Comparison of the CEDIA® and MEIA® assays for measurement of tacrolimus in organ transplant recipients

ObjectivesTacrolimus is widely used in organ transplantation. We evaluated 2 immunoassays, CEDIA® and MEIA®, for the measurement of whole blood tacrolimus concentrations.MethodsFor each assay the following were evaluated: total precision, limit of detection (analytical sensitivity), limit of quantitation (functional sensitivity), linearity, and accuracy. Patient correlation studies were performed, comparing each assay with liquid chromatography-tandem mass spectrometry (LC-MS/MS).ResultsTotal precision for MEIA, corresponding to mean concentrations of 6.8 and 22.5 ng/ml, was 17.4 and 11.9%, respectively. The limit of detection was 0.9 ng/ml, and the limit of quantitation was 4.7 ng/ml. Total precision for CEDIA, corresponding to mean concentrations of 5.3 and 19.9 ng/ml, was 20.6 and 6.3%, respectively. The limit of detection was 0.8 ng/ml, with a limit of quantitation of 4.9 ng/ml. Analysis of proficiency material demonstrated acceptable performance for both assays. In addition, both assays were acceptably linear over their respective reportable ranges. Analysis of patient correlation data using Passing–Bablok analysis and Bland–Altman plots demonstrated a positive average bias for both assays versus LC-MS/MS results.ConclusionBased on our evaluation, both assays demonstrated acceptable performance for use in clinical monitoring of tacrolimus.