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Pediatrics:Chlamydia, Sickle Cell Anemia and Stroke Risk - Ancillary to STOP II

This study has been completed.
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI) Identifier:
First received: May 16, 2002
Last updated: July 28, 2016
Last verified: January 2008
To establish a link among Chlamydia infection, sickle cell anemia, and stroke risk.

Blood Disease Anemia, Sickle Cell Chlamydia Infections Cerebrovascular Accident

Study Type: Observational
Study Design: Time Perspective: Retrospective

Resource links provided by NLM:

Further study details as provided by National Heart, Lung, and Blood Institute (NHLBI):

Study Start Date: July 2004
Study Completion Date: June 2006
Primary Completion Date: June 2006 (Final data collection date for primary outcome measure)
Detailed Description:


Infection with Chlamydia pneumoniae (C. pneumoniae) is associated with an increased risk of cerebrovascular disease in the general population. Children with sickle cell anemia (SCA) are 200 times more likely to have cerebrovascular disease than normal children and are known to have an altered immune response to many infectious pathogens. C. pneumoniae is the leading infectious cause of acute chest syndrome which, interestingly, is a well- established risk factor for stroke in children with SCA. Preliminary data indicates that SCA patients with magnetic resonance imaging (MRI)-documented cerebral infarction are 12 times more likely to have C. pneumoniae infection than SCA patients with normal MRI scans. The investigators hypothesize that SCA patients have an abnormal immune response to C. pneumoniae that results in persistent infection which, in turn, triggers the development of cerebrovascular disease. Sickle cell anemia patients with an elevated velocity on transcranial doppler ultrasound (TCD) are known to be at high risk to develop stroke and an elevated TCD likely reflects underlying vascular disease. In addition, the Stroke Prevention in Sickle Cell Anemia Trial (STOP) demonstrated that almost 40 percent of children with an elevated TCD have evidence of cerebral infarction on MRI. Children with abnormal TCDs are, therefore, an appropriate population to investigate an association between cerebrovascular disease and C. pneumoniae infection.

The study is in response to an initiative on Ancillary Studies in Heart, Lung, and Blood Disease Trials released in June, 2000.


The study is ancillary to the STOP II clinical trial. The intent is: 1) To determine if C. pneumoniae infection is associated with cerebral infarction in children with SCA; 2) To characterize the immunological response to C. pneumoniae infection in patients with SCA. Establishing a link between C.pneumoniae infection and cerebral infarction will open the door to novel, less toxic approaches to the treatment and prevention of stroke in SCA, including antibiotics and vaccines.


Ages Eligible for Study:   up to 100 Years   (Child, Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
No eligibility criteria
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00037388

Sponsors and Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
OverallOfficial: Lori Styles Children's Hospital & Research Center Oakland
  More Information Identifier: NCT00037388     History of Changes
Other Study ID Numbers: 1167
R01HL069114 ( U.S. NIH Grant/Contract )
Study First Received: May 16, 2002
Last Updated: July 28, 2016

Additional relevant MeSH terms:
Chlamydia Infections
Anemia, Sickle Cell
Hematologic Diseases
Cerebrovascular Disorders
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases
Vascular Diseases
Cardiovascular Diseases
Chlamydiaceae Infections
Gram-Negative Bacterial Infections
Bacterial Infections
Sexually Transmitted Diseases, Bacterial
Sexually Transmitted Diseases
Genital Diseases, Male
Genital Diseases, Female
Anemia, Hemolytic, Congenital
Anemia, Hemolytic
Genetic Diseases, Inborn processed this record on September 20, 2017