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Preview: Nephrology Dialysis Transplantation - current issue

Nephrology Dialysis Transplantation Current Issue

Published: Fri, 12 May 2017 00:00:00 GMT

Last Build Date: Fri, 12 May 2017 07:49:42 GMT




News from ERA-EDTA:

Farewell Editorial


When I started my directorship of NDT 6 years ago, the journal was in an expanding phase. During the tenure of Professor Norbert Lameire, the number of submissions to our journal grew to exceed 2500 articles per year, the highest submission rate recorded among journals dedicated to renal disease and among the highest in the internal medicine area. Due to this high rate of submissions, over the years NDT became a thick journal, publishing about 45 manuscripts per issue. The number of pages in each issue regularly exceeded 400 pages. Rightly so, Norbert Lameire was proud of the fact that articles published in NDT were frequently quoted and commented on by lecturers at international congresses. Overall, NDT was a journal that was popular worldwide, particularly for the publication of articles relevant for medical practice.

Opponent’s comments


Dr Dekker and colleagues assert that prediction is difficult, and recommend that researchers focus efforts on validation and implementation studies rather than the development of new models. They argue that flaws in model development and questionable findings from impact studies have limited the clinical utility of most risk prediction models.

Moderator’s view: Predictive models: a prelude to precision nephrology


Appropriate diagnosis is fundamental in medicine because it sets the basis for the prediction of disease outcome at the single patient level (prognosis) and decisions regarding the most appropriate therapy. However, given the large series of social, clinical and biological factors that determine the likelihood of an individual’s future outcome, prognosis only partly depends on diagnosis and aetiology and treatment is not decided solely on the basis of the underlying diagnosis. This issue is crucial in multifactorial diseases like atherosclerosis, where the use of statins has now shifted from ‘treating hypercholesterolaemia’ to ‘treating the risk of adverse cardiovascular events’. Approaches that take due account of prognosis limit the lingering risk of over-diagnosis and maximize the value of prognostic information in the clinical decision process. In the nephrology realm, the application of a well-validated risk equation for kidney failure in Canada led to a 35% reduction in new referrals. Prognostic models based on simple clinical data extractable from clinical files have recently been developed to predict all-cause and cardiovascular mortality in end-stage kidney disease patients. However, research on predictive models in renal diseases remains suboptimal and non-accounting for competing events and measurement errors, and a lack of calibration analyses and external validation are common fallacies in currently available studies. More focus on this blossoming research area is desirable. The nephrology community may now start to apply the best validated risk scores and further test their potential usefulness in chronic kidney disease patients in diverse clinical situations and geographical areas.

Pro: Risk scores for chronic kidney disease progression are robust, powerful and ready for implementation


Accurate risk prediction for chronic kidney disease (CKD) progression can inform the patient–provider dialogue, and provide actionable thresholds for key clinical decisions. In 2011, we developed the kidney failure risk equations (KFREs) to predict the risk of kidney failure requiring dialysis or transplant in patients with CKD. Subsequently, the KFREs have been extensively validated, and have now been proven accurate in multiple continents, ethnicities and disease-specific subpopulations. They can discriminate progressors from non-progressors, and are well calibrated and easy to use. We believe that current and future studies should now focus on clinical implementation of the KFREs, through quality improvement initiatives and cluster randomized trials. A risk-based care paradigm for CKD care can be achieved through knowledge translation and implementation research.

Opponent’s comments


The paper by Tangri et al. provides a clear overview of the studies he performed regarding the development and validation of the kidney failure risk equation (KFRE). This prediction model has been shown to have a good discriminatory ability for patients with future renal failure as well as a good calibration, also when it was tested in several other study populations. This is quite exceptional, as most published risk scores have a much lower predictive value in external validation studies, if they are even externally validated. Even more important, using the KFRE has been shown to have an impressive impact on relevant outcomes in clinical practice, as after implementation in Manitoba, Canada, new referrals dropped by 35% and waiting times for nephrology consultation declined by 90%. This convincingly proves that at least not all clinical risk scores are useless.

