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Completed

NCT Number: NCT01178333

Heparin-Induced Thrombocytopenia - Retrospective Analysis of Data on Incidence and Outcomes Study

HIT-RADIO is a study of patients who had a positive heparin PF-4 antibody test between 1/21/2008 and 9/25/2008 at selected hospitals. The study will collect and analyse information that is already in the patients' medical records. Information about laboratory values (such as platelet counts), treatments (such as medications), and outcomes (such as blood clots, amputation, and death) will be included.

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Key information

Conditions

Heparin Induced Thrombocytopenia Blood Platelet Disorders Cytopenia Hematologic Diseases Hemic and Lymphatic Diseases Thrombocytopenia

Sex eligibility

All sexes

Study type

Observational

Primary location

University of Iowa, Iowa City, Iowa, United States

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About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • All subjects with a positive heparin PF-4 antibody test occurring between 1/21/2008 and 9/25/2008
  • Medical record available for the admission during which the positive heparin PF-4 antibody test was obtained

Exclusion criteria

  • None

Treatment and study plan

Primary outcomes

  1. 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.

    The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias.

  2. 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.

    The median survival time is reported by each group for the time to occurrence of a composite triple endpoint consisting of death, limb amputation/gangrene, and new thrombosis.

Secondary outcomes

  1. 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

    The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias.

  2. 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

    The median survival time is reported by each group for the time to death.

  3. 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

    Due to the small number of events, the median or mean survival time could not be defined. Therefore, the number of subjects with limb amputation or limb gangrene was reported in "Outcome Measure Data Table".

  4. 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

    The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias. However, the median survival times could not be defined for all three groups, so the mean time was reported in "Outcome Measure Data Table".

  5. 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

    The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias.

  6. 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

    The median survival time is reported by each group for the time to occurrence of major bleeding.

  7. 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

    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 thrombosis and or without thrombocytopenia (HIT-T): 16% of 442 subjects.
    • Group 2: Those with thrombocytopenia but not thrombosis (Isolated HIT): 64% of 442 subjects.
    • Group 3: Those with neither thrombocytopenia nor thrombosis (Neither HIT-T nor Isolated HIT): 20% of 442 subjects.

  8. Type of Heparin Exposure - Unfractionated Heparin (UFH)

    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

    Two types of heparins are commonly used as anticoagulants - unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH). UFH has been used for the prevention and treatment of thrombosis for several decades.

  9. Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH)

    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

    Two types of heparins are commonly used as anticoagulants - unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH). LMWHs are derived from UFH by depolymerization. Each LMWH product has a specific molecular weight distribution that determines its anticoagulant activity and duration of action.

  10. Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis

    Time frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

    Heparin PF-4 (platelet factor 4) optical density (OD) test results were the dichotomous outcome (<1.0 vs. >=1.0). Clinical diagnosis was three groups (HIT-T, Isolated HIT and No HIT). The Heparin PF-4 optical density test looks for antibodies to complexes of heparin combined with platelet factor 4. Higher optical density indicates higher antibody concentration. We could say that generally OD values above 0.4 are considered a positive result, and that the higher the OD, the greater the concentration of antibodies in the patient's blood.

  11. Relationship of the Heparin PF-4 Antibody Titer to the Degree of Thrombocytopenia

    Time frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

    Heparin PF-4 optical density (OD) test results were the dichotomous outcome (<1.0 vs. >=1.0). Nadir Platelet Count (x10^9 / L) was used for the degree of thrombocytopenia. The Heparin PF-4 optical density test looks for antibodies to complexes of heparin combined with platelet factor 4. Higher optical density indicates higher antibody concentration. We could say that generally OD values above 0.4 are considered a positive result, and that the higher the OD, the greater the concentration of antibodies in the patient's blood.

  12. Relationship of the Heparin PF-4 Antibody Titer to 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

    Heparin PF-4 OD test results were the dichotomous outcome (<1.0 vs. >=1.0). Primary endpoint was the composite endpoint of death, limb amputation/gangrene, or new thrombosis.

  13. Use of Treatment (Non-heparin Anticoagulant) Used in Hospital

    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

    Types of treatment (direct thrombin inhibitor, fondaparinux, warfarin, no treatment) provided to subjects in hospital

  14. Use of Treatment (Non-heparin Anticoagulant) Used 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

  15. 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 nadir platelet count was drawn until hospital discharge, death, or day 45, whichever occurred first

Sponsors and collaborators

Lead sponsor

Carelon Research

Other

Collaborators

  • National Heart, Lung, and Blood Institute (NHLBI)

Registry information

Official study title

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

Acronym: HIT-RADIO

Important dates

Study start
2010
Primary completion
2010
Study completion
2010
First posted
Aug 10, 2010
Registry last updated
May 22, 2015

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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