title: Many randomized trials of physical therapy interventions are not adequately registered: a survey of 200 published trials.
abstract: BACKGROUND
  Clinical trial registration has several putative benefits: prevention of selective reporting, avoidance of duplication, encouragement of participation, and facilitation of reviews. Previous surveys suggest that most trials are registered. However, these surveys examined only trials in journals with high impact factors, which may bias the results.
  
  
  OBJECTIVE
  This study examined the completeness of clinical trial registration and the extent of selective reporting of outcomes in a random sample of published randomized trials in physical therapy.
  
  
  METHODS
  This was a retrospective cohort study in which 200 randomized trials of physical therapy interventions were randomly selected from those published in 2009 and indexed in the Physiotherapy Evidence Database (PEDro), regardless of the publishing journal.
  
  
  METHODS
  Evidence of registration was sought for each trial in the study, on clinical trial registers, and by contacting authors.
  
  
  RESULTS
  The proportion of randomized trials that were registered was 67/200 (34%). This proportion was significantly lower than among the trials in journals with high impact factors, where the proportion was 75% (odds ratio=7.4, 95% confidence interval=2.6-21.4). Unambiguous primary outcomes (ie, method and time points of measurement clearly defined in the trial registry entry) were registered for 32 trials, and registration was adequate (ie, prospective with unambiguous primary outcomes) for 5/200 (2.5%) trials. Selective outcome reporting occurred in 23 (47%) of the 49 trials in which selective reporting was assessable.
  
  
  CONCLUSIONS
  The inclusion of only English-language trials prevents generalization of the results to non-English-language trials.
  
  
  CONCLUSIONS
  Registration of randomized trials of physical therapy interventions is rarely adequate. Consequently, the putative benefits of registration are not being fully realized.
authors.affiliation: The George Institute for Global Health and Sydney Medical School, University of Sydney, PO Box M201, Missenden Road, Sydney, New South Wales 2050, Australia. rafaelzambelli@gmail.com
authors.forename: Rafael Zambelli
authors.initials: RZ
authors.lastname: Pinto
authors.forename: Mark R
authors.initials: MR
authors.lastname: Elkins
authors.forename: Anne M
authors.initials: AM
authors.lastname: Moseley
authors.forename: Catherine
authors.initials: C
authors.lastname: Sherrington
authors.forename: Robert D
authors.initials: RD
authors.lastname: Herbert
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Maher
authors.forename: Paulo H
authors.initials: PH
authors.lastname: Ferreira
authors.forename: Manuela L
authors.initials: ML
authors.lastname: Ferreira
mesh_terms: D015706:Bibliometrics; D006801:Humans; D010506:Periodicals as Topic / Q000706:statistics & numerical data; D026741:Physical Therapy Modalities; D011643:Publishing / Q000706:statistics & numerical data; D016032:Randomized Controlled Trials as Topic; D012042:Registries / Q000706:statistics & numerical data*; D012189:Retrospective Studies