Measures of care in adult renal transplant recipients in the United Kingdom (Chapter 11)
1University Hospital of Wales, Cardiff, 2UK Renal Registry, Bristol, 3Royal Liverpool University Hospital, Liverpool and 4Morriston Hospital, Swansea
Correspondence and offprint requests to: Rommel Ravanan, UK Renal Registry, Southmead Hospital, Southmead Rd, Bristol, BS10 5NB, UK. Email: rommel.ravanan{at}cardiffandvale.wales.nhs.uk
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Abstract |
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 Top Abstract IntroductionOverviewPost-transplant follow upDemographic variablesPost-transplant outcomeAnalysis of prevalent transplant...Reference |
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The total number of patients active on the transplant waiting list (adult and paediatric) on 31 December 2005 was 5736, an 8% increase from the previous year. On 31 December 2005, 45.7% of prevalent adult RRT patients in the UK, had a functioning renal transplant which equated to 19 074 patients. During 2005, the death rate in prevalent transplant patients was 2.7 per 100 patient years. An additional 3.1% of all prevalent transplants failed with patients returning to dialysis.
During 2005, deceased heart beating donor numbers decreased by 18% compared to 2004. In comparison, non-heart beating donors and living kidney donors increased by 35% and 17%, respectively, in 2005. The proportion of renal transplants performed from deceased heart beating donors fell from 68% in 2004 to 60% in 2005. There is wide variation in prevalence per million population (pmp) of transplanted patients resident in each local authority area across the United Kingdom. Total 11.4% of incident transplants in 2005 were due to patients with diabetes. The median eGFR was 46.1 ml/min/1.73 m2, with 18% of prevalent transplant recipients having an eGFR <30 ml/min/1.73 m2. The median Hb in prevalent transplant recipients was 12.9 g/dl, with 10% of patients having an Hb <10 g/dl. The median systolic and diastolic BP was 136 and 79 mmHg, respectively, with only 25% of patients within guidelines.
Transplant function analysed by CKD stages 1–2 (eGFR < 60), 3 (eGFR 30–59), 4 (eGFR 15–29) and 5 (eGFR < 15), shows that these categories account for 24%, 59%, 15% and 2.5% of patients, respectively. Haemoglobin values fall with decreasing eGFR such that of the 2.5% of transplant patients with eGFR <15 ml/min, 27% had an Hb <10 g/dl and 51% <11 g/dl. Control of iPTH was poor in transplant recipients in CKD stages 4 and 5, with 22% and 50% of patients, respectively, having a PTH > 32 pmol/l (=300 ng/l). Patients with failing transplants are less likely to achieve RA targets of key biochemical variables when compared to patients on dialysis. There is still wide variability in the completeness of data returns from individual units.
Keywords: chronic kidney disease; eGFR; end stage renal disease; epidemiology; renal transplantation; transplant CKD stage; transplant function; transplant survival
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Introduction |
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TopAbstractIntroductionOverviewPost-transplant follow upDemographic variablesPost-transplant outcomeAnalysis of prevalent transplant...Reference |
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This chapter reports on collaborative analyses carried out between the UK Renal Registry and UK Transplant (UKT), in conjunction with the support from the British Transplantation Society. This continues to be a fruitful and mutually beneficial relationship, as the details of the episode of transplantation held on the UKT database and the key clinical/biochemical variables other than just survival data held on the UKRR database complement each other. This combination of comprehensive data on transplant recipients is internationally unique and a great resource to assess renal transplant activity and its distribution across the United Kingdom, to compare practices and key outcome variables between centres and to provide insight into the processes involved in the care of renal transplant patients.
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Overview |
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TopAbstractIntroductionOverviewPost-transplant follow upDemographic variablesPost-transplant outcomeAnalysis of prevalent transplant...Reference |
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In December 2005, there were 20 transplant centres in England (including six in London of which one is based in Great Ormond St Paediatric Hospital), one in Northern Ireland, two in Scotland and one in Wales. The number of centres in England has been reduced by the amalgamation in London of Hammersmith with St Mary's to form the West London Renal Transplant Centre, of the Royal Free with the Middlesex and of St Helier's with St George's.
Comprehensive information from 1995, concerning the number of patients on the transplant waiting list, the number of transplants performed, the number of heart beating, non heart beating and living donors, and patient and graft survival are available on the UKT website (www.uktransplant.org/ukt/statistics).
