In this retrospective observational cohort study, we included all deceased donor grafts performed at the Turin University Renal Transplant Center “A. Vercellone” from January 2003 to December 2013; multi-organ grafts, dual kidney transplantation, and KTs who received previous transplants were excluded to limit confounding factors and homogenize the study population. To assess the difference between recipients of standard vs. marginal kidneys, we stratified the population according to donor ages (<50 years, between 50 and 69 years, and ≥70 years). Follow-up ended in November 2021. The local Ethical Committee approved this study (Comitato Etico Interaziendale A.O.U. Città Della Salute e Della Scienza di Torino-A.O. Ordine Mauriziano-A.S.L. Città di Torino, resolution 1449/2019 on 11/08/2019—“TGT observational study”).
All data were extracted from the recipients’ scheduled clinical visits and hospital admissions. D+/R− recipients and all KTs receiving ATG induction underwent CMV prophylaxis with valganciclovir for six and two months, respectively. The duration of prophylaxis could be modified in a small number of cases based on clinical judgment.
After transplantation, CMV viremia was regularly monitored in all recipients, irrespective of serostatus and donor/recipient CMV matching. The control schedule was biweekly in the first three months, monthly in the fourth month, and then every two months until one year after transplantation. Further controls were performed on a clinical basis.
CMV DNAemia was detected in whole blood using a commercially available real-time PCR assay (CMV-ELITe MGB® kit, ELITechGroup, Milan, Italy). CMV replication is defined as DNAemia > 1160 UI/mL (=2000 copies/mL). This threshold was considered susceptible to pre-emptive therapy with oral valganciclovir to achieve the complete negativization of viremia. Intravenous ganciclovir use was limited to severe forms of CMV disease or in cases without response to valganciclovir.
Discrete data were described as percentages and analyzed with Pearson’s Χ2 or, for small samples, with Fisher’s exact test. The distribution of continuous variables was analyzed with the Kolmogorov–Smirnov test. Continuous variables were described as mean ± standard deviation when normal and as median with interquartile ranges when non-normally distributed. When appropriate, Mann–Whitney, Kruskal–Wallis, t-test, or variance analysis with a Bonferroni post hoc test were used to analyze the difference between groups. Kaplan–Meier (KM) curves analyzed cumulative graft and patient survival. A univariate model for the main clinically chosen covariates was adopted to identify significant predictors (level α = 0.05, log-rank test), followed by a multivariate analysis fitted with significant univariate variables.
To consider the potential role of death with a functioning graft as a competitive event with graft dysfunction and to avoid overestimation compared to the traditional Kaplan–Meier, we also calculated the cumulative incidence function [10 (link)]. Gray’s test assessed the statistical significance of the difference in the cumulative incidences of competing events among groups.
SPSS software was adopted for all the analyses (IBM Corp. Released 2021. IBM SPSS Statistics for Windows, Version 28.0.1.0, IBM Corp., Armonk, NY, USA).
Competing risk analyses were conducted using R Statistical Software (v4.2.2; R Core Team 2022) and theR package cmprsk (v2.2-11). The significance level was α < 0.05.
All data were extracted from the recipients’ scheduled clinical visits and hospital admissions. D+/R− recipients and all KTs receiving ATG induction underwent CMV prophylaxis with valganciclovir for six and two months, respectively. The duration of prophylaxis could be modified in a small number of cases based on clinical judgment.
After transplantation, CMV viremia was regularly monitored in all recipients, irrespective of serostatus and donor/recipient CMV matching. The control schedule was biweekly in the first three months, monthly in the fourth month, and then every two months until one year after transplantation. Further controls were performed on a clinical basis.
CMV DNAemia was detected in whole blood using a commercially available real-time PCR assay (CMV-ELITe MGB® kit, ELITechGroup, Milan, Italy). CMV replication is defined as DNAemia > 1160 UI/mL (=2000 copies/mL). This threshold was considered susceptible to pre-emptive therapy with oral valganciclovir to achieve the complete negativization of viremia. Intravenous ganciclovir use was limited to severe forms of CMV disease or in cases without response to valganciclovir.
Discrete data were described as percentages and analyzed with Pearson’s Χ2 or, for small samples, with Fisher’s exact test. The distribution of continuous variables was analyzed with the Kolmogorov–Smirnov test. Continuous variables were described as mean ± standard deviation when normal and as median with interquartile ranges when non-normally distributed. When appropriate, Mann–Whitney, Kruskal–Wallis, t-test, or variance analysis with a Bonferroni post hoc test were used to analyze the difference between groups. Kaplan–Meier (KM) curves analyzed cumulative graft and patient survival. A univariate model for the main clinically chosen covariates was adopted to identify significant predictors (level α = 0.05, log-rank test), followed by a multivariate analysis fitted with significant univariate variables.
To consider the potential role of death with a functioning graft as a competitive event with graft dysfunction and to avoid overestimation compared to the traditional Kaplan–Meier, we also calculated the cumulative incidence function [10 (link)]. Gray’s test assessed the statistical significance of the difference in the cumulative incidences of competing events among groups.
SPSS software was adopted for all the analyses (IBM Corp. Released 2021. IBM SPSS Statistics for Windows, Version 28.0.1.0, IBM Corp., Armonk, NY, USA).
Competing risk analyses were conducted using R Statistical Software (v4.2.2; R Core Team 2022) and theR package cmprsk (v2.2-11). The significance level was α < 0.05.
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