For education and research only. This calculator illustrates how the Transplant Benefit Score works. It must not be used to make or influence decisions about any individual's clinical care, listing or organ offers.
Transplant Benefit Score calculator
The Transplant Benefit Score (TBS) decides which adult on the UK waiting list is offered a liver from a donor after brain death (DBD): it estimates the extra life a transplant would give over the next five years compared with staying on the list, and the liver is offered to the patient with the highest score. DCD livers are allocated by transplant centres, not by the score. Nothing entered here is stored or sent anywhere.
Enter the liver disease details and blood results; tick the sections of the results to show.
Transplant Benefit Score results
Something went wrong updating the results for these values. Change a value or reload the page; if it keeps happening, please let us know which values you entered.
Please check the values entered: age, blood results and waiting time must be numbers, and creatinine, bilirubin, INR and sodium must be above zero.
Estimated time alive over the next five years
How this compares with scores of patients offered a liver
The score changes with each liver that is offered
The score is not fixed. It is recalculated for every donor liver, because the predicted survival after transplant depends on the donor as well as on the patient. For example:
| Donor liver | Score | Extra life expected |
|---|
The score is not the whole story
Things to keep in mind
- The score is a statistical estimate for groups of people with similar results, not a prediction of what will happen to an individual.
- It changes as the blood tests change. The transplant team updates patient details regularly, and so the score changes too.
- A higher score means a liver is more likely to be offered sooner, but the final decision for each liver is made by the transplant team, who weigh many factors the score does not capture.
- Some patients (for example those with acute liver failure, or needing an urgent re-transplant) are prioritised through other routes, not this score.
This tool is for information and understanding only. It is not medical advice and must not be used to make treatment decisions. Please talk to the transplant team about anything it raises.
Need, utility and severity scores
Survival curves behind the score
Two statistical models, built from the outcomes of thousands of previous UK patients, estimate the chance of being alive at each day over the next five years: one if the patient stayed on the waiting list without a transplant, and one after a transplant with this donor liver. The area under each curve is the expected number of days alive. The Transplant Benefit Score is the difference between the two.
What drives the score
Each bar is the net effect of one clinical factor: β × (x − model mean) summed over the model terms that involve it, so it is relative to the average patient in the model's development cohort. The models use age and age² together, and bilirubin and sodium with an interaction term; because each term is centred on its own mean, the separate terms can be large and opposite while their sum is modest, which is why they are combined here by default. Factors with zero contribution are not shown.
Donor sensitivity
How this patient's score changes with the donor
Other donor characteristics held as currently entered.
Published context in detail (NHSBT LAG(26)03)
Median (line) and interquartile range (band) of TBS at the time of named DBD offers, livers ultimately transplanted. Source: NHSBT LAG(26)03, Table 12A; 2020/21 excludes 27 Mar – 9 Jul 2020; the last period is 5.5 months.
Model table
Every term of the v2 model with its value for this patient/donor, the coefficients for the applicable cohort, and the contribution to each linear predictor (as in NHSBT's reference spreadsheet).
| Term | Parameter | x | M1 β | M1 mean | M1 contribution | M2 β | M2 mean | M2 contribution |
|---|
Text summary
Plain-text summary of the inputs and results for notes or correspondence.
About this calculator
This calculator implements the UK liver Transplant Benefit Score (TBS) used by NHS Blood and Transplant's National Liver Offering Scheme (NLOS) to offer livers from deceased donors to adults on the elective waiting list. It reproduces the current scheme (TBS version 2, in use since October 2022) and, for comparison, the original scheme (version 1, March 2018 – October 2022).
How the score works
Two Cox proportional-hazards models estimate daily survival over five years (1,826 days): M1 (need) — survival on the waiting list without a transplant, from recipient factors — and M2 (utility) — survival after transplantation, from recipient, donor and transplant factors.
The expected number of days alive is the area under each curve. TBS = M2 − M1: the expected gain in days of life over five years from transplanting this patient with this liver. Patients with hepatocellular carcinoma (and no previous transplant) are scored with separate cancer models.
For each liver, the score is calculated for every eligible patient and the liver is offered to the highest-scoring patient (subject to tiering, blood group, size and clinical acceptance). Super-urgent, paediatric, variant-syndrome and some other patients are prioritised through separate routes.
