Background: The UK Registry of Rare Kidney Diseases (RaDaR) Idiopathic Nephrotic Syndrome cohort includes adults and children with genetic nephrotic syndrome, Focal Segmental Glomerulosclerosis (FSGS) and minimal change disease. This study examines long-term patient outcomes as a function of kidney biopsy diagnosis and proteinuria control. Methods: 2467 adults and 1599 children were followed to establish outcomes including eGFR slope and kidney survival by diagnosis, analysed as a function of proteinuria from disease onset for FSGS and minimal change disease. Enrollment began in 2010, with follow-up to September 2023. Index date for the survival analyses was date of disease onset. Results: The cohort had median [IQR] follow up of 8.2 [4.3-13.1] years; 30% of patients reached kidney failure or died. 1303 patients had FSGS, 1153 minimal change disease, 105 monogenic nephrotic syndrome. Children showed relatively preserved mean kidney function at disease onset (eGFR>100 ml/min/1.73m 2 ), compared to adults (FSGS 61ml/min/1.73m 2 ; minimal change disease 76ml/min/1.73m 2 ). Kidney survival probability (95% CI) at 10 years varied with diagnosis: Genetic 29% (20-38), FSGS 58% (55-61), minimal change disease 87% (85-89) with mean (SD) rates of eGFR loss -26.5 (34.7), -6.2 (14.3), and -1.9 (10.2) ml/min/1.73m 2 per year respectively. FSGS 10-year kidney survival (95% CI) for 6-12 months lowest proteinuria value in complete remission (<0.3g/g), partial remission (0.3-3.5g/g) and no remission (>3.5g/g) was 88% (70-96). 65% (50-76) and 37% (26-48), respectively. Time-averaged proteinuria of <1.5g/g over 6-24 months from disease onset was associated with 90% 10-year kidney survival. For minimal change disease, patients’ 10-year kidney survival (95% CI) stratified by 6-12 months lowest proteinuria value was: complete remission 89% (79-94), partial remission 75% (51-89), and no remission 64% (41-81). In FSGS and minimal change disease 10-year eGFR slope was strongly correlated with absolute levels of proteinuria. Conclusions: Kidney outcomes were poor in genetic nephrotic syndrome; in FSGS outcomes were strongly associated with proteinuria level. Minimal change disease patients had better proteinuria control than FSGS and had better outcomes at each proteinuria level.

Background. Patients with membranous nephropathy (MN) and poor kidney function or active disease despite previous immunosuppression are underrepresented in clinical trials. It is unknown how effective rituximab is in this population. Methods. This prospective, multi-centre, single-arm, real-world study of patients with active MN [urine protein-creatinine ratio (uPCR) >350 mg/mmol and serum albumin <30 g/L, or a fall in estimated glomerular filtration rate (eGFR) of at least 20% or more over at least 3 months] evaluated rituximab in those with contraindications to calcineurin inhibitors and cytotoxic therapy. The primary outcome was change in rate of eGFR decline before and after rituximab. Complete or partial remission were defined as uPCR <30 mg/mmol or uPCR <350 mg/mmol with a >= 50% fall from baseline, respectively. Results. A total of 180 patients [median age 59 years, interquartile range (IQR) 48-68] received rituximab and were followed up for a median duration of 17 months. Seventy-seven percent had prior immunosuppression. Median eGFR and uPCR at baseline were 49.2 mL/min/1.73 m(2) (IQR 34.4-80.6) and 766 mg/mmol (IQR 487-1057), respectively. The annual rate of decline of eGFR fell from 13.9 to 1.7 mL/min/1.73 m(2)/year following rituximab (Z score = 2.48, P < .0066). At 18 months 12% and 42% of patients were in complete or partial remission, respectively. Rituximab was well tolerated; patient survival was 95.6% at 2 years and in patients in whom eGFR was available, kidney survival was 93% at 2 years. Conclusion. Rituximab significantly reduced the rate of eGFR decline in active MN including those who had received prior immunosuppression or with poor baseline kidney function.

