Liver Allocation Proposal Summary

The Liver Patients' Transplant Consortium (LPTC) has prepared this summary of the liver allocation proposals for patients. If you would like to give your feedback on these proposals, we would be grateful if you could do so by 3 March 2015. Skip this and go to directly to feedback section.

 

Additional reading:

In this document, organ allocation refers to the offering of livers from deceased donors to adult elective NHS group 1 ‘active’ registration for a liver only transplant.

 

The ‘Backbone Allocation’ Fixed Term Working Unit  (FTWU) has been asked try to find if there is a better way to allocate organs for liver transplantation. The FTWU are a group of transplant clinicians who work in various liver transplant centres across the UK.

 

  • The parameters of a better system as defined by NHSBT and the FTWU are:
    • Be transparent
    • Have the confidence of all stakeholders
    • Have the lowest number of deaths on the transplant waiting list
    • Maximize survival from the point when a patient is registered for their transplant

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  • The criteria that must be met in the development of a new allocation policy as defined by NHSBT are:
    • patient focus
    • transparency
    • equity
    • patient benefit
    • compliance with current legislation
    • public support

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  • The FTWU compared the outcome of liver donor allocation for adult elective transplantation as currently performed in each centre during 2013 to the predicted outcomes if that same donor had been allocated to the patient with the following scenarios*:
    • Needs-based allocation: Greatest risk of dying without a transplant
    • Utility-based allocation: Longest survival time after transplantation
    • Transplant benefit based allocation: Most years of life to gain from the transplant

* excludes super-urgent indications, which are allocated separately.

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  • The FTWU found from their simulation that transplant benefit based allocation was predicted to give the least number of deaths on the transplant list and showed the best population survival from the point of registration when measured for five years after a transplant.

This method of allocation has been recommended to LAG.

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  • However, it is recognised that more work will be needed to refine this proposal before implementation and there will need to be regular checks once introduced to ensure that there are no specific disadvantaged groups.

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Please consider the following questions when reviewing the recommendations provided below. The LPTC would like to garner patient group feedback on the following specific questions:

  1. Do you agree that the proposed model, if introduced, should be subject to continuous monitoring to identify disadvantaged groups with the opportunity for scheme-checkpoints three times over the first five years of running?
  2. Do you agree that the proposed model should be subject to further real-time shadow donor offering in 2015 to identify centre decline rates and give units experience of using the proposed transplant benefit model?
  3. Do you agree that the proposed allocation model meets the criteria defined by NHSBT?
  4. Please tell us your opinion on your preferred allocation model, providing a rationale for your position.

You may feedback directly by email, using this Word document or by using our survey. Please feedback to us by 3 March 2015. We will use your feedback to help shape PSC Support's response to NHSBT. Thank you.

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The key recommendations

 

Recommendation 1

 

Unit based correction factors for some pathology tests will be required for any national liver transplant allocation scheme.

 

Why?

 

Part of the offering sequence calculation depends on four components of a patient’s UK end-stage liver disease (UKELD) score: international normalised ratio (INR), creatinine, sodium and bilirubin.

 

These pathology tests are calculated in different laboratories depending on where a patient lives and there can be slight differences in results between laboratories. For example Laboratory A bilirubin results may be slightly lower than Laboratory B bilirubin results for the same patient. This could mean that results from Laboratory B unduly contribute to higher bilirubin values  than those from Laboratory A, meaning Laboratory A and B patients are  inequitably assessed in the proposed transplant benefit model.

 

It is important to ensure that patients are neither advantaged or disadvantaged as a result of laboratory differences, and for this reason, the FTWU recommend that correction factors be developed for each laboratory used by each transplant unit. This means that we can then be confident that:

  • INR, creatinine, sodium and bilirubin scores will be fairly compared and used to rank our position in the offering sequence;
  • there will be consistency in minimum listing criteria between liver transplant centres.

 

It is also important to note that the transplant benefit model doesn’t use the UKELD score to rank patients. It uses INR, creatinine, sodium and bilirubin as individual values and not as an aggregated score. In addition to INR, creatinine, sodium and bilirubin, patients are ranked in transplant benefit using the list of variables in paragraphs 6.7, 6.8, 7.6 and 7.7 in LAG(14)31c.

 

For a more detailed review assessing variability in UKELD scores across United Kingdom liver transplant centres, see LAG14 31(b).

