Platelet Function in Patients With Hemophilia A

This study is enrolling participants by invitation only.
Baxter Healthcare Corporation
Information provided by (Responsible Party):
Alan D. Michelson, Children's Hospital Boston Identifier:
First received: March 19, 2014
Last updated: September 4, 2015
Last verified: September 2015

Abnormalities in the gene encoding Factor VIII (FVIII) results in hemophilia A, an X-linked recessive bleeding disorder with a prevalence of 1 in 5000 males. Hemophilia A patients are classified into 3 different categories based on residual FVIII activity compared to normal: mild (6-40%), moderate (1-5%) and severe (<1%). This categorization correlates to some degree with bleeding phenotype, but does not completely define it. Some patients with hemophilia A bleed less often than others despite identical plasma FVIII levels. The cause(s) of this phenotype heterogeneity in hemophilia A remains largely unknown, despite a number of studies of possible factors.

Activated platelets, in addition to their role in primary hemostasis, play a major role in secondary hemostasis (coagulation) by providing a phospholipid surface to which coagulation factors bind. A role for platelets in the hemorrhagic propensity of hemophilia A has been suggested in the past, but only a small number of studies have been performed with limitations in assays performed and numbers of patients. The purpose of the present study is to determine whether platelet reactivity in severe hemophilia A patients is associated with past bleeding frequency and/or predicts future bleeding frequency.

Hemophilia A

Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Prospective
Official Title: Decreased Platelet Function as a Cause of Increased Bleeding in Patients With Hemophilia A

Resource links provided by NLM:

Further study details as provided by Children's Hospital Boston:

Primary Outcome Measures:
  • The percentage of coated platelets. [ Time Frame: 2 years ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Platelet reactivity. [ Time Frame: 2 years ] [ Designated as safety issue: No ]
  • The number of procoagulant platelet-derived microparticles. [ Time Frame: 2 years ] [ Designated as safety issue: No ]
  • The level of FVIII bound to platelets. [ Time Frame: 2 years ] [ Designated as safety issue: No ]

Biospecimen Retention:   Samples With DNA
whole blood

Estimated Enrollment: 36
Study Start Date: March 2015
Estimated Primary Completion Date: May 2016 (Final data collection date for primary outcome measure)

Ages Eligible for Study:   2 Years to 18 Years
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Patients with severe hemophilia A who do not have inhibitors against FVIII and who have a bleeding history of at least 6 months.

Inclusion Criteria:

  • Patients with severe hemophilia A who are being prophylactically treated with FVIII.
  • Age of at least 2 years.
  • Bleeding history of at least 6 months.
  • IRB-approved informed consent.

Exclusion Criteria:

  • Presence of FVIII inhibitors.
  • Greater than 7 days since active bleeding.
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Please refer to this study by its identifier: NCT02093065

United States, Massachusetts
Boston Children's Hospital, Boston Hemophilia Center
Boston, Massachusetts, United States, 02115
Sponsors and Collaborators
Children's Hospital Boston
Baxter Healthcare Corporation
Principal Investigator: Alan D Michelson, MD Children's Hospital Boston
  More Information

Responsible Party: Alan D. Michelson, Professor of Pediatrics and Professor of Medicine, Harvard Medical School Director, Center for Platelet Research Studies Director, Thrombosis and Anticoagulation Program Boston Children's Hospital / Dana-Farber Cancer Institute, Children's Hospital Boston Identifier: NCT02093065     History of Changes
Other Study ID Numbers: BCH-CPRS-hemophilia A 
Study First Received: March 19, 2014
Last Updated: September 4, 2015
Health Authority: United States: Institutional Review Board

Keywords provided by Children's Hospital Boston:
severe hemophilia A
coated platelets

Additional relevant MeSH terms:
Hemophilia A
Blood Coagulation Disorders
Blood Coagulation Disorders, Inherited
Coagulation Protein Disorders
Genetic Diseases, Inborn
Hematologic Diseases
Hemorrhagic Disorders
Factor VIII
Coagulants processed this record on May 30, 2016