Con: Most clinical risk scores are useless


While developing prediction models has become quite popular both in nephrology and in medicine in general, most models have not been implemented in clinical practice on a larger scale. This should be no surprise, as the majority of published models has been shown to be poorly reported and often developed using inappropriate methods. The main problems identified relate to either using too few candidate predictors (based on univariable P < 0.05) or too many (for the number of events), resulting in poorly performing prediction models. Guidelines on how to develop and test a prediction model all stress the importance of external validation to test discrimination and calibration in other populations, as prediction models usually perform less well in new subjects. However, external validity has not often been tested for prediction models in renal patients. Moreover, impact studies showing improved clinical outcomes when using a prediction model in routine clinical practice have been reported rarely. By and large, notwithstanding a few notable exceptions like the kidney failure risk equation prediction model, most models have not been validated externally or are at best inadequately reported, preventing them from be used in clinical practice. Therefore, we recommend researchers to spend more energy on validation and assessing the impact of existing models, instead of merely developing more models that will most likely never be used in clinical practice as well.

A risk prediction score for acute kidney injury in the intensive care unit


Background. Acute kidney injury (AKI) is common in critically ill patients and is associated with high morbidity and mortality. Early identification of high-risk patients provides an opportunity to develop strategies for prevention, early diagnosis and treatment of AKI.Methods. We undertook this multicenter prospective cohort study to develop and validate a risk score for predicting AKI in patients admitted to an intensive care unit (ICU). Patients were screened for predictor variables within 48 h of ICU admission. Baseline and acute risk factors were recorded at the time of screening and serum creatinine was measured daily for up to 7 days. A risk score model for AKI was developed with multivariate regression analysis combining baseline and acute risk factors in the development cohort (573 patients) and the model was further evaluated on a test cohort (144 patients). Validation was performed on an independent prospective cohort of 1300 patients. The discriminative ability of the risk model was assessed by the area under the receiver operating characteristic curve (AUROC) and model calibration was evaluated by Hosmer–Lemeshow statistic. AKI was defined by the Kidney Disease: Improving Global Outcomes criteria (absolute change of 0.3 mg/dL or relative change of 50% from baseline serum creatinine in 48 h to 7 days, respectively).Results. AKI developed in 754 (37.2%) patients. In the multivariate model, chronic kidney disease, chronic liver disease, congestive heart failure, hypertension, atherosclerotic coronary vascular disease, pH ≤ 7.30, nephrotoxin exposure, sepsis, mechanical ventilation and anemia were identified as independent predictors of AKI and the AUROC for the model in the test cohort was 0.79 [95% confidence interval (CI) 0.70–0.89]. On the external validation cohort, the AUROC value was 0.81 (95% CI 0.78–0.83). The risk model demonstrated good calibration in both cohorts. Positive and negative predictive values for the optimal cutoff value of ≥ 5 points in test and validation cohorts were 22.7 and 96.1% and 31.8 and 95.4%, respectively.Conclusions. A risk score model integrating chronic comorbidities and acute events at ICU admission can identify patients at high risk to develop AKI. This risk assessment tool could help clinicians to stratify patients for primary prevention, surveillance and early therapeutic intervention to improve care and outcomes of ICU patients.

Barriers to living donor kidney transplantation in the United Kingdom: a national observational study


Background. Living donor kidney transplantation (LDKT) provides more timely access to transplantation and better clinical outcomes than deceased donor kidney transplantation (DDKT). This study investigated disparities in the utilization of LDKT in the UK.Methods. A total of 2055 adults undergoing kidney transplantation between November 2011 and March 2013 were prospectively recruited from all 23 UK transplant centres as part of the Access to Transplantation and Transplant Outcome Measures (ATTOM) study. Recipient variables independently associated with receipt of LDKT versus DDKT were identified.Results. Of the 2055 patients, 807 (39.3%) received LDKT and 1248 (60.7%) received DDKT. Multivariable modelling demonstrated a significant reduction in the likelihood of LDKT for older age {odds ratio [OR] 0.11 [95% confidence interval (CI) 0.08–0.17], P < 0.0001 for 65–75 years versus 18–34 years}; Asian ethnicity [OR 0.55 (95% CI 0.39–0.77), P = 0.0006 versus White]; Black ethnicity [OR 0.64 (95% CI 0.42–0.99), P = 0.047 versus White]; divorced, separated or widowed [OR 0.63 (95% CI 0.46–0.88), P = 0.030 versus married]; no qualifications [OR 0.55 (95% CI 0.42–0.74), P < 0.0001 versus higher education qualifications]; no car ownership [OR 0.51 (95% CI 0.37–0.72), P = 0.0001] and no home ownership [OR 0.65 (95% CI 0.85–0.79), P = 0.002]. The odds of LDKT varied significantly between countries in the UK.Conclusions. Among patients undergoing kidney transplantation in the UK, there are significant age, ethnic, socio-economic and geographic disparities in the utilization of LDKT. Further work is needed to explore the potential for targeted interventions to improve equity in living donor transplantation.

