Expected effect of the lung Composite Allocation Score system on US lung transplantation

Maryam Valapour, Carli J. Lehr, Andrew Wey, Melissa A. Skeans, Jonathan Miller, Erika D. Lease

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Efforts are underway to transition the current lung allocation system to a continuous distribution framework whereby multiple factors are simultaneously combined into a Composite Allocation Score (CAS) to prioritize candidates for lung transplant. The purpose of this study was to compare discrete CAS scenarios with the current concentric circle–based allocation system to assess their potential effects on the US lung transplantation system using the Scientific Registry of Transplant Recipients' thoracic simulated allocation model. Six alternative CAS scenarios were compared over 10 simulation runs using data from individuals on the lung transplant waiting list from January 1, 2018, through December 31, 2019. Outcome measures were transplant rate, count, waitlist deaths, posttransplant deaths within 2 years, donor-to-recipient distance, and percentage of organs predicted to have flown. Across scenarios, waitlist deaths decreased by 36% to 47%, with larger decreases in deaths at lower placement efficiency weight and higher weighting of the waitlist outcomes. When waitlist outcomes were equally weighted to posttransplant outcomes, more transplants occurred in individuals with the highest expected posttransplant survival. All CAS scenarios led to improved overall measures of equity compared with the current Lung Allocation Score system, including reduced waitlist deaths, and resulted in similar posttransplant survival.

Original languageEnglish (US)
Pages (from-to)2971-2980
Number of pages10
JournalAmerican Journal of Transplantation
Issue number12
StatePublished - Dec 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 The American Society of Transplantation and the American Society of Transplant Surgeons.


  • continuous distribution
  • geography
  • lung transplant
  • organ allocation
  • outcomes


Dive into the research topics of 'Expected effect of the lung Composite Allocation Score system on US lung transplantation'. Together they form a unique fingerprint.

Cite this