Longitudinal Decline in Kidney Graft Function Following COVID‐19 in Kidney Transplant Recipients

To the Editor, Kidney transplant recipients (KTRs) are particularly vulnerable during the coronavirus disease 2019 (COVID-19) due to chronic immunosuppression and comorbidities. While acute kidney injury during COVID-19 has been well described, data on long-term graft function trajectories remain limited, particularly in patients with mild disease. We conducted a single-center retrospective study of 52 KTRs diagnosed with COVID-19 between 2020 and 2022 at the Hôtel Dieu de France University Hospital in Beirut, Lebanon (approved by the Ethics Committee of the Faculty of Medicine at Saint Joseph University, Tfem/2023/48). Serial serum creatinine measurements were available for 12 months before and after infection. COVID-19 severity was predominantly mild (79%), with fewer patients experiencing moderate, severe, or critical illness. Using linear mixed-effects models to account for repeated measures, we observed a significant increase in creatinine following COVID-19. The adjusted mean creatinine rose from 1.18 mg/dL (95% CI, 1.16–1.20) pre-infection to 1.41 mg/dL (95% CI, 1.39–1.44) post-infection (p < 0.001). Similar results were seen when comparing the last pre-infection and last post-infection measurements. Importantly, this association persisted even among patients with mild COVID-19, suggesting that clinically mild infection may still impact long-term graft function (Table 1). Exploratory univariate analyses showed that older age (> 50 years) and longer graft duration were associated with graft function decline (OR 2.28 and 2.59, respectively; p < 0.01). Although graft function naturally declines over time, the within-patient longitudinal design suggests that the post-COVID-19 decline exceeds expected pre-infection trajectories. Our findings align with emerging literature. Malinowska et al. reported modest post-COVID-19 graft function changes over 1 year [1], while Caillard et al. highlighted increased morbidity and mortality among KTRs without assessing graft function [2]. This study extends these observations by demonstrating measurable long-term effects even after mild infection. Potential mechanisms include endothelial injury, microvascular thrombosis, and immune dysregulation, though causal inference is limited by the observational design [3-5]. Limitations include the retrospective single-center design, small sample size, and lack of a non-COVID KTR control group. Residual confounding from immunosuppressive adjustments or comorbidities cannot be excluded. Despite these limitations, repeated within-patient measurements provide a robust assessment of longitudinal graft function. In conclusion, COVID-19 may be associated with a sustained decline in kidney graft function, even after mild infection. These findings support close post-COVID-19 monitoring of KTRs and underscore the need for larger, prospective studies with control groups to better define long-term graft outcomes. The authors have nothing to report. The study was approved by the Ethics Committee of the Faculty of Medicine at Saint Joseph University (Tfem/2023/48). The authors declare no conflicts of interest.