Challenges in harmonizing integrated healthcare network laboratories: Multi-center evaluation of the AccuTnI+3 troponin assay

Background: Beckman Coulter has recently introduced a new troponin assay manufactured for the Access2 and DxI platforms, releasing it under the name AccuTnI+3. Clinical laboratories are required to validate method performance before testing and reporting patient results.

Methods: Beckman Coulter Access 2 instruments (n=42) across Kaiser Permanente Northern California were evaluated for their performance characteristics using the AccuTnI+3 reagent. Precision, linearity, and patient sample comparisons were performed on each instrument. Limit of the blank (LOB), limit of detection (LOD), limit of quantitation (LOQ), serum plasma comparisons, and specimen stability were evaluated using a single instrument.

Results: The assay was linear from 0-100,000ng/L. The LOB, LOD and LOQ were determined to be 5, 8 and 20ng/L, respectively. Interday precision on the low QC (mean concentration 41ng/L) ranged from 3.0% to 14.2%. The bias observed between the former assay (AccuTnI) and the AccuTnI+3 was comparable to the inter-instrument bias for either assay. Non-uniform distribution was observed in the precision and inter-instrument/inter-assay comparisons among the instruments evaluated.

Conclusions: The AccuTnI and AccuTnI+3 troponin assays are equivalent across the analytical measuring range. There was no significant difference at the medical decision point. No changes in patient results are anticipated. However, the assay-independent inter-instrument bias observed is an important consideration for harmonization efforts.