The Surplus Transplant Lung Allocation System in Italy: An Evaluation of the Allocation Process via Stochastic Modeling

Abstract

Background: Lung transplantation is a specialized procedure used to treat chronic end-stage respiratory diseases. Due to the scarcity of lung donors, constructing fair and equitable lung transplant allocation methods is an issue that has been addressed with different strategies worldwide. This work aims to describe how Italy’s “national protocol for the management of surplus organs in all transplant programs” functions through an online app to allocate lung transplants. We have developed two probability models to describe the allocation process among the various transplant centers. An online app was then created. The first model considers conditional probabilities based on a protocol flowchart to compute the probability for each area and transplant center to receive each n-th organ in the period considered. The second probability model is based on the generalization of the binomial distribution to correlated binary variables, which is based on Bahadur’s representation, to compute the cumulative probability for each transplant center to receive at least nth organs. Our results show that the impact of the allocation of a surplus organ depends mostly on the region where the organ was donated. The discrepancies shown by our model may be explained by a discrepancy between the northern and southern regions in relation to the number of organs donated.

Worldwide organ allocation systems for pediatric lung transplantation

“…Priority for pediatric organ transplant candidates extends to kidney, liver, and heart, either officially or with unwritten policy depending on the organ group. LAS was introduced in 2016 to northern Italy, with three LTX centers’ wait lists being merged into a single regional list 21 . Following this, in 2010, the Urgent Lung Transplant program (ULTp) was introduced, coordinated by the Centro Nazionale Trapianti (CNT), to identify recipients requiring priority for LTX at the national level 21 .…”

“…LAS was introduced in 2016 to northern Italy, with three LTX centers’ wait lists being merged into a single regional list 21 . Following this, in 2010, the Urgent Lung Transplant program (ULTp) was introduced, coordinated by the Centro Nazionale Trapianti (CNT), to identify recipients requiring priority for LTX at the national level 21 . In the instance that there are no urgent candidates nationally and available lungs are not used locally, they are then allocated at the regional level based on the CNT program.…”

“…It is hypothesized that the continuous lung distribution will also address limitations to a traditionally boundary based system, allowing for allocation of lungs locally barring any distant donors who take priority through medical urgency 34 . While LAS has been adopted in European countries including Eurotransplant regions and Italy with positive impacts, 21 time will tell if CAS models become more widely adopted beyond the United States once its effects are studied.…”