Abstract
Background: To provide independent evidence of the analytical performance of the i-STAT high-sensitivity troponin I assay using the i-STAT Alinity system, we assessed imprecision, hemolysis interference, and concordance with laboratory assays.
Methods: Nine whole-blood samples with concentrations from below the limit of quantitation to approximately 10 times the upper reference limit were analyzed 20 times in succession. Four samples across a similar range were used to assess hemolysis interference induced by repeated aspiration through a 25-gauge needle. Concordance with 4 laboratory comparison assays was assessed with 200 samples by Pearson correlation and κ statistics at the upper reference limit (URL) and compared to concordance between the laboratory assays.
Results: CVs were <10% across the range of 10 to 20 ng/L, below the universal URL. There were small changes with hemolysis but within acceptable limits (±3 ng/L below 10 ng/L and ±30% above 10 ng/L). Correlation coefficients with high-sensitivity troponin I laboratory assays ranged from 0.96 to 0.99, and performance across the URL ranged from a κ of 0.67 to 0.89, similar to results between laboratory assays (correlation range, 0.87-0.98; κ at the URL range, 0.71-0.88).
Conclusions: Imprecision met manufacturer claims and was consistent with a high-sensitivity assay. There was no significant hemolysis interference. Concordance with comparison laboratory assays was similar to that between laboratory assays. The results support performance characteristics previously reported by the manufacturer, and the assay and analyzer offer acceptable performance for intended clinical use.
Australian New Zealand Clinical Trials Registry number: ACTRN12625000710426.