Long-term renal function following radical cystectomy and ileal conduit creation

BACKGROUND

Treatment for bladder cancer includes radical cystectomy (RC) and urinary diversion; RC is associated with long-term morbidity, kidney impairment and mortality.

AIM

To identify risk factors associated with postoperative long-term kidney function and mortality.

METHODS

Retrospective study of patients with RC and urinary diversion in Beaumont Hospital from 1996 to 2016. We included patients who had follow-up at least 2 years post-procedure. We assessed estimated glomerular filtration rate (eGFR) preoperatively and yearly post-procedure, dialysis commencement and mortality. Cox and Fine-Gray regression analyses were applied; p-value < 0.05 was considered significant.

RESULTS

We included 264 patients, median age 68.3 years, 73.7% males. The most common diagnosis was bladder cancer 93.3%, TNM stages T ≥ 2 75.9%, N ≥ 1 47.6% and M1 28%. The median eGFR preoperative was 65.8 ml/min/1.73m2 and after 2 years 58.2 ml/min/1.73m2 (p: 0.009); 5.3% required chronic dialysis and 32.8% had a decrease > 10 ml/min/1.73m2. Risk factors associated with ESKD and start dialysis included younger age (HR: 0.90, CI 95% 0.87-0.94) and lower pre-operative eGFR (HR: 0.97, CI 95% 0.94-1.00). Overall mortality was 43.2% and 54.1% at 5 and 10 years, respectively; risk factors were older age (HR: 1.04, CI 95% 1.02-1.06), tumour stage T ≥ 2 (HR: 2.22, CI 95% 1.39-3.54) and no chemotherapy (HR: 1.72, CI 95% 1.18-2.51). Limitations include retrospective design, absence of control group and single centre experience.

CONCLUSIONS

Patients with RC are at risk of progressive kidney function deterioration and elevated mortality and the main risk factors associated were age and preoperative eGFR. Regular monitoring of kidney function will permit early diagnosis and treatment.

High frequency and mortality of head and neck malignancy in organ transplant recipients in Ireland - A national cohort study

BACKGROUND

Solid organ transplant recipients are recognized to carry a high burden of malignancy and frequently this cancer develops in the head and neck region. Furthermore, cancer of the head and neck post-transplant carries a significantly increased mortality. In this study, we aim to conduct a national retrospective cohort study to investigate the impact of head and neck cancer in terms of frequency and mortality in a large group of solid organ transplant recipients over a 20 year time span and compare the mortality in transplant patients to non-transplant patients with head and neck cancer.

METHODS

Patients in the Republic of Ireland who underwent solid organ transplantation between 1994 and 2014 who developed post-transplant head and neck malignancy were identified from the records of two prospective, national databases (National Cancer Registry of Ireland (NCRI) and The Irish Transplant Cancer Group database) working in conjunction with each other. Incidence of head and neck malignancy post-transplant was compared with the general population by means of standardised incidence ratios (SIR). Cumulative incidence of all cause and cancer related mortality from head and neck keratinocytic was undertaken by a competing risks analysis.

RESULTS

A total of 3346 solid organ transplant recipients were identified, 2382 (71.2 %) kidney, 562 (16.8 %) liver, 214 (6.4 %) cardiac and 188 (5.6 %) lung. During the period of follow up of 428 patients developed head and neck cancer, representing (12.8 %) of the population. 97 % of these patients developed keratinocytic cancers, specifically, of head and neck. The frequency of post-transplant head and neck cancer was related to the duration of immunosuppression with 14 % of patients developing cancer at 10 years and 20 % having developed at least one cancer by 15 years. 12 (3 %) patients developed non-cutaneous head and neck malignancy. 10 (0.3 %) patients died due to head and neck keratinocytic malignancy post-transplant. Competing risk analysis demonstrated that organ transplantation conferred a strong independent effect of death, compared to non-transplant patients with head and neck keratinocytes. This applied specifically for kidney (HR 4.4, 95 % CI 2.5-7.8) and heart transplants (HR 6.5, 95 % CI 2.1-19.9), and overall, across the four transplant categories (P < 0.001). The SIR of developing keratinocyte cancer varied based on primary tumor site, gender, and type of transplant organ.

CONCLUSION

Transplant patients demonstrate a particularly high rate of head and neck keratinocyte cancer with a very high rate of associated mortality. Physicians should be cognizant of the increased rate of malignancy in this population and monitor for red flag signs/symptoms.

Epigenome-wide meta-analysis identifies DNA methylation biomarkers associated with diabetic kidney disease

Type 1 diabetes affects over nine million individuals globally, with approximately 40% developing diabetic kidney disease. Emerging evidence suggests that epigenetic alterations, such as DNA methylation, are involved in diabetic kidney disease. Here we assess differences in blood-derived genome-wide DNA methylation associated with diabetic kidney disease in 1304 carefully characterised individuals with type 1 diabetes and known renal status from two cohorts in the United Kingdom-Republic of Ireland and Finland. In the meta-analysis, we identify 32 differentially methylated CpGs in diabetic kidney disease in type 1 diabetes, 18 of which are located within genes differentially expressed in kidneys or correlated with pathological traits in diabetic kidney disease. We show that methylation at 21 of the 32 CpGs predict the development of kidney failure, extending the knowledge and potentially identifying individuals at greater risk for diabetic kidney disease in type 1 diabetes.

Persistent DNA damage underlies tubular cell polyploidization and progression to chronic kidney disease in kidneys deficient in the DNA repair protein FAN1

Defective DNA repair pathways contribute to the development of chronic kidney disease (CKD) in humans. However, the molecular mechanisms underlying DNA damage-induced CKD pathogenesis are not well understood. Here, we investigated the role of tubular cell DNA damage in the pathogenesis of CKD using mice in which the DNA repair protein Fan1 was knocked out. The phenotype of these mice is orthologous to the human DNA damage syndrome, karyomegalic interstitial nephritis (KIN). Inactivation of Fan1 in kidney proximal tubule cells sensitized the kidneys to genotoxic and obstructive injury characterized by replication stress and persistent DNA damage response activity. Accumulation of DNA damage in Fan1 tubular cells induced epithelial dedifferentiation and tubular injury. Characteristic to KIN, cells with chronic DNA damage failed to complete mitosis and underwent polyploidization. In vitro and in vivo studies showed that polyploidization was caused by the overexpression of DNA replication factors CDT1 and CDC6 in FAN1 deficient cells. Mechanistically, inhibiting DNA replication with Roscovitine reduced tubular injury, blocked the development of KIN and mitigated kidney function in these Fan1 knockout mice. Thus, our data delineate a mechanistic pathway by which persistent DNA damage in the kidney tubular cells leads to kidney injury and development of CKD. Furthermore, therapeutic modulation of cell cycle activity may provide an opportunity to mitigate the DNA damage response induced CKD progression.

An intermediate-effect size variant in UMOD confers risk for chronic kidney disease

The kidney-specific gene UMOD encodes for uromodulin, the most abundant protein excreted in normal urine. Rare large-effect variants in UMOD cause autosomal dominant tubulointerstitial kidney disease (ADTKD), while common low-impact variants strongly associate with kidney function and the risk of chronic kidney disease (CKD) in the general population. It is unknown whether intermediate-effect variants in UMOD contribute to CKD. Here, candidate intermediate-effect UMOD variants were identified using large-population and ADTKD cohorts. Biological and phenotypical effects were investigated using cell models, in silico simulations, patient samples, and international databases and biobanks. Eight UMOD missense variants reported in ADTKD are present in the Genome Aggregation Database (gnomAD), with minor allele frequency (MAF) ranging from 10-5 to 10-3. Among them, the missense variant p.Thr62Pro is detected in ∼1/1,000 individuals of European ancestry, shows incomplete penetrance but a high genetic load in familial clusters of CKD, and is associated with kidney failure in the 100,000 Genomes Project (odds ratio [OR] = 3.99 [1.84 to 8.98]) and the UK Biobank (OR = 4.12 [1.32 to 12.85). Compared with canonical ADTKD mutations, the p.Thr62Pro carriers displayed reduced disease severity, with slower progression of CKD and an intermediate reduction of urinary uromodulin levels, in line with an intermediate trafficking defect in vitro and modest induction of endoplasmic reticulum (ER) stress. Identification of an intermediate-effect UMOD variant completes the spectrum of UMOD-associated kidney diseases and provides insights into the mechanisms of ADTKD and the genetic architecture of CKD.