Introduction: The National Registry of Rare Kidney Diseases (RaDaR) collects data from people living with rare kidney diseases across the UK, and is the world's largest, rare kidney disease registry. We present the clinical demographics and renal function of 25,880 prevalent patients and sought evidence of bias in recruitment to RaDaR. Methods: RaDaR is linked with the UK Renal Registry (UKRR, with which all UK patients receiving kidney replacement therapy [KRT] are registered). We assessed ethnicity and socioeconomic status in the following: (i) prevalent RaDaR patients receiving KRT compared with patients with eligible rare disease diagnoses receiving KRT in the UKRR, (ii) patients recruited to RaDaR compared with all eligible unrecruited patients at 2 renal centers, and (iii) the age-stratified ethnicity distribution of RaDaR patients with autosomal dominant polycystic kidney disease (ADPKD) was compared to that of the English census. Results: We found evidence of disparities in ethnicity and social deprivation in recruitment to RaDaR; however, these were not consistent across comparisons. Compared with either adults recruited to RaDaR or the English population, children recruited to RaDaR were more likely to be of Asian ethnicity (17.3% vs. 7.5%, P-value < 0.0001) and live in more socially deprived areas (30.3% vs. 17.3% in the most deprived Index of Multiple Deprivation (IMD) quintile, P-value < 0.0001). Conclusion: We observed no evidence of systematic biases in recruitment of patients into RaDaR; however, the data provide empirical evidence of negative economic and social consequences (across all ethnicities) experienced by families with children affected by rare kidney diseases.

Background Idiopathic nephrotic syndrome (INS) is a heterogenous disease and current classification is based on observational responses to therapies or kidney histology. The National Unified Renal Translational Research Enterprise (NURTuRE)-INS cohort aims to facilitate novel ways of stratifying INS patients to improve disease understanding, therapeutics and design of clinical trials.Methods NURTuRE-INS is a prospective cohort study of children and adults with INS in a linked biorepository. All recruits had at least one sampling visit collecting serum, plasma, urine and blood for RNA and DNA extraction, frozen within 2 hours of collection. Clinical histology slides and biopsy tissue blocks were also collected.Results A total of 739 participants were recruited from 23 centres to NURTuRE-INS, half of whom were diagnosed in childhood [n = 365 (49%)]. The majority were white [n = 525 (71%)] and the median age at recruitment was 32 years (interquartile range 12-54). Steroid-sensitive nephrotic syndrome (SSNS) was the most common clinical diagnosis [n = 518 (70%)]. Of patients diagnosed in childhood who underwent a kidney biopsy, for SSNS (n =103), 76 demonstrated minimal change disease (MCD), whereas for steroid-resistant nephrotic syndrome (n =80), 21 had MCD. Almost all patients diagnosed in adulthood had a kidney biopsy [n = 352 (94%)]; 187 had MCD and 162 had focal segmental glomerulosclerosis.Conclusions NURTuRE-INS is a prospective cohort study with high-quality biosamples and longitudinal data that will assist research into the mechanistic stratification of INS. Samples and data will be available through a Strategic Access and Oversight Committee. Graphical Abstract

