Purpose:To investigate the effect of tacrolimus(tac) variability on the development of Donor Specific Antibodies(DSA),rejection and outcome in relation to Age, Gender, Ethnicity and Body Mass Index(BMI) in a single high volume center. Methods:The study included 209 kidney transplant recipients aged between 17 and 79 years, from Jan 2013 to Dec 2013. Mean, Standard Deviation(SD) and Coefficient Variability(CV) of 5 consecutive tac trough measurements after first 3 months of transplant were calculated. A tac variability calculator was utilized, using the formula “CV=(SD/Mean)x100”. CV>20% was considered significant. Primary end points of rejection episodes and graft outcome at 1 year were recorded. Results:25.4%(n=53) of the cohort achieved the desired average tac levels(4-7ng/ml) at the end of 3 months post transplant. Only 62%(n=130) achieved tac CV≤20%, of which 2.3%(n=3) developed a rejection episode. 38%(n=79) had a tac CV>20%, of which 5.13%(n=4) developed a rejection episode(p=0.43). DSA followed same pattern, with 3.4% developing DSA from the tac CV>20% group and only 2.4% DSA from the Tac≤20% group. There were no significant correlations of tac CV with age and BMI (Pearson's correlation). Gender and ethnicity did not associate with tac CV(Chi-square). Mean tac levels were highest in the White recipient group(8.7ng/ml) and lowest on the Black group(4.4ng/ml)(p=0.006 student t test). At 1 year post transplant, 98%(n=205) had a functioning graft. Of the failed ones, all of them had tac CV>20%, with 1 death(no rejections), and 2 graft failures due to rejection. When comparing mean tac levels with rejection, there was 2.6% rejections in the high mean tac group while in the group with mean tac levels within the desired range, rejection rate was 4%. Similarly, development of DSA was only 2.6% in the high mean tac group and 4% in the normal range mean tac group.Conclusions: 38% of our cohort presented high Tac variability. As the episodes for rejection and DSA were low, we found no significant correlation between tac CV, rejection and DSA, even though there was a trend for higher rejection and DSA in the tac CV>20% group. We had 2 graft losses due to rejection, both from the high tac CV group. Interestingly, there was no association between tac CV and age, gender, BMI or ethnicity.

CITATION INFORMATION: Papachristos S, John Velvet A, Summers A, Tavakoli A, Dhanda R, Pararajasingam R, Forgacs B. How Tacrolimus Variability Affects Donor Specific Antibodies, Rejection and Outcome After Kidney Transplantation. Am J Transplant. 2016;16 (suppl 3).

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