Abstract Number: LPB0126
Meeting: ISTH 2021 Congress
Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Platelet Function Disorders, Hereditary
Background: Light transmission aggregometry (LTA) is the gold standard to diagnose inherited platelet function disorders (IPFD) and von Willebrand disease type 2B (VWD2B). LTA is a time-consuming method requiring large blood volumes. In contrast, whole blood impedance aggregometry (WBIA) is a quicker and simpler method requiring limited volume of blood.
Aims: We evaluate the ability of WBIA to identify already diagnosed IPFD and VWD2B. We also compare the results of both methods in patients referred for unexplained bleeding tendency.
Methods: One hundred sixty patients were studied (Table 1). LTA was performed on platelet-rich plasma according to international recommendations (SSC/ISTH). WBIA was performed on hirudin-anticoagulated blood using the Multiplate® analyzer (Roche) according to manufacturer’s instructions. Normal ranges were calculated in 30 healthy individuals.
| N= | Gendre (F/M) | Age (years±SD) | Platelet Count (x 109L-1±SD) | |
| Glanzmann Thrombasthenia | 18 | 10/18 | 31±17 | 146±83 |
| Bernand-Soulier Syndrome | 3 | 2/1 | 24±3 | 27±6 |
| MYH9-related disease | 7 | 1/6 | 21±18 | 61±24 |
| VWD type 2B | 14 | 9/5 | 36±21 | 146±83 |
| Platelet-type VWD | 3 | 2/1 | 35±20 | 190±25 |
| VWD | 29 | 22/7 | 28±16 | 295±188 |
| Gray Platelet Syndrome Scott Syndrome Wiscott-Aldrich Syndrome |
1 1 1 |
1/0 0/1 0/1 |
37 28 46 |
41 208 57 |
| Unexplained bleeding tendency | 83 | 62/21 | 29±18 | 234±90 |
| Healthy individuals | 30 | 15/15 | 39±14 | 245±80 |
Characteristic of the 160 patients studied. VWD: von Willebrand disease.
Results: WBIA correctly diagnosed all patients with Glanzmann Thrombasthenia, Bernard-Soulier Syndrome, platelet-type VWD as well as 13/14 patients with VWD2B, whatever the platelet count. Thrombocytopenic patients with MYH9-related disease had sub-normal results with all agonists. However, VWD patients were poorly detected (15/29, 51.7%). Among 83 patients referred for unexplained bleeding tendency, WBIA and LTA gave concordant results in 48/83 (57.8%) patients: 29 had normal results and 19 had abnormal results with one or more agonists using both methods. Discrepant results were observed in 35/83 (42.1%) patients (Table 2).
| LTA | ||||||
| WBIA | Abnormal | Normal | PPV | NPV | Sensitivity | Specificity |
| Abnormal | 19 | 30 | 0.38 | 0.85 | 0.79 | 0.49 |
| Normal | 5 | 29 | ||||
Agreement between WBIA and LTA in patients referred for unexplained bleeding tendency (n = 83). PPV: positive predictive value. NPV: negative predictive value.
Conclusions: Our study shows that WBIA 1/ is able to properly characterize patients with severe IPFD and VWD2B, including those with thrombocytopenia 2/ is less sensitive/specific in detecting mild platelet abnormalities compared to LTA. The negative predictive value of 0.85 suggests that it might be a useful quick and easy-to use screening test while it cannot avoid further testing by LTA in patients with unexplained bleeding tendency.
To cite this abstract in AMA style:
Ellouze S, Lavenu-Bombled C, Perrier-Cornet A, Combe S, Blandinieres A, Lambert T, D'Oiron R, Proulle V. Whole Blood Impedance Aggregometry: A Usefool Tool but Still Not the Gold Standard [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/whole-blood-impedance-aggregometry-a-usefool-tool-but-still-not-the-gold-standard/. Accessed November 28, 2021.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/whole-blood-impedance-aggregometry-a-usefool-tool-but-still-not-the-gold-standard/