Influence of U.S. lung composite allocation score components on transplant candidate prioritization

Area of Science:

• Transplant Surgery
• Organ Allocation Policy
• Health Services Research

Background:

• The Composite Allocation Score (CAS) was implemented in March 2023 to prioritize lung transplant candidates.
• An increase in exception requests post-CAS implementation suggests a potential disconnect between policy goals and achieved prioritization.

Purpose of the Study:

• To analyze the contribution of individual CAS components to the total CAS variability.
• To assess the alignment between the intended weighting of CAS factors and their actual impact on candidate prioritization.

Main Methods:

• Utilized data from the Scientific Registry of Transplant Recipients.
• Calculated CAS component scores and quantified their contribution to total CAS variation.

Main Results:

• Medical urgency (25 points) accounted for 40.6% of CAS variation, while biological disadvantage (15 points) accounted for 33.3%.
• Geographic efficiency (10 points) drove 16.6% of variation, whereas post-transplant survival (25 points) explained only 6.4% of variation.
• Prioritization is dominated by medical urgency, biological disadvantage, and geographic efficiency, diverging from intended contributions.

Conclusions:

• Current lung transplant allocation in the U.S. is heavily influenced by medical urgency, biological disadvantage, and geographic factors.
• A divergence exists between the intended weighting of CAS components and their actual impact on candidate prioritization.
• Further evaluation of the CAS policy is warranted to ensure alignment with intended outcomes.