Background Individuals with rare kidney diseases account for 5-10% of people with chronic kidney disease, constitute more than 25% of patients receiving kidney replacement therapy. The National Registry of Rare Kidney Diseases (RaDaR) gathers longitudinal data from patients with these conditions, which we used to study disease progression and outcomes of death and kidney failure. Methods People aged 0-96 years living with 28 types of rare kidney diseases were recruited from 108 UK renal facilities. The primary outcomes were cumulative incidence of mortality and kidney failure in individuals with kidney diseases, which were calculated and compared with that of unselected patients with chronic kidney disease. Cumulative incidence and Kaplan-Meier survival estimates were calculated for the following outcomes: median at kidney failure; median age at death; time from start of dialysis to death; and time from diagnosis to estimated glomerular filtration rate (eGFR) thresholds, allowing calculation of time from last eGFR of 75 mL/min per 173 or more to first eGFR of less than 30 mL/min per 173 m 2 (the therapeutic trial window). Findings Between Jan 18, 2010, and July 25, 2022, 27 285 participants were recruited to RaDaR. Median follow-up from diagnosis was 96 years (IQR 59-167). RaDaR participants had significantly higher 5 -year cumulative incidence of kidney failure than 281 million UK patients with all-cause chronic kidney disease (28% vs 1%; p<00001), but better survival rates (standardised mortality ratio 042 [95% CI 032-052]; p<00001). Median age at failure, median age at death, time from start of dialysis to death, time from diagnosis to eGFR thresholds, therapeutic trial window all varied substantially between rare diseases. Interpretation Patients with rare kidney diseases differ from the general population of individuals with chronic disease: they have higher 5 -year rates of kidney failure but higher survival than other patients with chronic disease stages 3-5, and so are over-represented in the cohort of patients requiring kidney replacement therapy. Addressing unmet therapeutic need for patients with rare kidney diseases could have a large beneficial effect on term kidney replacement therapy demand.

Abstract Background and Aims Idiopathic nephrotic syndrome (INS) is an important class of proteinuric renal disease leading to kidney failure (KF). Here we describe the natural history of INS and congenital nephrotic syndrome (NS) using the UK National Registry of Rare Kidney Diseases Idiopathic Nephrotic Syndrome (RaDaR-INS) Cohort, including retrospective and prospective data from 4610 patients with NS not attributable to glomerulonephritis or systemic disorders recruited from 107 adult and paediatric kidney units across the UK since 2010. Method Participant eligibility of RaDaR-INS Cohort patients included ≥12 months observation from disease onset and no KF (CKD stage 5 or on renal replacement therapy) at or prior to disease onset. Disease onset date was defined as first database occurrence of kidney biopsy, primary diagnosis or protein-creatinine ratio (PCR) ≥1.5 g/g. Participants were sub-categorized into those with a genetic diagnosis (INS-genetic), biopsy-proven FSGS (FSGS-biopsy), biopsy–proven minimal change disease (MCD-biopsy) and those with no genetic or biopsy-proven diagnosis (INS-no genetic or biopsy diagnosis). Participants with a biopsy-proven MCD diagnosis and a subsequent biopsy proven FSGS diagnosis were included in both MCD-biopsy and FSGS-biopsy categories and formed a category of their own (MCD progressing to FSGS). Longitudinal proteinuria, assessed as time-average protein-to-creatinine ratio (TA-PCR), and eGFR slope were calculated over the full duration of follow-up or until KF. Kidney survival was calculated from disease onset to event (KF or death) and censored at last follow-up. Results Of the 4066 patients meeting eligibility, median age at disease onset was 28 years (IQR 6-51), with children (<18 yrs) representing 39% of the study population. Median proteinuria was 6.4 g/g (IQR 3.1-10.8; n = 923), while mean eGFR was 118 mL/min/1.73 m2 (SD 49; n = 240) and 69 mL/min/1.73 m2 (SD 34; n = 906) for children and adults, respectively. Median follow-up duration was 8.2 yrs (IQR 4.3-13.1) with KF/death events occurring in 30% of patients. Mean TA-PCR was greater in children than adults (5.0 g/g (SD 13.9) vs. 1.9 g/g (SD 2.5), as was annual rate of loss of eGFR (−7.4 mL/min/1.73 m2 (SD 21.8) vs. −3.1 mL/min/1.73 m2 (SD 10.2)). Characteristics at disease onset and clinical outcomes of the INS cohort sub-categories are presented in Fig. 1. Kaplan Meier survival plots of each sub-category, and further divided into children and adults, illustrate the poor survival probability for patients with FSGS, particularly INS-genetic patients who are predominantly diagnosed in childhood (Fig. 2). While INS with no genetic or biopsy diagnosis presenting in childhood exhibits disease course and outcomes similar to MCD-biopsy patients, those diagnosed in adulthood have a more rapid disease course similar to FSGS-biopsy patients. Conclusion The RaDaR-INS cohort represents a large study population with lengthy follow-up data. These analyses illustrate the difference in disease progression and survival rates for INS patients with different causes or histological descriptions, highlighting in particular an unmet need for effective treatments for patients with nephrotic syndrome and FSGS.