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Recommendation 2

 

The FTWU recommends that LAG should consider transplant benefit based allocation as the optimum and needs based allocation as a second alternative for patients with chronic liver disease who have a UKELD score greater than 49 and those with liver cancer (HCC). 

 

Why?

 

Allocation by utility and by the current centre-based method is predicted to give worse outcomes.

 

 

Table 1 (from LAG14 (31)d)

 

 

 

Table 1    Mortality and patient-years associated with the current liver allocation scheme and the simulated allocation schemes based on the simulation period, 1 January 2013 to 31 December 2013 (1287 registrations)

 

 

 

 

No (%) died/ removed1

Patient-years

 

 

 

Current scheme

93 (7%)

4581

Need (M1)

48 (4%)

5187

Utility (M2)

95 (7%)

4779

Transplant benefit (M3)

48 (4%)

5262

 

 

 

1 Removed due to condition deteriorated

 

 

 

 

 

This table shows that under the current allocation scheme:

  • 93 patients died on the waiting list in 2013, or were removed from the list due to deterioration of their condition.
  • 45 fewer patients would have died in the same time period had the ‘transplant benefit’ model or the ‘need’ model been adopted.
  • 4,581 patient years were gained from transplants under the current scheme and 681 additional population life years would have been gained by implementing the transplant benefit model.
  • Overall survival from point of registration (population life years which includes post-transplant survival) would be highest with benefits-based allocation.

 

Therefore, the FTWU recommend the adoption of a transplant benefit-based offering sequence, as this will:

  • Reduce the number of deaths on the waiting list
  • Increase in the overall number of population life years gained

 

For more detailed information about the methodology and a breakdown of the statistics, see LAG14(31)c and LAG(14)31d.

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Recommendation 3

 

The FTWU recommends:

  • Regular three monthly updating of HCC parameters on the transplant list to be introduced from 2015
  • Improved definition of radiological methods and scanners used for defining an HCC.

 

Why?

For patients with hepatocellular carcinoma (HCC), tumour size, tumour number and AFP (alpha feto-protein) score should all be regularly checked, and any new offering sequence should require that these parameters be updated at least every 3 months. Standardisation of imaging techniques in all centres evaluating HCC is also required to ensure consistency.

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Recommendation 4

 

Patients with a low UKELD Variant Syndrome should be allocated organs in proportion to their annual percentage of the total elective transplant registrant pool.

 

Why?

Cases with a ‘low UKELD Variant Syndrome’ (LUVS) suffer from intolerable symptoms that can only be alleviated or cured with a liver transplant. However, it should be noted that LUVS are rare; around 4% of the patients waiting on the transplant list are classed as LUVS. However, their UKELD scores do not reflect the severity or extent of their disease or quality of life, and so an alternative, fair allocation system should be sought. It is proposed that LUVS should be allocated organs in proportion to their annual percentage of the total transplant registrant pool (proportional allocation).

 

This means that if there were 20 LUVS registrations on a waiting list of 1000 patients (2% of elective registrant pool), proportional allocation would offer every 50th liver to the LUVS group (2% of donor liver pool). This liver would then be matched for size and blood group to select the recipient from the LUVS.


Alternative options were also considered but disregarded because each disease type within LUVS would require separate and complicated calculation of additional points and the potential risk of ‘gaming’.

 

The LAG Core group is looking at the details of how proportional allocation will work in practice, both at a regional and national level to ensure equity within the LUVS group.

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Recommendation 5

 

Improved, auditable, definitions of low UKELD Variant Syndrome cases should be introduced.

 

Why?

The following cases are considered LUVS and in order to remove any room for error or doubt regarding inclusion in the LUVS group, clear definitions should be developed:

  • Familial Hypercholesterolaemia/ Primary Hyperlipidemia
  • Intractable Pruritus
  • Cholangiopathy with refractory cholangitis or intrahepatic sepsis
  • Hepatopulmonary Syndrome (HPS)
  • Polycystic Liver Disease (PCLD)
  • Gylycogen Storage Disease
  • Portopulmonary Hypertension (PPH)
  • Hepatic Epithelioid Haemangiendothelioma (HEHE)
  • Porphyria

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Recommendation 6

 

The FTWU recommends that further, real-time shadow donor offering is undertaken during 2015 to identify centre decline rates and give units experience of using the proposed transplant benefit model.

