title: Interobserver and intraobserver reliability of the modified Waldenström classification system for staging of Legg-Calvé-Perthes disease.
abstract: BACKGROUND
  The absence of a reliable classification system for Legg-Calvé-Perthes disease has contributed to difficulty in establishing consistent management strategies and in interpreting outcome studies. The purpose of this study was to assess interobserver and intraobserver reliability of the modified Waldenström classification system among a large and diverse group of pediatric orthopaedic surgeons.
  
  
  METHODS
  Twenty surgeons independently completed the first two rounds of staging: two assessments of forty deidentified radiographs of patients with Legg-Calvé-Perthes disease in various stages. Ten of the twenty surgeons completed another two rounds of staging after the addition of a second pair of radiographs in sequence. Kappa values were calculated within and between each of the rounds.
  
  
  RESULTS
  Interobserver kappa values for the classification for surveys 1, 2, 3, and 4 were 0.81, 0.82, 0.76, and 0.80, respectively (with 0.61 to 0.80 considered substantial agreement and 0.81 to 1.0, nearly perfect agreement). Intraobserver agreement for the classification was an average of 0.88 (range, 0.77 to 0.96) between surveys 1 and 2 and an average of 0.87 (range, 0.81 to 0.94) between surveys 3 and 4.
  
  
  CONCLUSIONS
  The modified Waldenström classification system for staging of Legg-Calvé-Perthes disease demonstrated substantial to almost perfect agreement between and within observers across multiple rounds of study. In doing so, the results of this study provide a foundation for future validation studies, in which the classification stage will be associated with clinical outcomes.
authors: Division of Pediatric Orthopaedic Surgery, New York Presbyterian Morgan Stanley Children's Hospital of New York, 3959 Broadway, CHONY-8N, New York, NY 10032-3784. E-mail address for H. Matsumoto: Hm2174@cumc.columbia.edu.
authors: Joshua E
authors: JE
authors: Hyman
authors: Division of Pediatric Orthopaedic Surgery, New York Presbyterian Morgan Stanley Children's Hospital of New York, 3959 Broadway, CHONY-8N, New York, NY 10032-3784. E-mail address for H. Matsumoto: Hm2174@cumc.columbia.edu.
authors: Evan P
authors: EP
authors: Trupia
authors: Division of Pediatric Orthopaedic Surgery, New York Presbyterian Morgan Stanley Children's Hospital of New York, 3959 Broadway, CHONY-8N, New York, NY 10032-3784. E-mail address for H. Matsumoto: Hm2174@cumc.columbia.edu.
authors: Margaret L
authors: ML
authors: Wright
authors: Division of Pediatric Orthopaedic Surgery, New York Presbyterian Morgan Stanley Children's Hospital of New York, 3959 Broadway, CHONY-8N, New York, NY 10032-3784. E-mail address for H. Matsumoto: Hm2174@cumc.columbia.edu.
authors: Hiroko
authors: H
authors: Matsumoto
authors: Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219.
authors: Chan-Hee
authors: CH
authors: Jo
authors: Department of Orthopaedic Surgery, BC Children's Hospital, Administrative Secretary Room A204, 4480 Oak Street, Vancouver, BC V6H 3V4, Canada.
authors: Kishore
authors: K
authors: Mulpuri
authors: MedCare Orthopaedics and Spine Hospital, Second Interchange, Sheikh Zayed Road, P.O. Box 215565, Dubai, United Arab Emirates.
authors: Benjamin
authors: B
authors: Joseph
authors: Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219.
authors: Harry K W
authors: HK
authors: Kim
mesh_terms: D002648:Child; D003625:Data Collection; D005260:Female; D006801:Humans; D007873:Legg-Calve-Perthes Disease / Q000145:classification* / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D011859:Radiography; D015203:Reproducibility of Results; D012720:Severity of Illness Index