Was sind die Fragen, die ein Kardiologe an das Labor stellt? Welche Anamnese steckt hinter dem Patienten und wie können wir aus der Labormedizin unterstützen? An Fallbeispielen soll der Hintergrund der Fragen und die zielgerichtete zelluläre und plasmatische Gerinnungsdiagnostik adressiert werden.
10:15 Uhr
P-02-10/FV-02:
The reliability of rapid immunoassay for the detection of anti-PF-4 antibodies in patients suspected of vaccine-induced immune thrombotic thrombocytopenia after COVID-19 vaccination
G. Uzun (Tübingen, DE)
Details anzeigen
Autor:innen:
G. Uzun (Tübingen, DE)
K. Althaus (Tübingen, DE)
S. Hammer (Tübingen, DE)
Y. Wanner (Tübingen, DE)
S. Nowak-Harnau (Tübingen, DE)
S. Enkel (Tübingen, DE)
T. Bakchoul (Tübingen, DE)
Aims: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but serious complication of vector based COVID-19 vaccines. Similar due heparin-induced thrombocytopenia (HIT), antibodies reacting to platelet factor 4 (PF4) are responsible from platelet activation in VITT. The diagnosis of VITT includes the detection of anti-PF4 antibodies. Particle gel immunoassay is one of the rapid tests, that is commonly used in the diagnosis of HIT to detect anti-PF4 antibodies. The aim of the current study was to investigate the diagnostic performance of rapid immunoassay in patients suspected of VITT.
Materials and Methods: In this retrospective, single-center study, the correlation between rapid immunoassay, enzyme-linked immunosorbent assay (ELISA) and modified heparin induced platelet aggregation assay (HIPA) in patients with findings suggestive of VITT was investigated. A commercially available PF4 rapid immunoassay (ID PaGIA H/PF4, Diamed) and an anti PF4/Heparin ELISA (Zymutest HIA IgG, Hyphen) were used according to manufacturer´s instructions. A sample was considered reactive in ELISA if the optical density (OD) was ≥0.500. Modified HIPA was accepted as the gold standard test.
Results: Between March 8th and May 20th, 21 samples from clinically well-characterized patients were analyzed with rapid immunoassay, ELISA and HIPA. Of these sera 8 revealed positive results and 13 tested negative in rapid immunoassay. Sensitivity and specificity of rapid immunoassay were 50% and 69%, respectively. On the other hand, sensitivity and specificity of ELISA were 88% and 92%, respectively.
Discussion: Particle gel immunoassay is not reliable in the detection of anti-PF4 antibodies in patients suspected of VITT. Commercially available PF4 rapid immunoassays are validated for the diagnosis of HIT. They should not be used to rule out VITT.