Abstract
【Objective】Five current immunoassay methods (chemiluminescent enzyme immunoassay [CLIA], affinity column mediated immune assay [ACMIA], enzyme multiplied immunoassay technique [EMIT], electro-chemi luminescence immunoassay [ECLIA], and enzyme-linked immunosorbent assay [ELISA]) in Japan were used there to monitor tacrolimus concentrations in the whole blood. The aim of this study was to assess interhospital laboratory variability (coefficient of variation: CV) for each of the 5 methods, the comparability of control samples, and the results obtained by immunoassay measurements (accuracy).
【Design and Methods】A total of 100 laboratories routinely performing therapeutic drug monitoring (TDM) of tacrolimus participated. Reports of 67, 19, 8, 5, and 1 laboratories reported showed results using, respectively, CLIA, ACMIA, EMIT, ECLIA, and ELISA merhods for the tacrolimus assay. In iMPT2014, four spiked samples (0, mean 1.7, 4.8, and 14.4 ng/ml for LC-MS) were sent to each hospital.
【Results】CVs for CLIA, ACMIA, EMIT, and ECLIA assays at a concentration of 4.8 and 14.4 ng/ml were less than 18.3%. Especially, CV values at 1.7 ng/ml for ECLIA were 8.9%. Accuracies for the EMIT assay at a concentration range of 1.7―14.4 ng/ml were 24.8% to 31.2%, whereas those for CLIA, ACMIA, and ECLIA were within ±16.9% at the same concentration range.
【Conclusion】The interlaboratory mean CVs at a target concentration of 5 ng/ml ranging from 6.8% to 18.3%, according to the immunoassay method. Higher interlaboratory variability mainly depends on the difference between analytical methods. Clinicians need to understand the precision and accuracy of using a tacrolimus assay well and should carry out a TDM.
