title: Fate of clinical research studies after ethical approval--follow-up of study protocols until publication.
abstract: BACKGROUND
  Many clinical studies are ultimately not fully published in peer-reviewed journals. Underreporting of clinical research is wasteful and can result in biased estimates of treatment effect or harm, leading to recommendations that are inappropriate or even dangerous.
  
  
  METHODS
  We assembled a cohort of clinical studies approved 2000-2002 by the Research Ethics Committee of the University of Freiburg, Germany. Published full articles were searched in electronic databases and investigators contacted. Data on study characteristics were extracted from protocols and corresponding publications. We characterized the cohort, quantified its publication outcome and compared protocols and publications for selected aspects.
  
  
  RESULTS
  Of 917 approved studies, 807 were started and 110 were not, either locally or as a whole. Of the started studies, 576 (71%) were completed according to protocol, 128 (16%) discontinued and 42 (5%) are still ongoing; for 61 (8%) there was no information about their course. We identified 782 full publications corresponding to 419 of the 807 initiated studies; the publication proportion was 52% (95% CI: 0.48-0.55). Study design was not significantly associated with subsequent publication. Multicentre status, international collaboration, large sample size and commercial or non-commercial funding were positively associated with subsequent publication. Commercial funding was mentioned in 203 (48%) protocols and in 205 (49%) of the publications. In most published studies (339; 81%) this information corresponded between protocol and publication. Most studies were published in English (367; 88%); some in German (25; 6%) or both languages (27; 6%). The local investigators were listed as (co-)authors in the publications corresponding to 259 (62%) studies.
  
  
  CONCLUSIONS
  Half of the clinical research conducted at a large German university medical centre remains unpublished; future research is built on an incomplete database. Research resources are likely wasted as neither health care professionals nor patients nor policy makers can use the results when making decisions.
authors.affiliation: Institute for Medical Biometry and Statistics, Center for Medical Biometry and Medical Informatics, University Medical Center, Freiburg, Germany.
authors.forename: Anette
authors.initials: A
authors.lastname: Blümle
authors.affiliation: Institute for Medical Biometry and Statistics, Center for Medical Biometry and Medical Informatics, University Medical Center, Freiburg, Germany.
authors.forename: Joerg J
authors.initials: JJ
authors.lastname: Meerpohl
authors.affiliation: Institute for Medical Biometry and Statistics, Center for Medical Biometry and Medical Informatics, University Medical Center, Freiburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schumacher
authors.affiliation: Cochrane Switzerland, Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: Erik
authors.initials: E
authors.lastname: von Elm
mesh_terms: D035843:Biomedical Research / Q000941:ethics*; D006801:Humans; D011643:Publishing / Q000941:ethics*