Nephrology clinical outcomes

Clinical outcomes are broadly agreed, measurable changes in health or quality of life that result from our care. Constant review of our clinical outcomes establishes standards against which to continuously improve all aspects of our practice.

The Renal Unit at Great Ormond Street Hospital (GOSH) provides a comprehensive diagnostic and treatment service for children with diseases affecting the kidneys. It is the largest paediatric renal unit in the UK and one of the largest in Europe. Each year there are approximately 300-350 admissions to the renal ward; 100 admissions to outlying wards; over 7,000 outpatient attendances; 30-40 new renal transplants including combined liver and kidney transplants, and 70 patients on dialysis (a treatment that helps to remove toxins from the blood and helps maintain salt and water balance).

The renal team provides expert care for a number of general kidney conditions and rare, very specialist conditions such as congenital renal anomalies including neonatal and infant end stage renal programme; home haemodialysis; antibody (ABO and HLA) incompatible transplantation; transplantation of children with complex vascular anomalies; glomerular diseases; hypertension and renovascular conditions; vasculitis; tubular, metabolic and stone disorders. In partnership with Kings College Hospital, we offer combined liver and kidney transplants. Our transplant team offers transplantation to children with methylmalonic acidemia. In addition, we support a number of District General Hospitals by running joint outreach clinics with their local teams.

The unit is an established quaternary centre for referrals of children with severe renovascular conditions, tubular disorders and those deemed un-transplantable elsewhere.

We are the first unit in the world to use 3D printing in clinical practice for renal transplantation.

We are the European referring centre for tubulopathies.

Our service is unique in the fact that we have the first fully established home haemodialysis programme for children in the UK. Dialysis is a life-saving treatment necessary for children whose kidneys have failed.

We have strong links with the UCL Institute of Child Health, our overall mission being to improve the diagnosis, treatment and prognosis of children with kidney and urinary tract diseases through high-quality basic science and clinical research. There are extensive laboratory facilities for molecular and cellular biology within the unit, and strong links to affiliated laboratories.

The best (gold standard) therapy for children with severe irreversible kidney failure (end-stage kidney disease) is kidney transplantation. Internationally, the best outcomes are achieved if the kidney is donated by living donors who are related to the child (as opposed to deceased donors) and if transplantation occurs before the child requires kidney replacement therapy with dialysis.

This is not always possible as some patients require surgery to have their kidneys removed prior to transplantation. Others may present suddenly with end-stage kidney disease, and we have no option but to initiate dialysis therapy to stabilize them, as it takes up to six months to prepare for transplantation. Many children will have other conditions that occur alongside their kidney failure. These are called co-morbidities and can pose medical and surgical problems when looking after children with kidney transplants.

The renal team at GOSH receive a number of referrals from national and international centres for complex patients requiring kidney transplantation.

We are also the first unit in the world to successfully perform HLA incompatible kidney transplantation in children with already well established blood group incompatible transplant programme which is delivered in collaboration with Guy's hospital.

Our transplant unit leads on transplantation of children with vascular anomalies with children being referred from other centres in the UK and internationally.

These patients tend to have higher morbidity and mortality risks. We record the survival of both children themselves (patient survival) as well as their kidney transplant (renal allograft survival).

Definition: Percentage of paediatric patients aged between 1 and 18 years undergoing a renal transplant who were alive at one year, and at five years after transplantation.

In this chart, we compare our results against the combined results from the other nine paediatric transplant centres in the UK in 2017-18.

Fig 1.1 One and five year patient survival in children receiving renal transplant, 2017-18

In addition to the survival of the children themselves (patient survival), we continuously monitor the kidney transplant or renal allograft survival rate. If the transplant does not survive, the child will need to be recommenced on dialysis.

Definition: Percentage of paediatric patients between 1 and 18 years undergoing a renal transplant who were alive with a functioning kidney transplant (not requiring dialysis) at one and at five years after transplantation.

In this chart, we compare our results against the combined results from the other nine paediatric transplant centres in the UK in 2017-18.

Fig 1.2 One and five year kidney transplant (renal allograft) survival in children receiving renal transplants, 2017-18

Children who have had a previous transplant or received a blood transfusion have an increased chance of being 'sensitised' and of developing human leukocyte antigen (HLA) antibodies. This means that a transplanted kidney has higher chances of being rejected because of pre-existing antibodies in the child’s blood. Our unit is the first in the world to perform HLA incompatible (HLAi) transplantation in paediatric. To date, we have transplanted three children with HLAi organs, two of which were referred from abroad.