BACKGROUND:Acute Kidney Injury (AKI) is a common and serious clinical syndrome. There is increasing recognition of heterogeneity in observed AKI across different clinical settings. In this analysis we have utilised a large national dataset to outline, for the first time, differences in burden of hospital acquired AKI (H-AKI) and mortality risk across different treatment specialities in the English National Health Service (NHS).METHODS:A retrospective observational study was conducted using a large national dataset of patients who triggered a biochemical AKI alert in England during 2019. This dataset was enriched through linkage with NHS hospitals administrative and mortality data. Episodes of H-AKI were identified and attributed to the speciality of the supervising consultant during the hospitalisation episode in which the H-AKI alert was generated. Associations between speciality and death in hospital or within 30 days of discharge (30-day mortality) was modelled using logistic regression, adjusting for patient age, sex, ethnicity, socioeconomic status, AKI severity, season and method of admission.RESULTS:In total, 93,196 episodes of H-AKI were studied. The largest number of patients with H-AKI were observed under general medicine (21.9%), care of the elderly (18.9%) and general surgery (11.2%). Despite adjusting for differences in patient case-mix, 30-day mortality risk was consistently lower for patients in surgical specialities compared to general medicine, including general surgery (OR 0.65, 95% CI 0.61 to 0.7) and trauma and orthopaedics (OR 0.52, 95% CI 0.48 to 0.56). Mortality risk was highest in critical care (OR 1.78, 95% CI 1.56 to 2.03) and oncology (OR 1.74, CI 1.54 to 1.96).CONCLUSIONS:Significant differences were identified in the burden of H-AKI and associated mortality risk for patients across different specialities in the English NHS. This work can help inform future service delivery and quality improvement activity for patients with AKI across the NHS.

Background IgA nephropathy can progress to kidney failure, and risk assessment soon after diagnosis has advantages both for clinical management and the development of new therapeutics. We present relationships among proteinuria, eGFR slope, and lifetime risks for kidney failure. Methods The IgA nephropathy cohort (2299 adults and 140 children) of the UK National Registry of Rare Kidney Diseases (RaDaR) was analyzed. Patients enrolled had a biopsy-proven diagnosis of IgA nephropathy plus proteinuria >0.5 g/d or eGFR <60 ml/min per 1.73 m 2 . Incident and prevalent populations and a population representative of a typical phase 3 clinical trial cohort were studied. Analyses of kidney survival were conducted using Kaplan–Meier and Cox regression. eGFR slope was estimated using linear mixed models with random intercept and slope. Results The median (Q1, Q3) follow-up was 5.9 (3.0, 10.5) years; 50% of patients reached kidney failure or died in the study period. The median (95% confidence interval [CI]) kidney survival was 11.4 (10.5 to 12.5) years; the mean age at kidney failure/death was 48 years, and most patients progressed to kidney failure within 10–15 years. On the basis of eGFR and age at diagnosis, almost all patients were at risk of progression to kidney failure within their expected lifetime unless a rate of eGFR loss ≤1 ml/min per 1.73 m 2 per year was maintained. Time-averaged proteinuria was significantly associated with worse kidney survival and more rapid eGFR loss in incident, prevalent, and clinical trial populations. Thirty percent of patients with time-averaged proteinuria of 0.44 to <0.88 g/g and approximately 20% of patients with time-averaged proteinuria <0.44 g/g developed kidney failure within 10 years. In the clinical trial population, each 10% decrease in time-averaged proteinuria from baseline was associated with a hazard ratio (95% CI) for kidney failure/death of 0.89 (0.87 to 0.92). Conclusions Outcomes in this large IgA nephropathy cohort are generally poor with few patients expected to avoid kidney failure in their lifetime. Significantly, patients traditionally regarded as being low risk, with proteinuria <0.88 g/g (<100 mg/mmol), had high rates of kidney failure within 10 years.

