title: Level of evidence trends in the Journal of Bone and Joint Surgery, 1980-2010.
abstract: BACKGROUND
  The Journal of Bone and Joint Surgery (JBJS-Am) began publishing the level of evidence (LOE) for manuscripts in 2003. From 1975 to 2005 JBJS-Am saw a trend towards higher leveled studies. We aimed to demonstrate trends in the country of origin of manuscripts published in JBJS-Am, and hypothesized that not only were more publications coming from groups outside of North America, but that the studies originating within North America were of higher LOE.
  
  
  METHODS
  All articles published in The Journal of Bone and Joint Surgery (American) in 1980, 1985, 1990, 1995, 2000, 2005, and 2010 were independently evaluated by two reviewers and graded based on country, LOE (using the JBJS-Am LOE guidelines), and study type. For articles published after 2003 we used the level and study type published within the manuscript.
  
  
  RESULTS
  The proportion of publications from North America decreased in 2005 and 2010 when compared to the previous 20 years (p>.03), but the overall number of publications appeared stable. Overall, there was an increase in Level I (r>.74, p>.03), Level II (r>.79, p>.02), and Level III (r>.95, p<.001) evidence studies. There was a statistically significant decrease in North American Level IV studies (r>-.81, p>.01) and an increase in international Level IV studies (r>.70, p>.04). International groups have increased therapeutic (r>.86, p<.01) and diagnostic studies (r>.93, p<.001). In North America and internationally, prognostic studies have not changed. North American groups have increased economic and decision analysis research (r>.69, p>.04).
  
  
  CONCLUSIONS
  Over the past 30 years JBJS-Am has become more internationally diverse. International groups are publishing more therapeutic and diagnostic research than in the past, while North American groups have increased economic and decision analysis research. There has been a global effort towards higher leveled research.
authors.affiliation: Department of Orthopaedic Surgery University Hospitals Case Medical Center (all authors).
authors.forename: M S
authors.initials: MS
authors.lastname: Reich
authors.affiliation: Department of Orthopaedic Surgery University Hospitals Case Medical Center (all authors).
authors.forename: J
authors.initials: J
authors.lastname: Shaw
authors.affiliation: Department of Orthopaedic Surgery University Hospitals Case Medical Center (all authors).
authors.forename: I
authors.initials: I
authors.lastname: Barrett
authors.affiliation: Department of Orthopaedic Surgery University Hospitals Case Medical Center (all authors).
authors.forename: V M
authors.initials: VM
authors.lastname: Goldberg
authors.affiliation: Department of Orthopaedic Surgery University Hospitals Case Medical Center (all authors).
authors.forename: E
authors.initials: E
authors.lastname: Schnaser
mesh_terms: D019317:Evidence-Based Medicine; D006801:Humans; D033181:Information Dissemination; D009985:Orthopedics / Q000592:standards*; D010506:Periodicals as Topic / Q000639:trends*; D011643:Publishing / Q000639:trends*; D012107:Research Design / Q000639:trends*