Introduction. Antibody-mediated rejection (ABMR) is the major cause of allograft failure. We studied whether the coefficient of variability (CV) of blood levels of tacrolimus can predict ABMR.

Material and methods. We studied 591 recipients of a renal transplant (RT) performed between January 2008 and December 2012, followed until June 2014 (median 40 months, interquartile range 26-58). We compared the CV of the blood levels of tacrolimus between the 21 patients who experienced ABMR and a control group (1:2) comprising randomized patients matched for age, gender and transplant year who did not have ABMR. The CV was obtained from the formula CV (%) = (SD/[micro]) [times] 100, using the 5 last measurements of tacrolimus blood levels before diagnosis of ABMR.

Results: The CV in the ABMR group compared with the controls was 38.3±14.3 vs. 20.7±11.0% (p<0.001). The area under the ROC curve was 0.84% (p<0.001). The Youden index showed that a CV≥27.5% was the best predictor of ABMR. Multivariate logistic regression analysis showed that risk factors associated with ABMP were CV≥27.5% (OR 12.4; 95% CI, 2.1-73.8; p=0.006); cellular rejection (OR 21.9; 95% CI, 3.7-131.6; p=0.001), pre-transplant antibodies (OR 28.4; 95% CI, 4.2-192.7; p=0.001), retransplantation (OR 10.5; 95% CI, 1.9-59.3; p=0.008) and time since dialysis (OR 1.02; 95% CI, 1.002-1.042; p=0.023). Isolated measurements of tacrolimus had no predictive role for ABMR, with an area under the curve of 0.46-0.56% (p=NS).

Conclusion. A CV of 27.5% of tacrolimus levels predicts the risk for ABMR with adequate sensitivity and specificity adjusting for confounding variables.

CITATION INFORMATION: Ruiz-Esteban P, Gonzalez-Molina M, Caballero A, Palma E, Burgos D, Cabello M, Alonso-Titos J, Duarte A, Hernandez D. The Coefficient of Variability of Tacrolimus Levels Can Predict Antibody-Mediated Rejection After Renal Transplantation. Am J Transplant. 2016;16 (suppl 3).

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