Introduction

Nonadherence to immunosuppressive medication is associated with rejection and graft loss. We have previously shown that intrapatient variability (IPV) of tacrolimus trough levels between 6-12 months post-transplant can be used as a surrogate marker for adherence and that a high IPV can predict rejection and graft loss. In this study we assess the variability of tacrolimus levels preceding an episode of late first episode rejection (after one year).

Method

We retrospectively analysed 668 patients who received a low risk kidney only transplant between 01/11/2005 and 01/09/2013. Patients who developed rejection in the first year post transplant were excluded. All patients received alemtuzumab induction and tacrolimus monotherapy with a steroid sparing protocol with a target pre-trough tacrolimus level of 5-8ng/ml. Controls were chosen as patients transplanted immediately before and after each rejection case from the overall cohort (N=124). Tacrolimus levels at matched time intervals to the rejection cases were used for analysis.

Results

62 cases of late first rejection episodes were identified. The mean time to rejection was 2.28 ± 1.16 years. Mean follow up 5.65 ± 2.12years

**Tacrolimus levels were taken from 6 months up until rejection in the rejection cases or matched time points in the controls.

Conclusion

This study shows that high IPV and lower minimum tacrolimus levels predict late first episode rejection. This analysis supports the need for a prospective study to assess strategies which minimise nonadherence, reduce the variability of tacrolimus levels, maintain patients within the therapeutic range of tacrolimus and reduce the risk of development of late rejection and graft loss.

CITATION INFORMATION: Goodall D, Willicombe M, McLean A, Taube D. Late Renal Allograft Rejection Is Predicted by High Intrapatient Variability of Tacrolimus Levels. Am J Transplant. 2016;16 (suppl 3).

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