ABO cPRA Adjustment Calculation Enhancement

French Translation Coming Soon.

 

Purpose

The calculated panel reactive antibody (cPRA) predicts the likelihood of finding a compatible donor for kidney transplant candidates by determining the frequency of Human Leukocyte Antigens (HLA), that a transplant candidate has antibodies against in a given donor population.  National kidney sharing policies assign priority in allocation lists for transplant candidates with increasing cPRA values.

The current Canadian cPRA calculator does not consider the patient ABO when calculating a transplant candidate’s cPRA, leading to inequity in access. 

 

Rationale

Modelling studies proved that blood group B and O candidates’ cPRA percentages were the most misrepresented. The ABO adjusted cPRA will help in two major ways:   

  1. Current non-HSP recipients could gain national access to deceased donor kidneys through national kidney sharing programs by elevating them above the minimum required 94.5% cPRA. 
  2. The ABO adjustment is expected to increase transplant opportunities for current HSP recipients by increasing their rank to the top tier in an allocation list. 

Including an ABO adjustment calculation to determine a candidate’s cPRA more accurately identifies the hardest-to-match transplant candidates and increases transplant opportunities. 

 

What is the scope of the project? 

  • The inclusion of the candidate’s blood group (A, B, AB, O) to the cPRA calculation formula.
  • Canadian Blood Services will upgrade the standalone cPRA calculator to include ABO adjustment capabilities. 
  • The Canadian Transplant Registry (CTR) will us the new calculation for interprovincial deceased donor kidney sharing only at this time. 

 

Who is impacted by the change and what does it mean to them? 

Organ Donation Organizations

  • After the launch there will be more HSP eligible deceased kidney candidates after inclusion of the ABO cPRA calculation and donor allocation lists may be longer than before with more matches. 
  • Awareness that when offering to HSP deceased kidney candidates the displayed cPRA percentages returned from the CTR will have the ABO adjustment calculation.

Transplant Centre Coordinators, Physicians/Clinicians, and Surgeons

  • Until the KPD program uses the ABO adjusted cPRA calculation, HSP transplant candidates could have a different cPRA in the HSP program versus KPD program.
  • For local provincial waitlists a transplant candidate may have a different cPRA in their local allocation system compared with the CTR.
  • A transplant candidate's cPRA is not expected to decrease with ABO cPRA adjustment because this new calculation accounts for immune incompatibility due to both HLA and ABO.
  • Transplant Centres should have received a list of current non-HSP transplant candidates that have become HSP eligible (with the ABO adjustment) and are not currently in the CTR, from their local HLA laboratories. These candidates should be consented for participation in the program.
  • The Canadian cPRA calculator will receive blood group data from the CTR for HSP Kidney patients only at this time.
  • Highly sensitized candidates who have not begun dialysis may obtain the minimum 99.5% cPRA to participate in IPOS Kidney if their eGFR is also <15 ml/min/1.73m2 using CKD-EPI 2021. 

HLA Laboratories (including HLA Lab Directors and Laboratory Technologists) 

  • The Canadian cPRA calculator was updated to allow the selection of ABO. When a blood group is provided the calculator will provide an ABO adjusted cPRA calculation
  • Where a typical cPRA calculation may provide a result of zero, the ABO adjusted cPRA calculation may provide a non-zero value. 
  • You may see different cPRA percentages between CTR and local provincial systems that may not be including ABO adjustments. 

 

What is changing and how does it work? 

The Canadian cPRA calculator tool and it’s API interface will now include a field to receive blood group data. 

  • If blood group data field is provided to the Canadian cPRA calculator, then an ABO adjusted cPRA calculation is produced.
  • If blood group data field is not provided to the Canadian cPRA calculator, then a regular cPRA calculation is produced.
  • The Canadian cPRA calculator will receive blood group data from the CTR for HSP Kidney patients only at this time.  

 

What are the expected implementation timelines? 

Timeline Update

  • The ABO adjusted cPRA calculation was successfully released for use by the CTR for the HSP program on March 25th, 2026. 
A visual timeline of the below dates.

 

Project documentation repository

A quick reference sheet for physicians, surgeons and clinicians is available here:

Go-live updates:

Education

CTR Training  

For coaching on the use of the stand-alone ABO adjusted cPRA calculator or questions how it is used by the CTR for the IPOS Kidney program, please contact CTR Customer Support at 1-855-274-2889 or email transplantregistry@blood.ca. 

 

Frequently Asked Questions

Is the ABO adjusted cPRA calculation being used for Kidney Paired Donation (KPD)?

No, not yet. Canadian Blood Services will communicate with the living kidney donation programs to confirm a future launch date.  

Will candidates whose cPRA percentage are elevated above 99.0% as a result of the ABO adjustment be eligible for  Willing-to-Cross? 

No, not yet. The Kidney Transplant Advisory Committee (KTAC), the National HLA Advisory Committee (NHLAAC), and the Willing to Cross working group agreed to monitor the launch of the ABO adjusted cPRA calculation first and will reassess their inclusion after 6 months of operations with the new calculation. 

Will the ABO adjusted cPRA calculation be used for non-renal candidates? 

No, not yet. The inclusion of ABO adjusted cPRA for highly sensitized heart candidates in the HSH program or any other non-renal organ group has not yet been approved. cPRA percentages from the CTR for non-renal candidates will be an HLA only calculation. 

Is the ABO adjusted cPRA affected by ABOi lite matching? 

Released in February 2026, ABOi Lite matching is only used in the KPD program at this time and does not impact the highly sensitized kidney candidates on the deceased donor waitlist. There is no crossover impact to one another. 

Will this affect pre-emptive (pre-dialysis) listings? 

Yes, highly sensitized candidates who have not begun dialysis may now obtain the minimum 99.5% cPRA to participate in IPOS Kidney and if their eGFR is also <15 ml/min/1.73m2 using CKD-EPI 2021. 

 

How to get in touch 

For questions about the project and the implementation timelines email the Canadian Blood Services team at ctr.ipos@blood.ca  

For user support and coaching on the use of the stand-alone ABO adjusted cPRA calculator, or how it is used by the CTR for the IPOS Kidney program, contact CTR Customer Support at: 

 

Related Links

 

About Canadian Blood Services

Canadian Blood Services works with the Organ and Tissue Donation & Transplantation (OTDT) community to improve national system performance. We do this through coordination of interprovincial organ sharing policies and programs through the Canadian Transplant Registry, the development of leading practices, professional education, public awareness and data analysis and reporting.