The utility of a genetic kidney disease clinic employing a broad range of genomic testing platforms: experience of the Irish Kidney Gene Project

BACKGROUND AND AIMS

Genetic testing presents a unique opportunity for diagnosis and management of genetic kidney diseases (GKD). Here, we describe the clinical utility and valuable impact of a specialized GKD clinic, which uses a variety of genomic sequencing strategies.

METHODS

In this prospective cohort study, we undertook genetic testing in adults with suspected GKD according to prespecified criteria. Over 7 years, patients were referred from tertiary centres across Ireland to an academic medical centre as part of the Irish Kidney Gene Project.

RESULTS

Among 677 patients, the mean age was of 37.2 ± 13 years, and 73.9% of the patients had family history of chronic kidney disease (CKD). We achieved a molecular diagnostic rate of 50.9%. Four genes accounted for more than 70% of identified pathogenic variants: PKD1 and PKD2 (n = 186, 53.4%), MUC1 (8.9%), and COL4A5 (8.3%). In 162 patients with a genetic diagnosis, excluding PKD1/PKD2, the a priori diagnosis was confirmed in 58% and in 13% the diagnosis was reclassified. A genetic diagnosis was established in 22 (29.7%) patients with CKD of uncertain aetiology. Based on genetic testing, a diagnostic kidney biopsy was unnecessary in 13 (8%) patients. Presence of family history of CKD and the underlying a priori diagnosis were independent predictors (P < 0.001) of a positive genetic diagnosis.

CONCLUSIONS

A dedicated GKD clinic is a valuable resource, and its implementation of various genomic strategies has resulted in a direct, demonstrable clinical and therapeutic benefits to affected patients.

Monoallelic IFT140 pathogenic variants are an important cause of the autosomal dominant polycystic kidney-spectrum phenotype

Autosomal dominant polycystic kidney disease (ADPKD), characterized by progressive cyst formation/expansion, results in enlarged kidneys and often end stage kidney disease. ADPKD is genetically heterogeneous; PKD1 and PKD2 are the common loci (∼78% and ∼15% of families) and GANAB, DNAJB11, and ALG9 are minor genes. PKD is a ciliary-associated disease, a ciliopathy, and many syndromic ciliopathies have a PKD phenotype. In a multi-cohort/-site collaboration, we screened ADPKD-diagnosed families that were naive to genetic testing (n = 834) or for whom no PKD1 and PKD2 pathogenic variants had been identified (n = 381) with a PKD targeted next-generation sequencing panel (tNGS; n = 1,186) or whole-exome sequencing (WES; n = 29). We identified monoallelic IFT140 loss-of-function (LoF) variants in 12 multiplex families and 26 singletons (1.9% of naive families). IFT140 is a core component of the intraflagellar transport-complex A, responsible for retrograde ciliary trafficking and ciliary entry of membrane proteins; bi-allelic IFT140 variants cause the syndromic ciliopathy, short-rib thoracic dysplasia (SRTD9). The distinctive monoallelic phenotype is mild PKD with large cysts, limited kidney insufficiency, and few liver cysts. Analyses of the cystic kidney disease probands of Genomics England 100K showed that 2.1% had IFT140 LoF variants. Analysis of the UK Biobank cystic kidney disease group showed probands with IFT140 LoF variants as the third most common group, after PKD1 and PKD2. The proximity of IFT140 to PKD1 (∼0.5 Mb) in 16p13.3 can cause diagnostic confusion, and PKD1 variants could modify the IFT140 phenotype. Importantly, our studies link a ciliary structural protein to the ADPKD spectrum.

Is Bigger Better? Living Donor Kidney Volume as Measured by the Donor CT Angiogram in Predicting Donor and Recipient eGFR after Living Donor Kidney Transplantation

BACKGROUND

The role of kidney volume measurement in predicting the donor and recipient kidney function is not clear.

METHODS

We measured kidney volume bilaterally in living kidney donors using CT angiography and assessed the association with the donor remaining kidney and recipient kidney (donated kidney) function at 1 year after kidney transplantation. Donor volume was categorized into tertiles based on lowest, middle, and highest volume.

RESULTS

There were 166 living donor and recipient pairs. The mean donor age was 44.8 years (SD ± 10.8), and donor mean BMI was 25.5 (SD ± 2.9). The recipients of living donor kidneys were 64% male and had a mean age of 43.5 years (SD ± 13.3). Six percent of patients experienced an episode of cellular rejection and were maintained on dialysis for a mean of 18 months (13-32) prior to transplant. Kidney volume was divided into tertiles based on lowest, middle, and highest volume. Kidney volume median (range) in tertiles 1, 2, and 3 was 124 (89-135 ml), 155 (136-164 ml), and 184 (165-240 ml) with donor eGFR ml/min (adjusted for body surface area expressed as ml/min/1.73 m2) at the time of donation in each tertile, 109 (93-129), 110 (92-132), and 101 ml/min (84-117). The median (IQR) eGFR in tertiles 1 to 3 in kidney recipients at 1 year after donation was 54 (44-67), 62 (50-75), and 63 ml/min (58-79), respectively. The median (IQR) eGFR in tertiles 1 to 3 in the remaining kidney of donors at 1 year after donation was 59 (53-66), 65 (57-72), and 65 ml/min (56-73), respectively.

CONCLUSION

Bigger kidney volume was associated with better eGFR at 1 year after transplant in the recipient and marginally in the donor remaining kidney.

A Rare Autosomal Dominant Variant in Regulator of Calcineurin Type 1 (RCAN1) Gene Confers Enhanced Calcineurin Activity and May Cause FSGS

BACKGROUND

Podocyte dysfunction is the main pathologic mechanism driving the development of FSGS and other morphologic types of steroid-resistant nephrotic syndrome (SRNS). Despite significant progress, the genetic causes of most cases of SRNS have yet to be identified.

METHODS

Whole-genome sequencing was performed on 320 individuals from 201 families with familial and sporadic NS/FSGS with no pathogenic mutations in any known NS/FSGS genes.

RESULTS

Two variants in the gene encoding regulator of calcineurin type 1 (RCAN1) segregate with disease in two families with autosomal dominant FSGS/SRNS. In vitro, loss of RCAN1 reduced human podocyte viability due to increased calcineurin activity. Cells expressing mutant RCAN1 displayed increased calcineurin activity and NFAT activation that resulted in increased susceptibility to apoptosis compared with wild-type RCAN1. Treatment with GSK-3 inhibitors ameliorated this elevated calcineurin activity, suggesting the mutation alters the balance of RCAN1 regulation by GSK-3β, resulting in dysregulated calcineurin activity and apoptosis.

CONCLUSIONS

These data suggest mutations in RCAN1 can cause autosomal dominant FSGS. Despite the widespread use of calcineurin inhibitors in the treatment of NS, genetic mutations in a direct regulator of calcineurin have not been implicated in the etiology of NS/FSGS before this report. The findings highlight the therapeutic potential of targeting RCAN1 regulatory molecules, such as GSK-3β, in the treatment of FSGS.

