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: January 18, 2008
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.


Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
No eligibility criteria
  Contacts and Locations
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Please refer to this study by its identifier: NCT00037388

Sponsors and Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
Investigator: Lori Styles Children's Hospital & Research Center Oakland
  More Information Identifier: NCT00037388     History of Changes
Other Study ID Numbers: 1167 
Study First Received: May 16, 2002
Last Updated: January 18, 2008
Health Authority: United States: Federal Government

Additional relevant MeSH terms:
Anemia, Sickle Cell
Chlamydia Infections
Hematologic Diseases
Anemia, Hemolytic
Anemia, Hemolytic, Congenital
Bacterial Infections
Brain Diseases
Cardiovascular Diseases
Central Nervous System Diseases
Cerebrovascular Disorders
Chlamydiaceae Infections
Genetic Diseases, Inborn
Genital Diseases, Female
Genital Diseases, Male
Gram-Negative Bacterial Infections
Nervous System Diseases
Sexually Transmitted Diseases
Sexually Transmitted Diseases, Bacterial
Vascular Diseases processed this record on May 23, 2016