Background: Numerous assays exist to detect lupus anticoagulants (LA), varying greatly in their principle, sensitivity, and specificity. The hexagonal phase phospholipid neutralization test (HPNT) is an integrated and automatable assay that detects LA by measuring shortened activated partial thromboplastin times (aPTT) in the presence of excess hexagonal phase phospholipid. The HPNT involves both a screening (“Start”) and confirmatory assay (“Correct”).

Aims: The goal of this work is to characterize the performance of our HPNT on three different models of automated coagulation analyzers manufactured by Diagnostica Stago, Siemens Healthcare, and Instrumentation Laboratory.

Methods: To gauge assay performance, we executed a 20-day precision study and a three-site reproducibility study using three pooled plasma controls, performed using three different lots of reagents. We also examined the stability of the assay reagents on board the analyzers and looked at the effects of common coagulation interferents on the performance of the assay. Lastly, we measured the normal range of our HPNT using 120 venipuncture plasma samples collected in 3.2% citrate.

Results: We observed excellent precision and reproducibility across all three study sites, with overall clot time %CVs below 10%. The assay was able to correctly diagnose each control with no false positives or negatives. The reagents themselves were stable on board the instrument for a full eight hours, with no impact on the diagnostic accuracy of the assay. Hemolytic, icteric, and lipemic samples showed no interference using mechanical endpoint detection.

Conclusions: We observed excellent performance and stability of our newly developed HPNT on three common coagulation analyzers. The precision and reproducibility are excellent across sites and the reagents are stable enough to be used without replacement throughout a typical working day. Our HPNT’s convenient packaging and pre-frozen format allows labs to cut down on preparation time and reagent spoilage without compromising performance.

« Back to ISTH 2020 Congress

ISTH Congress Abstracts - https://abstracts.isth.org/abstract/laboratory-validation-of-a-novel-hexagonal-phase-phospholipid-neutralization-assay-for-lupus-anticoagulant-detection/