The impact of switching to mTOR inhibitor-based immunosuppression on long-term non-melanoma skin cancer incidence and renal function in kidney and liver transplant recipients

Background

Solid organ transplantation is associated with increased risk of non-melanoma skin cancer. Studies with short follow up times have suggested a reduced occurrence of these cancers in recipients treated with mammalian target of rapamycin inhibitors as maintenance immunosuppression. We aimed to describe the occurrence of skin cancers in renal and liver transplant recipients switched from calcineurin inhibitor to sirolimus-based regimes.

Methods

We performed a retrospective study of sirolimus conversion within the Irish national kidney and liver transplant programs. These data were linked with the National Cancer Registry Ireland to determine the incidence of NMSC among these recipients. The incidence rate ratio (IRR) for post versus pre-conversion NMSC rates are referred in this study as an effect size with [95% confidence interval].

Results

Of 4,536 kidney transplants and 574 liver transplants functioning on the 1 January 1994 or transplanted between 1 January 1994 and 01 January 1994 and 01 January 2015, 85 kidney and 88 liver transplant recipients were transitioned to sirolimus-based immunosuppression. In renal transplants, the rate of NMSC was 131 per 1000 patient years pre-switch to sirolimus, and 68 per 1000 patient years post switch, with adjusted effect size of 0.48 [0.31 − 0.74] (p = .001) following the switch. For liver transplant recipients, the rate of NMSC was 64 per 1,000 patient years pre-switch and 30 per 1,000 patient years post switch, with an adjusted effect size of 0.49 [0.22 − 1.09] (p .081). Kidney transplant recipients were followed up for a median 3.4 years. Liver transplants were followed for a median 6.6 years.

Conclusions

In this study, the conversion of maintenance immunosuppression from calcineurin inhibitors to mTOR inhibitors for clinical indications did appear to reduce the incidence of NMSC in kidney and liver transplant recipients.

Progressive survival improvement of incident dialysis patients in a tertiary center, Ireland

BACKGROUND

The survival of incident dialysis patients' end-stage kidney disease in some European and American has been reported to improve in modern era compared to earlier periods. However, in Ireland, this has not been well documented.

AIM

To investigate the survival outcomes of incident end-stage kidney failure dialysis patients in a tertiary center over a 24-year period, 1993-2017.

METHODS

A retrospective analysis was carried out utilizing the Beaumont Hospital Renal Database. Consecutive adults with incident dialysis were analyzed. Kaplan-Meier methods and the estimated mean survival times were used to evaluate survival at successive 4-year periods of time.

RESULTS

In total, 2106 patients were included, of whom 830 underwent subsequent renal transplantation during follow-up. During the study period, from 1993 up to 2017, the mean patients' age increased from 56.3 ± 17.4 in 1993-1996 to 60.6 ± 18.3 in 2014-2017. There was an overall decrement in mortality over successive time intervals which were mirrored by the improvements in median survival after commencement of dialysis treatment from 6.14 years during 1993-1996 to 8.01 years during 2009-2012. Patients' survival has steadily improved, with the 5-year survival has risen over time, by almost 15%. This positive signal persisted and became more pronounced after adjusting Kaplan-Meier curve to age, where the 5-year survival estimates were exceeding 80% in 2014-2017.

CONCLUSION

Survival rates among incident dialysis patients have improved progressively between 1993 and 2017 in Beaumont Hospital in Dublin, Ireland. The factors which led to this improvement are not entirely clear, but likely to be multifactorial.

Cancer survival in kidney transplant recipients in Ireland

BACKGROUND

Transplantation is a well-known risk factor for malignancy. However, outcomes of cancer in transplant recipients compared with non-transplant recipients are less well studied. We aim to study the survival in kidney transplant recipients who develop cancer and compare this with cancer outcomes in the general population.

METHODS

We linked data from the National Cancer Registry Ireland with the National Kidney Transplant Database. The period of observation was from 1 January 1994 until 31 December 2014. Transplant recipients were considered at risk from the time of diagnosing cancer. We administratively censored data at 10 years post-cancer diagnosis. Survival was compared with all patients in the general population that had a recorded diagnosis of cancer.

RESULTS

There were 907 renal transplant recipients and 426679 individuals in the general population diagnosed with cancer between 1 January 1994 and 31 December 2014. In those with non-melanoma skin cancer, the hazard ratio (HR) for 10-year, all-cause mortality [HR = 3.06, 95% confidence interval (CI) 2.66-3.52] and cancer-specific mortality (HR = 3.91, 95% CI 2.57-5.96) was significantly higher among transplant recipients than the general population. Patients who developed non-Hodgkin lymphoma (HR = 2.89, 95% CI 1.96-4.25) and prostate cancer (HR = 4.32, 95% CI 2.39-7.82) had increased all-cause but not cancer-specific mortality. Colorectal, lung, breast and renal cell cancer did not show an increased risk of death in transplant recipients.

CONCLUSION

Cancer-attributable mortality is higher in kidney transplant recipients with non-melanoma skin cancer compared with non-transplant patients. The American Joint Committee on Cancer staging should reflect the increased hazard of death in these immunosuppressed patients.

Integration of genetic and histopathology data in interpretation of kidney disease

For many years renal biopsy has been the gold standard for diagnosis in many forms of kidney disease. It provides rapid, accurate and clinically useful information in most individuals with kidney disease. However, in recent years, other diagnostic modalities have become available that may provide more detailed and specific diagnostic information in addition to, or instead of, renal biopsy. Genomics is one of these modalities. Previously prohibitively expensive and time consuming, it is now increasingly available and practical in a clinical setting for the diagnosis of inherited kidney disease. Inherited kidney disease is a significant cause of kidney disease, in both the adult and paediatric populations. While individual inherited kidney diseases are rare, together they represent a significant burden of disease. Because of the heterogenicity of inherited kidney disease, diagnosis and management can be a challenge and often multiple diagnostic modalities are needed to arrive at a diagnosis. We present updates in genomic medicine for renal disease, how genetic testing integrates with our knowledge of renal histopathology and how the two modalities may interact to enhance patient care.

Kidney injury in COVID-19

Coronavirus disease 2019 (COVID-19) continues to affect millions of people around the globe. As data emerge, it is becoming more evident that extrapulmonary organ involvement, particularly the kidneys, highly influence mortality. The incidence of acute kidney injury has been estimated to be 30% in COVID-19 non-survivors. Current evidence suggests four broad mechanisms of renal injury: Hypovolaemia, acute respiratory distress syndrome related, cytokine storm and direct viral invasion as seen on renal autopsy findings. We look to critically assess the epidemiology, pathophysiology and management of kidney injury in COVID-19.

Pilot Randomized Controlled Trial of a Standard Versus a Modified Low-Phosphorus Diet in Hemodialysis Patients

INTRODUCTION

The standard low-phosphorus diet restricts pulses, nuts, and whole grains and other high phosphorus foods to control hyperphosphatemia. We conducted a randomized controlled trial to evaluate the effectiveness, safety, and tolerability of the modified diet, which introduced some pulses and nuts, increased the use of whole grains, increased focus on the avoidance of phosphate additives, and introduced the prescription of low-biological-value protein such as bread.

METHODS

We conducted a multicenter, pragmatic, parallel-arm, open-label, randomized controlled trial of modified versus standard diet in 74 adults on hemodialysis with hyperphosphatemia over 1 month. Biochemistry was assessed using monthly laboratory tests. Dietary intake was assessed using a 2-day record of weighed intake of food, and tolerability was assessed using a patient questionnaire.

