Evaluation of 2 batched pretreatment systems for the measurement of whole blood tacrolimus on the ARCHITECT immunoassay analyzer

Background: Measurement of tacrolimus using the ARCHITECT immunoassay analyzer requires a manual extraction step that puts clinical laboratory workers at risk for ergonomic injury. Therefore, we developed 2 batched extraction systems for tacrolimus measurement on the ARCHITECT analyzer and describe their features herein. Methods: Two batched extraction methods were developed at 2 different laboratories. The batched extraction methods allow processing of at least 20 specimens at a time. We evaluated the analytical performance of those methods and compared them with the United States Food and Drug Administration (FDA)–cleared process for manually extracting individual specimens. Results: Comparing the performance of batched- and individual-extraction methods revealed that both methods had comparable between-day imprecision, high patient-results correlation (R² values ≥0.9869), equivalent functional sensitivity (0.48 ng/mL), and good linearity between 1 ng per mL and 25 ng per mL. Further, we observed decreased delta check–identified errors using the batched method. Conclusion: The 2 developed batched extraction methods for tacrolimus measurement that we describe herein demonstrate excellent performance and can replace individual specimen extraction.