Unacceptable human leucocyte antigens: how to navigate between increased immunological risk and waiting time?


The continuous improvement of techniques used to detect antibodies directed against human leucocyte antigens (HLAs) during the last decade has important implications for our understanding of transplantation immunology and alloimmunization and consequently the allocation of kidneys for transplantation.

Unacceptable human leucocyte antigens for organ offers in the era of organ shortage: influence on waiting time before kidney transplantation


Background. The assignment of human leucocyte antigens (HLAs) against which antibodies are detected as unacceptable antigens (UAGs) avoids allocation of HLA- incompatible allografts. There is uncertainty as to what extent UAGs decrease the probability of receiving a kidney offer.Methods. Kidney transplantations in 3264 patients on the waiting lists of six German transplant centres were evaluated for a period of at least 2 years. The proportion of excluded offers due to UAGs was calculated as virtual panel-reactive antibodies (vPRAs).Results. In the common Eurotransplant Kidney Allocation Scheme, the transplant probability was unaffected by vPRAs in exploratory univariate analyses. In the multivariable model, a 1% increase in vPRA values was outweighed by an additional waiting time of 2.5 weeks. The model was confirmed using an external validation cohort of 1521 patients from seven centres. If only patients with standard risk were considered (e.g. no simultaneous transplantation of other organs), only 1.3 weeks additional waiting time was needed. In the Eurotransplant Senior Program, patients with vPRA values >50% had a strongly reduced transplant probability in the unadjusted analyses. In the multivariable model, a 1% increase in vPRA values was outweighed by an additional waiting time of 5 weeks.Conclusions: This study demonstrates that the assignment of UAGs decreases the transplant probability in both main Eurotransplant allocation programs because of insufficient compensatory mechanisms. At present, for immunized patients, a prolonged waiting time has to be weighed against the increased immunologic risk due to donor-specific antibodies not assigned as UAGs.

Role of biomechanical forces in hyperfiltration-mediated glomerular injury in congenital anomalies of the kidney and urinary tract


Congenital anomalies of the kidney and urinary tract (CAKUT) including solitary kidney constitute the main cause of progressive chronic kidney disease (CKD) in children. Children born with CAKUT develop signs of CKD only during adolescence and do not respond to renin-angiotensin-aldosterone system blockers. Early cellular changes underlying CKD progression to end-stage renal disease by early adulthood are not well understood. The mechanism of maladaptive hyperfiltration that occurs from loss of functional nephrons, including solitary kidney, is not clear. We re-examine the phenomenon of hyperfiltration in the context of biomechanical forces with special reference to glomerular podocytes. Capillary stretch exerts tensile stress on podocytes through the glomerular basement membrane. The flow of ultrafiltrate over the cell surface directly causes fluid flow shear stress (FFSS) on podocytes. FFSS on the podocyte surface increases 1.5- to 2-fold in animal models of solitary kidney and its effect on podocytes is a subject of ongoing research. Podocytes (i) are mechanosensitive to tensile and shear forces, (ii) use prostaglandin E2, angiotensin-II or nitric oxide for mechanoperception and (iii) use specific signaling pathways for mechanotransduction. We discuss (i) the nature of and differences in cellular responses to biomechanical forces, (ii) methods to study biomechanical forces and (iii) effects of biomechanical forces on podocytes and glomeruli. Future studies on FFSS will likely identify novel targets for strategies for early intervention to complement and strengthen the current regimen for treating children with CAKUT.