As of 31st December 2005, 5736 patients (including adult and paediatric) were active on the renal or renal + pancreas transplant waiting list, an increase of 8% when compared with 2004. Live donor and non-heart-beating donor transplants continue to increase and in 2005 formed 29% and 11% of all kidney transplants performed, respectively (Table 11.1), although there has been a further large fall in heart-beating donors.
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There was no statistically significant difference in 1 year and 5-year risk-adjusted patient and graft survival rates amongst UK renal transplant centres (Table 11.2). These graft survival rates include grafts with primary non-function (which is excluded in some countries).
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Data from the UK Renal Registry show that 3.1% of patients with a functioning transplant on 1 January 2005 returned to dialysis after their transplants failed in 2005. This has remained unchanged since 2000.
Using data from the UKRR, the death rate in the prevalent transplant cohort was 2.7 (95% CI 2.5–3.0) censoring at return to dialysis and 2.9 per 100 patient years including those who restarted dialysis. This remains unchanged from previous years.
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Post-transplant follow up |
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TopAbstractIntroductionOverviewPost-transplant follow upDemographic variablesPost-transplant outcomeAnalysis of prevalent transplant...Reference |
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There are 65 renal units, which send data electronically to the UK Renal Registry with 53 also providing additional demographic, laboratory and blood pressure data for renal transplant patients during 2005. The five remaining UK renal units (Canterbury, Manchester RI, Stoke, London St Mary's & London St George's) not yet linked electronically have supplied summary statistics. Three centres (Chelmsford, Clwyd and Derby) have been excluded from data analyses below due to small numbers (<10 pts in each unit). Due to differences in the timing of repatriation of patients after transplantation from the transplanting centre to the host/non-transplanting renal unit, caution needs to be exercised when comparing results between centres. The number of prevalent patients on renal replacement therapy (RRT) in each renal unit and the proportion of transplant patients are shown in Table 11.3.
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On 31 December 2005, 45.7% of UK RRT patients had a functioning renal transplant. This ratio seems to have stabilised over the last 3 years. During the period 1997–2002 it had decreased from 51.0% to 46.0%.
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Demographic variables |
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TopAbstractIntroductionOverviewPost-transplant follow upDemographic variablesPost-transplant outcomeAnalysis of prevalent transplant...Reference |
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Age and gender
There has been no significant change in the gender ratio of incident and prevalent transplant patients between 1998 and 2005 (Table 11.4; Figure 11.1) This ratio reflects that found in patients starting RRT and indicates there is no gender bias in patient selection for transplantation. The median age of patients has been slowly rising.
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Centre and Local Authority prevalence of renal transplant patients
In the UK there are approximately 19 000 RRT patients with a functioning renal transplant and the numbers under follow up in each UK renal unit are shown in Table 11.5. The prevalence (pmp) of patients with renal transplants living in each local authority (LA) is shown in Table 11.6 and was derived from the patient postcode which was validated against the full address using software from QAS systems. LA boundaries and population numbers were obtained from the UK 2001 census and the methodology is described in Appendix D on the web (www.renalreg.org). As five renal units in England are not yet submitting individual patient data electronically, any partially covered LA areas have been removed (this includes many areas in London due to high rates of cross boundary flow).
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Although differences in local arrangements for transplant follow up impact on the proportion of patients followed up in transplant centres as opposed to referring renal units, this will not explain the variation in prevalence (pmp) of transplanted patients resident in different local authority areas as this has been allocated by patient postcode. These data need to be taken into consideration when planning the allocation of resources for transplant follow up, in order to ensure equity of access to medical care for these patients. Guidelines specifying minimum manpower requirements for the management of renal transplant patients are not currently available either from the British Transplantation Society or the UK Renal Association.
Comorbidity and transplantation
The number of patients with established renal failure who are accepted onto the renal transplant waiting list is limited by comorbidity. Comparison of the prevalence of comorbidity (at the onset of renal replacement therapy) in dialysis patients with patients who have subsequently been transplanted (data from centres who have provided comorbidity information on >80% of patients starting renal replacement therapy between 2000 and 2005) is shown in Table 11.7. Unsurprisingly there is less comorbidity at the time of onset of renal replacement therapy in patients who are subsequently transplanted than in those who remain on dialysis, but the incidence of ‘smokers’ (as recorded in renal unit clinical databases) is the same in both groups. For next years report it is hoped to provide analysis of prevalence of comorbidity in waitlisted and not waitlisted dialysis patients (in conjunction with waiting list data supplied by UKT) in comparison to patients who have been successfully transplanted.
