The purpose of this study was to analyze outcomes in patients with mycophenolate mofetil (MMF) dose reductions below doses proven to prevent rejection in a tacrolimus-based maintenance regimen (1500mg daily).

Methods:

This was a retrospective longitudinal cohort study of patients receiving a solitary kidney transplant from 2010-13 at a large academic medical center. Patients included were over the age of 18, maintained on tacrolimus, MMF, and prednisone per institution protocol and had at least one year of follow-up. The primary outcome was a composite of biopsy proven acute rejection (BPAR), graft loss, and progression to Stage 4 CKD. Secondary endpoints included classifying reason for reduction and identifying patient characteristics associated with reduction.

Results:

A total of 329 patients were included in the analysis. The mean follow-up time was 2.3 years. Patients in the reduction cohort were significantly older, more likely to receive a deceased donor, and more frequently received cytolytic induction therapy (Table 1). Reasons for reduction are outlined in Table 2. The reduction cohort demonstrated higher rates of the composite endpoint (Table 3). The higher rate of the composite endpoint in the reduction cohort was primarily driven by the Infection/Cancer group (see Figure 1). The dose reductions in the Infection/Cancer cohort tended to occur earlier post-transplant and, on average, were more drastic than the reductions that occurred for other reasons (Table 4).

Conclusion:

More severe and early reductions in mycophenolate dose are associated with increased rates of graft loss, biopsy proven rejection, or Stage 4 CKD, which was primarily a circumstance of early and significant dose reductions due to infection.

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