title: All that glitters isn't gold: a survey on acknowledgment of limitations in biomedical studies.
abstract: BACKGROUND
  Acknowledgment of all serious limitations to research evidence is important for patient care and scientific progress. Formal research on how biomedical authors acknowledge limitations is scarce.
  
  
  OBJECTIVE
  To assess the extent to which limitations are acknowledged in biomedical publications explicitly, and implicitly by investigating the use of phrases that express uncertainty, so-called hedges; to assess the association between industry support and the extent of hedging.
  
  
  METHODS
  We analyzed reporting of limitations and use of hedges in 300 biomedical publications published in 30 high and medium -ranked journals in 2007. Hedges were assessed using linguistic software that assigned weights between 1 and 5 to each expression of uncertainty.
  
  
  RESULTS
  Twenty-seven percent of publications (81/300) did not mention any limitations, while 73% acknowledged a median of 3 (range 1-8) limitations. Five percent mentioned a limitation in the abstract. After controlling for confounders, publications on industry-supported studies used significantly fewer hedges than publications not so supported (p = 0.028).
  
  
  CONCLUSIONS
  Detection and classification of limitations was--to some extent--subjective. The weighting scheme used by the hedging detection software has subjective elements.
  
  
  CONCLUSIONS
  Reporting of limitations in biomedical publications is probably very incomplete. Transparent reporting of limitations may protect clinicians and guideline committees against overly confident beliefs and decisions and support scientific progress through better design, conduct or analysis of new studies.
authors: Department of General Practice, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors: Gerben
authors: G
authors: Ter Riet
authors: Paula
authors: P
authors: Chesley
authors: Alan G
authors: AG
authors: Gross
authors: Lara
authors: L
authors: Siebeling
authors: Patrick
authors: P
authors: Muggensturm
authors: Nadine
authors: N
authors: Heller
authors: Martin
authors: M
authors: Umbehr
authors: Daniela
authors: D
authors: Vollenweider
authors: Tsung
authors: T
authors: Yu
authors: Elie A
authors: EA
authors: Akl
authors: Lizzy
authors: L
authors: Brewster
authors: Olaf M
authors: OM
authors: Dekkers
authors: Ingrid
authors: I
authors: Mühlhauser
authors: Bernd
authors: B
authors: Richter
authors: Sonal
authors: S
authors: Singh
authors: Steven
authors: S
authors: Goodman
authors: Milo A
authors: MA
authors: Puhan
mesh_terms: D015706:Bibliometrics; D035843:Biomedical Research; D011642:Publications / Q000706:statistics & numerical data*