Performance comparison of VACUETTE® CAT serum separator clot activator and LH Lithium heparin tubes with two different gel types on Siemens Atellica® analyzer: A bicentric study

Background: Preanalytical errors are the most common laboratory errors and are often related to manual steps in blood sample collection and handling. Blood collection devices, particularly tube materials and separator gels, are important sources of preanalytical variability. VACUETTE® CAT serum separator tubes (SSTs) and LH Lithium heparin plasma separator tubes (PSTs) recently transitioned from one separator gel formulation (Reference Gel B) to the other (Gel 2.0). To understand whether and how this change affects the analytical performance of routine clinical chemistry and immunochemistry testing, we have compared the performance of tubes containing Gel 2.0 with that of tubes containing Reference Gel B. Methods: This bicentric, retrospective study was conducted at two clinical laboratories during two observation periods: one using VACUETTE® CAT SSTs and LH PSTs with Reference Gel B, and a subsequent period using tubes with Gel 2.0. Centrifugation conditions routinely applied in participating laboratories were not aligned with the manufacturer's Instructions for Use (IFU), which are considered binding. This deviation was locally validated and accepted for scientific purposes, reflecting routine practices in a real-world laboratory environment. Routine testing on the Siemens Atellica® Solution clinical chemistry and immunoassay system was evaluated. Equivalence was assessed using the nonparametric Hodges-Lehmann estimate of the median difference. Haemolysis index (H-index) categories were compared using Chi-squared testing. Stable patient populations and sufficient sample sizes were assumed. Results: A total of 253261 serum and 161486 plasma results were analysed. No significant differences were observed between gel types for any analyte, confirming analytical equivalence. Haemolysis frequencies in 24025 serum and 10807 plasma samples were comparable between periods, with no significant differences detected. Conclusion: Gel 2.0 demonstrated equivalent analytical performance and preanalytical quality to Reference Gel B. Its implementation did not result in analyte drift or increased haemolysis, supporting its safe use in routine laboratory testing.