title: Are surgical trials with negative results being interpreted correctly?
abstract: BACKGROUND
  Many published accounts of clinical trials report no differences between the treatment arms, while being underpowered to find differences. This study determined how the authors of these reports interpreted their findings.
  
  
  METHODS
  We examined 54 reports of surgical trials chosen randomly from a database of 110 influential trials conducted in 2008. Seven that reported having adequate statistical power (β ≥ 0.9) were excluded from further analysis, as were the 32 that reported significant differences between the treatment arms. We examined the remaining 15 to see whether the authors interpreted their negative findings appropriately. Appropriate interpretations discussed the lack of power and/or called for larger studies.
  
  
  RESULTS
  Three of the 7 trials that did not report an a priori power calculation offered inappropriate interpretations, as did 3 of the 8 trials that reported an a priori power < 0.90. However, we examined only a modest number of trial reports from 1 year.
  
  
  CONCLUSIONS
  Negative findings in underpowered trials were often interpreted as showing the equivalence of the treatment arms with no discussion of the issue of being underpowered. This may lead clinicians to accept new treatments that have not been validated.
authors.affiliation: Department of Philosophy, Rice University, Houston, TX 77251, USA. bbrody@rice.edu
authors.forename: Baruch A
authors.initials: BA
authors.lastname: Brody
authors.forename: Carol M
authors.initials: CM
authors.lastname: Ashton
authors.forename: Dandan
authors.initials: D
authors.lastname: Liu
authors.forename: Youxin
authors.initials: Y
authors.lastname: Xiong
authors.forename: Xuan
authors.initials: X
authors.lastname: Yao
authors.forename: Nelda P
authors.initials: NP
authors.lastname: Wray
mesh_terms: D002986:Clinical Trials as Topic / Q000941:ethics / Q000379:methods / Q000706:statistics & numerical data*; D003627:Data Interpretation, Statistical; D006801:Humans; D017063:Outcome Assessment, Health Care / Q000941:ethics / Q000706:statistics & numerical data*; D012107:Research Design / Q000706:statistics & numerical data*; D013514:Surgical Procedures, Operative / Q000706:statistics & numerical data*