Associations between anthropometric measures and patient outcomes in children are inconsistent and mainly based on data at kidney replacement therapy (KRT) initiation. We studied associations of height and body mass index (BMI) with access to kidney transplantation, graft failure, and death during childhood KRT. We included patients < 20 years starting KRT in 33 European countries from 1995–2019 with height and weight data recorded to the ESPN/ERA Registry. We defined short stature as height standard deviation scores (SDS) < –1.88 and tall stature as height SDS > 1.88. Underweight, overweight and obesity were calculated using age and sex-specific BMI for height-age criteria. Associations with outcomes were assessed using multivariable Cox models with time-dependent covariates. We included 11,873 patients. Likelihood of transplantation was lower for short (aHR: 0.82, 95

Rare kidney diseases are not well characterised, despite making a significant contribution to the burden of kidney disease globally. The National Registry of Rare Kidney Diseases (RaDaR) collects longitudinal disease and treatment related data from people living with rare kidney diseases across the UK, and is the largest rare kidney disease registry in the world. We present the clinical demographics and renal function of 25,880 prevalent patients and evaluate for any potential recruitment bias to RaDaR. RaDaR recruits patients from 108 UK hospitals and is linked with the UK Renal Registry (UKRR, with which all UK patients receiving Kidney Replacement Therapy (KRT) are registered). To assess for recruitment bias to RaDaR we performed three comparisons of ethnicity and socioeconomic status: 1) All prevalent RaDaR patients receiving KRT were compared with patients with eligible rare disease diagnoses receiving KRT in the UKRR 2) Patients recruited to RaDaR and all eligible unrecruited patients at two renal centres were compared 3) The age-stratified ethnicity distribution RaDaR patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD) was compared with the English Census. We observed over-representation of individuals reporting South Asian ethnicity in some rare diseases (most markedly Cystinosis and Primary Hyperoxaluria). We found no evidence of systematic bias in recruitment to RaDaR in terms of ethnicity or social deprivation. Predominant rare kidney diseases in adults ([≥]18 years) were ADPKD (29.2%), Vasculitis (15.8%) and IgA nephropathy (15.7%), compared to Idiopathic nephrotic syndrome (43.6%), Vasculitis (10.8%) and Alport Syndrome (5.9%) in children (<18 years). Compared with either adults recruited to RaDaR or the general UK population, children recruited to RaDaR were more likely to be of Asian ethnicity and live in more socially deprived areas.

