Association of Serum Mycophenolic Acid (MPA) Levels & Mycophenolic Acid (MMF) Dose With BK Viremia Post Kidney Transplantation (KT).

Abstract

The utility of routine monitoring of MPA serum trough levels to adjust MMF dosing in patients status post KT is poorly established. There is little real-world data to demonstrate a correlation between routine MPA level monitoring and clinical outcomes. We performed a retrospective analysis on our center database to evaluate whether routine MPA monitoring would correlate with opportunistic infection such as BK viremia. Our retrospective analysis included all adult solitary KT recipients at our center on MMF who had MPA trough levels measured during the 1st year of follow up. BK virus was detected in blood samples using the quantitative real time PCR technique with positive range of ≥200 copies/mL. MPA trough level and MMF dose were compared between the patients with and without BK viremia. Multivariate analysis was conducted to identify the association of MMF dose and BK viremia after controlling for other potential risk factors. MPA levels drawn after development of BK viremia were excluded. Results: A total of 244 patients were included, age 52.4±14.2 years, 34% African American, 37% female, 75% deceased donor KT, and 16.8% sensitized (CPRA >0%). There was no significant difference in MPA levels between the patients who were BK viremic or not (2.73±0.21 vs 2.35±0.14 mcg/mL,P=0.1138). However, the MMF dose was significantly different between the two groups (1808.5±34.1 vs 1612.7±29.4 mg/day total dose, P<.0001). The significant difference for MMF dose still holds after adjusting for covariant risk factors including recipient age, gender, race, dialysis length, HLA mismatch, previous KT, diabetes, tacrolimus trough level, cytomegalovirus, donor type, and induction medicine (HR: 1.18, 95%CI: 1.10-1.27, P<.0001).Figure: No Caption available.In our retrospective analysis, we did not find any significant correlation between MPA trough levels and BK viremia, whereas we did find a correlation between total daily MMF dose and BK viremia. These results suggest doubtful efficacy of MPA trough levels in determining overimmunosuppression and resulting BK viremia.