(706) Prevalence and Risk Factors for Rejection Following COVID-19 in a Single Centre Australian Lung Transplant Cohort

PURPOSE: Persistent and irreversible loss of allograft function has been described in lung transplant recipients post COVID-19 illness. The prevalence of and risk factors for acute cellular (ACR) and antibody mediated rejection (AMR) in this cohort is unclear. METHODS: A retrospective cohort study of all living LTx recipients between Jan-2020 and Sep-2022 was performed. Medical record review identified recipients with COVID-19 infection and those diagnosed with, and/or treated for ACR or AMR. AMR was defined as new or >10% increase in donor specific antibodies with associated loss of lung function. ACR was defined as biopsy proven ISHLT Grade A or B rejection. Baseline demographics are described. A logistic regression univariate analysis was used to identify risk factors for rejection. RESULTS: 128/387 (33%) LTx recipients tested positive to SARS-CoV-2 during the study period. 44 (32.3%) patients were investigated for graft dysfunction, 37 (31.4%) recipients had persistent loss of ≥10% of FEV(1) at ≥90-days. Median age in this cohort is 54.5 years (23-76). There was no significant difference between gender, disease severity or presence of CLAD at COVID-19 infection. Rejection was identified in 9(20.5%) recipients, 3 (6.8%) with AMR, 5 (11.4%) ACR, and 1 (2.3%) both. The median onset of rejection was 59 days (16-239). Volume and percent change in FEV(1) post COVID-19 was not significantly different between recipients with and without rejection. Those with rejection had a mean volume loss of 559 mL (SD 678 mL, 22.9%), while those without rejection had 842 mL (SD 824 mL, 42.9%). Univariate logistic regression analysis demonstrated positive association of younger patients for risk of rejection (OR 0.95, 95% CI 0.90-1.00, p=0.05). Female gender was weakly associated with rejection (OR 0.21, 95% CI 0.04-1.18, p=0.08). There was no significant association with time post-transplant, severe COVID illness, early COVID-19 treatment and rejection. CONCLUSION: Acute rejection was frequent post COVID infection and should be considered a differential in persistent allograft dysfunction. Younger age and female gender were associated with increased risk of rejection. The volume of lung function lost did not differentiate between those who did and did not suffer rejection. This may be explained by non-alloimmune inflammatory processes resulting in graft dysfunction.