A clinical-laboratory approach contributing to a rapid and reliable diagnosis of heparin-induced thrombocytopenia.
BACKGROUND
Heparin-induced thrombocytopenia (HIT) remains a very challenging diagnosis. The first objective of this study was to compare the performance of the ID-H/PF4 PaGIA with the Asserachrom HPIA ELISA. The main purpose was to evaluate the diagnostic utility of the combination of the H/PF4 PaGIA with the clinical "4T's" score as a screening strategy.


METHODS
102 patients with clinical suspicion of HIT were classified into risk groups using the 4T's score. The presence of HIT antibodies was assessed by two immunoassays and confirmed by a functional flow cytometric assay.


RESULTS
Comparison of the ID-H/PF4 PaGIA with the Asserachrom HPIA ELISA demonstrated a comparable technical performance, being an excellent screening test to rule out HIT (negative predictive value or NPV=100%). According to the 4T's score, HIT was excluded in all low risk patients (NPV=100%). ELISA optical density levels were significantly different between all risk groups (P-values<0.01). In contrast, due to the low positive predictive value (22%) and weak positive likelihood ratio (2.6), a positive ID-H/PF4 PaGIA result did not considerably increase the probability of HIT.


CONCLUSIONS
Our study confirms the combination of the 4T's score with the ID-H/PF4 PaGIA as a reliable strategy to rule out HIT. Yet, confirming positive ID-H/PF4 PaGIA results by flow cytometry within 1-2 h after blood sampling remains necessary. This novel clinical-laboratory approach can contribute in a rapid and reliable way to the definite diagnosis of HIT.
Denys
Barbara
B
Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, Ghent, Belgium. barbara.denys@ugent.be
Stove
Veronique
V
Philippé
Jan
J
Devreese
Katrien
K
D000368:Aged; D000906:Antibodies / Q000097:blood*; D000925:Anticoagulants / Q000009:adverse effects*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis*
D000906:Antibodies; D000925:Anticoagulants; D006493:Heparin