Klotho suppresses the renin-angiotensin system in adriamycin nephropathy


Backgrounds: Klotho protein interacts with the transforming growth factor β (TGF-β) receptor and Wnt, which contribute to the progression of renal disease, inhibiting their signals. Renal and circulating klotho levels are diminished in chronic kidney disease.Methods: Experiments were performed to assess whether supplementation of klotho protein could have protective effects on the kidney. Rats were injected with adriamycin (5 mg/kg) and divided into three groups: those treated with vehicle, those treated with klotho protein and those treated with klotho plus 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD). Rats without adriamycin treatment were used as a control.Results: Adriamycin reduced the serum klotho concentration and renal expression of klotho and E-cadherin. Adriamycin also increased the renal expression of Wnt, TGF-β, and angiotensinogen, as well as the renal abundance of β-catenin and angiotensin II. Klotho supplementation suppressed adriamycin-induced elevations of β-catenin and angiotensin II with sustained Wnt expression. Combined treatment with klotho and TDZD reversed the klotho-induced improvements in the renal abundance of β-catenin and angiotensin II as well as the expression of TGF-β and angiotensinogen without affecting E-cadherin.Conclusions: Our data indicate that Wnt is involved in the pathogenesis of adriamycin nephropathy. Furthermore, klotho supplementation inhibited Wnt signaling, ameliorating renal angiotensin II. Finally, klotho protein appears to suppress epithelial–mesenchymal transition by inhibiting TGF-β and Wnt signaling.

Matrix metalloproteinase 9-dependent Notch signaling contributes to kidney fibrosis through peritubular endothelial–mesenchymal transition


Background: Endothelial cells are known to contribute to kidney fibrosis via endothelial–mesenchymal transition (EndoMT). Matrix metalloproteinase 9 (MMP-9) is known to be profibrotic. However, whether MMP-9 contributes to kidney fibrosis via EndoMT is unknown.Methods: Primary mouse renal peritubular endothelial cells (MRPECs) were isolated and treated by recombinant human transforming growth factor beta 1 (rhTGF-β1) with or without MMP-9 inhibitor or by recombinant human MMP-9 (rhMMP-9) alone. Kidney fibrosis was induced by unilateral ureteral obstruction (UUO) in MMP-9 knockout (KO) and wide-type (WT) control mice. The effects of MMP-9 on EndoMT of MRPECs and kidney fibrosis were examined.Results: We showed that MRPECs underwent EndoMT after rhTGF-β1 treatment or in UUO kidney as evidenced by decreased expression of endothelial markers, vascular endothelial cadherin (VE-cadherin) and CD31, and increased levels of mesenchymal markers, α-smooth muscle actin (α-SMA) and vimentin. The expression of fibrosis markers was also up-regulated significantly after rhTGF-β1 treatment in MRPECs. The EndoMT and fibrosis markers were significantly less in rhTGF-β1-treated MMP-9 KO MRPECs, whereas MMP-9 alone was sufficient to induce EndoMT in MRPECs. UUO kidney of MMP-9 KO mice showed significantly less interstitial fibrosis and EndoMT in MRPECs. Notch signaling shown by Notch intracellular domain (NICD) was increased, while Notch-1 was decreased in rhTGF-β1-treated MRPECs of MMP-9 WT but not MMP-9 KO mice. Inhibition of MMP-9 or Notch signaling prevented rhTGF-β1- or rhMMP-9-induced α-SMA and NICD upregulation in MRPECs. UUO kidney of MMP-9 KO mice had less staining of Notch signaling transcription factor Hey-1 in VE-cadherin-positive MRPECs than WT controls.Conclusions: Our results demonstrate that MMP-9-dependent Notch signaling plays an important role in kidney fibrosis through EndoMT of MRPECs.

