Evaluation of digital measuring device with an ADAMTS13 Activity Screening Test

Introduction The determination of von Willebrand Factor cleaving protease ADAMTS13 activity in plasma is an important diagnostic test to enable the differentiation of patients with thrombotic thrombocytopenic purpura (TTP) from those with other thrombotic microangiopathies (TMAs). It is critical to have a reliable ADAMTS13 Activity result within a quick reporting turn-around time to increase the possibility of a positive outcome of patient care, especially with TTP patients. The screening test has been described by Moore et al¹. It is a rapid semi quantitative assay requiring no special laboratory equipment or highly skilled technician to perform the test. The operator determines the ADAMTS13 activity level by comparing the color (red) intensity of the 4 different levels (0, 0.1, 0.4 and 0.8 IU/mL) indicated on the color card verses the test well coloration. However, on relying in human interpretation from the colour card can potentially lead to variations in reported results. The aim wasto improve result interpretation by evaluating a small mobile measuring device to determine the colour intensity of the screen test. With a digital patient read out of the ADAMTS13 activity level, this should improve the consistency of result reporting, easy of use and confidence of patient results with the screening test [1].

Method To test the analytical performance of the measuring device in combination with the screening test, a three-way method comparison was performed. Patient and normal samples were assayed in a FRET assay, which was considered as the reference method and a Screening method with result interpretation using a colour card and a measuring device.

Results The repeatability using the measuring device for low sample and high sample was 2.4 & 0.4% n=10. Determining the colour intensity using the colour card (x3 operators) vs the measuring device value gave very comparable results. The calculated correlation betweenFRET vs Screening method/measuring device was r²=0.83. The analytical performance of the FRET vs Screening method/device was calculated using a cut off value of≤0.1 IU/mL and≤20 respectively, resulting in a specificity of 89% and sensitivity of 79%.

Conclusion Our results showan excellent correlation between all 3 methods, suggesting the mobile measuring device would be an appropriate and reliable device for determining the ADAMTS13 Activity in the screening test. Therefore, patient results could be reported with confidence in timely manner aiding the rapid diagnosis TTP patients.

Publikationsverlauf

Artikel online veröffentlicht:
26. Februar 2024

• References

• 1 Moore GW. 1 et al A multi-center evaluation of Technoscreen ADAMTS-13 activity assay as a screening tool for detecting deficiency of ADAMTS-13. J Thromb Haemost 2020; 18 (07) 1686-1694