title: Systematic review of interventional sickle cell trials registered in ClinicalTrials.gov.
abstract: OBJECTIVE
  The registry ClinicalTrials.gov was created to provide investigators and patients an accessible database of relevant clinical trials.
  
  
  METHODS
  To understand the state of sickle cell disease clinical trials, a comprehensive review of all 174 "closed," "interventional" sickle cell trials registered at ClinicalTrials.gov was completed in January 2015.
  
  
  RESULTS
  The majority of registered sickle cell disease clinical trials listed an academic center as the primary sponsor and were an early phase trial. The primary outcome for sickle cell disease trials focused on pain (23%), bone marrow transplant (BMT) (13%), hydroxyurea (8%), iron overload (8%), and pulmonary hypertension (8%). A total of 52 trials were listed as terminated or withdrawn, including 25 (14% of all trials) terminated for failure to enroll participants. At the time of this review, only 19 trials uploaded results and 29 trials uploaded a manuscript in the ClinicalTrials.gov database. A systematic review of pubmed.gov revealed that only 35% of sickle cell studies completed prior to 2014 resulted in an identified manuscript. In comparison, of 80 thalassemia trials registered in ClinicalTrials.gov, four acknowledged failure to enroll participants as a reason for trial termination or withdrawal, and 48 trials (60%) completed prior to 2014 resulted in a currently identified manuscript.
  
  
  CONCLUSIONS
  ClinicalTrials.gov can be an important database for investigators and patients with sickle cell disease to understand the current available research trials. To enhance the validity of the website, investigators must update their trial results and upload trial manuscripts into the database. This study, for the first time, quantifies outcomes of sickle cell disease trials and provides support to the belief that barriers exist to successful completion, publication, and dissemination of sickle cell trial results.
authors.affiliation: Division of Pediatric Hematology and Oncology, Department of Pediatrics, The University of Alabama at Birmingham, Birmingham, AL, USA jlebensburger@peds.uab.edu.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Lebensburger
authors.affiliation: Division of Pediatric Hematology and Oncology, Department of Pediatrics, The University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Lee M
authors.initials: LM
authors.lastname: Hilliard
authors.affiliation: Division of Pediatric Hematology and Oncology, Department of Pediatrics, The University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Pair
authors.affiliation: Division of Preventive Medicine, Department of Medicine, The University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Oster
authors.affiliation: Division of Pediatric Hematology and Oncology, Department of Pediatrics, The University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Howard
authors.affiliation: Department of Biostatistics, The University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Gary R
authors.initials: GR
authors.lastname: Cutter
mesh_terms: D000755:Anemia, Sickle Cell; D002986:Clinical Trials as Topic; D016208:Databases, Factual; D057239:Early Termination of Clinical Trials / Q000706:statistics & numerical data; D054625:Healthcare Disparities; D006801:Humans; D012042:Registries
keywords: Sickle cell disease; clinical trials; disparities research; thalassemia