Organ Donation

Deceased Donor Kidney Allocation Scheme

Kidney Allocation Scheme

First published: April 2006

All kidneys from deceased heartbeating donors are allocated through the national scheme.

This scheme is based on five Tiers:

1. 000 mismatched paediatric patients - highly sensitised* or HLA-DR homozygous
2. 000 mismatched paediatric patients - others
3. 000 mismatched adult patients - highly sensitised* or HLA-DR homozygous
4. 000 mismatched adult patients – others & favourably matched paediatric patients (100, 010, 110 mismatches)
5. All other eligible patients

* ≥ 85% calculated reaction frequency (based on comparison with pool of 10,000 donor HLA types on national database)

Paediatric patients in Tiers A and B are prioritised according to waiting time. In the remaining Tiers, patients are prioritised according to a points score based on:

Waiting time (1)
HLA match & age combined (2)
Donor-recipient age difference (3)
Location of patient relative to donor (4)
HLA-DR homozygosity (5)
HLA-B homozygosity (6)
Blood group match (7)

Points scores are calculated as shown:

(1) Waiting time points = number of days of waiting time accrued (see definitions)

(2) HLA match & age points combined are defined as:
points = 3500/(1+(age/55)5) if level 1 mismatch
2000/(1+(age/55)5) if level 2 mismatch
500/(1+(age/55)5) if level 3 mismatch
Points scores are illustrated in Figure A and mismatch levels are shown in Table C below

(3) Age difference points = – ½ (donor-recipient age difference)2

(4) Location points =

• 900 for patients at the same centre as the donor
• 750 for patients at another centre within the local area as defined below:
  Area A - Bristol, Cardiff, London (Guy’s, Royal Free, Royal London, St George’s and the West London Renal Transplant Centre), Oxford, Plymouth and Portsmouth
  Area B – Belfast, Birmingham, Coventry, Cambridge, Leicester, Nottingham and Sheffield
  Area C - Edinburgh, Glasgow, Leeds, Liverpool, Manchester and Newcastle.

(5) HLA-DR homozygous points = 500 for all HLA-DR homozygous patients
(where HLA level>1)

(6) HLA-B homozygous points = 100 for all HLA-B homozygous patients
(where HLA level>1)

(7) Blood group points = –1000 for blood group B patients when the donor is group O (Tiers D and E only)

Additional points for Tier E patients

(1) Additional points for paediatric patients
For paediatric patients (<18 years) who have a waiting time in excess of 2 years, additional points will be allocated in Tiers D and E to improve the chance of being allocated a kidney. It is preferable for paediatric patients to receive a well-matched kidney but in some cases this is not possible and if a patient has not been transplanted within 2 years they will be prioritised for any compatible kidney. For patients waiting 2-3 years, 2500 extra points will be awarded and for patients waiting in excess of 3 years, 5000 additional points will be awarded.

(2) Patients reaching 18 years old on the transplant list
Patients on the transplant list under 18 years old are classed as paediatric patients for the purposes of the kidney allocation scheme. However, since 15 July 2009, patients registered active on the list prior to their 18th birthday but still waiting for a kidney after they reach 18 years, retain their paediatric status and the associated benefits until such time as they are removed from the list for whatever reason, eg transplant. Periods of suspension from the list do not affect this entitlement.

Definitions

All deceased heartbeating donor kidneys are allocated according to

• Restricted blood group compatible matches (see Table A).
• Defaulting of rare HLA specificities to more common equivalents (see Table B).
• HLA mismatch levels (see Table C).

 

The rare specificities indicated will be ‘defaulted’ to their more common equivalents so that patients with rare tissue types match with more donors. The defaults will be applied (as appropriate) at NHS Blood and Transplant as part of the allocation algorithm. This will enable patients with rare specificities also to be considered a match should a donor with the same rare specificity become available.

 

Waiting time

Waiting time is determined from date of first active listing for a graft. Each day on the list accrues 1 point, including all days of temporary suspension from the list.

For the majority of patients, waiting time starts at zero on the day they are set as active on the kidney transplant list. However, any patient whose previous graft failed within the first 180 days post-transplant, starts with a waiting time as it was on the day of that (failed) transplant. The failure must be reported to NHS Blood and Transplant through a follow-up return to enable the waiting time to be calculated accurately.

Waiting time is transferable when a patient transfers from one transplant centre to another. The time will be calculated automatically provided the patient has not been ‘removed’ from the list as part of the transfer. When a patient is notified as ‘removed’ from the list their waiting time is lost.

Further allocation details

Reallocation of kidneys –

If a kidney needs to be reallocated because the patient for whom the kidney has been accepted cannot subsequently receive the transplant, the following rules apply:

• If the kidney has not been dispatched to the transplant centre it will continue to be offered for prioritised patients in the usual way.
• If the kidney has been dispatched to the transplant centre, it will be offered back for any patients in Tiers A to D. If there are no suitable patients in Tiers A to D, the kidney can be kept by the centre to which the kidney has been dispatched. The centre will select the most appropriate patient from their local list.
• In all cases, offering of kidneys will only continue in the order specified until 20 hours of cold ischaemia time have been accrued, at which point the centre holding the kidney (or the centre to which the kidney has been dispatched) can use the kidney in a patient of their choice.
• In either of these cases, the kidney will be offered back to the designated local transplant centre if not required for local use as permitted.

Note that when selecting a patient of their own choice, a centre may, in exceptional circumstances, select a patient with a level 4 HLA match or a patient who is blood group compatible but falls outside of the blood group matching criteria specified.

Highly sensitised patients (HSPs) – HSPs (>=85% calculated reaction frequency) will be considered for offers of kidneys as follows –
Level 1 HLA match (000 mismatches) - all HSPs
Level 2 HLA match (100, 010, 110, 200 or 210 mismatches) – all local centre HSPs and all other HSPs where all antibody specificities have been identified (ie residual sensitisation level=0).
Levels 3 and 4 (all other mismatches) – no kidneys will be offered to HSPs.
Note that the HLA match is that based on defaulting of rare antigens.

Paediatric patients – kidneys from donors over 50 years of age will not be offered for paediatric patients (ie those <18 years at time of offer).

Prioritisation of patients requiring a kidney/pancreas transplant – these patients will be prioritised after Tier A–C kidney only patients (ie after 000 mismatched children and 000 mismatched HSP/HLA-DR homozygous adults).

Allocation of en bloc kidneys – kidneys from donors aged 4 years and under will be retrieved and offered en bloc (but may be split if appropriate) while kidneys from donors aged 5 years and over will be retrieved and transplanted singly wherever possible. En bloc kidneys will be offered on a centre rather than patient basis to any centre wishing to receive offers of such kidneys.

Version 5 (July 2009)

Annex A: Direction of the Secretary of State for Health: 1st October 2005 - The NHS Blood and Transplant (Gwaed a Thrawsblaniadau’r GIG) (England) Directions 2005 (133Kb) - Guidance

Annex B: Cadaveric Donor Assurances and Damage Reporting, Updated December 2002 (84Kb) - Protocol prepared by the British Transplantation Society, the UK Transplant Co-ordinators' Association and UK Transplant.