Abstract Background and Aims Idiopathic Steroid Resistant Nephrotic Syndrome, SRNS (incorporating FSGS) is an important cause of proteinuric renal disease leading to kidney failure. Here we describe the outcomes of SRNS using the UK National Registry of Rare Kidney Diseases Idiopathic Nephrotic Syndrome (RaDaR-INS) Cohort, including retrospective and prospective data from 4274 patients with nephrotic syndrome (NS) not attributable to glomerulonephritis or systemic disorders, recruited from 107 adult and paediatric kidney units across the UK since 2010. In patients with FSGS, severity of proteinuria at onset and during follow up is associated with renal failure. In this study, we tested for associations between defined proteinuria endpoints with both eGFR slope and renal survival, in children and adults. Method Participants included those with renal biopsy diagnosis of FSGS or minimal change disease (MCD), or monogenic NS. Patients with no proteinuria measurement ≥1.0 g/g >6 months after disease onset were excluded as likely fully steroid-sensitive. Patients with kidney failure (KF) (CKD stage 5 or on renal replacement therapy) at or prior to first proteinuria measurement after baseline were excluded. Disease onset was defined as time of renal biopsy; primary renal diagnosis (PRD) date if no biopsy date recorded, and first proteinuria ≥1 g/g if neither biopsy/PRD date was available. Baseline was defined as first proteinuria ≥1 g/g >6 months after disease onset. Kaplan-Meier methods were used to analyze renal survival, defined as absence of KF or death with survival time calculated from baseline to last follow up. eGFR slope was measured from 6 months after baseline for the duration of follow up. Results Of 612 MCD and FSGS patients meeting eligibility, median time from disease onset to baseline was 1.2 years (IQR 0.6-4.4). Median baseline age was 38 years (IQR 21–56) with paediatric patients representing 21% of the study population. Median proteinuria at baseline was 3.4 g/g (IQR 1.9-6.2), while mean eGFR was 89 mL/min/1.73 m2 (SD 39). Mean rate of loss of eGFR over follow-up was 4.4mL/min/1.73 m2/year (SD 10.9). Complete proteinuria remission (CR) and FSGS partial remission (FPR) were defined as shown in Table 1 using values of time-averaged proteinuria (TA-PU) over months 6–24 from baseline. For patients achieving CR or FPR, the rate of loss of eGFR was slower (Table 1), with a higher probability of survival from KF/death (Table 1 & Figure 1), than patients failing to achieve CR or FPR. Conclusion This is a study of proteinuria and outcomes in a population of patients with FSGS or steroid-resistant MCD. We regard the latter group as likely also to have FSGS. In this population of patients with overt proteinuria, achieving partial or complete remission of proteinuria is associated with slower disease progression and reduced risk of KF/death.

ABSTRACT Background Chronic kidney disease (CKD) is common but heterogenous and is associated with multiple adverse outcomes. The National Unified Renal Translational Research Enterprise (NURTuRE)-CKD cohort was established to investigate risk factors for clinically important outcomes in persons with CKD referred to secondary care. Methods Eligible participants with CKD stages G3–4 or stages G1–2 plus albuminuria >30 mg/mmol were enrolled from 16 nephrology centres in England, Scotland and Wales from 2017 to 2019. Baseline assessment included demographic data, routine laboratory data and research samples. Clinical outcomes are being collected over 15 years by the UK Renal Registry using established data linkage. Baseline data are presented with subgroup analysis by age, sex and estimated glomerular filtration rate (eGFR). Results A total of 2996 participants was enrolled. Median (interquartile range) age was 66 (54–74) years, eGFR 33.8 (24.0–46.6) mL/min/1.73 m2 and urine albumin to creatinine ratio 209 (33–926) mg/g; 58.5% were male. Of these participants, 1883 (69.1%) were in high-risk CKD categories. Primary renal diagnosis was CKD of unknown cause in 32.3%, glomerular disease in 23.4% and diabetic kidney disease in 11.5%. Older participants and those with lower eGFR had higher systolic blood pressure and were less likely to be treated with renin–angiotensin system inhibitors (RASi) but were more likely to receive a statin. Female participants were less likely to receive a RASi or statin. Conclusions NURTuRE-CKD is a prospective cohort of persons who are at relatively high risk of adverse outcomes. Long-term follow-up and a large biorepository create opportunities for research to improve risk prediction and to investigate underlying mechanisms to inform new treatment development.

