Clinical Trial: Platelet Function in Patients With Hemophilia A

Study Status: Enrolling by invitation
Recruit Status: Enrolling by invitation
Study Type: Observational

Official Title: Decreased Platelet Function as a Cause of Increased Bleeding in Patients With Hemophilia A

Brief Summary:

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.


Detailed Summary:
Sponsor: Boston Children’s Hospital

Current Primary Outcome: The percentage of coated platelets. [ Time Frame: 2 years ]

Original Primary Outcome: Determine whether the percentage of coated platelets in severe hemophilia A patients is associated with past bleeding frequency and/or predicts future bleeding frequency. [ Time Frame: 2 years ]

Current Secondary Outcome:

  • Platelet reactivity. [ Time Frame: 2 years ]
  • The number of procoagulant platelet-derived microparticles. [ Time Frame: 2 years ]


Original Secondary Outcome:

  • Determine whether platelet reactivity in severe hemophilia A patients is associated with past bleeding frequency and/or predicts future bleeding frequency. [ Time Frame: 2 years ]
  • Determine whether the number of procoagulant platelet-derived microparticles in severe hemophilia A patients is associated with past bleeding frequency and/or predicts future bleeding frequency. [ Time Frame: 2 years ]
  • Determine whether the level of FVIII bound to platelets in severe hemophilia A patients is associated with past bleeding frequency and/or predicts future bleeding frequency. [ Time Frame: 2 years ]


Information By: Boston Children’s Hospital

Dates:
Date Received: March 19, 2014
Date Started: March 2015
Date Completion:
Last Updated: January 30, 2017
Last Verified: January 2017