title: Trends in worldwide volume and methodological quality of surgical randomized controlled trials.
abstract: OBJECTIVE
  To assess worldwide trends in volume and methodological quality of published surgical randomized controlled trials (RCTs) over the past decade.
  
  
  BACKGROUND
  Randomized controlled trials are essential for clinical decision making. It has repeatedly been suggested that surgical RCTs are scarce and of mediocre quality.
  
  
  METHODS
  We systematically searched PubMed for surgical RCTs published in 1999 and 2009. Characteristics and risks of bias were extracted. Trials where compared between study years and geographical regions. Primary outcome was "low risk of bias," defined by all of the following: adequate allocation generation and concealment, intention-to-treat analysis, and adequate dropout handling.
  
  
  RESULTS
  The volume of published surgical RCTs increased by 50%, from 300 in 1999 to 450 in 2009. Volume increased in Europe (27% increase), Asia/Oceania (160% increase), and Africa/South America (416% increase) but decreased in North America (23% decrease), although the United States remained the country with the highest number of published RCTs. In 2009, methodological quality of surgical trials improved in terms of sample size calculation, adequate generation of randomization sequence, concealment of randomization sequence, and use of intention-to-treat analysis as compared with 1999 (P < 0.001 for all). The proportion of low risk of bias trials increased from 6% to 14% (prevalence ratio 2.59; 95% confidence interval 1.55-4.32). In 2009, the highest proportion of low risk of bias trials was from Europe (23%), whereas the lowest was from Asia/Oceania (5%).
  
  
  CONCLUSIONS
  Volume and quality of surgical RCTs improved although striking differences exist between continents and countries. Structured education in trial methodology, enforced adherence to existing guidelines, and improved research infrastructure may guide further improvements.
authors.affiliation: Department of Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Usama
authors.initials: U
authors.lastname: Ahmed Ali
authors.forename: Pieter C
authors.initials: PC
authors.lastname: van der Sluis
authors.forename: Yama
authors.initials: Y
authors.lastname: Issa
authors.forename: Ibrahim Abou
authors.initials: IA
authors.lastname: Habaga
authors.forename: Hein G
authors.initials: HG
authors.lastname: Gooszen
authors.forename: David R
authors.initials: DR
authors.lastname: Flum
authors.forename: Ale
authors.initials: A
authors.lastname: Algra
authors.forename: Marc G
authors.initials: MG
authors.lastname: Besselink
mesh_terms: D015982:Bias; D015706:Bibliometrics; D006801:Humans; D057194:Intention to Treat Analysis; D010352:Patient Dropouts; D016032:Randomized Controlled Trials as Topic / Q000592:standards / Q000706:statistics & numerical data / Q000639:trends*; D012107:Research Design / Q000592:standards* / Q000706:statistics & numerical data / Q000639:trends; D018401:Sample Size; D013043:Specialties, Surgical