Validating 4Ts for Heparin Induced Thrombocytopenia (HIT)

Prospectively Validating the 4Ts and Chong Score for Heparin Induced Thrombocytopenia

The purpose of this study is to evaluate a scoring tool to help determine the presence of Heparin Induced Thrombocytopenia (HIT), which is an adverse reaction to heparin. We hypothesize that this scoring tool will be very useful in excluding patients who are suspected of having HIT.

Study Overview

• Status: Unknown
• Conditions: Heparin-Induced Thrombocytopenia
• Intervention / Treatment: Other: Scoring 4Ts and Chong scale; Other: Blood draw

Detailed Description

HIT is an immune response to heparin that can result in thrombogenic thrombocytopenia. It is often a difficult diagnosis to make, and its diagnosis is dependent upon both clinical and serologic criteria. Due to this ambiguity, increased testing and treatment may occur until serologic test results return. Recently, scoring tools have been developed to assist with the diagnosis of this disease. However, these scoring tools have yet to be validated. Thus, we plan to conduct a prospective, observational study to validate two scoring tools, the 4Ts and the Chong scale, in the diagnosis of HIT.

In order to validate these scoring tools, two physicians will independently score the 4Ts and the Chong scale for all patients suspected of having HIT. These patients will be identified if a physician has ordered HIT antibody testing using the enzyme immunoassay (EIA) method. Confirmatory testing with a serotonin release assay (SRA) will also be performed.

• Study Type: Observational
• Enrollment (Anticipated): 500

Contacts and Locations

Study Locations

• United States
  • District of Columbia
    • Washington, District of Columbia, United States, 20010
      • Washington Hospital Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

For this study, patients already admitted to the hospital whose physician suspects the presence of HIT will be recruited for this study. Specifically, the trigger for recruitment include patients who have a HIT antibody test ordered.

Description

Inclusion Criteria:

• Patients with suspected HIT.

Exclusion Criteria:

• None.

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Suspected HIT; Those who are clinically suspected of having HIT will be enrolled in this study.	Other: Scoring 4Ts and Chong scale; Two physicians will independently score both the 4Ts and the Chong scale on all patients enrolled in this study.; Other: Blood draw; Patient serum will be collected to perform Serotonin Release Assay testing to verify the presence of HIT.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
To validate the 4Ts as a pretest probability tool for HIT.	End of study.
To validate the Chong scale as a tool to determine the post-test probability for HIT.	End of study.

Secondary Outcome Measures

Outcome Measure	Time Frame
To determine the inter-rater variability for scoring the 4Ts.	End of study.
To determine the inter-rater variability for scoring the Chong scale.	End of study.

Collaborators and Investigators

• Sponsor: Medstar Health Research Institute
• Collaborators: GlaxoSmithKline
• Investigators: Principal Investigator: Chee M Chan, MD, Medstar Health Research Institute; Study Director: Andrew F Shorr, MD, MPH, Medstar Health Research Institute

Publications and helpful links

General Publications

• Lo GK, Juhl D, Warkentin TE, Sigouin CS, Eichler P, Greinacher A. Evaluation of pretest clinical score (4 T's) for the diagnosis of heparin-induced thrombocytopenia in two clinical settings. J Thromb Haemost. 2006 Apr;4(4):759-65. doi: 10.1111/j.1538-7836.2006.01787.x.
• Chong BH, Chong JJ. Heparin-induced thrombocytopenia. Expert Rev Cardiovasc Ther. 2004 Jul;2(4):547-59. doi: 10.1586/14779072.2.4.547.
• Chan CM, Woods CJ, Warkentin TE, Sheppard JI, Shorr AF. The Role for Optical Density in Heparin-Induced Thrombocytopenia: A Cohort Study. Chest. 2015 Jul;148(1):55-61. doi: 10.1378/chest.14-1417.

Study record dates

Study Major Dates

• Study Start: August 1, 2009

Study Registration Dates

• First Submitted: July 24, 2009
• First Submitted That Met QC Criteria: July 24, 2009
• First Posted (Estimate): July 27, 2009

Study Record Updates

• Last Update Posted (Estimate): July 27, 2009
• Last Update Submitted That Met QC Criteria: July 24, 2009
• Last Verified: July 1, 2009

More Information

Terms related to this study

• Keywords: HIT; Heparin-induced thrombocytopenia; 4Ts; Chong scale; interobserver variability
• Additional Relevant MeSH Terms: Hematologic Diseases; Blood Platelet Disorders; Thrombocytopenia
• Other Study ID Numbers: 2009-202