An Improved Definition of Immune Heparin-Induced Thrombocytopenia in Postoperative Orthopedic Patients

  • Warkentin T
  • Roberts R
  • Hirsh J
 et al. 
  • 29


    Mendeley users who have this article in their library.
  • 227


    Citations of this article.


BACKGROUND: Diagnosis of immune heparin-induced thrombocytopenia (HIT) is usually based on a fall in platelet count below 150 x 109/L (standard definition of thrombocytopenia). However, this definition may be inappropriate for postoperative patients who often develop postoperative thrombocytosis. We sought to determine an improved definition of thrombocytopenia indicating HIT in postoperative orthopedic patients, including its impact on frequency and thrombotic risk of HIT. METHODS: We performed a secondary analysis of a clinical trial of 665 patients who received unfractionated or low-molecular-weight heparin following elective hip arthroplasty. Daily platelet counts and objective studies for deep vein thrombosis were performed in all patients. Laboratory detection of HIT antibodies from a 362-patient subgroup was used to define sensitivity and specificity of various definitions of thrombocytopenia to indicate HIT. RESULTS: The improved definition of HIT was a 50% or greater platelet count fall from the postoperative peak, as this definition had greater sensitivity (50% vs 25%) and similar high specificity (99.1% vs 99.4%) for detecting HIT-IgG compared with the standard definition. Patients with HIT who were identified using the improved definition had a higher frequency of thrombosis than patients without HIT (72.2% vs 17.3%; P

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Theodore E. Warkentin

  • Robin S. Roberts

  • Jack Hirsh

  • John G. Kelton

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free