 

The reported results of the transplant benefit model simulation assume that every single liver offered to the patient at the top of the offering sequence list is accepted and used for that patient. It is expected that such a high rate of acceptance will not occur in real life. During 2015, it is recommended that the transplant benefit model offering sequence be tested (in theory) by asking transplant teams if they would have been able to transplant each available liver into the patient at the top of the transplant benefit model list. (NB the allocation system has not yet changed, and livers will be continue to be offered under the current guidelines).

 

Why?

This shadowing is important because it will allow the FTWU to determine if any particular patients or groups of patients are disadvantaged by the proposed offering sequence. There is flexibility in the proposals to adjust or respond to any unintended consequences.

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Recommendation 7

 

The impact of additional parameters within the models, such as cold ischaemic time (CIT), is required as is the impact of alternative DBD/DCD organ distribution (local, regional, contiguous zones).

 

Why?

 

The models can be applied using the existing zonal distribution system. They could also be applied to a national system but if that was the case, then further work would be required to ensure consistency of UKELD component sample analysis between centres (see Recommendation 1) and factors such as the impact of cold ischaemic time (CIT) (the length of time the organ has been removed from the body).

 

Currently, a zonal distribution system is used. That is, the offer of the liver is made, in the first instance, to the transplant centre in the zone in which the donor occurs. The transplant centre has the prerogative to allocate the liver amongst a local waiting list of patients.

 

The UK liver transplant community is currently seeking to move towards a national distribution system where organs are allocated to a patient irrespective of the centre to which they are registered or the donor zone where the organ occurs. This would mean for elective (non-super-urgent) transplant, the offering sequence would be on one list for the whole of the UK, and the donor liver would be offered to the patient at the top of the list, regardless of their postcode.

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Background to the review and how the recommendations were defined

 

  • The Liver Advisory Group (LAG) considered the outcome after all 629 adult elective transplants during 2013 and compared that to the predicted outcome if the organs had been allocated on the basis of:
    • Need (greatest risk of dying on a transplant list)
    • Utility (longest survival time after transplantation)
    • Transplant benefit (greatest net life years gained)

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Key findings

  • Fewer registrants are predicted to die on the transplant list with allocation by need or transplant benefit.

 

  • Population survival from point of registration is greatest with transplant benefit and need based allocation and lowest with current allocation.

 

  • The FTWU recommends that the Liver Advisory Group (LAG) should consider transplant benefit based allocation as the optimum and needs based allocation as a second alternative.

 

  • Allocation by utility and by the current centre based method is predicted to give worse outcomes

 

  • The FTWU considers that people with liver cancer (HCC) are appropriately allocated in the transplant benefit allocation model

 

  • The FTWU considered a number of options to address low UKELD Variant Syndromes (LUVS) with a low risk of mortality on the transplant list and recommends using a proportion of the donor pool specifically for these cases, defined by the proportion of low UKELD variant syndrome registrants.

 

  • The FTWU recommends that once introduced any new allocation scheme will need continuous monitoring to identify if there are any specific new disadvantaged groups of patients, with the opportunity for scheme check-points for modifications (if required) three times over the first five years of running.

 

  • The FTWU recommends that further real time shadow donor offering is undertaken during 2015 to identify centre decline rates and give units experience of using the proposed transplant benefit model.

 

  • More work is needed to:
    • Better define liver cancer (HCC) diagnostic criteria;
    • Regularly update liver cancer parameters (size, number, AFP);
    • Explicitly define low UKELD variant syndromes;
    • Examine additional parameters including surrogates for CIT;
    • Examine the impact of alternative distribution (local, regional) of organs;
    • Examine the possibility of continuing simulation for 18 months.
    • Determine centre-specific correction factors for UKELD components bilirubin, sodium and creatinine

 

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Facts and figures from the statistical models

 

You can review data on the transplant benefit model compared to the current system and the other two models considered in the detailed simulation results provided by NHSBT

In particular, note:

  • the predicted number of deaths/removals for each model per condition in Table 3 LAG14(31)d on page 58-59
  • the predicted time on the waiting list for each model per condition in Table 8 LAG14(31)d on page 64
  • the predicted outcome for each model per condition in Table 5 LAG14(31)d on page 61-62

 

M1 = needs based model

M2 = utility based model

M3 = transplant benefit based model (recommended)

 

 

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