Dosage simulation
Dosage regimens were simulated based on eGFRCysC and MPO stratification. AAV patients with elevated CysC should receive lower dose of MPA while patients with elevated MPO should receive higher dose of MPA (Supplemental Table 1). A dose of 750 mg (650 mg·m-2) twice daily was needed to achieve the target AUC0-12h in AAV children with normal renal function and no inflammation. Impaired renal function (eGFRCysC =15 mL/min/1.73m2) significantly impacted MPA CL, with almost a 2/3 dose reduction than normal renal function (eGFRCysC=90 mL/min/1.73m2). The combined effects of MPO and renal function resulted in a 6-fold range in MPA dose.