Some patients have potential living donors with different blood groups. This means the child’s antibodies could reject the kidney of the donor because of the different blood group types. We have a well-established ABO incompatible (ABOi) programme using a tailored desensitization protocol to allow ABOi transplants. To date, we have performed ten ABOi transplants. The number of ABOi transplants has reduced in recent years due to the increasing number of children receiving organs from the UK Living Kidney Sharing Scheme.

Renal allograft and patient survival at five years for ABOi transplant, and at four years for HLAi transplant is shown below, as at Dec 2018. No data is reported by other UK centres for comparison.

Fig 1.3 Renal allograft and patient survival in children receiving antibody incompatible transplants, as at Dec 2018

Note: The next data refresh for the renal transplantation outcome measures will be in 2023.

The number of paediatric kidney only recipients in the UK has remained relatively unchanged in the last decade, with the number of transplants per year ranging from 115 – 149 (NHS Blood and Transplant 2021/2022). In the UK, majority of the children receive living donor kidney transplants, which is the preferred type of donation.

As per the previous decade, GOSH remains the largest paediatric transplant centre in the UK. Of note is that in this year, GOSH has done 33% more transplants than the second largest centre. GOSH continues to have large living donor programme leading the way in paediatric kidney transplantation. Out of 39 transplants, several were referrals from other transplant centres as GOSH continues to be a referring centre for complex and elsewhere un-transplantable patients.

Fig 1.4 Total number of paediatric only transplants by centre performed in 2021-2022, by centre and type of donor.

Key:

DBD – Donor after brain death

DCD – Donor after circulatory death

Living – A donor who is a living person

Source: Annual Report on Kidney Transplantation 2021/2022, NHS Blood and Transplant

All groups representing the renal community, such as NICE, the Renal Association, BAPN and the Government, are recommending home dialysis. That is, either peritoneal dialysis (PD), or home haemodialysis (HD), which is delivered at home, in preference to in-centre dialysis. This is particularly important for children because there are only ten dedicated paediatric haemodialysis units in England and therefore some children have to travel up to three hours to get to hospital, three times per week for their haemodialysis treatment. As a consequence, they cannot attend school full-time and their social and family time is severely disrupted. Therefore, we at GOSH firmly believe that wherever possible children should be dialysed at home.

There has been a growing trend towards home HD internationally. This has been partly driven by the increasing demand on in-centre dialysis beds, but also by research that indicates superior clinical outcomes compared with all other dialysis modalities.

When selecting between PD and HD, many factors need to be considered. As a rule of thumb, home PD is the treatment of choice in babies and infants. In older children and adults, home HD may be the preferred option.

Definition: For paediatric dialysis patients aged between 0 and 18 years, we report the number of children on home HD, PD, and in-centre HD.

We were the first paediatric dialysis centre in Europe to introduce home HD using a mobile dialysis machine: the NxStage™. This machine is specifically designed for home use and is thus more user-friendly. It is a mobile system that does not require a home water conversion to supply dialysate. Instead, it uses pre-prepared, ultrapure dialysate bags. This allows children to travel between homes and, importantly, offers opportunities for holidays.

Input from psychology, social work and family therapy services is integral to the support provided to families preparing for home HD.

The chart below shows that GOSH’s home HD provision has increased significantly from one patient in 2010 to 17 in 2021.

Fig 2.1 Number of patients by dialysis modality, 2010-2021

Definition: For paediatric patients aged between 0 and 18 years, who are on long-term dialysis, we report the percentage of children on home dialysis (PD and home HD).

In most adult centres, only a small percentage of patients are on home dialysis – in-centre HD dominates. In paediatric centres, home dialysis figures are better as babies and infants typically start on PD.

Here at GOSH, we offer both home PD and HD and therefore the percentage of our patients on home dialysis therapies exceeds 50% since 2010. The decrease in the percentage of children on home dialysis in 2012 was due to a larger proportion of infants on HD than in previous years and equipment restrictions that meant children weighing less than 20kg could not be offered the NxStage dialysis machine.

Adaptations in late 2012 have addressed these restrictions for children up to 12kg, and the percentage of children on home dialysis exceeds 60% since 2014, rising to 69% in 2021. In 2021-2022, there were 17 children on HHD.

Fig 2.2 Percentage of children on home dialysis (Home HD and PD), 2010 to 2021

Children with renal failure have a number of factors that in combination can have a negative impact on growth. This is explained by nausea associated with end stage renal disease; their taste sensation being altered; abnormal blood hormone levels that influence appetite, and they often have strict fluid and dietary restrictions limiting access to foods they enjoy. Peritoneal dialysis (PD) treats children with kidney failure by removing toxins and excess water. Our centre has a well-established PD programme.

