Korean J Transplant.  2021 Oct;35(Supple 1):S88. 10.4285/ATW2021.OP-1118.

Intra-patient variability in tacrolimus trough levels over 2 years affects long-term allograft outcomes of kidney transplantation

• Park Y
• Lee H
• Eum SH
• Kim HD
• Ko EJ
• Yang CW
• Chung BH

• KMID: 2521388
• DOI: http://doi.org/10.4285/ATW2021.OP-1118

Abstract

Background
The current study aimed to determine the impact of tacrolimus (TAC) trough level (C0) intra-patient variability (IPV) over 2 years after kidney transplantation (KT) on allograft outcomes.
Methods
In total, 1,143 patients with low immunologic risk were enrolled. The time-weighted coefficient variability (TWCV) of TAC-C0 was calculated, and patients were divided into tertile groups (T1: <24.6%, T2: 24.6%–33.7%, T3: ≥33.7%) according to TAC-C0-TWCV until post-transplant 1st year. Moreover, they were classified into the low/low, low/high, high/low, and high/high groups based on a TAC-C0-TWCV value of 33.7% during post-transplant 0–1st and 1st–2nd years. We compared the allograft outcomes among the three tertile and four TAC-C0-TWCV groups.
Results
The T3 group had the highest rate of death-censored allograft loss (DCGL), and T3 itself was an independent risk fac-tor for DCGL (adjusted hazard ratio [HR], 1.853; P=0.029). In addition, sustained TWCV ≥33.7% until 2 years after KT showed the highest risk for DCGL (HR, 2.395; P=0.013). Moreover, the changes in TWCV during the 1st–2nd post-transplant year significantly affect to DCGL occurrence (HR of low/high 2.086, P=0.045; HR of high/low 1.813, P=0.021). Patients with an average TAC-C0 of ≥5 ng/mL in the high/high group were at highest risk for DCGL as well.
Conclusions
TAC-IPV is an important factor that can significantly affect comprehensive allograft outcomes. TAC-IPV after 1st year of KT was also considered an important factor for allograft outcomes. Moreover, TAC-IPV can significantly affect allograft outcomes even with a high average TAC-C0.