COVID pandemic change in practice effect on biopsy proven rejection after liver transplantationsingle center experience

Background: The first cases of COVID in the United States were reported in January 2020. The pandemic has resulted in significant precautionary measures, prolonged quarantine, and minimization of patient exposure to public areas, including in-person outpatient clinic visits and labs. Post liver transplant patients require close monitoring to ensure optimal graft function and immunosuppression modifications in order to prevent or early diagnose rejection. The aim of this study was to assess the effect of the COVID pandemic on the incidence of biopsy proven rejection. Methods: All liver biopsies of patients obtained by the Miami Transplant Institute were reviewed by the center's transplant pathologist. Histology was reported as mild, moderate- severe acute T cell mediated rejection, chronic rejection or no evidence of rejection (including indeterminate rejection) based on the Banff criteria. The year 2019 was compared to the year 2020 and 2021 in which COVID erupted in the US. Chi square test was used to compare between the groups for statistical significance. Results: Out of 1482, 1618 and 1679 adult and pediatric patients followed at our center in 2019, 2020 and 2021 (data available until May 2021) 188 (12.7%), 156(9.6%) and 79 (4.7%) had a liver biopsy in 2019, 2020, 2021 respectively (p<0.0001). Rejection was mild in 5.5/6.6%, moderatesevere in 1.6/1.1%, chronic 0.4/0.1% and no rejection in 92.6/92.2% in 2019 vs 2020 for the entire outpatient cohort. Of the biopsies performed in 2019, mild, mod-severe, chronic and no rejection was found in 43.1%, 12.2%, 3.2% and 41.5% compared with 68.6%, 10.1%, 1.3% and 19.2% in 2020 and 44.3%, 12.7%, 6.3% and 36.7% in 2021 (p<0.001) (table 1). Conclusion: Despite overall reduction in the frequency of liver biopsies performed on post LT patients during COVID, there was no overall increased percentage of rejection considering all outpatients followed. There was a substantial increase in histologically confirmed rejection during COVID of the patients who had a liver biopsy, without a surge in 2021 suggesting that clinicians were diagnosing rejections appropriately despite COVID restrictions.