Systemic amyloidosis: novel therapies and role of biomarkers


Systemic amyloidosis is caused by misfolding and extracellular deposition of one of an ever-growing list of circulating proteins, resulting in vital organ dysfunction and eventually death. Despite different predisposing conditions, including plasma cell dyscrasias [immunoglobulin light chain (AL) amyloidosis], long-lasting inflammation [reactive (AA) amyloidosis] or mutations (hereditary amyloidoses), clinical manifestations are conspicuously overlapping and mimic more prevalent conditions, significantly complicating and often delaying the recognition of these rare, complex diseases. However, refined diagnostic and imaging approaches and the increasing role of biomarkers, which help in establishing the diagnosis, assessing the prognosis and evaluating the response to therapy, have considerably improved the management of these conditions. The pillar of anti-amyloid therapy remains the prompt reduction or elimination of the amyloidogenic precursor. This is accomplished by targeting the underlying condition, and recent improvements in the treatment of plasma cell disorders and chronic inflammatory conditions have positively reverberated onto the management of AL and AA amyloidosis, respectively. Moreover, recent, substantial improvements in the understanding of the molecular underpinnings of systemic amyloidosis have unveiled different key steps in the amyloidogenic cascade which can be valid therapeutic targets. These include stabilizers of the native conformation of the amyloidogenic precursor, inhibitors of fibrillogenesis, amyloid fibril disruptors and promoters of amyloid clearance. Innovative pharmacological strategies, including rational, structure-based drug design, gene knockdown and immunotherapy, but also repurposing of old, safe drugs with newly recognized anti-amyloid properties, are currently being pursued already in the clinical setting, holding the promise of dramatically improving the outcome of these dismal conditions in the near future.

The pressing need for real-time risk assessment of hospital-acquired acute kidney injury


Acute Kidney Injury (AKI) is associated with short- and long-term outcomes that reflect the severity of the injury. Recent studies have suggested that ‘early’ initiation of renal replacement therapy may alter the course of AKI and improve short-term outcomes like inpatient mortality. The current Kidney Disease Improving Global Outcomes (KDIGO) consensus definition of AKI has been criticized for misclassification bias, lack of sensitivity and the static manner in which AKI stages are defined. This editorial reviews various approaches to improving the specificity and sensitivity of the KDIGO AKI criteria, and also concludes that a staging system based on creatinine trajectories would be better suited for developing a prognostic index for real-time, dynamic risk assessment that the current KDIGO staging criteria.

Clinical and mutational spectrum of hypoparathyroidism, deafness and renal dysplasia syndrome


Background: Hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome is a rare autosomal dominant disorder, secondary to mutations in the GATA-3 gene. Due to its wide range of penetrance and expressivity, the disease may not always be recognized. We herein describe clinical and genetic features of patients with HDR syndrome, highlighting diagnostic clues.Methods: Medical records of eight patients from five unrelated families exhibiting GATA-3 mutations were reviewed retrospectively, in conjunction with all previously reported cases.Results: HDR syndrome was diagnosed in eight patients between the ages of 18 and 60 years. Sensorineural deafness was consistently diagnosed, ranging from clinical hearing loss since infancy in seven patients to deafness detected only by audiometry in adulthood in one single patient. Hypoparathyroidism was present in six patients (with hypocalcaemia and inaugural seizures in two out of six). Renal abnormalities observed in six patients were diverse and of dysplastic nature. Three patients displayed nephrotic-range proteinuria and reached end-stage renal disease (ESRD) between the ages of 19 and 61 years, whilst lesions of focal and segmental glomerulosclerosis were histologically demonstrated in one of them. Interestingly, phenotype severity differed significantly between a mother and son within one family. Five new mutations of GATA-3 were identified, including three missense mutations affecting zinc finger motifs [NM_001002295.1: c.856A>G (p.N286D) and c.1017C>G (p.C339W)] or the conserved linker region [c.896G>A (p.R299G)], and two splicing mutations (c.924+4_924+19del and c.1051-2A>G). Review of 115 previously reported cases of GATA-3 mutations showed hypoparathyroidism and deafness in 95% of patients, and renal abnormalities in only 60%. Overall, 10% of patients had reached ESRD.Conclusions: We herein expand the clinical and mutational spectrum of HDR syndrome, illustrating considerable inter- and intrafamilial phenotypic variability. Diagnosis of HDR should be considered in any patient with hypoparathyroidism and deafness, whether associated with renal abnormalities or not. HDR diagnosis is established through identification of a mutation in the GATA-3 gene.

