Multi-site analytical evaluation of a chemiluminescent magnetic microparticle immunoassay (CMIA) for sirolimus on the Abbott ARCHITECT analyzer

ObjectiveThis study evaluated a new chemiluminescent magnetic microparticle immunoassay (CMIA) for sirolimus on the ARCHITECT analyzer.Design and methodsPatient and laboratory proficiency samples were tested at three European sites and one site in the United States.ResultsThe CMIA total %CV's were all < 8% and the Limit of Quantification (LOQ) was < 1.52 ng/mL across the four sites. It cross-reacts to sirolimus metabolites F4 and F5 and showed no hematocrit interference over a range of 25% to 55%. Patient specimen correlations to three LC/MS/MS methods gave R ≥ 0.91 at three sites and mean biases of 14%, 25% and 39%. CMIA patient specimen correlations to the Abbott IMx gave R ≥ 0.94 at 2 sites and mean biases of 5.4% and 6.9%.ConclusionsCMIA is a precise and sensitive immunoassay method without hematocrit interference. It correlates well to both LC/MS/MS and immunoassay results, but shows an expected positive bias to LC/MS/MS.