Mapping the Landscape of European Kidney Exchange Programmes: A Comparative Analysis of Operational and Immunological Frameworks

Introduction: Kidney transplantation remains the gold standard for end-stage renal disease, yet immunological barriers—such as ABO incompatibility and HLA sensitization—often render direct living donation infeasible. Kidney Paired Donation (KPD), or Kidney Exchange Programmes (KEPs), have emerged as a vital strategy to overcome these barriers. While several national and transnational KEPs exist across Europe, they operate under diverse legal, clinical, and algorithmic frameworks. This study, conducted by WP3 as a part of the EuroKEP collaboration , aims to systematically map the European KEP landscape to identify the potential for a standardized pan-European framework.
Methods: A structured 95-item survey was distributed to all European countries with established KEPs, including both national (e.g., UK, Spain, Netherlands) and transnational collaborations (e.g., STEP, KEPSAT). The survey covered seven domains: organizational aspects, activity levels, information sharing, immunological testing, acceptance criteria, optimization/prioritization, and follow-up procedures.
Results: Responses were received from all surveyed programs, revealing significant heterogeneity:
Organization and eligibility: Requirements for center participation vary from strict accreditation (e.g., Spain) to informal membership-based entry. While HLA-incompatible pairs form the largest participant group, the inclusion of non-directed altruistic donors varies, with the UK showing the highest integration of these donors to initiate chains.
Activity and Scalability: Large variations in program size were observed, influenced by population density, legislative history, and clinical acceptance. Matching run frequencies are generally standardized at four times per year.
Immunology and data: Most programs utilize proprietary software for matching, with moving toward high-resolution (2-field) HLA genotyping. However, the mandatory datasets for registration range from basic demographic data to detailed clinical parameters.
Optimization: The primary objective across most algorithms is the maximization of the total number of transplants, with a general preference for shorter cycles and a "kidney travels" model. Efficiency indicators (transplants performed relative to entries) showed wide variance across borders.
Conclusion: Current European KEPs share a foundational goal but differ substantially in operational execution. Variations in pool size, the use of altruistic donors, and center accreditation standards directly impact program efficiency. The findings suggest that while transnational collaborations provide a template for scaling, a successful pan-European exchange requires greater standardization of immunological protocols, shared data structures, and unified allocation algorithms to benefit highly sensitized patients across the continent.