Version 1 vs version 2
Version 1 (March 2018 – October 2022) was fitted on registrations and transplants from 2006–2012.
Version 2 (October 2022 – present) was re-estimated on registrations 2006–2016 (non-cancer) and 2009–2016 (cancer), with revised baseline survivor functions. Only factors that remained statistically significant were kept: sex, encephalopathy, waiting time, recipient diabetes and donor BMI dropped out, in-patient status and renal support dropped out of the cancer models, and registration years were grouped (2006–2008, 2009–2012, 2013 onwards as reference).
Because both the coefficients and the baseline curves changed, a v1–v2 difference for a given patient reflects the whole model, not any single factor.
Model provenance and verification
Version 1: coefficients, centring means and baseline survivor functions from NHSBT's reference spreadsheet Liver TBS calculator v1.4. The engine reproduces the spreadsheet's worked example exactly and NHSBT's own v1 scores for 545 registrations to 10 decimal places.
Version 2: coefficients from the table supplied to the Edinburgh team (Beta estimates TBS v2.xlsx) and baseline survivor functions from the NHSBT-template calculator Liver TBS calculator upd 2022.xlsx; the engine reproduces that calculator's worked example exactly. Checked against NHSBT's own v2 scores for 545 registrations in a 2022 waiting-list snapshot: the M2 (utility) models and the cancer M1 model agree exactly, but for the non-cancer M1 (need) model the snapshot implies slightly different coefficients from the supplied table — terms differ by up to 0.05 in log-hazard, which moves TBS by a median of 3 and at most 23 days (most for PBC, ‘other’ and re-transplant candidates). The calculator uses the supplied table by default; the snapshot-fitted alternative can be shown from ‘More details and options’ and is listed below. Which set NHSBT's live system uses is being confirmed with NHSBT.
Separately, NHSBT's monitoring report records that the in-patient status term in the non-cancer models was set to zero in the live scheme on 23 May 2023 because of concern over counterintuitive predictions. This calculator applies the published coefficient by default so that its effect can be demonstrated (an in-patient with otherwise good results scores markedly lower); the option under ‘More details and options’ scores as the live scheme does now.
Arithmetic follows NHSBT's convention: logarithms, products, contributions and daily survival probabilities are rounded to five decimal places. This web version is generated from the Edinburgh group's R implementation; every build is checked against it on the NHSBT worked examples and 500 random patient–donor pairs for every model variant it includes.
Non-cancer M1 coefficients: supplied table vs snapshot-fitted
| Term | Parameter | Supplied | Snapshot-fitted | Difference |
|---|
Published context used in this calculator
Key dates recorded in the report: NLOS introduced 20 March 2018; TBS parameter estimates and baseline survivor functions updated 4 October 2022; in-patient status term set to zero 23 May 2023; named-patient offering suspended 27 March – 9 July 2020 (COVID-19).
References
- NHS Blood and Transplant. Liver Transplantation: Selection Criteria and Recipient Registration (POL195) and Deceased Donor Liver Distribution and Allocation (POL196). odt.nhs.uk
- NHSBT Liver Advisory Group. National Liver Offering Scheme: updating the estimates used to calculate the Transplant Benefit Score — methods paper LAG(21)29, November 2021.
- NHS Blood and Transplant, Statistics and Clinical Research. National Liver Offering Scheme: ninety-six month review. LAG(26)03, May 2026.
- Allen E, et al. Communicating the complexity of the transplant benefit score. J Hepatol 2024;81:471–478.
- Attia A, et al. Effect of recipient age on prioritisation for liver transplantation in the UK: a population-based modelling study. Lancet Healthy Longev 2024.
- Barber K, et al. Elective liver transplant list mortality: development of a United Kingdom end-stage liver disease score. Transplantation 2011;92:469–476 (UKELD).
- Harrison E, et al. TransplantBenefit.org (Surgical Informatics, University of Edinburgh) — the original open-source TBS calculator this work builds on.
Use and privacy
Developed by the Edinburgh organ allocation research group for education and research.
The calculator runs entirely in your web browser. Nothing entered is saved, logged or sent anywhere, and it keeps working without an internet connection once the page has loaded.
The information provided is for understanding the offering scheme only. It is not medical advice, not a substitute for the NHSBT offering system, and must not be used alone for any diagnostic or treatment decision.