One of the key objectives of the service is to actively monitor a child’s height and weight, utilizing the expertise of a renal dietician to intervene early to optimize the growth potential. Here at GOSH, we consider that for the vast majority of children, nutritional intake has the greatest potential to influence growth (through maximizing calories from the foods children eat, providing additional supplements to drinks, or using nasogastric tubes or gastrostomies). This has to be balanced against the possibility of introducing excessive calories and causing obesity. In contrast, many centres internationally use growth hormone injections to promote growth with a smaller emphasis on nutrition.

We report our weight, BMI (body mass index) and growth data to an international registry that compares the height and weight standard deviation of 100 Paediatric Peritoneal Centres worldwide. The BMI gives us a surrogate marker of obesity. The standard deviation score (SDS) tells us how different the patient’s measurement is against population averages. For example, a height SDS value of 0 means that the patient’s height is the same as the population average. The more positive a number, the taller the patient is compared to population averages and the more negative the number, the shorter the patient is compared to population averages.

One potential complication of PD is the risk of peritonitis, an infection affecting the lining of the peritoneum (where the dialysis catheter is located). We report low rate of peritonitis episodes in accordance with the British Association for Paediatric Nephrology (BAPN) 2007 guideline of less than one episode per patient year. The rate of peritonitis is consistently below this rate since 2011-12 and was 0.40 for 2021-22. For patients on PD during 2021-22, 82% (32/39) of patients had no episodes of peritonitis.

Numerator: Number of episodes of peritonitis in a year.

Denominator: Sum of total days that all patients are on PD divided by 365 (e.g. a patient receiving PD for six months is 0.5 of a patient year).

Figure 3.1 Peritonitis rates shown as episodes per patient year, 2011-12 to 2021-22

The haemodialysis (HD) data below was submitted to IPHN (Institute for Public Health Nutrition) in October 2022 for international benchmarking amongst other participating countries.

The graph shows that GOSH continues to have higher number of small patients on HD compared to all others. Smaller patients are more challenging for HD.

Fig 4.1 Percentage of children treated across age groups 0-17 years, 2021-2022

The graph shows that GOSH has similar percentage of patients who receive HD via AVF and CVL as other paediatric HD centres. Slightly higher number of patients dialysed via CVL could be explained by the fact that GOSH has higher number of small children on HD and it whom formation of AVF is not feasible (see previous graph).

Fig 4.2 Percentage of access type for patients with CVL and AVF, 2021-2022

At GOSH, patients are hospitalized on for an average of three days compared to the international average of six and half days – which contributes to better quality of life.

Definition: Interdialytic weight refers to weight gain between dialysis sessions.

The weight gain between dialysis sessions should be minimal. At GOSH, patients gain less weight between dialysis sessions, up to 2.6% on average compared to the international average gain of 5.2%.

Definition: Well-controlled blood pressure reduces end organ damage, therefore preserving cardiac function and reducing incidence of hypertensive retinopathy.

GOSH reports better pre-dialysis blood pressure control in patients on HD compared to the international average.

Pre-dialysis blood pressure systolic / diastolic (Mean ± SD)

• GOSH - 104 ± 16 / 64 ± 15 mmHg
• All - 123 ± 18 / 75 ± 15
  mmHg

Definition: Maintaining haemoglobin (Hb) levels within normal range or as close to it as possible reduces anaemia, with overall improvement in patient quality of life.

At GOSH, the average Hb levels observed for haemodialysis patients is 12.0 g/dl compared to the international average of 10.8 g/dl. This suggests anaemia associated with end stage renal disease is better controlled in patients receiving HD at GOSH.

Definition: Maintaining serum phosphorus (Pi) levels within normal range prevents mineral bone disease associated with CKD.

At GOSH, 78.6% of patients have Pi within the normal range compared to 53.2% in internationally. A lower serum Pi concentration indicates better controlled CKD.

Fig 4.7 Percentage of patients below/ within and above normal serum Pi range for age, 2021-2022

At GOSH, 82.1% of patients have parathyroid hormone (PTH) within the recommended PTH range of the Kidney Disease Outcomes Quality Initiative (K/DOQI) compared to 45.6% reported internationally. A lower serum Pi concentration indicates a better control of mineral bone disease associated with end stage kidney disease (ESKD).

Fig 4.8 Percentage of patients below/ within and above K/DOQI PTH target range, 2021-2022

Definition: Maintaining D3 levels within normal range or as close to it contributes to the optimisation of mineral bone disease associated with CKD.

Here at GOSH, 96.4% of haemodialysis patients take vitamin D3 supplements compared to 58.7% nationally. This contributes to a better controlled mineral bone disease.

