title: Substantial accuracy of fracture classification in the Swedish Fracture Register: Evaluation of AO/OTA-classification in 152 ankle fractures.
abstract: BACKGROUND
  Since 2011 the Swedish Fracture Register (SFR) has collected information on fracture epidemiology, treatment and outcome. More than 112 000 fractures, including 11 600 ankle fractures, have been registered so far. The accuracy of the classification is crucial when using the register in future research and quality improvement of care. In this study we examine the degree of accuracy of the AO/OTA-classification in which ankle fractures are recorded in the SFR.
  
  
  METHODS
  152 randomly selected ankle fractures registered in the SFR were classified independently by a reference group of three orthopedic surgeons on two occasions. The agreed AO/OTA-classification of the reference group was regarded as the gold standard classification for each case. The originally recorded classification in the SFR was subsequently compared with the classification of the reference group and accuracy calculated.
  
  
  RESULTS
  The agreement between the classification in the SFR and of the reference group was 74%, corresponding to kappa 0.67, 95% CI (0.58-0.76) for AO/OTA group level. An agreement of 88% equivalent to kappa 0.77, 95% CI (0.67-0.87) was noted for AO/OTA type level. The agreement corresponds to substantial according to Landis and Koch. The kappa value of inter- and intraobserver agreement ranged from 0.67 to 0.93.
  
  
  CONCLUSIONS
  The study results show substantial agreement between classifications made in the SFR and gold standard classification. The finding is equivalent to or higher than in previous studies. Consequently, we conclude that classifications of ankle fractures in the SFR are accurate and valid.
authors.affiliation: Department of Surgical and Perioperative Science (Orthopedics), Sunderby Research Unit, Umeå University, Umeå, Sweden. Electronic address: hans.juto@nll.se.
authors.forename: Hans
authors.initials: H
authors.lastname: Juto
authors.affiliation: Department of Orthopedics and Trauma, Sahlgrenska University Hospital, Gothenburg/Mölndal, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Möller
authors.affiliation: Department of Orthopedics and Trauma, Sahlgrenska University Hospital, Gothenburg/Mölndal, Sweden.
authors.forename: David
authors.initials: D
authors.lastname: Wennergren
authors.affiliation: Department of Surgical and Perioperative Science (Orthopedics), Sunderby Research Unit, Umeå University, Umeå, Sweden.
authors.forename: Klas
authors.initials: K
authors.lastname: Edin
authors.affiliation: Department of Surgical and Perioperative Science (Orthopedics), Sunderby Research Unit, Umeå University, Umeå, Sweden.
authors.forename: Ida
authors.initials: I
authors.lastname: Apelqvist
authors.affiliation: Department of Surgical and Perioperative Science (Orthopedics), Sunderby Research Unit, Umeå University, Umeå, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Morberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D064386:Ankle Fractures / Q000145:classification* / Q000000981:diagnostic imaging / Q000453:epidemiology; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D008297:Male; D016347:Medical Records Systems, Computerized; D008875:Middle Aged; D015588:Observer Variation; D011859:Radiography; D011897:Random Allocation; D012042:Registries; D015203:Reproducibility of Results; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
keywords: Accuracy; Agreement; Ankle fractures; Classification; Register