RESULTS

There was no significant difference in the change in serum phosphate between the standard and modified diets. Although total dietary phosphorus intake was similar, phytate-bound phosphorus, found in pulses, nuts, and whole grains, was significantly higher in the modified diet (P < 0.001). Dietary fiber intake was also significantly higher (P < 0.003), as was the percentage of patients reporting an increase in bowel movements while following the modified diet (P = 0.008). There was no significant difference in the change in serum potassium or in reported protein intake between the 2 diets. Both diets were similarly well tolerated.

CONCLUSION

The modified low phosphorus diet was well tolerated and was associated with similar phosphate and potassium control but with a wider food choice and greater fiber intake than the standard diet.

Diagnostic utility of genetic testing in patients undergoing renal biopsy

High-throughput DNA testing is becoming established as a standard diagnostic test in the renal clinic. Previously published studies on cohorts of patients with unexplained chronic kidney disease of a suspected genetic aetiology have suggested a diagnostic yield for genomic sequencing of up to 18%. Here we determine the yield of targeted gene panel in a clinically unscreened cohort of patients referred for percutaneous native renal biopsy. Patients who underwent renal biopsy for investigation of chronic kidney disease were sequenced using a genomic sequencing panel covering 227 genes in which variation is known to be associated with monogenic chronic kidney disease (CKD). Candidate disease-causing variants were assessed for pathogenicity using guidelines from the American College for Medical Genetics and Genomics. Fifty CKD patients were recruited and sequenced. A molecular diagnosis was obtained for two patients (4%). A molecular diagnosis is possible using genomic testing in ∼4% of clinically unscreened patients undergoing renal biopsy. Genetic screening may be useful for diagnosis in a subset of CKD patients but is most valuable when applied to patients with suspected heritable forms of kidney disease.

Genetic and Clinical Predictors of Age of ESKD in Individuals With Autosomal Dominant Tubulointerstitial Kidney Disease Due to UMOD Mutations

INTRODUCTION

Autosomal dominant tubulo-interstitial kidney disease due to UMOD mutations (ADTKD-UMOD) is a rare condition associated with high variability in the age of end-stage kidney disease (ESKD). The minor allele of rs4293393, located in the promoter of the UMOD gene, is present in 19% of the population and downregulates uromodulin production by approximately 50% and might affect the age of ESKD. The goal of this study was to better understand the genetic and clinical characteristics of ADTKD-UMOD and to perform a Mendelian randomization study to determine if the minor allele of rs4293393 was associated with better kidney survival.

METHODS

An international group of collaborators collected clinical and genetic data on 722 affected individuals from 249 families with 125 mutations, including 28 new mutations. The median age of ESKD was 47 years. Men were at a much higher risk of progression to ESKD (hazard ratio 1.78, P < 0.001).

RESULTS

The allele frequency of the minor rs4293393 allele was only 11.6% versus the 19% expected (P < 0.01), resulting in Hardy-Weinberg disequilibrium and precluding a Mendelian randomization experiment. An in vitro score reflecting the severity of the trafficking defect of uromodulin mutants was found to be a promising predictor of the age of ESKD.

CONCLUSION

We report the clinical characteristics associated with 125 UMOD mutations. Male gender and a new in vitro score predict age of ESKD.

The relationship between donor-recipient genetic distance and long-term kidney transplant outcome

Background: We set out to quantify shared genetic ancestry between unrelated kidney donor-recipient pairs and test it as a predictor of time to graft failure.   Methods: In a homogenous, unrelated, European cohort of deceased-donor kidney transplant pairs (n pairs = 1,808), we calculated, using common genetic variation, shared ancestry at the genic (n loci=40,053) and genomic level. We conducted a sub-analysis focused on transmembrane protein coding genes (n transcripts=8,637) and attempted replication of a previously published nonsynonymous transmembrane mismatch score. Measures of shared genetic ancestry were tested in a survival model against time to death-censored graft failure. Results: Shared ancestry calculated across the human leukocyte antigen (HLA) significantly associated with graft survival in individuals who had a high serological mismatch (n pairs = 186) with those who did not have any HLA mismatches indicating that shared ancestry calculated specific loci can capture known associations with genes impacting graft outcome. None of the other measures of shared ancestry at a genic level, genome-wide scale, transmembrane subset or nonsynonymous transmembrane mismatch score analysis were significant predictors of time to graft failure. Conclusions: In a large unrelated, deceased-donor European ancestry renal transplant cohort, shared donor-recipient genetic ancestry, calculated using common genetic variation, has limited value in predicting transplant outcome both on a genomic scale and at a genic level (other than at the HLA loci).

Calcium and phosphate levels after kidney transplantation and long-term patient and allograft survival

Background

Non-traditional cardiovascular risk factors, including calcium and phosphate derangement, may play a role in mortality in renal transplant. The data regarding this effect are conflicting. Our aim was to assess the impact of calcium and phosphate derangements in the first 90 days post-transplant on allograft and recipient outcomes.

Methods

We performed a retrospective cohort review of all-adult, first renal transplants in the Republic of Ireland between 1999 and 2015. We divided patients into tertiles based on serum phosphate and calcium levels post-transplant. We assessed their effect on death-censored graft survival and all-cause mortality. We used Stata for statistical analysis and did survival analysis and spline curves to assess the association.

Results

We included 1525 renal transplant recipients. Of the total, 86.3% had hypophosphataemia and 36.1% hypercalcaemia. Patients in the lowest phosphate tertile were younger, more likely female, had lower weight, more time on dialysis, received a kidney from a younger donor, had less delayed graft function and better transplant function compared with other tertiles. Patients in the highest calcium tertile were younger, more likely male, had higher body mass index, more time on dialysis and better transplant function. Adjusting for differences between groups, we were unable to show any difference in death-censored graft failure [phosphate = 1.14, 95% confidence interval (CI) 0.92–1.41; calcium = 0.98, 95% CI 0.80–1.20] or all-cause mortality (phosphate = 1.10, 95% CI 0.91–1.32; calcium = 0.96, 95% CI 0.81–1.13) based on tertiles of calcium or phosphate in the initial 90 days.

Conclusions

Hypophosphataemia and hypercalcaemia are common occurrences post-kidney transplant. We have identified different risk factors for these metabolic derangements. The calcium and phosphate levels exhibit no independent association with death-censored graft failure and mortality.

Autosomal dominant tubulointerstitial kidney disease (ADTKD) in Ireland

Introduction: Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a rare genetic cause of renal impairment resulting from mutations in the MUC1, UMOD, HNF1B, REN, and SEC61A1 genes. Neither the national or global prevalence of these diseases has been determined. We aimed to establish a database of patients with ADTKD in Ireland and report the clinical and genetic characteristics of these families.

Methods: We identified patients via the Irish Kidney Gene Project and referral to the national renal genetics clinic in Beaumont Hospital who met the clinical criteria for ADTKD (chronic kidney disease, bland urinary sediment, and autosomal dominant inheritance). Eligible patients were then invited to undergo genetic testing by a variety of methods including panel-based testing, whole exome sequencing and, in five families who met the criteria for diagnosis of ADTKD but were negative for causal genetic mutations, we analyzed urinary cell smears for the presence of MUC1fs protein.

Results: We studied 54 individuals from 16 families. We identified mutations in the MUC1 gene in three families, UMOD in five families, HNF1beta in two families, and the presence of abnormal MUC1 protein in urine smears in three families (one of which was previously known to carry the genetic mutation). We were unable to identify a mutation in 4 families (3 of whom also tested negative for urinary MUC1fs).

Conclusions: There are 4443 people with ESRD in Ireland, 24 of whom are members of the cohort described herein. We observe that ADTKD represents at least 0.54% of Irish ESRD patients.

Variation in Nonmelanoma Skin Cancer Incidence by Treatment Modality Among Patients Receiving Multiple Kidney Transplants

Importance

Existing data suggest that nonmelanoma skin cancer (NMSC) is more common in renal transplant recipients than in maintenance dialysis patients. However, whether the risk of NMSC varies as the treatment modality for end-stage kidney disease (ESKD) changes between dialysis and transplantation is not well described.