Good vascular access is essential for haemodialysis. With children, we have two options, a tunnelled, central venous catheter or 'line' (CVC/CVL) or a surgically formed arteriovenous fistula (AVF). Internationally, there is a consensus opinion that AVF is the ‘gold standard’ approach for haemodialysis access. However, despite our good intentions AVF is not always possible for children. The smaller blood vessels pose technical surgical challenges and are associated with a higher primary failure rate, namely that the fistula doesn’t work. Fistulae have to be needled before each dialysis session. In practical terms, this equates to two needles, at least three times per week. Understandably, for the vast majority of children, an active desensitisation and educational programme is necessary for them to even consider and then accept an AVF as a realistic option.

For paediatric haemodialysis patients between 1 and 18 years, we report the percentage of patients with a functioning AVF and a CVL.

Owing to the technical and psychological barriers to creating fistulae and then successfully needling them, many paediatric centres shy away from fistulae in children – especially in children younger than eight years old.

At GOSH, we take a proactive approach to fistulae. Since 2009, the percentage of patients with fistulae has been rising. Between 2012 and 2014, the percentage decreases, but this reflects the larger number of babies and infants on HD in these years.

Our greatest success to date has been successfully creating and needling a fistula in a three-year-old child. This reflects the dedication and commitment from our multi-professional team including surgeons, medical and nursing staff, play therapists and the psychosocial team.

Fig 5.1 Percentage of children with functioning CVL and AVF, 2010-2021

The GOSH renovascular service receives referrals from all paediatric nephrology centres in the UK and from all over the world. About 34% of all referrals are from outside the UK with patients from 19 countries. Renovascular team consists of dedicated nephrologists, interventional radiologists, renal and vascular surgeons, intensivists, cardiologists, anaesthetists, neurologists, neurosurgeons and hypertension advanced nurse practitioners. We have regular fortnightly multidisciplinary meetings. Our service is specialised for the management of small children with severe renovascular disease including children whose weight is 4-5kg at the time of endovascular intervention. We report excellent clinical outcomes following endovascular interventions with preserved kidney function, reduction in requirement for medications and low level of complications. Please note that other renovascular centres in the world do not report publicly their complication rates following endovascular intervention so we are unable to compare this.

The team also provides education on renovascular disease by publishing book chapters and organising PRED (Paediatric Renovascular Education Days) with ongoing publishing in peer-reviewed journals.

Fig 6 Number of referrals to the renovascular service as of April 2022

The graph shows serum creatinine levels (renal function) pre-endovascular intervention.

Fig 6.1 Number of children with first recorded serum creatinine level, (all patients up to April 2022)

As it can be seen in the graph, no significant change in serum creatinine levels (i.e., preserved renal function) following at least one endovascular intervention.

Fig 6.2 Number of children with last recorded serum creatinine level, (all patients up to April 2022)

Definition: Renovascular disease is not usually associated with impaired kidney function due to the development collateral vasculature.

The graph shows estimated GFR before endovascular intervention (normal is <90ml/min/1.73m2). GFR was estimated using Schwartz formula and k=36.5

Fig 6.3 Number of children at each GFR value from first recorded values based on height and serum creatinine level, (up to April 2022)

Definition: Any endovascular intervention such as renal angioplasty has a risk of damaging the kidney and potentially causes loss of kidney function.

Graph indicates preservation of estimated GFR following at least one endovascular intervention at GOSH.

Fig 6.4 Number of children at each GFR value from last recorded values based on height and serum creatinine level, (up to April 2022)

It is reported in the literature that medication burden is associated with non-adherence which as a consequence can have a poor disease control.

The bar chart shows high number of patients (>50%) who had reduction in number of medications required for blood pressure control. Reducing number of medications needed to be taken regularly increases quality of life (QoL) and medication adherence.

Fig 6.5 Number of children with a change in the number of medications prescribed, (by April 2022)

Definition: Renovascular hypertension is often drug resistant and patients frequently require 2 or more medications for blood pressure control.

The graph shows majority of patients taking more than 3 medications at the time of referral to our service.

Fig 6.6 Number of children taking each total number of medications at referral after an intervention, (by April 2022)

Definition: One of the secondary outcomes for endovascular or surgical interventions is the reduction in the number of medications the patient takes, with the aim to improve adherence.

Graph shows that vast majority of patients are taking less than 3 medications after at least one endovascular intervention with more than half being on no medication at all or one medicine only.

Fig 6.7 Number of children taking each total number of medications at last follow-up after an intervention, (by April 2022)

Definition: Any endovascular or surgical intervention has associated risks as indicated in the table below. These outcomes cannot be compared to other centres as there is no reportable data available.

Contingency table shows the number of complications at each intervention number, percentage of interventions in which they attempted Percutaneous transluminal angioplasty (PTA) and of those which they attempted PTA, how many were technically successful.

Table 6 Percentage of complications at each intervention, 2000-2022

This information was updated in March 2023.