title: A systematic review of discontinued trials suggested that most reasons for recruitment failure were preventable.
abstract: To collect and classify reported reasons for recruitment failure in discontinued randomized controlled trials (RCTs) and to assess reporting quality.
  
  
  
  We systematically searched MEDLINE and EMBASE (2010-2014) and a previous cohort of RCTs for published RCTs reporting trial discontinuation due to poor recruitment. Teams of two investigators selected eligible RCTs working independently and extracted information using standardized forms. We used an iterative approach to classify reasons for poor recruitment.
  
  
  
  We included 172 RCTs discontinued due to poor recruitment (including 26 conference abstracts and 63 industry-funded RCTs). Of those, 131 (76%) reported one or more reasons for discontinuation due to poor recruitment. We identified 28 different reasons for recruitment failure; most frequently mentioned were overestimation of prevalence of eligible participants and prejudiced views of recruiters and participants on trial interventions. Few RCTs reported relevant details about the recruitment process such as how eligible participants were identified, the number of patients assessed for eligibility, and who actually recruited participants.
  
  
  
  Our classification could serve as a checklist to assist investigators in the planning of RCTs. Most reasons for recruitment failure seem preventable with a pilot study that applies the planned informed consent procedure.
authors: Department of Clinical Research, Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Spitalstrasse 12, 4031 Basel, Switzerland; Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada. Electronic address: matthias.briel@usb.ch.
authors: Matthias
authors: M
authors: Briel
authors: Department of Clinical Research, Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Spitalstrasse 12, 4031 Basel, Switzerland.
authors: Kelechi Kalu
authors: KK
authors: Olu
authors: Cochrane Switzerland, Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Route de la Corniche 10, Lausanne, 1010, Switzerland.
authors: Erik
authors: E
authors: von Elm
authors: Department of Clinical Research, Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Spitalstrasse 12, 4031 Basel, Switzerland; Department of Oncology, University Hospital Basel, Petersgraben 4, Basel, 4031, Switzerland.
authors: Benjamin
authors: B
authors: Kasenda
authors: Department of Clinical Research, Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Spitalstrasse 12, 4031 Basel, Switzerland.
authors: Reem
authors: R
authors: Alturki
authors: Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada.
authors: Arnav
authors: A
authors: Agarwal
authors: Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada.
authors: Neera
authors: N
authors: Bhatnagar
authors: Department of Clinical Research, Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Spitalstrasse 12, 4031 Basel, Switzerland; Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada.
authors: Stefan
authors: S
authors: Schandelmaier
mesh_terms: D015340:Epidemiologic Research Design; D006801:Humans; D059012:Lost to Follow-Up; D018579:Patient Selection; D016032:Randomized Controlled Trials as Topic / Q000379:methods* / Q000706:statistics & numerical data*
keywords: Early termination of clinical trials; Poor recruitment; Randomized controlled trials as topic; Reasons for recruitment failure; Reporting quality; Systematic review