Performance of Tacrolimus Electrochemiluminescence Immunoassay on Cobas Pure Integrated Solutions

Background: Cobas pure integrated solutions (Roche Diagnostics International AG, Switzerland) is a newly launched automatic analyzer combining clinical chemistry, immunoassay, and ion-selective electrode diagnostic testing.We evaluated the analytical performance of tacrolimus electrochemiluminescence immunoassay (ECLIA) on cobas pure and compared it with that of affinity chrome-mediated immunoassay (ACMIA) and liquid chromatography tandem mass spectrometry (LC-MS/MS).Methods: Quality control materials and residual whole blood samples from patients receiving tacrolimus were used in evaluating the performance metrics, including the precision, linearity, comparison, and carryover, of tacrolimus ECLIA (Roche Diagnostics GmbH, Germany) on cobas pure.The precision, linearity, and comparison were assessed in accordance with Clinical and Laboratory Standards Institute guidelines EP5-A3, EP6-A, and EP9-A3, respectively, and the carryover was calculated.Results of tacrolimus ECLIA on cobas pure were compared with those of tacrolimus ACMIA (Siemens Healthineers, USA) and LC-MS/MS (Waters Corporation, USA) on other platforms.Results: The within-laboratory precisions of tacrolimus ECLIA on cobas pure were 4.0%, 3.1%, and 3.2% at low, medium, and high concentrations of quality control materials.The linearity of the assay was acceptable (0.91-27.43 ng/mL).Correlation analysis indicated that the results of tacrolimus ECLIA on cobas pure were comparable to those of Dimension TAC and LC-MS/MS (r=0.977 and 0.994, respectively) with slight difference.Moreover, the carryover effect was 0.03%.Conclusions: Tacrolimus ECLIA on cobas pure showed acceptable precision, linearity, and correlation with ACMIA and LC-MS/MS except for a slight difference.The overall performance of tacrolimus ECLIA on cobas pure is suitable for the therapeutic drug monitoring of tacrolimus in clinical laboratories.