Objective

To determine whether the incidence of NMSC is attenuated during periods of graft loss with a return to dialysis in those who receive multiple kidney transplants.

Design, Setting, and Participants

Retrospective analysis of data from recipients of kidney transplants from the Irish National Kidney Transplant Service database, linked with the Irish Cancer Registry, from 1994 to 2014. All analysis took place between January 10, 2018 and March 31, 2018. Standardized incidence ratios (SIRs) were calculated for NMSC incidence in comparison with the general population using Irish census data as the denominator. Incidence of NMSC was calculated with modality of treatment for ESKD varying over time; incidence rates and rate ratios associated with dialysis intervals were calculated using Poisson regression; and disease was defined according to International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes for cancer diagnosis.

Exposures

Kidney transplantation.

Main Outcomes and Measures

Incidence rates per 1000 patient-years and incident rate ratios of NMSC after kidney transplant.

Results

Data from the records of 3821 deceased or living donor kidney transplant recipients were assessed; 2399 (62.8%) male and 1422 (37.2%) female recipients; mean (SD) age at time of first data recorded, 41.9 (16.0) years. A total of 3433 recipients were included who had a functioning transplant on January 1, 1994, or received a transplant after that date up to December 31, 2014: 3215 received 1 transplant, 522 a second kidney transplant, and 84 had 3 or more kidney transplants. Periods of treatment with a functioning transplant were associated with a higher incidence of NMSC diagnosis than periods of graft failure: adjusted incidence rate ratio (aIRR), 2.19 (95% CI, 1.56-3.07), P < .001. The aIRRs of NMSC fell from 41.7 (95% CI, 39.38-44.15) per 1000 patient-years in the first transplant to 19.29 (95% CI, 13.41-27.76) in the dialysis period following the first allograft failure. Incidence similarly rose and fell following each subsequent consecutive transplant.

Conclusions and Relevance

In recipients of multiple kidney transplants, while the incidence of NMSC fell during periods defined by transplant failure, there was residual elevated risk. While ascertainment bias may have contributed to the observed trends, the stagnant incidence of invasive cancer overall highlights the need for continued cancer surveillance during graft failure.

Renal transplant outcomes in patients with autosomal dominant tubulointerstitial kidney disease

INTRODUCTION

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a rare genetic cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD). We aimed to compare renal transplant outcomes in people with ESRD due to ADTKD to those with other causes of renal failure.

METHODS

Patients with clinical characteristics consistent with ADTKD by the criteria outlined in the 2015 KDIGO consensus were included. We compared ADTKD transplant outcomes with those of 4633 non-ADTKD renal transplant recipients.

RESULTS

We included 31 patients who met diagnostic criteria for ADTKD in this analysis, 23 of whom had an identified mutation (28 were categorized as definite-ADTKD and 3 as suspected ADTKD). Five patients received a second transplant during follow-up. In total, 36 grafts were included. We did not identify significant differences between groups in terms of graft or patient survival after transplantation. Twenty-five transplant biopsies were performed during follow-up, and none of these showed signs of recurrent ADTKD post-transplant.

CONCLUSION

In patients with ESRD due to ADTKD, we demonstrate that transplant outcomes are comparable with the general transplant population. There is no evidence that ADTKD can recur after transplantation.

An Exome Sequencing Study of 10 Families with IgA Nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is a heterogeneous disorder with a strong genetic component. The advent of whole exome sequencing (WES) has accelerated the discovery of genetic risk factors underlying familial disorders.

OBJECTIVES

We set out to test whether damaging variants in known kidney disease genes explain a proportion of IgAN cases recruited in Ireland.

METHODS

We performed WES in 10 Irish families with multiple affected members having kidney disease where at least one member had biopsy confirmed IgAN. Candidate variants were identified based on being shared between affected family members, minor allele frequency, function and predicted pathogenicity. Pathogenicity of variants was determined according to American College of Medical Genetics and Genomics guidelines.

RESULTS

We detected candidate variants in 3 of 10 families. We identified a likely pathogenic variant in COL4A5 in one family and a variant of unknown significance (VUS) in COL4A3 in another. Variants in COL4A5 and COL4A3 are known to cause Alport syndrome. In the third family, we identified a VUS in LMX1B, a gene associated with Nail-patella syndrome.

CONCLUSIONS

We identified a number of cases of familial IgAN where the families harbored variants in known kidney disease-related genes indicating that potentially a number of cases of familial IgAN are mistaken for other familial kidney disorders. However, the majority of families studied did not carry a candidate variant in a known kidney disease causing gene indicating that there may be >1 underlying genetic mechanism present in these families.

Utility of Genomic Testing after Renal Biopsy

BACKGROUND

Renal biopsy is the mainstay of renal pathological diagnosis. Despite sophisticated diagnostic techniques, it is not always possible to make a precise pathological diagnosis. Our aim was to identify a genetic cause of disease in patients who had undergone renal biopsy and determine if genetic testing altered diagnosis or treatment.

METHODS

Patients with suspected familial kidney disease underwent a variety of next-generation sequencing (NGS) strategies. The subset of these patients who had also undergone native kidney biopsy was identified. Histological specimens were reviewed by a consultant pathologist, and genetic and pathological diagnoses were compared.

RESULTS

Seventy-five patients in 47 families underwent genetic sequencing and renal biopsy. Patients were grouped into 5 diagnostic categories based on pathological diagnosis: tubulointerstitial kidney disease (TIKD; n = 18); glomerulonephritis (GN; n = 15); focal segmental glomerulosclerosis and Alport Syndrome (n = 11); thrombotic microangiopathy (TMA; n = 17); and nonspecific pathological changes (n = 14). Thirty-nine patients (52%) in 21 families (45%) received a genetic diagnosis; 13 cases (72%) with TIKD, 4 (27%) with GN, 6 (55%) with focal segmental glomerulosclerosis/Alport syndrome, and 10 (59%) with TMA and 6 cases (43%) with nonspecific features. Genetic testing resulted in changes in understanding of disease mechanism in 21 individuals (54%) in 12 families (57%). Treatment would have been altered in at least 26% of cases (10/39).

CONCLUSIONS

An accurate genetic diagnosis can result in changes in clinical diagnosis, understanding of pathological mechanism, and treatment. NGS should be considered as a complementary diagnostic technique to kidney biopsy in the evaluation of patients with kidney disease.

Neutrophil gelatinase-associated lipocalin (NGAL) is localised to the primary cilium in renal tubular epithelial cells - A novel source of urinary biomarkers of renal injury

BACKGROUND

Primary cilia have been shown to play a central role in regulating epithelial cell differentiation during injury and repair. Growing evidence implicates structural and functional abnormalities of primary cilia in kidney epithelial cells in the onset and development of various kidney diseases including polycystic kidney disease (PKD). Neutrophil-gelatinase associated lipocalin (NGAL) has been identified as a reliable urinary biomarker of kidney injury. However, the mechanism by which this protein accumulates in patient urine samples has not been fully elucidated.

METHODS

Human renal tubular epithelial cells (RPTECs) were exposed to previously characterized deciliating agents to assess mechanisms of primary cilium loss. Confocal immunofluorescent imaging was employed to visualise the effects on cilia. Western blot analysis was utilised to quantify the ciliary protein Arl13b in both RPTEC whole cell lysates and supernatants. Co-immunoprecipitation was used to demonstrate co-localisation of Arl13b and NGAL in urinary samples from a clinical Chronic Allograft Nephropathy (CAN) cohort.

RESULTS

Immunofluorescent analysis revealed that NGAL was localised to the primary cilium in RPTECs, co-localizing with a ciliary specific protein, Arl13b. Deciliation experiments showed that loss of the cilia coincided with loss of NGAL from the cells.

