Heparin-Induced Thrombocytopenia - Retrospective Analysis of Data on Incidence and Outcomes Study (HIT-RADIO)

• Time to occurrence of a composite triple endpoint consisting of death, limb amputation/gangrene, and new thrombosis [ Time Frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge or day 45, whichever occurred first. ] [ Designated as safety issue: No ]
  

• Time to occurrence of radiographically confirmed thromboembolism [ Time Frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first ] [ Designated as safety issue: No ]
  
• Time to death [ Time Frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first ] [ Designated as safety issue: No ]
  
• Time to occurrence of limb amputation or limb gangrene [ Time Frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first ] [ Designated as safety issue: No ]
  
• Proportion of subjects with HIT with thrombosis (HIT-T) and isolated HIT [ Time Frame: From the date 5 days before the positive heparin PF-4 antibody test was drawn to the date it was drawn ] [ Designated as safety issue: No ]

  Proportion of subjects who, at the time the positive heparin PF-4 antibody test was drawn, were in each of the following categories:

  • Group 1: Those with both thrombosis and thrombocytopenia (HIT-T)
  • Group 2: Those with thrombosis but not thrombocytopenia (HIT-T)
  • Group 3: Those with thrombocytopenia but not thrombosis (Isolated HIT)
  • Group 4: Those with neither thrombocytopenia nor thrombosis (Neither HIT-T nor Isolated HIT)
  
  
• Type of heparin exposure [ Time Frame: Hospital admission to date the positive heparin PF-4 antibody test was drawn, or 28 days prior to the date it was drawn, whichever is later, through the date it was drawn ] [ Designated as safety issue: No ]
  
• Relationship of the heparin PF-4 antibody titer to the clinical diagnosis, degree of thrombocytopenia, and the primary endpoint [ Time Frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first ] [ Designated as safety issue: No ]
  
• Type of treatment provided to subjects in hospital and at the time of discharge [ Time Frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first ] [ Designated as safety issue: No ]
  Types of treatment (direct thrombin inhibitor, fondaparinux, warfarin, no treatment) provided to subjects in hospital and at the time of discharge
  
  
• Time to platelet recovery, among subjects with a low platelet count when the positive PF4 antibody test was drawn [ Time Frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first ] [ Designated as safety issue: No ]
  
• Time to occurrence of major bleeding [ Time Frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first ] [ Designated as safety issue: No ]
  Time to occurrence of major bleeding. A major bleeding event is defined as any 24 hour period in which 2 or more units of RBC are transfused OR radiographically confirmed intracranial hemorrhage.
  
  

HIT-RADIO is a retrospective chart-review study of patients who had a positive heparin PF-4 antibody test between 1/21/2008 and 9/25/2008 at selected hospitals associated with the Transfusion Medicine/Hemostasis Clinical Trials Network .

Heparin-induced thrombocytopenia (HIT) is a major complication of the administration of heparin and can result in life-threatening thrombosis with or without thrombocytopenia (HIT-T) or can produce thrombocytopenia without clinically symptomatic thrombosis ("isolated" HIT). Isolated heparin-induced thrombocytopenia is defined as a fall in platelet count associated with a positive heparin PF-4 antibody test, in the absence of clinically overt thrombosis. While the treatment of HIT-T (HIT with thrombosis) with anticoagulation is well established, the risks and treatment of isolated HIT are unclear.

It is anticipated that this data analysis will provide a current overview of the implications of a positive heparin PF-4 antibody test in clinical practice. It should determine the percentage of positive heparin PF-4 antibody tests that are associated with thrombocytopenia and thrombosis (HIT-T) or "isolated" HIT at diagnosis and the subsequent major clinical outcomes of death, limb amputation/gangrene, and new thrombosis. No "snapshot" of such HIT patients has been conducted in the past decade and the results will be important in assessing the impact of HIT in current medical care as well as documenting current treatment strategies.