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Ethnicity and transplantation
It is difficult to tell whether there has been any significant change in the ethnic ratio of patients receiving a renal transplant between 2000 and 2005. An apparent increase in the proportion of recipients who are of South Asian or African Caribbean ethnicity is likely to be due to improvements in the completion of data returns. This opinion is supported by the fact that there has been no reduction in the proportion of transplanted patients who are White whilst there has been a reduction in the proportion of patients reported as being of unknown ethnic origin (Table 11.8).
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Other demographic variables
There has been no change in the relative proportions of the primary renal diagnosis of patients transplanted in 2005 compared with previous years (Table 11.9).
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Post-transplant outcome |
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TopAbstractIntroductionOverviewPost-transplant follow upDemographic variablesPost-transplant outcomeAnalysis of prevalent transplant...Reference |
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The number of UK renal transplant patients included in this year's Renal Registry Report has increased with more renal units contributing data to the Registry. However, there is room for improvement in the completeness of information about clinical variables from each centre (Table 11.10), with data returns from some centres being better than others. Therefore caution is needed when interpreting the following information from centres with a substantial proportion of missing data.
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Methods
Prevalent patient data
Data from both transplanting and non-transplanting renal units concerning biochemical and clinical variables for patients with a functioning transplant were included in the analyses. The cohort is comprised of patients transplanted before 30 September 2005. Patients were considered as having a functioning transplant if ‘transplant’ was listed as the mode of renal replacement therapy in one or more of the quarters in 2005 without any other modality of treatment or death being entered for any of the subsequent quarters in 2005. Patients were assigned to the renal unit that sent the data to the Renal Registry but some patients will have received care in more than one unit. If data for the same transplant patient were received from both the transplant centre and non-transplant centre, care was allocated to the non-transplant centre.
For laboratory results, the last value in quarter 3 or quarter 4 of 2005 was used (last 6 months). For blood pressure recordings the latest value from 2005 was used.
eGFR
For the purpose of eGFR calculation, the four-variable MDRD formula was used, although serum creatinine has not been standardised to that of the assay used at the MDRD laboratory, or taken into account the different creatinine assay methods in use in the UK.
By May 2006, over 60% of UK laboratories had aligned their creatinine assays with that of the creatinine concentration obtained using the Beckman analyzer running a compensated kinetic Jaffe assay as used in the MDRD study. In the UK there is now a further move towards standardizing against an isotope dilution mass spectrometry (ID-MS) traceable creatinine result, which will then require use of an adjusted 4v MDRD equation. The UK Association of Clinical Biochemists have stated that most UK laboratories were using the kinetic Jaffe assay and the standard 4v MDRD equation is most appropriate (personal communication E Lamb).
Patients without ethnicity information were excluded from the eGFR analysis.
One-year post-transplant data
Whilst comparing data relating to transplant patients from different renal units it is important to recognise that in addition to individual centre clinical practice, the results may be affected by a number of factors such as differences in local transplant repatriation policies and the relative numbers of patients with recent as opposed to long established grafts. To minimize such bias, for the first time the UKRR has analysed the outcome in patients at one year after transplantation.
Patients who received a renal transplant between 1 January 2000 and 31 December 2004 were assigned according to the renal unit in which they were transplanted. Transplant units were only included if they had submitted data throughout the 5-year period. Patients who had died or experienced graft failure within 12 months post transplantation were excluded from analysis.
For each patient, the last laboratory or BP value in the fourth quarter or the first value in the fifth quarter after renal transplantation was taken to be representative of the ‘one year post transplant outcome’. For the purpose of eGFR calculation (four-variable MDRD formula), if there was a valid serum creatinine but no ethnicity data available, patients were classed as White.
