Prevalence and Risk of Preexisting Heparin-Induced Thrombocytopenia Antibodies in Patients With Acute VTE

Theodore E. Warkentin, Bruce L. Davidson*, Harry R. Buller, Alexander S. Gallus, Michael Gent, Anthonie W. A. Lensing, Franco Piovella, Martin H. Prins, Annelise E. M. Segers, John G. Kelton

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

49 Citations (Web of Science)

Abstract

Background: Some patients with acute VTE who may previously have been exposed to heparin products have unrecognized antibodies implicated in heparin-induced thrombocytopenia (HIT). Antibody prevalence and patient consequences upon exposure to heparin, low-molecular-weight heparin, and fondaparinux are uncertain. Methods: In this secondary analysis, we tested patients in the Matisse VTE studies at study entry for heparin-dependent antibodies and further tested patients with enzyme-linked immunosorbent assay (ELISA)-positive results for platelet-activating antibodies. We compared the risk of HIT (> 50% fall in platelet count, heparin-dependent antibodies, no contradicting features) between patients treated with heparin (either unfractionated or low molecular weight [enoxaparin]) vs those who received fondaparinux. Comparison groups for thrombocytopenia occurrence comprised patients with ELISA-positive, platelet-activating, antibody-positive results; ELISA-positive, but platelet-activating antibody-negative results; and randomly selected antibodynegative results. Results: A total of 127 of 3,994 patients (3.2%) had ELISA-positive results at baseline, but only 14 (0.4%; 95% CI, 0.2%-0.6%) had platelet-activating antibodies. Among these 14, four treated with unfractionated or low-molecular-weight heparin developed HIT compared with zero of 10 fondaparinux-treated patients (OR, 95; 95% CI, 8-1,123; P <.001). This frequency (four of four, 100%) significantly differed from that of both heparin-treated patients whose results were ELISA positive but platelet-activating antibody negative and from heparin-treated antibody-negative control subjects (zero of 15 and zero of 27, respectively; P <.001 for both). Conclusions: Of patients with VTE, 0.4% had pathologic platelet-activating heparin-dependent antibodies rather than the 3.2% detected by the recommended cutoff of the commercial ELISA. Among study patients with acute VTE who had platelet-activating antibodies, treatment with fondaparinux reduced the risk of precipitating rapid-onset HIT. CHEST 2011; 140(2):366-373
Original languageEnglish
Pages (from-to)366-373
JournalChest
Volume140
Issue number2
DOIs
Publication statusPublished - Aug 2011

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