title: Premature Discontinuation of Prospective Clinical Studies Approved by a Research Ethics Committee - A Comparison of Randomised and Non-Randomised Studies.
abstract: BACKGROUND
  Premature discontinuation of clinical studies affects about 25% of randomised controlled trials (RCTs) which raises concerns about waste of scarce resources for research. The risk of discontinuation of non-randomised prospective studies (NPSs) is yet unclear.
  
  
  OBJECTIVE
  To compare the proportion of discontinued studies between NPSs and RCTs that received ethical approval.
  
  
  METHODS
  We systematically surveyed prospective longitudinal clinical studies that were approved by a single REC in Freiburg, Germany between 2000 and 2002. We collected study characteristics, identified subsequent publications, and surveyed investigators to elucidate whether a study was discontinued and, if so, why.
  
  
  RESULTS
  Of 917 approved studies, 547 were prospective longitudinal studies (306 RCTs and 241 NPSs). NPSs were on average smaller than RCTs, more frequently single centre and pilot studies, and less frequently funded by industry. NPSs were less frequently discontinued than RCTs: 32/221 (14%) versus 78/288 (27%, p<0.001, missing data excluded). Poor recruitment was the most frequent reason for discontinuation in both NPSs (36%) and RCTs (37%).
  
  
  CONCLUSIONS
  Compared to RCTs, NPSs were at lower risk for discontinuation. Measures to reliably predict, sustain, and stimulate recruitment could prevent discontinuation of many RCTs but also of some NPSs.
authors: Cochrane Germany, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
authors: Anette
authors: http://orcid.org/0000-0003-2877-1029
authors: A
authors: Blümle
authors: Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Basel, Switzerland.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors: Stefan
authors: S
authors: Schandelmaier
authors: Cochrane Germany, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
authors: Patrick
authors: P
authors: Oeller
authors: Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Basel, Switzerland.
authors: Benjamin
authors: B
authors: Kasenda
authors: Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Basel, Switzerland.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors: Matthias
authors: M
authors: Briel
authors: Cochrane Switzerland, Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Lausanne, Switzerland.
authors: Erik
authors: E
authors: von Elm
mesh_terms: D028744:Ethics Committees, Research; D006801:Humans; D008137:Longitudinal Studies; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic / Q000941:ethics / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires