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Consequences of suspected heparin-induced thrombocytopenia in the ICU

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Critical Care201216 (Suppl 1) :P423

  • Published:


  • Heparin
  • Thrombocytopenia
  • Economic Burden
  • Clinical Suspicion
  • Unfractionated Heparin


Clinical suspicion of heparin-induced thrombocytopenia (HIT) may prompt changes in drug management and alert clinicians to an increased risk of thrombosis. However, thrombocytopenia in the ICU occurs in about 50% of patients, is multifactorial and is due to HIT in <1%. We aimed to describe the consequences of suspected HIT among medical-surgical critically ill patients in terms of drug and device management, and thrombotic outcomes.


We enrolled 3,746 patients in the PROTECT trial comparing prophylactic dalteparin to unfractionated heparin. We defined HIT as occurring in patients with a clinical or laboratory-driven suspicion of HIT and a positive serotonin release assay (SRA). We defined suspected HIT as patients whose clinicians were sufficiently concerned about HIT to withhold heparin. We defined consequences of HIT as occurring from 1 day before it was suspected to 30 days thereafter.


One hundred and thirty patients (3.5%) had heparin held due to clinical suspicion of HIT. Of these, 10 (7.7%) had a positive SRA test. The drugs and devices used for thromboprophylaxis, as well as thrombotic events, are outlined in Table 1. At least one new thrombotic event developed in 23.8% of patients with suspected HIT and 40.0% of patients with HIT.
Table 1

(abstract P423)


1 day before to 30 days after heparin held for suspect HIT




34 (26.2)


8 (6.2)


11 (8.5)


19 (14.6)

   Any of the above drugs

67 (51.5)

   Anti-embolic stockings

25 (19.2)

   Pneumatic compression device

37 (28.5)

   Anti-embolic stockings or pneumatic compression device

49 (37.7)

   Any of the above interventions

96 (73.8)

Incident thromboses


   Venous thrombosis (including PE)

30 (23.1)

   Arterial thrombosis

1 (0.8)

   Progression of a previous thrombus

2 (1.5)

   Any of the above

31 (23.8)


Over 90% of patients with suspected HIT did not have HIT. One-half of patients with suspected HIT were prescribed another anticoagulant and one-third received mechanical prophylaxis. Thrombotic rates are higher in patients with HIT and suspected HIT than other patients. The frequent suspicion of HIT in critically ill patients and initiation of other interventions may create a greater clinical and economic burden than HIT itself.

Authors’ Affiliations

King's College London, London, UK
University of Ottawa, Ottawa, Canada
CHA-Hôpital de l'Enfant-Jésus, Université Laval, Québec, Canada
King AbdulAziz University, Jeddah, Saudi Arabia
King Faisal Hospital, Jeddah, Saudi Arabia
University of British Columbia, Vancouver, Canada
Université de Montréal, Montréal, Canada
Université McGill, Montréal, Canada
University of Alberta, Edmonton, Canada
University of Toronto, Toronto, Canada
The George Institute, Sidney, Australia
McMaster University, Hamilton, Canada


© Ostermann et al.; licensee BioMed Central Ltd. 2012

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.