The Impact of HLA Mismatch Level in COPD Lung Transplantation Patients

Abstract

<h3>Purpose</h3> Lack of research exists on Human Leukocyte Antigen (HLA) Mismatch on lung transplantation (LTx) survival outcome, particularly in Chronic Obstructive Pulmonary Disease (COPD) patients. This study analyzes how HLA mismatch affects survival outcome in LTx COPD patients since lung allocation score (LAS) implementation. <h3>Methods</h3> We retrospectively analyzed 41,675 LTx patients from The United Network for Organ Sharing (UNOS) database and extracted 5,411 COPD patients (2005-2020) since LAS implementation. Redo LTx's were excluded, and remaining patients were divided into two groups, HLA mismatch level from 0-2 and HLA mismatch level from 3-6. These groups were further divided by having had a single LTx (SLT) or double LTx (DLT). Kaplan-Meier survival analysis and log-rank tests were done to compare the two HLA mismatch level groups among all COPD patients and between each transplant type using JMP Pro 16, SAS Inc. A p-value <0.05 was considered statistically significant. <h3>Results</h3> Of the LTx COPD patients in the HLA mismatch level 0-2 group (n=236), 82 had a SLT and 154 had a DLT. In the HLA mismatch level ≥ 3 group (n=5175), 1711 had a SLT and 3464 had a DLT. Using Kaplan-Meier curves, there was no significant difference in survival outcome (p=.16) between the two HLA mismatch level groups among all COPD LTx patients. Survival rates for the HLA mismatch 0-2 group at 30 days, 5-years and 10-years were 98%, 64% and 34% respectively vs. 97%, 58% and 29% for the HLA mismatch ≥ 3 group. However, when comparing the two HLA mismatch level groups between patients having a SLT or DLT using Kaplan-Meier curves, a significant difference (p<.0001) was found (Figure 1) in the HLA mismatch group ≥ 3 which showed DLT providing improved survival outcomes compared to SLT. <h3>Conclusion</h3> There remains unclear evidence regarding HLA mismatch level and its impact on LTx survival outcome. Since LAS implementation, the results of this study suggest that DLT provides better survival outcomes even with a HLA mismatch level ≥ 3 for lung transplantation patients with COPD.