BackgroundThe immunosuppressive agents mycophenolate acid (MPA) and tacrolimus (Tac) are associated with a higher incidence of BK polyomavirus nephropathy (BKPyVAN).In this observational retrospective cohort study, the frequency of BK polyomavirus (BKPyV) complications over a 24-month period was studied.Methods358 renal transplant recipients (RTR) treated with MPA, with either cyclosporine A (CsA) (CsAM group) or Tac (TacM group) and mostly prednisolone, were included.ResultsIncidence of BKPyV-viremia was not significantly different between the CsAM (n = 42/191) (22.0%) and the TacM (n = 36/167) (21.6%) group. Biopsy proven BKPyVAN occurred more often in the TacM group (6.6%) versus the CsAM group (2.1%) (p = 0.03). Longitudinal data analysis showed a significant earlier decline of viral load in plasma in the CsAM group compared to the TacM group (p = 0.005).The incidence of biopsy proven acute rejection (BPAR) was significantly higher in the CsAM (19.9%) compared to the TacM (10.8%) (p = 0.02) group. Graft loss, estimated glomerular filtration rate and mortality rate did not differ in both treatment groups.ConclusionIn conclusion, this study shows that immunosuppressive treatment with Tac and MPA compared to CsA and MPA is associated with a lower incidence of BPAR, but at the cost of an increased risk of developing BKPyVAN in the first two years post-transplant.

Transplant recipients are prone to viral infections, which could affect renal transplantation outcome. Our aim was to assess the effects of early human cytomegalovirus (CMV) DNAemia on transplant renal function. A total of 264 (age 50.9 ± 13.5; male 55%) renal transplantation recipients undergoing preemptive anti-CMV therapy were retrospectively categorized based on early (<3 months post-Tx) CMV peak viral load (PVL); PVL ≤ 536, PVL536-6310, or PVL > 6310 International Units/ml (IU/ml). Estimated glomerular filtration rate (eGFR) was analyzed between 1 and 36 months post-transplantation with Kruskal-Wallis test, linear regression, and a linear mixed-effects model. CMV infection was detectable in 113 (43%) recipients within 49 [38-67] days. Subjects with PVL > 6310 had statistically significant ~5-13 ml/min lower eGFR between 3 and 36 months compared to PVL ≤ 536 and PVL536-6310. eGFR declined from 46.1 to 40.7 ml/min/1.73 m (-12%) over 3 years, and the annual decrease for pronounced infection with high PVL was 2.0 ml/min/1.73 m faster than for noninfected or mildly infected subjects. In conclusion, high CMV DNAemia early after renal transplantation was associated with significant loss of renal function, from which subjects did not recover. The severity of infection (high PVL early post-transplantation), more than the infection per se, was related to irreversible and progressive loss of renal function.

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