Hydroxyurea to Prevent Stroke in Children With Sickle Cell Anemia and Elevated TCD Flow Velocity

June 17, 2013 updated by: Duke University

Effects of Hydroxyurea on the Prevention of Primary Stroke in Children With Sickle Cell Anemia and Elevated Transcranial Doppler (TCD) Flow Velocity

The purpose of this study is to assess prospectively the efficacy of hydroxyurea therapy in the setting of cerebrovascular disease, manifest as conditional or abnormal transcranial doppler ultrasonography (TCD) flow velocities, in children with sickle cell anemia (SCA). TCD is used to measure flow velocity in intracranial arteries as a marker of increased stroke risk in children with SCA. The primary objective of this protocol is to determine whether hydroxyurea reduces elevated TCD velocity.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The purpose of this study is to assess prospectively the efficacy of hydroxyurea therapy in the setting of cerebrovascular disease, manifest as conditional or abnormal transcranial doppler ultrasonography (TCD) flow velocities, in children with sickle cell anemia (SCA). TCD is used to measure flow velocity in intracranial arteries as a marker of increased stroke risk in children with SCA. The primary objective of this protocol is to determine whether hydroxyurea reduces elevated TCD velocity.

The STOP (Stroke Prevention in Sickle Cell Anemia) trial, a multicenter, randomized, controlled trial for primary stroke demonstrated that monthly blood transfusions, when compared to observation alone, significantly reduced the risk of primary stroke for children with SCA whose TCD velocity exceeded 200 cm/sec. Despite the STOP trial's clear results, there are unresolved issues regarding TCD and stroke risk in children with SCA. First, the predictive value of an abnormal result is not compelling since less than a third of children with an abnormal TCD velocity and even fewer with conditional results will ever develop a clinical stroke. There is also discordance between TCD and MRI results. Only 40% of children with abnormal TCD velocity will have abnormalities on brain MRI (Wang, et al. J Pediatr Hematol/Oncol 2000;22(4):335-339, Pegelow, et al. Arch Neurol 2001;58:2017-2021). There are also well recognized risks of chronic blood transfusions, including iron overload and alloimmunization, and the necessary duration of transfusion protection for children with abnormal TCD velocity is unknown. Unfortunately, there are currently no therapeutic options besides blood transfusions for patients with SCA and an abnormal TCD velocity.

Erythrocyte transfusions and hydroxyurea have many similar beneficial effects in patients with SCA. Transfusions may prevent primary stroke by lowering the % HbS, by increasing the hematocrit, by improving red cell rheology, by decreasing red cell adhesion, and by lowering TCD velocity. Hydroxyurea leads to many of the same changes, thus in this protocol, we will examine whether hydroxyurea, like transfusions, can lower TCD velocity. In our patients with SCA who have been screened with TCD ultrasonography, we have observed that children who were screened while receiving hydroxyurea had lower TCD velocity measurements than those who were not on hydroxyurea. In a small number of patients with TCD velocity measurements before and after initiation of hydroxyurea for non-neurological reasons, the TCD velocity declined significantly after achieving full dose hydroxyurea therapy. The changes in TCD velocity were correlated with changes in hematocrit since hydroxyurea increases blood counts in patients with SCA. For each % increase in hematocrit, the TCD velocity increased by 6.3 cm/sec. This was similar to an abstract from the STOP trial, in which TCD flow velocity declined by 7.9 cm/sec for each increase in % hematocrit from transfusions.

Based on this preliminary data, we initiated this prospective, single-institution, pilot trial to determine whether hydroxyurea therapy lowers TCD flow velocity in children with sickle cell anemia.

Study Type

Interventional

Enrollment

50

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • North Carolina
      • Durham, North Carolina, United States, 27710
        • Duke University Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

3 years to 18 years (Child, Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Children with Sickle Cell Anemia
  • Aged 3 to 18 years
  • Confirmed TCD velocity greater than or equal to 140cm/sec
  • Negative serum pregnancy test for subjects of childbearing potential
  • Decline transfusions (for subjects with TCD velocity greater than or equal to 200 cm/sec)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Change in TCD flow velocity

Secondary Outcome Measures

Outcome Measure
Stroke

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Duke University

Investigators

  • Principal Investigator: Sherri Zimmerman, MD, Duke University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

April 1, 2003

Study Completion

March 1, 2006

Study Registration Dates

First Submitted

November 21, 2006

First Submitted That Met QC Criteria

November 21, 2006

First Posted (Estimate)

November 22, 2006

Study Record Updates

Last Update Posted (Estimate)

June 19, 2013

Last Update Submitted That Met QC Criteria

June 17, 2013

Last Verified

November 1, 2006

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 4744

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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