A scoping review of adult chronic kidney disease clinical pathways for primary care


Background: Chronic kidney disease (CKD) affects ∼10% of the adult population. The majority of patients with CKD are managed by primary care physicians, and despite the availability of effective treatment options, the use of evidence-based interventions for CKD in this setting remains suboptimal. Clinical pathways have been identified as effective tools to guide primary care physicians in providing evidence-based care. We aimed to describe the availability, characteristics and credibility of clinical pathways for adult CKD using a scoping review methodology.Methods: We searched Medline, Embase, CINAHL and targeted Internet sites from inception to 31 October 2014 to identify studies and resources that identified adult CKD clinical pathways for primary care settings. Study selection and data extraction were independently performed by two reviewers.Results: From 487 citations, 41 items were eligible for review: 7 published articles and 34 grey literature resources published between 2001 and 2014. Of the 41 clinical pathways, 32, 24 and 22% were from the UK, USA and Canada, respectively. The majority (66%, n = 31) of clinical pathways were static in nature (did not have an online interactive feature). The majority (76%) of articles/resources reported using one or more clinical practice guidelines as a resource to guide the clinical pathway content. Few articles described a dissemination and evaluation plan for the clinical pathway, but most reported the targeted end-users.Conclusions: Our scoping review synthesized available literature on CKD clinical pathways in the primary care setting. We found that existing clinical pathways are diverse in their design, content and implementation. These results can be used by researchers developing or testing new or existing clinical pathways and by practitioners and health system stakeholders who aim to implement CKD clinical pathways in clinical practice.

Reaccumulation of globotriaosylceramide in podocytes after agalsidase dose reduction in young Fabry patients


Background: Agalsidase-α 0.2 mg/kg every other week (eow) and agalsidase-β 1.0 mg/kg/eow are licensed in Europe as equipotent treatment of the α-galactosidase deficiency in Fabry disease. This case series describes the effects of agalsidase dose adjustments in serial kidney biopsies in switch patients.Methods: All treatment-naïve patients with classical Fabry disease in our centre started on agalsidase-β 1.0 mg/kg/eow and subsequently switched to agalsidase-α 0.2 mg/kg/eow were included (n= 3). The median age at enzyme replacement therapy start was 11 (range 7–18) years. Kidney biopsies were performed at baseline, after 5 years of agalsidase-β 1.0 mg/kg/eow and after 3 subsequent years of agalsidase-α 0.2 mg/kg/eow. One patient was re-biopsied 2 years after reswitch to agalsidase-β 1.0 mg/kg/eow. The scoring system of the International Scoring Group of Fabry Nephropathy was used.Results: The patients completely cleared globotriaosylceramide (GL3) from mesangial and endothelial cells and partly cleared podocytes on agalsidase-β 1.0 mg/kg/eow. Reaccumulation of GL3 in podocytes, but not in the mesangium or endothelium, occurred after 3 years of agalsidase-α 0.2 mg/kg/eow. Subsequent reduction of podocyte GL3 was observed in the single patient rebiopsied 2 years after reswitch to agalsidase-β 1.0 mg/kg/eow.Conclusion: Partial clearance, reaccumulation and renewed partial clearance of podocyte GL3 deposits in serial kidney biopsies over 8–10 years were seen in parallel with agalsidase dose adjustments. Repeated kidney biopsies may impact therapeutic choices in Fabry disease.

Elevated urinary podocyte-derived extracellular microvesicles in renovascular hypertensive patients


Background: An increased number of podocyte-derived extracellular vesicles (pEVs) may reflect podocyte injury in renal disease. Elevated glomerular pressure and other insults may injure podocytes, yet it remains unclear whether the numbers of pEVs are altered in hypertensive patients. We tested the hypothesis that urinary pEV levels would be elevated in patients with renovascular hypertension (RVH) compared with essential hypertension (EH) or healthy volunteers (HVs).Methods: We prospectively enrolled patients with EH (n = 30) or RVH (n = 31) to study renal blood flow (RBF) and cortical perfusion using multidetector computed tomography under controlled condition (regulated sodium intake and renin—angiotensin blockade). After isolation from urine samples, pEVs (nephrin and podocalyxin positive) were characterized by flow cytometry. Fourteen RVH patients were studied again 3 months after stenting or continued medical therapy. HVs (n = 15) served as controls.Results: The fraction of pEV among urinary EVs was elevated in RVH compared with HVs and EH (11.4 ± 6.4, 6.8 ± 3.4 and 6.3 ± 3.7%, respectively; P < 0.001) and remained unchanged after 3 additional months of therapy and after controlling for clinical parameters. However, eGFR- and age-adjusted pEV levels did not correlate with any clinical or renal parameters.Conclusions: In hypertensive patients under controlled conditions, urinary pEV levels are elevated in patients with RVH and low eGFR compared with patients with EH and relatively preserved renal function. These pEVs may reflect podocyte injury secondary to kidney damage, and their levels might represent a novel therapeutic target.

