Challenges in harmonizing integrated healthcare network laboratories: multi-center evaluation of the hCG5 assay

• Harmonization of integrated healthcare network laboratories is complex.
• The analytical evaluation of the hCG5 assay was completed on 41 Access 2 instruments across 21 laboratories.
• Precision and linearity were comparable between the laboratories.
• Between instruments and between assay biases varied significantly between laboratories.

BackgroundBeckman Coulter recently introduced a new hCG assay manufactured for the Access 2 and DxI platforms. This assay is the first to use the 5th International Standard (5th IS) as its primary calibration material. Clinical laboratories are required to validate the method performance before testing and reporting patient results.MethodsBeckman Coulter Access 2 instruments (n = 41) across Kaiser Permanente Northern California were evaluated for their performance characteristics using the hCG5 reagent. Precision, linearity, dilution verification, and patient sample comparisons were performed on each instrument.ResultsThe assay was linear up to 1350 IU/L. Intra-day and inter-day precision ranged from 1.0%–3.3% and 1.8–7.3%, respectively, for the low QC material (mean concentration 4.6 IU/L). Percent bias between the previous assay (hCG2) and the hCG5 assay was 3.2 to 22.7% for hCG concentrations < 1000 IU/L and − 2.9 to 30% for concentrations > 1000 IU/L. On board and manual dilutions agreed within 15% following proper adjustment of the instrument dilution factor.ConclusionsAchieving Access 2 inter-instrument agreement on specimens needing dilutions (hCG > 1350 IU/L) requires validation of the on board dilution factor. Laboratories should use QC material above the linear range to monitor instrument dilution accuracy and precision.