As Munro and Faust point out, there appears a stark contrast in the case and mortality rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among children compared with the adult population.1 Whether infection in children is generally mild or asymptomatic, which goes undetected, or children are less susceptible to contracting the infection is unclear until screening programmes are introduced. What also remains uncertain is the risk of severe infection for children with significant underlying health concerns, including those with chronic kidney disease (CKD). The few studies reported have so far shown reassuringly low numbers and complication rates in children with coexisting diseases such as cancer and liver transplant recipients.2 3 The NHS England COVID-19 service evaluation (https://www.rcpch.ac.uk/resources/covid-19-service-evaluation-audit-care-needs-children-admitted-hospital-england), to date, has identified 220 confirmed cases in England of whom 44.4% of cases have coexisting disease; two children are reported to have CKD. At the UK Renal Registry (UKRR) and in collaboration with the British Association for …

In 2016, the median height z-score for prevalent paediatric patients on dialysis was -1.8 and -1.1 for those with a functioning transplant (p < 0.0001). The median weight z-score for children receiving dialysis in 2016 was -1.2 compared with -0.2 for children with a functioning transplant. The median systolic blood pressure (SBP) z-score for transplanted children was 0.3 compared with 0.9 for dialysis patients (p < 0.0001). Of those with complete data, 72% of the prevalent paediatric renal replacement therapy (RRT) population in 2016 had one or more risk factors for cardiovascular disease; 6% had three risk factors present. All centres reported quarterly laboratory data in 2016. Quarterly data for transplant patients revealed a median creatinine of 77 mu mol/L. Data for dialysis patients revealed median values within the normal range for most biochemical and laboratory parameters, however wide inter-centre variation was seen for parameters such as ferritin and phosphate. Evidence of hyperparathyroidism (median parathyroid hormone (PTH) 16.5 pmol/L) was noted within this cohort. Most (91%) prevalent transplant patients achieved the national haemoglobin standard in 2016: 86% had a normal range bicarbonate level and 81% had a PTH within acceptable range. For prevalent patients on haemodialysis in 2016, 56% achieved SBP values of less than the 90th percentile. Achievement of standards was 71%, 79%, 54% and 41% for haemoglobin, calcium, phosphate and PTH respectively. For prevalent patients on peritoneal dialysis in 2016, 65% achieved SBP values of less than the 90th percentile. Achievement of standards was 77%, 69%, 59% and 35% for haemoglobin, calcium, phosphate and PTH standards respectively.

In 2016, 964 children and young people aged less than 18 years were receiving long-term renal replacement therapy (RRT) for established renal failure (ERF) at UK paediatric nephrology centres. A total of 125 incident patients under 18 years commenced RRT. At the census date (31 December 2016), 77% of prevalent paediatric patients aged <16 years had a functioning kidney transplant (43% live and 34% deceased donor), 12% were receiving haemodialysis (HD) and 11% were receiving peritoneal dialysis (PD). In 2016, the prevalence of ERF in patients aged less than 16 years was 64.1 per million age-related population (pmarp). The incidence of ERF for 2016 was 9.0 pmarp. Using ERA-EDTA Registry classification, tubulo-interstitial disease (which includes congenital structural anomalies) accounted for over half of all primary renal diagnoses in prevalent patients, with a high male: female ratio (3.3 : 1). Over time, there has been a progressive decline in glomerular disease as a primary renal cause of ERF. Between 2002 and 2016, a third of prevalent children in ERF aged three months to 16 years who were referred early received a pre-emptive transplant. Males and White ethnic children were significantly more likely to benefit from pre-emptive transplantation, adjusting for time-period, age at RRT start and primary renal diagnosis. At the time of transfer to adult services, 89.4% of patients had a functioning kidney transplant.

The incident population is defined as all patients over 18 who started renal replacement therapy (RRT) at UK renal centres and did not have a recovery lasting more than 90 days within 90 days of starting RRT. The treatment timeline is used to define incident patients as follows. If a patient has timeline entries from more than one centre then these are all combined and sorted by date. Then, the first treatment entry from any centre gives the first date when they received RRT. This is defined as a ‘start date’. However, in the following situations there is evidence that the patient was already receiving RRT before this ‘start date’ and these people are not classed as incident patients: