Abstract Number: PB0357
Meeting: ISTH 2021 Congress
Background: Prothrombin time (PT) is the first essential routine hemostasis parameter monitored in every laboratory. Consequently, ensuring its proper precision whatever the laboratory configuration is of utmost importance.
Aims: We evaluated the intra-site and inter-site precision of PT when determined with STA-NeoPTimal reagent used on the semi-automated instrument STart Max, following recommendations of EP05-A3 CLSI guidelines.
Methods: STA-NeoPTimal precision was evaluated on 6 unitary samples covering the whole measuring range: 2 normal, 3 from patients under vitamin K antagonist (VKA) and 1 deficient factor V, using 3 batches of STA-NeoPTimal.
For single-site precision, a total of 40 runs with each batch of reagent were measured in duplicates on STart Max with 2 independent runs per day and 2 operators.
Multisite precision was determined on 3 sites, with 2 runs per day on 5 non-consecutive days, and 3 replicates per run.
All reagents and instruments were from Stago, Asnières-sur-Seine, France. 1 site was internal and 2 external.
For each STA-NeoPTimal batch used, the ISI used for INR determination was the one provided by the manufacturer. The mean normal prothrombin time used was the same for all sites, after local determination on the same normal samples.
Results: Results were calculated utilizing ANOVA tests.
| Sample | N | Mean (sec) | within-lab precision CV(%) | Mean (INR) | within-lab precision CV(%) |
| Normal 1 | 240 |
13.0
|
4.3 | / | / |
| Normal 2 | 240 | 15.3 | 4.0 | / | / |
| VKA 1 | 240 | 31.5 | 4.8 | 2.20 | 3.7 |
| Deficient V | 240 | 49.0 | 10.0 | / | / |
| VKA 2 | 240 | 61.0 | 6.1 | 4.17 | 5.2 |
| VKA 3 | 240 | 89.6 | 7.3 | 6.04 | 6.7 |
Intra-site precision – all lots combined
| Sample | N | Mean (sec) | Total precision CV(%) | Mean (INR) | Total precision CV(%) |
| Normal 1 | 270 | 13.4 | 5.0 | / | / |
| Normal 2 | 270 | 15.8 | 4.9 | / | / |
| VKA 1 | 270 | 32.9 | 6.7 | 2.29 | 5.9 |
| Deficient V | 270 | 49.4 | 9.7 | / | / |
| VKA 2 | 270 | 62.5 | 7.0 | 4.27 | 6.0 |
| VKA 3 | 270 | 91.1 | 7.2 | 6.14 | 6.3 |
Inter-site precision – all lots and sites combined
Conclusions: PT and INR determination with STA-NeoPTimal, on STart Max is very precise and reproducible at single site and multisite extent, over the whole measuring range. Besides, the intra-site precision confirmed the excellent between-operators precision. These results allow the safe implementation of the assay on this semi-automated technique.
To cite this abstract in AMA style:
Le Goff G, Bouchain M, Chaillet L, Gautier J, Genty V, Langlet S, Carlo A, Beltran J. Evaluation of Intra-site and Inter-site Precision of PT Determination with STA-NeoPTimal on Start Max Semi-automated Instrument [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/evaluation-of-intra-site-and-inter-site-precision-of-pt-determination-with-sta-neoptimal-on-start-max-semi-automated-instrument/. Accessed January 23, 2022.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/evaluation-of-intra-site-and-inter-site-precision-of-pt-determination-with-sta-neoptimal-on-start-max-semi-automated-instrument/