Clinical insights into the role of immunosuppression in solid organ transplant recipients with COVID-19.

INTRODUCTION: The COVID-19 pandemic has disproportionately affected patients who have undergone solid organ transplantation (SOT). OBJECTIVES: We aimed to assess a cohort of transplant recipients who developed COVID­19, with a focus on immunosuppressive regimen, blood tacrolimus levels, clinical course, and patient and graft outcomes. PATIENTS AND METHODS: During the first 12 months of the pandemic, we identified ambulatory SOT recipients, including kidney, liver, and heart transplant recipients, diagnosed with SARS­CoV­2 infection. Baseline and follow­up data on graft function, immunosuppression, and patient and graft outcomes were assessed. RESULTS: Of the 2091 ambulatory patients, we identified 201 transplant recipients (9.6%) with SARS­CoV­2 infection (kidney transplant, n = 112; heart transplant, n = 56; liver transplant, n = 33). Patients after recent kidney (during 2015-2020) or heart (during 2020) transplant were significantly more often diagnosed with COVID ­19 than patients with a longer time since transplant. Additionally, blood trough tacrolimus levels measured during or shortly after COVID­19 in 23 kidney graft recipients were significantly increased by a median of 76.1% (interquartile range, 47.4%-109.4%) relative to predose trough levels. However, liver function parameters were not elevated, necessitating a tacrolimus dose reduction in 73.9% of the patients. CONCLUSIONS: In our study, kidney transplant recipients showed significant disturbances of tacrolimus metabolism, which may account for kidney function worsening during COVID­19. Moreover, infection was more common in patients with recent kidney or heart transplant, which suggests that the level of immunosuppression may affect morbidity related to SARS­CoV­2 infection.