Usefulness of mycophenolic acid monitoring with PETINIA for prediction of adverse events in kidney transplant recipients

Background Therapeutic drug monitoring of mycophenolic acid (MPA) is required to optimize the immunosuppressive effect and minimize toxicity. We validated a new particle-enhanced turbidimetric inhibition immunoassay (PETINIA) for the determination of MPA levels and evaluated the relationship of MPA trough level with drug-related adverse events. Methods PETENIA and liquid chromatography-mass spectrometry (LC-MS) were used to determine MPA concentrations from 54 kidney transplant recipients (KTRs). Agreement between PETINIA and LC-MS results was assessed by Passing-Bablok regression and the Bland-Altman plot method. The association of adverse events with MPA trough level obtained by PETINIA was analyzed. Results PETINIA revealed a good agreement with the LC-MS; Regression analysis gave an equation of y¼1.27x_0.12 (r2¼0.975, p<0.001). PETINIA showed a systemic positive bias with a mean difference of 0.66mg/L compared to LC-MS. However, the magnitude of the positive bias decreased to 0.44mg/L within the therapeutic range of MPA. Multiple logistic regression showed that MPA trough level determined by PETINIA was an independent risk factor for adverse events (odds ratio 2.28, 95% CI 1.25–4.16, p¼0.007). MPA trough level predicted adverse events with a sensitivity of 77.8% and a specificity of 86.7% using a cut-off level of 5.25mg/L. Conclusions Good correlation between the two methods indicates that PETINIA is an acceptable method for the monitoring of MPA therapeutic levels. Furthermore, MPA trough level obtained by PETINIA is a useful monitoring tool to minimize toxicity in KTRs.