Clinical Trial: Optimizing the Diagnosis of Heparin Induced Thrombocytopenia

Study Status: Not yet recruiting
Recruit Status: Not yet recruiting
Study Type: Interventional

Official Title: Optimizing the Diagnosis of Heparin Induced Thrombocytopenia Using Quantified Anti-Platelet Factor 4 Immunological Testing: A Pilot Multicentre Cohort Study

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.

Detailed Summary: 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.
Sponsor: Ottawa Hospital Research Institute

Current Primary Outcome:

  • 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.
  • 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).


Original Primary Outcome: Same as current

Current Secondary Outcome:

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


Original Secondary Outcome: Same as current

Information By: Ottawa Hospital Research Institute

Dates:
Date Received: April 10, 2017
Date Started: June 2017
Date Completion: September 2019
Last Updated: May 8, 2017
Last Verified: May 2017