A-121 Analytical performance evaluation of the next generation Abbott enzyme assays on the Alinity c system

Abstract Background Liver enzyme assays, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), and alkaline phosphatase (ALP), are essential in clinical laboratories for assessing liver function, diagnosing liver diseases, and monitoring treatment efficacy. Thus, accurate measurement of these enzyme activities is crucial for clinical diagnostics. Recently, Abbott introduced a next generation of Alinity and Architect enzyme assays, incorporating a multianalyte calibrator (Consolidated Chemistry Calibrator, ConCC) with extended stability. For these new formulation assays, both ConCC and calibration factors are offered for all the assays except GGT, which had better performance with the ConCC calibrator. These assays achieve high Sigma metrics on the Alinity c system, minimizing variability and errors. This study evaluated the analytical performance of these newly developed next generation assays on the Abbott Alinity c platform. Methods Using 2 levels of quality control (QC) material (Bio-Rad Chemistry UA) and 3 pooled patient samples, we assessed imprecision by measuring these 5 samples twice per day (morning and afternoon), for five days. Acceptable imprecision and bias were determined based on the Accreditation Canada Diagnostics (ACDx) recommendations. Linearity testing consisted of 6 levels of commercially available linearity materials, with 3 replicates per level. Method comparison between the next generation assays and on-market conventional assays were evaluated in duplicates using patient specimens (n= 145 – 155) on the Abbott Alinity c platform. Passing-Bablok and Bland-Altman plots were used for the method comparison analyses. The precision and bias (external standard) studies were used to calculate the Sigma-metric using the formula, Sigma-metric=(%TEa-|%bias|)/%CV. TEa was defined based on ACDx and Clinical Laboratory Improvement Amendments (CLIA) recommendations. Results The Alinity next generation assays demonstrated acceptable imprecision, meeting the ACDx goals of ±2 U/L for concentrations =40 U/L and ±4% for concentrations >40 U/L for AST, ALT and GGT, and for ALP at ±4 U/L for concentrations =100 U/L and ±4% for concentrations >100 U/L. Furthermore, these assays exhibited linearity across the six concentration levels tested. All next generation Alinity clinical chemistry enzyme assays showed a Pearson*s R value of 1.0, indicating a strong linear correlation. The linearity slope ranged from 0.76 (ALP2) to 1.04 (AST2) whereas the y-intercept ranged from –59.40 (GGT2) to 8.78 (AST2). The majority of next generation assays performed at or above 6 Sigma. Good agreements were observed between the on-market assay and the next generation (ConCC and factor calibrated) assays. Conclusion The Alinity next generation assays (ALT2, AST2, GGT2 and ALP2) demonstrated acceptable performance for precision and linearity, with good agreement with the conventional factor-based assays on the Alinity c system. These next generation assays had a high sigma value; hence laboratories can expect excellent performance. The precision and method comparison agreement with the conventional assays were satisfactory.