CONCLUSION

The accumulation of NGAL in supernatants in vitro and in the urine of CAN patients was concurrent with loss of Arl13b, a specific ciliary protein. The findings of this study propose that increased NGAL urinary concentrations are directly linked to deciliation of the renal epithelial cells as a result of injury.

Post-transplant malignancy in solid organ transplant recipients in Ireland, The Irish Transplant Cancer Group

OBJECTIVE

Solid organ transplant recipients are at increased risk of cancer compared to the general population. To date, this risk in Ireland has not been investigated. We conducted a national registry study of cancer incidence following solid organ transplantation.

METHODS

National centers for solid organ transplantation supplied their respective registry databases to cross-reference with episodes of malignancy from the National Cancer Registry Ireland (NCRI) between 1994 and 2014. Standardized incidence of cancer post-transplant was compared to the general population by means of standardized incidence ratios (SIRs), and between solid organ transplant types by incidence rate ratios.

RESULTS

A total of 3346 solid organ transplant recipients were included in this study. Kidney transplant recipients constituted the majority of participants (71.2%), followed by liver (16.8%), heart (6.4%), and lung (5.6%) transplants. The most common cancers within the composite of all transplant recipients included the following (SIR [95% CI]): squamous and basal cell carcinoma (20.05 [17.97, 22.31] and 7.16 [6.43, 7.96], respectively), non-Hodgkin lymphoma (6.23 [4.26, 8.59]), and renal cell carcinoma (3.36 [1.96, 5.38]).

CONCLUSIONS

This study reports the incidence of cancer following solid organ transplantation in Ireland. These results have significant national policy implications for surveillance, and early diagnosis in this patient group.

The impact of donor and recipient common clinical and genetic variation on estimated glomerular filtration rate in a European renal transplant population

Genetic variation across the human leukocyte antigen loci is known to influence renal-transplant outcome. However, the impact of genetic variation beyond the human leukocyte antigen loci is less clear. We tested the association of common genetic variation and clinical characteristics, from both the donor and recipient, with posttransplant eGFR at different time-points, out to 5 years posttransplantation. We conducted GWAS meta-analyses across 10 844 donors and recipients from five European ancestry cohorts. We also analyzed the impact of polygenic risk scores (PRS), calculated using genetic variants associated with nontransplant eGFR, on posttransplant eGFR. PRS calculated using the recipient genotype alone, as well as combined donor and recipient genotypes were significantly associated with eGFR at 1-year posttransplant. Thirty-two percent of the variability in eGFR at 1-year posttransplant was explained by our model containing clinical covariates (including weights for death/graft-failure), principal components and combined donor-recipient PRS, with 0.3% contributed by the PRS. No individual genetic variant was significantly associated with eGFR posttransplant in the GWAS. This is the first study to examine PRS, composed of variants that impact kidney function in the general population, in a posttransplant context. Despite PRS being a significant predictor of eGFR posttransplant, the effect size of common genetic factors is limited compared to clinical variables.

Polygenic risk score as a determinant of risk of non-melanoma skin cancer in a European-descent renal transplant cohort

Renal transplant recipients have an increased risk of non-melanoma skin cancer (NMSC) compared to in the general population. Here, we show polygenic risk scores (PRS) calculated from genome-wide association studies (GWAS) of NMSC in a general, nontransplant setting, can predict risk of, and time to posttransplant skin cancer. Genetic variants, reaching predefined P-value thresholds were chosen from published squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) nontransplant GWAS. Using these GWAS, BCC and SCC PRS were calculated for each sample across three European ancestry renal transplant cohorts (n = 889) and tested as predictors of case:control status and time to NMSC posttransplant. BCC PRS calculated at P-value threshold 1 × 10-5 was the most significant predictor of case:control status of NMSC posttransplant (OR = 1.61; adjusted P = .0022; AUC [full model adjusted for clinical predictors and PRS] = 0.81). SCC PRS at P-value threshold 1 × 10-5 was the most significant predictor of time to posttransplant NMSC (adjusted P = 9.39 × 10-7 ; HR = 1.41, concordance [full model] = 0.74). PRS of nontransplant NMSC is predictive of case:control status and time to NMSC posttransplant. These results are relevant to how genomics can risk stratify patients to help develop personalized treatment regimens.

Assessing the discrimination of the Kidney Donor Risk Index/Kidney Donor Profile Index scores for allograft failure and estimated glomerular filtration rate in Ireland's National Kidney Transplant Programme

Background

The Kidney Donor Risk Index (KDRI)/Kidney Donor Profile Index (KDPI) is relied upon for donor organ allocation in the USA, based on its association with graft failure in time-to-event models. However, the KDRI/KDPI has not been extensively evaluated in terms of predictive metrics for graft failure and allograft estimated glomerular filtration rate (eGFR) outside of the USA.

Methods

We performed a retrospective analysis of outcomes in the Irish National Kidney Transplant Service Registry for the years 2006–13. Associations of the KDRI/KDPI score with eGFR at various time points over the follow-up and ultimate graft failure were modelled.

Results

A total of 772 patients had complete data regarding KDRI/KDPI calculation and 148 of these allografts failed over the follow-up. The median and 25–75th centile for KDRI/KDPI was 51 (26–75). On repeated-measures analysis with linear mixed effects models, the KDRI/KDPI (fixed effect covariate) associated with eGFR over 5 years: eGFR = −0.25 (standard error 0.02; P < 0.001). The variability in eGFR mathematically accounted for by the KDRI/KDPI score was only 21%. The KDRI/KDPI score did not add significantly to graft failure prediction above donor age alone (categorized as > and <50 years of age) when assessed by the categorical net reclassification index.

Conclusions

In this cohort, while the KDRI/KDPI was predictive of eGFR over the follow-up, it did not provide additive discrimination above donor age alone in terms of graft failure prediction. Therefore it is unlikely to help inform decisions regarding kidney organ allocation in Ireland.

Pre-transplant histology does not improve prediction of 5-year kidney allograft outcomes above and beyond clinical parameters

Pre-implant kidney biopsy is used to determine suitability of marginal donor kidneys for transplantation. However, there is limited data examining the utility of pre-implant histology in predicting medium term graft outcome. This retrospective study examined kidney transplants over a 10-year period at a single center to determine if pre-implant histology can identify cases of eGFR ≤35 ml/min/1.73m² at 5 year follow up beyond a clinical predictive logistic regression model. We also compared outcomes of dual kidney transplants with standard single kidney transplants. Of 1195 transplants, 171 received a pre-implant kidney biopsy and 15 were dual transplants. There was no significant difference in graft and patient survival rates. Median eGFR was lower in recipients of biopsied kidneys compared with standard kidney transplants (44 vs. 54 ml/min/1.73m², p < .001). Median eGFR of dual transplant and standard kidney transplants were similar (58 vs. 54 ml/min/1.73m², p = .64). Glomerular sclerosis (p = .05) and Karpinski Score (p = .03) were significant predictors of eGFR at 5-years in multivariate analysis but did not improve discrimination of eGFR ≤35 ml/min/1.73m² at 5-years beyond a clinical prediction model comprising donor age, donor hypertension and terminal donor creatinine (C-statistic 0.67 vs. 0.66; p = .647). Pre-implant histology did not improve prediction of medium-term graft outcomes beyond clinical predictors alone. Allograft function of dual transplant kidneys was similar to standard transplants, suggesting that there is scope to increase utilization of kidneys considered marginal based on histology.

