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Optimizing the Diagnosis of Heparin Induced Thrombocytopenia (HIT)

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ClinicalTrials.gov Identifier: NCT03148912
Recruitment Status : Recruiting
First Posted : May 11, 2017
Last Update Posted : February 24, 2021
Information provided by (Responsible Party):
Ottawa Hospital Research Institute

Brief Summary:
Multicentre (Ottawa and Halifax) prospective cohort study using a diagnostic approach in patients clinically suspected to have HIT that combines pretest probability assessment with quantitative interpretation of anti-PF4 assay.

Condition or disease Intervention/treatment Phase
Heparin-induced Thrombocytopenia (HIT) Diagnostic Test: Diagnostic algorithm Not Applicable

Detailed Description:
The proposed is a prospective cohort study exploring a novel diagnostic approach to Heparin Induced Thrombocytopenia (HIT) using a combination of pretest probability assessment and quantitative interpretation of the anti-platelet factor 4 Immunological assay (anti-PF4). Patient with a clinical suspicion of HIT will follow the study diagnostic algorithm (Figure 1). The study algorithm will be considered a safe approach to move forward into a larger RCT if the upper limit of the 95% confidence interval for 'false negative management failures' is ≤ 4% based on a Serotonin Release Assay (SRA) gold standard. The main objective of the pilot study is to inform feasibility and recruitment barriers for a larger randomized control trial.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 180 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Official Title: Optimizing the Diagnosis of Heparin Induced Thrombocytopenia Using Quantified Anti-Platelet Factor 4 Immunological Testing: A Pilot Multicentre Cohort Study
Actual Study Start Date : November 23, 2018
Estimated Primary Completion Date : December 2021
Estimated Study Completion Date : December 2022

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Blood Thinners

Arm Intervention/treatment
Experimental: diagnostic algorithm
Optimizing the interpretation of the more readily available anti-PF4 assay would reduce the reliance on functional testing/ confirmatory testing (Serotonin Release Assay, SRA) and the number of patients exposed to unnecessary changes in anticoagulation therapy while awaiting the timely functional test results
Diagnostic Test: Diagnostic algorithm
The treating physician will complete an enrollment assessment including the 4T score pretest probability assessment14. All patients will have laboratory testing for HIT anti-PF4 as well as SRA testing. Results of the anti-PF4 assay (OD value) will be available to the treating physician who will be instructed to follow the study diagnostic algorithm

Primary Outcome Measures :
  1. Recruitment [ Time Frame: 2 years ]
    The pilot will be considered feasible if recruitment of at least 7.5 patients per month (total between the two sites) is achieved.

  2. False negative management failures [ Time Frame: 2 years ]
    The rate of false negative 'management failures' where the study protocol concludes HIT unlikely but SRA (reference standard laboratory test) is positive for HIT (≥50% Serotonin release).

Secondary Outcome Measures :
  1. Major arterial and venous thromboembolism events [ Time Frame: 24 hours of baseline and 24 of study enrolment ]
    Events will be ascertained from the date of study consent. However, venous or arterial thrombotic events detected on investigations ordered within 24 hours of study entry will be captured as baseline events and will be counted separately from thrombotic events which occur after the initial 24 hours of study enrolment.

  2. Proximal deep vein thrombosis [ Time Frame: 2 years ]
    Testing performed because of symptoms in a patient with (new) non-compressibility of the common femoral vein, popliteal vein or calf trifurcation vein of the leg on ultrasound; or new non-compressibility or visualization of thrombus in the jugular vein, subclavian vein or axillary vein on ultrasound; or an intraluminal defect seen in one more than one view in proximal leg or arm veins on venography will be diagnostic for deep vein thrombosis.

  3. Pulmonary embolism [ Time Frame: 2 years ]
    Testing performed because of symptoms in a patient with a high probability lung scan (i.e. at least one segmental perfusion mismatch) or CT pulmonary angiography (i.e. intraluminal filling defect in the main, lobar or segmental pulmonary arteries) will be diagnostic for pulmonary embolism.

  4. Stroke [ Time Frame: 2 years ]
    New infarction or hemorrhagic event confirmed on CT or MRI.

  5. Myocardial infarction [ Time Frame: 2 years ]
    Detection of rise and/or fall of cardiac biomarkers (preferably troponin) with at least one value above the 99th percentile of the upper reference limit together with evidence of myocardial ischemia with at least one of the following: Symptoms of ischemia for ≥ 20 minutes ECG changes indicative of new ischemia: new ST-T changes ≥0.1 mV or new left bundle branch block Development of pathological Q waves in the ECG; Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality.

  6. Systemic arterial embolism [ Time Frame: 2 years ]
    Acute vascular occlusion confirmed on ultrasound or angiography Adrenal hemorrhagic infarction (indicating adrenal vein thrombosis) - radiologic diagnosis on ultrasound or CT.

  7. Death [ Time Frame: 30 days of follow up ]
    Due to major arterial or venous thromboembolism within 30days of follow up and major and minor bleeding.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Patient with clinical suspicion of HIT by treating physician

Exclusion Criteria:

  1. Less than 18 years of age;
  2. Prior diagnosis of HIT ever;
  3. Patient enrolled within preceding 100 days;
  4. Functional/ confirmatory platelet activation results available at the time of enrollment;
  5. Requiring cardio-pulmonary bypass or percutaneous cardiac angioplasty or any other cardiac or vascular surgery/procedure requiring intra-operative/procedural heparin administration planned within 30 days;
  6. Unable to complete study follow up;
  7. Unable to obtain consent (or proxy consent from substitute decision maker where applicable);
  8. Life expectancy less than 30 days;
  9. Greater than 72 hours from clinical suspicion of HIT and/or request for HIT anti-PF4 ELISA testing.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03148912

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Contact: Chantal Rockwell, BA 613-737-8899 ext 73958 crockwell@ohri.ca

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Canada, Ontario
The Ottawa Hospital Recruiting
Ottawa, Ontario, Canada, KIH 8L6
Contact: Lisa Duffett, MSc., MD    613-737-8899 ext 71069    lduffett@toh.ca   
Contact: Chantal Rockwell, BA    613-737-8899 ext 73958    crockwell@ohri.ca   
Sponsors and Collaborators
Ottawa Hospital Research Institute
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Principal Investigator: Lisa Duffett, MSc, MD Ottawa Hospital Research Institute

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Responsible Party: Ottawa Hospital Research Institute
ClinicalTrials.gov Identifier: NCT03148912    
Other Study ID Numbers: IRIS6428
First Posted: May 11, 2017    Key Record Dates
Last Update Posted: February 24, 2021
Last Verified: February 2021
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Blood Platelet Disorders
Hematologic Diseases