title: Have levels of evidence improved the quality of orthopaedic research?
abstract: BACKGROUND
  Since 2003 many orthopaedic journals have adopted grading systems for levels of evidence (LOE). It is unclear if the quality of orthopaedic literature has changed since LOE was introduced.
  
  
  OBJECTIVE
  We asked three questions: (1) Have the overall number and proportion of Level I and II studies increased in the orthopaedic literature since the introduction of LOE? (2) Is a similar pattern seen in individual orthopaedic subspecialty journals? (3) What is the interobserver reliability of grading LOE?
  
  
  METHODS
  We assigned LOE to therapeutic studies published in 2000, 2005, and 2010 in eight major orthopaedic subspecialty journals. Number and proportion of Level I and II publications were determined. Data were evaluated using log-linear models. Twenty-six reviewers (13 residents and 13 attendings) graded LOE of 20 blinded therapeutic articles from the Journal of Bone and Joint Surgery for 2009. Interobserver agreement relative to the Journal of Bone and Joint Surgery was assessed using a weighted kappa.
  
  
  RESULTS
  The total number of Level I and II publications in subspecialty journals increased from 150 in 2000 to 239 in 2010. The proportion of high-quality publications increased with time (p < 0.001). All subspecialty journals other than the Journal of Pediatric Orthopaedics and the Journal of Orthopaedic Trauma showed a similar behavior. Average weighted kappa was 0.791 for residents and 0.842 for faculty (p = 0.209).
  
  
  CONCLUSIONS
  The number and proportion of Level I and II publications have increased. LOE can be graded reliably with high interobserver agreement. The number and proportion of high-level studies should continue to increase.
authors.affiliation: Orthopaedic Residency, Banner Good Samaritan Medical Center, 901 East Willetta Street, Floor 2, Phoenix, AZ, 85006-2511, USA.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Cunningham
authors.forename: Samuel
authors.initials: S
authors.lastname: Harmsen
authors.forename: Chris
authors.initials: C
authors.lastname: Kweon
authors.forename: Jason
authors.initials: J
authors.lastname: Patterson
authors.forename: Robert
authors.initials: R
authors.lastname: Waldrop
authors.forename: Alex
authors.initials: A
authors.lastname: McLaren
authors.forename: Ryan
authors.initials: R
authors.lastname: McLemore
mesh_terms: D000818:Animals; D015706:Bibliometrics; D035843:Biomedical Research / Q000592:standards*; D019317:Evidence-Based Medicine / Q000592:standards*; D017408:Guidelines as Topic; D006801:Humans; D015588:Observer Variation; D009985:Orthopedics / Q000592:standards*; D010506:Periodicals as Topic / Q000592:standards*; D011786:Quality Control; D015203:Reproducibility of Results