NPHP1 (Nephrocystin-1) Gene Deletions Cause Adult-Onset ESRD

Background Nephronophthisis (NPH) is the most prevalent genetic cause for ESRD in children. However, little is known about the prevalence of NPH in adult-onset ESRD. Homozygous full gene deletions of the NPHP1 gene encoding nephrocystin-1 are a prominent cause of NPH. We determined the prevalence of NPH in adults by assessing homozygous NPHP1 full gene deletions in adult-onset ESRD.Methods Adult renal transplant recipients from five cohorts of the International Genetics and Translational Research in Transplantation Network (iGeneTRAiN) underwent single-nucleotide polymorphism genotyping. After quality control, we determined autosomal copy number variants (such as deletions) on the basis of median log2 ratios and B-allele frequency patterns. The findings were independently validated in one cohort. Patients were included in the analysis if they had adult-onset ESRD, defined as start of RRT at ≥18 years old.Results We included 5606 patients with adult-onset ESRD; 26 (0.5%) showed homozygous NPHP1 deletions. No donor controls showed homozygosity for this deletion. Median age at ESRD onset was 30 (range, 18-61) years old for patients with NPH, with 54% of patients age ≥30 years old. Notably, only three (12%) patients were phenotypically classified as having NPH, whereas most patients were defined as having CKD with unknown etiology (n=11; 42%).Conclusions Considering that other mutation types in NPHP1 or mutations in other NPH-causing genes were not analyzed, NPH is a relatively frequent monogenic cause of adult-onset ESRD. Because 88% of patients had not been clinically diagnosed with NPH, wider application of genetic testing in adult-onset ESRD may be warranted.

Home haemodialysis in Ireland

BACKGROUND

Home haemodialysis (HHD) has the potential to impact positively on patient outcomes and health resource management. There has been rejuvenated international interest in HHD in recent years.

AIM

We aimed to review the activity and outcomes of the Irish HHD Programme since inception (2009-16).

DESIGN

Retrospective review.

METHODS

Patient data were collected using the national electronic Renal Patient database (eMEDRenal version 3.2.1) and individual centre records. All data were recorded in a coded fashion on a Microsoft Excel Spread-sheet and analysed with Stata SE software.

RESULTS

One hundred and one patients completed training and commenced HHD; a further fourty-five patients were assessed for HHD suitability but did not ultimately dialyse at home. Twenty patients switched to nocturnal HHD when this resource became available. The switch from conventional in-centre dialysis to HHD led to an increase in the mean weekly hours on haemodialysis (HD) and a reduction in medication burden for the majority of patients. The overall rate of arteriovenous fistula (AVF) as primary vascular access was 62%. Most HHD complications were related to access function or access-related infection. Over the 7-years, 29 HHD patients were transplanted and 9 patients died. No deaths resulted directly from a HHD complication or technical issue.

CONCLUSIONS

Patient and technique survival rates compared favourably to published international reports. However, we identified several aspects that require attention. A small number of patients were receiving inadequate dialysis and require targeted education. Ongoing efforts to increase AVF and self-needling rates in HD units must continue. Psychosocial support is critical during the transition between dialysis modalities.

Successful kidney transplantation normalizes platelet function

Background

Uraemic platelet dysfunction is not completely understood, in part due to non-physiological platelet function assays. We have developed a physiological flow-based assay that quantifies platelet function in microlitre volumes of blood under arterial shear. The aim of this study was to characterize platelet function before and after kidney transplantation.

Methods

Ten patients scheduled for living donor kidney transplant surgery and nine healthy controls were analysed using the assay. The motional parameters of platelet behaviour on von Willebrand factor (VWF) were recorded using customized platelet tracking software. The assay was repeated 3–8 weeks post-transplant in the transplant group and at an interval of >3 weeks in normal healthy volunteers.

Results

Platelet–VWF interactions were markedly reduced in the 10 pre-transplant patients compared with the healthy controls. In seven patients with immediate graft function, dynamic platelet function returned to normal (despite a small decrease in haemoglobin and haematocrit), but remained markedly abnormal in the three patients with delayed graft function (DGF).

Conclusions

Dynamic platelet function returned to normal following transplantation in those with immediate graft function. This early improvement was not observed in those with DGF. There may be important clinical implications, as patients with DGF are more likely to undergo invasive procedures, including transplant biopsies and insertion of central venous catheters.

The impact of donor and recipient weight incompatibility on renal transplant outcomes

BACKGROUND

Donor/recipient size mismatching and correlation to allograft outcome remains poorly defined. This study assessed the impact of donor body weight (DBW) to recipient body weight (RBW) ratio on allograft function and survival.

METHODS

A total of 898 deceased donor renal transplant recipients were included in the study. Patients were divided into quartiles depending on the ratio of DBW/RBW: Q1 (≤ 0.88), Q2 (0.89-1.00), Q3 (1.01-1.22) and Q4 (> 1.22). Donor and recipient characteristics were obtained from the national kidney transplant service database. Serum creatinine and estimated glomerular filtration rate (eGFR) at 1 and 5 years after transplant were compared.

RESULTS

Q4 patients had a higher eGFR 1 year post-transplant (median 59.5 ml/min, IQR 46.8-76.2) compared to Q1-Q3 which had median eGFRs of 54.3, 54.8 and 55.3 ml/min, respectively (p < 0.001). At 5 years post-transplant, there were modest differences in the eGFR across the four quartiles, Q1-4 with median eGFRs of 56.9, 61.1, 61.2 and 58.6 ml/min, respectively (p = 0.02). However, there were no significant differences in 1- and 5-year allograft survival between groups.

CONCLUSIONS

In the setting of deceased donor renal transplantation, mismatching of donor to recipient weight had no impact on 5-year allograft survival, but a low DBW/RBW ratio is modestly associated with lower eGFR.

A comparative analysis of survival of patients on dialysis and after kidney transplantation

Background

Kidney transplant survival benefits are not observed for around 8 months after transplantation because of a higher complications rate in early post-transplant periods. This study compares survival of patients awaiting transplantation with survival of transplant recipients and non-listed dialysis patients in Ireland.

Methods

In this retrospective analysis, the relative-risk (RR) of death was assessed with time-dependent, non-proportional hazards analysis, with adjustment for age, cause of end-stage kidney disease (ESKD), time from first treatment for ESKD to placement on the waiting list and year of initial placement on the list.

Results

A total of 3597 patients were included. Annual death rates per 100 patient-years at risk for all patients on dialysis, waiting-list patients and transplant recipients were 16.5, 2.4 and 1.2, respectively. Death rate was highest among diabetics. The relative risk of death for all patients on dialysis was five times higher than the waiting-list patients [RR, 4.90; 95% confidence interval (CI), 3.70–6.52; P < 0.001]. Time to survival equilibration was 1 year. Thereafter, the 5-year mortality risk was estimated to be 47% lower than that of the patients on the waiting list (RR, 0.53; 95% CI, 0.37–0.77; P = 0.001).

Conclusions

Transplant recipients had a higher risk of death initially, but a better long-term survival. Time to death risk equilibration was longer compared with other studies. This could be explained by better survival rates in our waiting-list cohort.

Using omics to explore complications of kidney transplantation

The importance of genetic and biochemical variation in renal transplant outcomes has been clear since the discovery of the HLA in the 1950s. Since that time, there have been huge advancements in both transplantation and omics. In recent years, there has seen an increased number of genome-, proteome- and transcriptome-wide studies in the field of transplantation moving away from the earlier candidate gene/protein approaches. These areas have the potential to lead to the development of personalized treatment depending on individual molecular risk profiles. Here, we discuss recent progress and the current literature surrounding omics and renal transplant complications.

Outcomes of kidney transplantation in Alport syndrome compared with other forms of renal disease

Introduction: Alport syndrome is an inherited renal disease characterized by hematuria, renal failure, hearing loss and a lamellated glomerular basement membrane. Patients with Alport syndrome who undergo renal transplantation have been shown to have patient and graft survival rates similar to or better than those of patients with other renal diseases.