Post-transplant eGFR in prevalent transplant recipients
Median eGFR in each centre and percentage of patients with eGFR 
60 or <30 ml/min/1.73 m2 are shown in Figures 11.2–11.4
. Only centres with >20 patients are shown in these figures. The median eGFR was 46.1 ml/min/1.73 m2, with 18% of prevalent transplant recipients having an eGFR <30 ml/min/1.73 m2. Some centres may have a higher proportion of patients with eGFR <30 ml/min/1.73 m2 because of local repatriation policies in which patients are only transferred back to the referring renal unit from the transplant centre when the need for dialysis is imminent. Patients with low eGFR, will require substantial resource allocation to prepare for dialysis or to be managed conservatively.
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eGFR in patients 1 year after transplantation
Renal function 1 year after transplantation is believed to be predictive of future graft performance [1]. Figure 11.5 shows that median eGFR 1-year post-transplant for patients transplanted between 2000 and 2004 was 48.3 ml/min/1.73 m2. All transplants (deceased and live kidney donors) from each unit were included in this analysis.
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Haemoglobin in prevalent transplant patients
Transplant patients are to be under the RA CKD guidelines that all patients should have a haemoglobin above 10 g/dl.
A number of factors including immunosuppressive medication, graft function, EPO use, IV/oral iron use as well as centre practices/protocols for management of anaemia affect haemoglobin levels in transplant patients. Figure 11.6 gives median Hb values from UK centres whilst Figure 11.7 shows the percentage of transplant patients with Hb <10 g/dl. Only centres with >20 patients and also >50% data returns are shown in these figures.
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The median Hb was 12.9 g/dl, with 4.1% of patients having a Hb <10 g/dl. It is interesting to note that the five centres with the highest percentage of prevalent transplant patients with eGFR <30 ml/min/1.73 m2 (Figure 11.3) are not the same as the five centres with the highest percentage of patients with Hb <10 g/dl.
Haemoglobin in patients 1 year after transplantation
Figure 11.8 shows that the median Hb at 1 year post-transplant was 13.0 g/dl. Some centres with above average eGFR also have above average haemoglobin results at 1 year after transplantation.
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Blood pressure in prevalent transplant patients
In the absence of controlled trial data, opinion based recommendation from the RA states that BP targets for transplant patients should be similar to the targets for patients with CKD i.e. systolic BP <130 and diastolic BP <80.
Although some centres provide BP data for the majority of their patients many centres provide little, if any. Median systolic BP (Figure 11.9), median diastolic BP (Figure 11.10) and the percentage of patients who achieve RA standards (Figure 11.11) are shown. The median systolic and diastolic BP was 136 and 79 mm Hg, respectively, with only 25% of patients within guidelines. Only centres with >20 patients and also >50% data returns are shown in these figures.
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Blood pressure in patients 1 year after transplantation
The number of patients who had valid returns for systolic (Figure 11.12) and diastolic BP (Figure 11.13) 1 year post-transplant are substantially less than the numbers available for eGFR and Hb. Since the completeness of data for this variable is very poor, comparison between units is open to criticism.
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Analysis of prevalent transplant patients by CKD stage |
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TopAbstractIntroductionOverviewPost-transplant follow upDemographic variablesPost-transplant outcomeAnalysis of prevalent transplant...Reference |
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About 3% of prevalent transplant patients return to dialysis each year. Patients with failing transplants are similar to other patients with CKD stage 5 in that they contribute substantially to the work load of the multidisciplinary renal team in order to ensure a safe and seamless transition to dialysis or conservative care. While centre practices vary, in most UK renal units such patients are routinely followed up in transplant out-patient clinics which may not be designed to address the needs of patients with stage 5T transplant function. The results of an analysis to establish the number of patients in each CKD stage T group and to determine if the common biochemical targets for patients on dialysis are comparable to patients post-transplantation are shown in Table 11.11. Approximately 18% of transplant recipients have CKD stages 4T or 5T. While the numbers of patients in the stage 5T group are small, the data suggests that fewer patients in this category achieve the clinical and biochemical targets when compared with patients on dialysis. Whether these results are substantially different to patients with stage 5 CKD prior to commencement of RRT is not known, but in contrast there are no ‘late referrals’ in the transplant group as they have all been under long term follow up.
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Conflict of interest statement. None declared.
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Reference |
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TopAbstractIntroductionOverviewPost-transplant follow upDemographic variablesPost-transplant outcomeAnalysis of prevalent transplant...Reference |
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- Hariharan S, McBride MA, Cherikh WS, et al. Post transplant renal function in the first year predicts long term kidney transplant survival. Kidney Int (2002) 61:311–318.
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