Efficacy and safety of nicotinamide in haemodialysis patients: the NICOREN study


Background: Nicotinamide (NAM) has been proposed as an alternative treatment to phosphate binders for hyperphosphataemia in chronic kidney disease.Methods: The NICOREN multicentre, open-label and randomized study was designed to examine non-inferiority and safety of NAM when compared with sevelamer (SEV) in chronic haemodialysis patients. One hundred patients were randomized to either NAM or SEV treatment for 24 weeks. Serum biochemistry and NAM's main metabolite, N-methyl-2-pyridone-5-carboxamide (2PY), were measured to assess compliance, efficacy and safety.Results: After 24 weeks, we observed a comparable decrease in serum phosphorus in the NAM and SEV treatment arms, from 2.1 ± 0.4 to 1.8 ± 0.5 and 2.3 ± 0.5 to 1.7 ± 0.5 mM (P = not significant), respectively. The criterion for non-inferiority was, however, not met due to a more limited number of patients being included than planned. Treatment discontinuation due to adverse events was 1.6 times higher in the NAM than in the SEV group with only 55% of study completers in the NAM arm versus 90% in the SEV arm. Thrombocytopenia was observed in four NAM-treated patients. Serum 2PY levels were comparable at baseline, but increased markedly in the NAM group, but not in the SEV group, at 24 weeks (P < 0.0001).Conclusions: Thus, both drugs are equally effective in lowering serum phosphorus, but patients' tolerance of NAM was largely inferior to that of SEV. Extremely high 2PY levels may contribute to NAM's side effects.

Impact of using two dialyzers in parallel on phosphate clearance in hemodialysis patients: a randomized trial


Background: Dietary restriction and phosphate binders are the main interventions used to manage hyperphosphatemia in people on hemodialysis, but have limited efficacy. Modifying conventional dialysis regimens to enhance phosphate clearance as an alternative approach remains relatively unstudied.Methods: This was a 10-week, 2-arm, randomized crossover study. Participants were prevalent dialysis patients (n = 32) with consecutive serum phosphate levels >1.6 mmol/L and on stable doses of a phosphate binder. Following a 2-week run-in period, participants were randomized to initiate dialysis using two high flux dialyzers in parallel (blood flow ≥350 mL/min, dialysate flow 800 mL/min) or standard dialysis using one high flux dialyzer (blood flow ≥350 mL/min, dialysate flow of 800 mL/min). Each regimen was 3 weeks in duration. After a 2-week washout period, participants received the alternate regimen. The primary outcome was the mean difference in phosphate clearance by dialyzer strategy. Secondary outcomes were phosphate removal and pre-dialysis serum phosphate.Results: Phosphate clearance for the double dialyzer strategy did not differ significantly from the single dialyzer strategy [mean difference 7.5 mL/min (95% confidence interval, 95% CI, −6.1, 21.0), P = 0.28]. There was no difference in total phosphate removal and pre-dialysis phosphate between the double and single dialyzer strategies [total phosphate removal mean difference −0.2 mmol (95% CI −4.1, 3.7), P = 0.93; pre-dialysis mean difference 0.01 mmol/L (95% CI −0.18, 0.21), P = 0.88]. There was no difference in the proportion of participants who experienced at least one episode of intradialytic hypotension (32 versus 47%, P = 0.13). A limitation of the study was frequent protocol deviations in the dialysis prescription.Conclusions: In this study, the use of two dialyzers in parallel did not increase phosphate clearance, phosphate removal or pre-dialysis serum phosphorus when compared with a standard dialysis treatment strategy. Future studies should continue to evaluate novel methods of phosphate removal using conventional hemodialysis.