Methods: In this national case series, based in Beaumont Hospital Dublin, we studied the cohort of patients who underwent renal transplantation over the past 33 years, recorded prospectively in the Irish Renal Transplant Registry, and categorized them according to the presence or absence of Alport syndrome. The main outcomes assessed were patient and renal allograft survival.

Results: Fifty-one patients diagnosed with Alport syndrome in Beaumont Hospital received 62 transplants between 1982 and 2014. The comparison group of non-Alport patients comprised 3430 patients for 3865 transplants. Twenty-year Alport patient survival rate was 70.2%, compared to 44.8% for patients with other renal diseases (p = .01). Factors associated with patient survival included younger age at transplantation as well as differences in recipient sex, donor age, cold ischemia time, and episodes of acute rejection. Twenty-year graft survival was 46.8% for patients with Alport syndrome compared to 30.2% for those with non-Alport disease (p = .11).

Conclusions: Adjusting for baseline differences between the groups, patients with end-stage kidney disease (ESKD) due to Alport syndrome have similar patient and graft survival to those with other causes of ESKD. This indicates that early diagnosis and management can lead to favorable outcomes for this patient cohort.

Kidney transplant outcomes in familial C3 glomerulopathy

C3 glomerulopathy, a newly designated entity, is characterized by glomerular disease associated with dysregulation of the alternative complement pathway and is a rare cause of end-stage kidney disease. Overall disease characteristics that include clinical presentation, laboratory assessment, histopathology and genetic background have only been unravelled in recent years and have led to the development of anti-complement therapies targeting different levels of the alternative pathway. We describe the long-term outcomes following kidney transplantation in an Irish family with familial C3 glomerulopathy due to a hybrid CFHR3-1 gene.

Arteriovenous fistula in dialysis patients: Factors implicated in early and late AVF maturation failure

Increasing numbers of patients are being diagnosed with end-stage renal disease (ESRD), and the demand for on haemodialysis (HD) is rising. Arteriovenous fistulae (AVFs) remain the best conduit for adequate HD, with fewer complications associated with long-term use compared to bypass grafts and central venous catheters. However, it is known that many newly formed fistulae do not mature to provide useful HD access. The paper provides a narrative overview of factors influencing the process of AVF maturation failure.

Urinary biomarkers of chronic allograft nephropathy

PURPOSE

Chronic allograft nephropathy (CAN) is widely accepted as the leading cause of renal allograft loss after the first year post transplantation. This study aimed to identify urinary biomarkers that could predict CAN in transplant patients.

EXPERIMENTAL DESIGN

The study included 34 renal transplant patients with histologically proven CAN and 36 renal transplant patients with normal renal function. OrbiTrap MS was utilized to analysis a urinary fraction in order to identify other members of a previously identified biomarker tree . This novel biomarker pattern offers the potential to distinguish between transplant recipients with CAN and those with normal renal function.

RESULTS

The primary node of the biomarker pattern was reconfirmed as β2 microglobulin. Three other members of this biomarker pattern were identified: neutrophil gelatinase-associated lipocalin, clusterin, and kidney injury biomarker 1. Significantly higher urinary concentrations of these proteins were found in patients with CAN compared to those with normal kidney function.

CONCLUSIONS AND CLINICAL RELEVANCE

While further validation in a larger more-diverse patient population is required to determine if this biomarker pattern provides a potential means of diagnosing CAN by noninvasive methods in a clinical setting, this study clearly demonstrates the biomarkers' ability to stratify patients based on transplant function.

Understanding What Influences the Health-Related Quality of Life of Hemodialysis Patients: A Collaborative Study in England and Ireland

CONTEXT

The international cohort of hemodialysis patients is aging and increasing in number. Nephrologists have a therapeutic relationship with their patients that may span decades. Often overlooked components of chronic disease management include symptom control and assessment of health-related quality of life (HRQoL).

OBJECTIVES

This study describes the symptom profile of a large cohort of patients with end-stage renal disease on hemodialysis in England and Ireland and evaluates how symptom burden and other factors influence quality-of-life scores.

METHODS

A prospective cross-sectional observational study of hemodialysis patients was conducted in Ireland and England during 2011 and 2012. Two validated clinical tools were used to determine HRQoL and symptom burden. Demographic and clinical data were examined, and regression analysis was used to determine associations with HRQoL scores.

RESULTS

A total of 893 patients on hemodialysis (mean [SD] age 64 [16] years) had a high symptom burden and poor HRQoL compared with population norms. Specifically, 64% of patients reported pain (95% confidence interval 61%-67%) and 79% reported weakness (95% confidence interval 75%-81%). A total of 43 percent of patients reported between six and 10 symptoms in the week preceding the survey. HRQoL was significantly and independently associated with poor mobility and pain and remained significant after adjusting for variations in clinical characteristics. Being listed on a transplant wait-list register was positively associated with HRQoL.

CONCLUSION

These findings illustrate the high symptom burden and poor HRQoL of the hemodialysis population. Emphasis during clinical reviews on pain assessment and on assessing mobility plus interventions, such as pain management and physiotherapy/occupational therapy, are practical ways for renal teams to help improve patients' quality of life.

The influence of socioeconomic status on patient survival on chronic dialysis

Socioeconomic status (SES) has been linked to worse end-stage kidney disease survival. The effect of SES on survival on chronic dialysis, including the impact of transplantation, was examined. A retrospective, observational study investigated the association of SES with dialysis patient survival, with censoring at time of transplantation. Adult patients commencing dialysis from 1990 to 2009 in an Irish tertiary center received a spatial SES score using the 2011 Pobal Haase-Pratschke Deprivation Index and were compared by quartile. Cox proportional hazard models and Kaplan-Meier survival analysis examined any association of SES with survival. The 1794 patients included had a median follow-up of 3.8 years. Patients in the lowest SES area quartile were significantly younger than the highest, mean age 56.7 vs. 59 years, P = 0.006, respectively. There was no association between SES area score and survival in an unadjusted model (hazard ratio [HR] 1.00, 95% confidence interval [CI] 0.99-1.01). Survival in the highest SES area quartile was superior to the lowest SES in a multivariable adjusted model including age, gender, and dialysis modality (HR 0.83, 95% CI 0.70-0.99, P = 0.04). These results were only mildly attenuated by censoring at time of transplantation (highest SES area quartile deprived vs. lowest SES area quartile, HR 0.85, 95% CI 0.70-1.03, P = 0.09). Superior patient survival was identified in the highest SES areas compared with the lowest following age-adjusted analyses, despite the older population in the most affluent areas. Further research should focus on identifying modifiable targets for intervention that account for this socioeconomic-related survival advantage.

Association of CYP3A variants with kidney transplant outcomes

Cyclosporine is used extensively in kidney transplantation and is a substrate for cytochrome P450 enzymes. The role of cytochrome p450 polymorphisms in kidney transplant outcome has not yet been fully elucidated. We investigate the clinical impact of single nucleotide polymorphisms in CYP3A4, CYP3A5, PPARα, and POR*28 in 255 kidney transplant recipients. We examine for any association with graft survival, time to first cancer, and delayed graft function, and also measure cyclosporine levels at days 3, 10, and months 1, 3, 6, and 12 after transplantation. The CYP3A4*22 allele is significant associated with the development of cancer post-kidney transplantation (HR 0.20, 95% CI 0.07-0.57, p = 0.003). It is not significantly associated with graft survival. No other SNP's were associated with graft survival time to first cancer, or delayed graft function. There was a non-significant trend of lower cyclosporine dose requirement in CYP3A4*22 carriers. Independent replication of our findings is now warranted to confirm or reject the role of CYP3A variants in cancer development following kidney transplantation.