p = 0.011 for high risk tertile). After adjusting by EPTS (Estimated Post Transplant Survival score) the association with GDF-15 remained significant: HR 3.24 95%CI (1.2-8.8), p = 0.021 for medium risk tertile and HR 4.3 95%CI (1.65-11.54), p = 0.003 for high risk tertile (calculated only in first renal transplants). Mortality at 3 years was 6.9% (27 patients) and it was only related to coronary artery disease and GDF-15 (OR 7.1 95%CI (1.6-32.1), p = 0.01 for high risk tertile) after adjustment.

Conclusion

In our cohort, higher GDF-15 levels were independently associated with mortality in kidney transplant candidates. This study suggests that GDF-15 may be useful in stratifying recipient risk, adding value to the prognostic tools already available in clinical practice. Further work is needed to confirm these findings and elucidate the mechanisms linking this protein with mortality and CV disease in patients with CKD.

High Pretransplant BAFF Levels and B-cell Subset Polarized towards a Memory Phenotype as Predictive Biomarkers for Antibody-Mediated Rejection

Antibody-mediated rejection (AbMR) is one of the leading causes of graft loss in kidney transplantation and B cells play an important role in the development of it. A B-cell activating factor (BAFF) is a cytokine involved in B cell ontogeny. Here, we analyzed whether B cell maturation and the effect of B cell soluble factors, such as BAFF could be involved in AbMR. Serum BAFF levels and B and T cell subpopulations were analyzed 109 kidney transplant patients before transplantation and at 6 and 12 months after kidney transplantation. Pretransplant serum BAFF levels as well as memory B cell subpopulations were significantly higher in those patients who suffered clinical AbMR during the first 12 months after kidney transplantation. Similar results were observed in the prospective analysis of patients with subclinical antibody-mediated rejection detected in the surveillance biopsy performed at 12 months after kidney transplantation. A multivariate analysis confirmed the independent role of BAFF in the development of AbMR, irrespective of other classical variables. Pretransplant serum BAFF levels could be an important non-invasive biomarker for the prediction of the development of AbMR and posttransplant increased serum BAFF levels contribute to AbMR.

Epidemiology of hyperkalemia in chronic kidney disease

BACKGROUND

Hyperkalaemia is a significant electrolyte imbalance in chronic kidney disease (CKD). Renin-angiotensin-aldosterone system inhibitors (RAASi) have beneficial cardio-renal properties, although they can often cause hyperkalaemia.

OBJECTIVE

To examine the prevalence of hyperkalaemia in CKD, identify factors associated with its appearance and the relationship between hyperkalaemia and mortality.

PATIENTS AND METHODS

Retrospective observational study on patients with CKD in the period 1971-2017. The population was categorised into 3groups: Group 1, patients with CKD without renal replacement therapy; Group 2, patients on haemodialysis; and Group 3, patients on continuous ambulatory peritoneal dialysis.

RESULTS

A total of 2,629 patients were evaluated. The prevalence observed in the different groups was: 9.6%, 16.4% and 10.6%, respectively. Risk factors related to the appearance of hyperkalaemia in the CKD group were glomerular filtration rate (GFR) (P<.001), plasma creatinine (P<.001), plasma sodium (P<.001), haemoglobin (P=.028), diastolic blood pressure (P=.012), intake of ACE inhibitors and/or angiotensin ii receptor blockers (P=.008), treatment with metformin (P<.001) and diabetes (P=.045). Treatment with RAASi significantly increased hyperkalaemia as GFR decreased, as well as in patients with diabetes or heart failure.

CONCLUSIONS

Hyperkalaemia is a frequent metabolic alteration in CKD patients that increases in the presence of drugs with beneficial cardio-renal properties (RAASi), which means that patients often lose the benefit associated with these drugs. New, recently-appearing non-absorbable compounds, which bind to potassium in the gastrointestinal tract, enhancing faecal excretion and thus maintaining the cardio-renal benefit of the RAASi, could be relevant in the progress of patients with CKD.

A high sodium intake reduces antiproteinuric response to renin-angiotensin-aldosterone system blockade in kidney transplant recipients

BACKGROUND

Post-transplant proteinuria is associated with lower graft and patient survival. Renin-angiotensin-aldosterone system blockers are used to reduce proteinuria and improve renal outcome. Although it is known that a high salt intake blunts the antiproteinuric effect of ACEI and ARB drugs in non-transplant patients, this effect has not been studied in kidney transplant recipients.

OBJECTIVE

To analyse the relationship between sodium intake and the antiproteinuric effect of ACEI/ARB drugs in kidney transplant recipients.