Determining the research priorities for patients with chronic kidney disease not on dialysis


Background: The importance of engaging key stakeholders, and patients in particular, in determining research priorities has been recognized. We sought to identify the top 10 research priorities for patients with non-dialysis chronic kidney disease (CKD), their caregivers, and the clinicians and policy-makers involved in their care.Methods: We used the four-step James Lind Alliance process to establish the top 10 research priorities. A national survey of patients with non-dialysis CKD (estimated glomerular filtration rate <45 mL/min/1.73 m2), their caregivers, and the clinicians and policy-makers involved in their care was conducted to identify research uncertainties. A Steering Group of patients, caregivers, clinicians and researchers combined and reduced these uncertainties to 30 through a series of iterations. Finally, a workshop with participants from across Canada (12 patients, 6 caregivers, 3 physicians, 2 nurses, 1 pharmacist and 1 policy-maker) was held to determine the top 10 research priorities, using a nominal group technique.Results: Overall, 439 individuals responded to the survey and identified 1811 uncertainties, from which the steering group determined the top 30 uncertainties to be considered at the workshop. The top 10 research uncertainties prioritized at the workshop included questions about treatments to prevent progression of kidney disease (including diet) and to treat symptoms of CKD, provider- and patient-targeted strategies for managing CKD, the impact of lifestyle on disease progression, harmful effects of medications on disease progression, optimal strategies for treatment of cardiovascular disease in CKD and for early identification of kidney disease, and strategies for equitable access to care for patients with CKD.Conclusions: We identified the top 10 research priorities for patients with CKD that can be used to guide researchers, as well as inform funders of health-care research.

The natural history of immunoglobulin M nephropathy in adults


Background: Immunoglobulin M (IgM) nephropathy is an idiopathic glomerulonephritis characterized by diffuse mesangial deposition of IgM. IgM nephropathy has been a controversial diagnosis since it was first reported, and there are few data identifying specific pathological features that predict the risk of progression of renal disease.Methods: We identified 57 cases of IgM nephropathy among 3220 adults undergoing renal biopsy at our institution. Biopsies had to satisfy the following three criteria to meet the definition of IgM nephropathy in this study: (i) dominant mesangial staining for IgM, (ii) mesangial deposits on electron microscopy (EM) and (iii) exclusion of systemic disease.Results: The median age was 42 years and 24 patients were male. Thirty-nine per cent of patients presented with the nephrotic syndrome, 49% presented with non-nephrotic proteinuria and 39% had eGFR <60 mL/min. The median post-biopsy follow-up was 40 months and serum creatinine had doubled in 31% by 5 years. Of histological parameters, glomerular sclerosis and tubular atrophy, but not mesangial proliferation, were risk factors for renal insufficiency. Thirty-nine per cent of nephrotic patients achieved complete remission, and outcome was significantly worse in those who did not respond to treatment. Focal segmental glomerulosclerosis was diagnosed in 80% of those undergoing repeat renal biopsy, despite ongoing mesangial IgM deposition.Conclusions: We propose criteria for a consensus definition of IgM nephropathy.

Angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use and cardiovascular outcomes in patients initiating peritoneal dialysis


Background: Data on the effectiveness of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) in reducing cardiovascular (CV) risk in patients undergoing peritoneal dialysis (PD) are limited. We investigated the association between ACEI/ARB use and CV outcomes in patients initiating PD.Methods: In this observational cohort study, we identified from the United States Renal Data System all adult patients who initiated PD from 2007 to 2011 and participated in Medicare Part D, a federal prescription drug benefits program, for the first 90 days of dialysis. Patients who filled a prescription for an ACEI or ARB in those 90 days were considered users. We applied Cox regression to an inverse probability of treatment weighted cohort to estimate the hazard ratios (HRs) for the combined outcome of death, ischemic stroke or myocardial infarction (MI) and each outcome individually.Results: Among 4879 patients, 2063 (42%) used an ACEI/ARB. Patients were followed up for a median of 1.2 years. We recorded 1771 events, for a composite rate of 25 events per 100 person-years. ACEI/ARB use (versus nonuse) was associated with a reduced risk of the composite outcome {HR 0.84 [95% confidence interval (CI) 0.76–0.93]}, all-cause mortality [HR 0.83 (95% CI 0.75–0.92)] and CV death [HR 0.74 (95% CI 0.63–0.87)], but not MI [HR 0.88 (95% CI 0.69–1.12)] or ischemic stroke [HR 1.06 (95% CI 0.79–1.43)]. Results were similar in as-treated analyses. In a subgroup analysis, we did not find any effect modification by residual renal function.Conclusions: ACEI/ARB use is common in patients initiating PD and is associated with a lower risk of fatal CV outcomes.