title: Prevalence, characteristics, and predictors of early termination of cardiovascular clinical trials due to low recruitment: insights from the ClinicalTrials.gov registry.
abstract: BACKGROUND
  Early termination of clinical trials due to low recruitment represents an understudied challenge for clinical research. We aimed to describe characteristics of cardiovascular trials terminated because of low recruitment and identify the major predictors of such early termination.
  
  
  METHODS
  We reviewed all cardiovascular clinical trials (7,042 studies) registered in ClinicalTrials.gov from February 29, 2000, to January 17, 2013, and assessed information about trials that were completed and those that were terminated early. Logistic regression models were developed to identify independent predictors of early termination due to low recruitment.
  
  
  RESULTS
  Our search strategy identified 6,279 cardiovascular clinical trials, of which 684 (10.9%) were terminated prematurely. Of these halted trials, the main reason for termination was lower than expected recruitment (278 trials; 53.6%). When comparing trials that terminated early because of low recruitment with those that were completed, we found that studies funded by the National Institutes of Health or other US federal agencies (odds ratio [OR] 0.35, 95% confidence interval [CI] 0.14-0.89), studies of behavior/diet intervention (OR 0.35, 95% CI 0.19-0.65), and single-arm design studies (OR 0.57, 95% CI 0.42-0.78) were associated with a lower risk of early termination. University/hospital-funded (OR 1.52, 95% CI 1.10-2.10) and mixed-source-funded studies (OR 2.14, 95% CI 1.52-3.01) were associated with a higher likelihood of early termination due to lower than expected recruitment rates.
  
  
  CONCLUSIONS
  Low recruitment represents the main cause of early termination of cardiovascular clinical trials. Funding source, type of intervention, and study design are factors associated with early termination due to low recruitment and might be good targets for improving enrollment into cardiovascular clinical trials.
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil; Fluminense Federal University, Niteroi, Rio de Janeiro, Brazil.
authors: Sabrina
authors: S
authors: Bernardez-Pereira
authors: Duke Clinical Research Institute, Duke University Medical Center, Durham, NC; Brazilian Clinical Research Institute, Sao Paulo, Brazil.
authors: Renato D
authors: RD
authors: Lopes
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Maria Julia Machline
authors: MJ
authors: Carrion
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Eliana Vieira
authors: EV
authors: Santucci
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Rafael Marques
authors: RM
authors: Soares
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Matheus
authors: M
authors: de Oliveira Abreu
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Ligia Nasi
authors: LN
authors: Laranjeira
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Dimas T
authors: DT
authors: Ikeoka
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Ana Denise
authors: AD
authors: Zazula
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Frederico Rafael
authors: FR
authors: Moreira
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil.
authors: Alexandre Biasi
authors: AB
authors: Cavalcanti
authors: Fluminense Federal University, Niteroi, Rio de Janeiro, Brazil.
authors: Evandro Tinoco
authors: ET
authors: Mesquita
authors: Duke Clinical Research Institute, Duke University Medical Center, Durham, NC.
authors: Eric D
authors: ED
authors: Peterson
authors: Duke Translational Medicine Institute, Duke University Medical Center, Durham, NC.
authors: Robert M
authors: RM
authors: Califf
authors: Research Institute, HCOR-Hospital do Coração, Sao Paulo, Brazil. Electronic address: oberwanger@hcor.com.br.
authors: Otavio
authors: O
authors: Berwanger
mesh_terms: D000328:Adult; D002318:Cardiovascular Diseases; D002986:Clinical Trials as Topic; D057239:Early Termination of Clinical Trials / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009317:National Library of Medicine (U.S.); D018579:Patient Selection; D015995:Prevalence; D012042:Registries / Q000706:statistics & numerical data; D015983:Selection Bias; D014481:United States