Atellica implementation of Roche Tina-quant Lp(a) Gen.2 matches Cobas comparators; fixed conversion formulas introduce bias (J Appl Lab Med 2026)

Original title: Implementation of an Automated Lipoprotein(a) Assay on a Third-Party Automated Analyzer: Validation, Method Comparison, and Clinical Impact of Formula-Based Mass-to-Molar Conversion

J Appl Lab Med · 19 August 2026 · 4

Sainz-Pastor N, Camos Anguila S, Albéniz Abaigar M, Molina A, Castellà H, Delgado M, Bedini JL, Muñoz R, Ortega E, Rico N

This analytical validation study of 126 serum samples confirms that the Roche Tina-quant Lp(a) Gen.2 assay adapted to the Atellica platform matches a Roche/Cobas molar comparator with high categorical concordance (weighted κ = 0.98). In contrast, fixed mass-to-molar conversion formulas introduce proportional bias (slope, 1.27), moderate agreement (weighted κ = 0.78), and frequent upward reclassification at ≥125 nmol/L. These data establish that direct molar reporting on third-party analyzers prevents the systematic misclassification inherent in manufacturer conversion equations.

Original abstract

Background: Lipoprotein(a) [Lp(a)] is an independent, genetically determined cardiovascular risk factor. Although consensus recommends reporting Lp(a) in molar units using assays with minimized apolipoprotein(a) [apo(a)] isoform size-related bias, some laboratories still use mass units with conversion formulas of uncertain reliability. This study describes the first adaptation and validation of the Roche Tina-quant® Lp(a) Gen.2 assay [TQ-Lp(a)] on the Atellica Solution platform, including method comparison and evaluation of formula-based mass-to-molar conversion.

Methods: A total of 126 serum samples were analyzed using 3 approaches: Roche TQ-Lp(a) as the molar comparator method, adapted Atellica-TQ-Lp(a), and native Siemens Lp(a) on Atellica CH, which reports results in mg/dL. Siemens mass-based results were converted to nmol/L using the manufacturer's equation. Analytical performance was assessed according to Spanish Society of Laboratory Medicine recommendations. Method comparison included Passing-Bablok regression, Bland-Altman, and Cohen κ at clinically relevant thresholds.

Results: Atellica-TQ-Lp(a) demonstrated acceptable precision (CV <6%), excellent linearity (r = 0.99), and adequate sensitivity (limit of quantification, 8 nmol/L). No relevant interference was observed, and stability was maintained for 4 days under refrigerated and frozen conditions. Agreement with the comparator method was high (slope, 0.99; intercept, 3.9 nmol/L; r = 0.99), with minimal constant bias and high categorical concordance (weighted κ = 0.98). In contrast, formula-derived values showed proportional bias (slope, 1.27), moderate agreement (weighted κ = 0.78), and frequent upward reclassification at ≥125 nmol/L.

Conclusions: The Roche Tina-quant® Lp(a) Gen.2 assay can be implemented on Atellica CH to report Lp(a) in nmol/L with high analytical comparability to the Roche/cobas implementation. Fixed mg/dL-to-nmol/L conversion formulas introduce systematic bias and clinically relevant misclassification.

Summary written by lp-a.org from the published abstract; figures as published. Page updated 20 August 2026. Methods.