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.

About the Nephrology Service

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. Each year there are approximately 300-350 admissions to the renal ward; 100 admissions to outlying wards; over 7,000 outpatient attendances; 25-30 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 acaedemia. 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.

Clinical outcome measures

1. Renal transplantation

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).

1.1 One and five year patient survival in children receiving renal transplants

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.

1.2 One and five year kidney transplant (renal allograft) survival in children receiving renal transplants

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

1.3 Antibody incompatible transplantation

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

2. Peritoneal dialysis

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.

2.1 Height standard deviation score

Definition: For paediatric patients aged between 1 and 18 years, who are treated with PD, we calculated the height SDS at April 2018. This is compared with the combined results from approximately 2,000 patients from 100 centres in 38 countries.

The chart below shows at GOSH children on PD are taller than children treated at centres across the world.

Fig 2.1 Height SDS for children receiving PD, April 2018

2.2 Parathyroid hormone control

Definition: For paediatric patients aged between 1 and 18 years, who are treated with PD, monitoring of parathyroid hormone (PTH) is essential as a marker of metabolic bone disease which is associated with end stage renal stage.

The chart below shows that at GOSH, children on PD have better PTH control than children treated at centres across the world at April 2018.

Fig 2.2 PTH levels for children receiving PD, at April 2018

2.3 Enteral feeds

Definition: For paediatric patients aged between 1 and 18 years, who are treated with PD, we calculate the percentage on enteral feeds at April 2018. This is compared with the combined results from approximately 2,000 patients from 100 centres in 38 countries.

To optimize the growth of children on PD they may require enteral feeding by nasogastric tubes or gastrostomies. The chart below shows more children on PD are on enteral feeds at GOSH, than children treated at centres across the world.

Fig 2.3 Proportion of children on PD at GOSH who are on enteral feeds, at April 2018

2.4 Peritonitis

One potential complication of PD is the risk of peritonitis, an infection affecting the lining of the peritoneum (where the dialysis cathether 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 0.37 for 2017-18. For patients on PD during 2017-18, 79% (22/28) 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 (eg a patient receiving PD for six months is 0.5 of a patient year).

Figure 2.4 Peritonitis rates shown as episodes per patient year, 2011-12 to 2017-18

3. Home Dialysis

All groups representing the renal community, such as NICE, the Renal Association, and the Government, are recommending home dialysis. That is, either peritoneal dialysis (PD), which is delivered at home, or home haemodialysis (HD), 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.

3.1 Dialysis modality

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 16 in 2017.

Fig 3.1 Number of patients by dialysis modality, 2010-2017

3.2 Home dialysis

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 72% in 2017.

Fig 3.2 Percentage of children on home dialysis (Home HD and PD), 2010 to 2017

In 2017-2018, we had 12 children on HHD. A quarter of those was dialysed via arteriovenous fistula.

4. Vascular access for haemodialysis

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.

4.1 Paediatric haemodialysis patients with functioning AVF

Definition: 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 4.1 Percentage of children with functioning CVL and AVF, 2010-2017

5. Renovascular service

The GOSH renovascular service receives referrals from all units in the UK and from all over the world. About 30% of all referrals are from outside the UK with patients from 11 countries. Our team consists of nephrologists, interventional radiologists, hypertension nurse and vascular surgeons. We have regular fortnightly multidisciplinary meetings.

In 2018, service received referrals for 59 children with complex renovascular disease and uncontrolled hypertension.

Fig 5.1 Number of referrals to the renovascular service in 2018

This information was published in May 2019.