METHODS

We selected 103 kidney transplant recipients receiving ACEI/ARB drugs for more than 6 months due to proteinuria>1 g/day. Proteinuria was analysed at baseline and at 6 months after starting ACEI/ARB treatment. Salt intake was estimated by urinary sodium to creatinine ratio (uNa/Cr).

RESULTS

Proteinuria fell to less than 1g/day in 46 patients (44.7%). High uNa/Cr was associated with a smaller proteinuria decrease (r=-0.251, P=.011). The percentage proteinuria reduction was significantly lower in patients in the highest uNa/Cr tertile [63.9% (IQR 47.1%), 60.1% (IQR 55.4%), 38.9% (IQR 85.5%), P=.047]. High uNa/Cr independently relates (OR 2.406 per 100 mEq/g, 95% CI: 1.008-5.745, P=.048) to an antiproteinuric response <50% after renin-angiotensin-aldosterone system blockade.

CONCLUSIONS

A high salt intake results in a smaller proteinuria decrease in kidney transplant recipients with proteinuria treated with ACEI/ARB drugs.

Predictive factors of allosensitization in renal transplant patients switched from calcineurin to mTOR inhibitors

Conversion of kidney-transplant recipients from calcineurin inhibitors to mTOR inhibitors has been suggested to be a risk factor for increased alloimmune response. We have analyzed the development of new HLA-antibodies (HLA-Abs) early after conversion in 184 patients converted in stable phase at our hospital and compared with a control group of nonconverted comparable 63 transplants. Using single-antigen solid-phase immunoassay analysis, a preconversion and a 3-6 months postconversion sera were prospectively analyzed in every patient for the appearance of new HLA-Abs. Renal function at 2 years postconversion and cumulative graft survival were compared between groups. In 16 patients, new HLA-Abs (3-DSA and 13-NonDSA), not present at the moment of conversion, were detected (8.7% vs. 3.1% in the control group). The type of mTORi used, type of CNI preconversion, the presence of steroids, time of conversion, or indication for conversion did not have influence on this effect but the presence of HLA-Abs before conversion highly correlated with the appearance of new specificities. Patients with de novo HLA-Abs showed a trend to worst graft function and survival. In conclusion, conversion to mTORi can be followed by early appearance of de novo HLA-Abs, especially in patients with HLA-Abs preconversion, and this complication should be screened early after conversion.

Prediction at first year of incident new-onset diabetes after kidney transplantation by risk prediction models

OBJECTIVE

Our aim was to analyze the performance of two scores developed for predicting diabetes in nontransplant populations for identifying kidney transplant recipients with a higher new-onset diabetes mellitus after transplantation (NODAT) risk beyond the first year after transplantation.

RESEARCH DESIGN AND METHODS

We analyzed 191 kidney transplants, which had at least 1-year follow-up posttransplant. First-year posttransplant variables were collected to estimate the San Antonio Diabetes Prediction Model (SADPM) and Framingham Offspring Study-Diabetes Mellitus (FOS-DM) algorithm.

RESULTS

Areas under the receiver operating characteristic curve of FOS-DM and SADPM scores to predict NODAT were 0.756 and 0.807 (P < 0.001), respectively. FOS-DM and SADPM scores over 75 percentile (hazard ratio 5.074 and 8.179, respectively, P < 0.001) were associated with NODAT.

CONCLUSIONS

Both scores can be used to identify kidney recipients at higher risk for NODAT beyond the first year. SADPM score detects some 25% of kidney transplant patients with an eightfold risk for NODAT.

[Estimation of glomerular filtration rate using weight/creatinine formula]

BACKGROUND AND OBJECTIVE

The correct management of patients with chronic renal disease depends on an early diagnosis. The aim of this study was to evaluate the usefulness, in the daily clinical practice, of the weight/creatinine formula as an indirect measurement of glomerular filtration.

PATIENTS AND METHOD

1,025 ambulatory patients were referred to the Nephrology Laboratory for basic blood and urine analysis. Creatinine clearance was calculated with the standard formula.

RESULTS

A good correlation between the creatinine clearance adjusted for the corporal surface and that estimated by the weight/creatinine formula was observed, especially when creatinine levels were between 1.5-3 mg/dl and patients were older than 60 years. The mean difference between both methods was 6.3 (14.5) ml/min for males and 2.4 (10.5) ml/min for females. The weight/creatinine formula had a sensitivity of 91% and a specificity of 80% to detect a clearance below 50 ml/min.

CONCLUSIONS

The weight/creatinine formula underestimates the clearance for normal creatinine values but fits quite well for creatinine levels between 1.5-3 mg/dl, mainly in patients older than 60 years. Although the estimation of clearance through this formula could be inaccurate, in most cases this is clinically irrelevant. Moreover, such a simple formula could avoid potential mistakes appearing at the time of evaluating renal function only by the serum creatinine.