Performance Assessment of Staclot‐LA Assay on Fully Automated Coagulation Analyser for Lupus Anticoagulant Testing Using Internal and External Quality Controls

Introduction It is recommended to detect lupus anticoagulant (LA) using two phospholipid‐dependent clotting assays, including a LA‐sensitive activated partial‐thromboplastin‐time (aPTT). Among these reagents, Staclot‐LA assay is performed on a mixture of test and normal plasma with and without hexagonal phase phospholipids. However, its lack of validation on automated coagulation analyser is a major drawback. We aimed i/to assess the analytical performance of Staclot‐LA assay on automated system; ii/to compare inter‐laboratory agreement of Staclot‐LA performed on semi‐automated or fully automated analysers using two external‐quality‐assurance (EQA) programs data. Methods We adapted the Staclot‐LA assay (Stago) set‐up on a STA‐R‐Max analyser and locally validated the manufacturer's recommended cut‐off for positive LA testing using samples from healthy volunteers. Reproducibility and accuracy were assessed using internal quality controls (IQC, Staclot‐LA1/LA2) over a five‐year period. Staclot‐LA results from EQA Probioqual and ECAT were compared between semi‐ and fully‐automated analysers. Results Agreement of our LA results (positive or negative) was observed in 100% of IQC ( n = 130) and EQA ( n = 58) samples. Probioqual and ECAT interlaboratory Staclot‐LA results showed full agreement for 96.2% and 89.7% in semi‐automated system users vs 96.7% and 92.5% in automated system users. The system had no significant impact on the qualitative results (Probioqual p = 1.000; ECAT p = 0.5912), even though we observed increasing biases of the differences in clotting times, especially in LA positive samples on automated vs semi‐automated analysers. Conclusion Staclot‐LA assay can be reliably performed on a fully automated system, thus paving the way for wider accessibility and widespread use.