Renal Transplantation With Final Allocation Based on the Virtual Crossmatch

Area of Science:

• Transplantation immunology
• Nephrology
• Clinical diagnostics

Background:

• Solid phase immunoassays (SPI) are standard for detecting HLA antibodies.
• Flow cytometric crossmatch (FCXM) is the traditional method for assessing donor-recipient compatibility in renal transplantation.
• A shift in protocol has occurred, prioritizing SPI over FCXM for final allocation decisions since 2005.

Purpose of the Study:

• To evaluate long-term graft outcomes in kidney transplant recipients.
• To compare outcomes between FCXM-positive (FCXM+) and FCXM-negative (FCXM-) recipients under a protocol using SPI for allocation.
• To determine if crossmatch status impacts graft survival and acute rejection rates.

Main Methods:

• Analysis of 508 consecutive kidney transplants where allocation was based on SPI.
• Categorization of recipients into FCXM+ (n=54) and FCXM- (n=454) groups.
• Assessment of primary outcomes: graft survival and acute rejection within 1 year, with a median follow-up of 7.1 years.

Main Results:

• FCXM+ recipients had higher rates of sensitization and specific risk factors (e.g., longer dialysis duration, retransplants).
• Despite risk factor differences, 5-year actual graft survival was comparable (87% FCXM+ vs. 84% FCXM-).
• Acute rejection within 1 year was similar between groups (13% FCXM+ vs. 12% FCXM-); crossmatch status did not predict outcomes.

Conclusions:

• Renal transplantation can be successfully performed using SPI as the definitive test for donor-recipient compatibility.
• The study supports the use of SPI, potentially simplifying the pre-transplant compatibility assessment process.
• Long-term graft survival is not adversely affected by relying on SPI over FCXM for allocation decisions.