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Chest. 2013 Sep;144(3):848-858. doi: 10.1378/chest.13-0057.

Heparin-induced thrombocytopenia in medical surgical critical illness.

Author information

1
Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada. Electronic address: twarken@mcmaster.ca.
2
Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
3
Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
4
St. Michael's Hospital and the University of Toronto, Toronto, ON, Canada.
5
Ottawa Hospital General Campus and University of Ottawa, Ottawa, ON, Canada.
6
Pavilhão Pereira Filho, Santa Casa de Porto Alegre, Brazil.
7
Mount Sinai Hospital and the University of Toronto, Toronto, ON, Canada.
8
Alfred Hospital, Melbourne, Melbourne, VIC, Australia.
9
Flinders Medical Centre and Flinders University, Adelaide, SA, Australia.
10
Monash Medical Centre, Melbourne, VIC, Australia.
11
Box Hill Hospital and Monash University, Melbourne, VIC, Australia.
12
Mayo Clinic, Rochester, MN.
13
Capital Health Queen Elizabeth II Health Science Center and Dalhousie University, Halifax, NS, Canada.
14
Vancouver Island Health Authority, Victoria, BC, Canada.
15
Charles LeMoyne Hospital, Longueuil, QC, Canada.
16
St. Joseph's Healthcare, Hamilton, ON, Canada.

Abstract

BACKGROUND:

In a recent multicenter randomized trial comparing unfractionated heparin (UFH) with low-molecular-weight heparin (dalteparin) for thromboprophylaxis in 3,746 critically ill patients, 17 patients (0.5%) developed heparin-induced thrombocytopenia (HIT) based on serotonin-release assay-positive (SRA+) status. A trend to a lower frequency of HIT with dalteparin vs UFH was observed in the intention-to-treat analysis (five vs 12 patients, P = .14), which was statistically significant (three vs 12 patients, P = .046) in a prespecified per-protocol analysis that excluded patients with DVT at study entry. We sought to characterize HIT outcomes and to determine how dalteparin thromboprophylaxis may reduce HIT frequency in patients in the ICU.

METHODS:

In 17 patients with HIT, we analyzed platelet counts and thrombotic events in relation to the study drug and other open-label heparin, to determine whether the study drug plausibly explained seroconversion to SRA+ status and/or breakthrough of thrombocytopenia/thrombosis. We also compared antibody frequencies (dalteparin vs UFH) in 409 patients serologically investigated for HIT.

RESULTS:

HIT-associated thrombosis occurred in 10 of 17 patients (58.8%) (8:1:1 venous:arterial:both). Dalteparin was associated with fewer study drug-attributable HIT-related events (P = .020), including less seroconversion (P = .058) and less breakthrough of thrombocytopenia/thrombosis (P = .032). Antiplatelet factor 4/heparin IgG antibodies by enzyme-linked immunosorbent assay were less frequent among patients receiving dalteparin vs UFH (13.5% vs 27.3%, P < .001). One patient with HIT-associated DVT died after UFH bolus (anaphylactoid reaction), whereas platelet counts recovered in two others with HIT-associated VTE despite continuation of therapeutic-dose UFH.

CONCLUSIONS:

The lower risk of HIT in patients in the ICU receiving dalteparin appears related to both decreased antibody formation and decreased clinical breakthrough of HIT among patients forming antibodies.

PMID:
23722881
DOI:
10.1378/chest.13-0057
[Indexed for MEDLINE]

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