title: Analysis of agreement between the German translation of the American Foot and Ankle Society's Ankle and Hindfoot Scale (AOFAS-AHS) and the Foot Function Index in its validated German translation by Naal et al. (FFI-D).
abstract: BACKGROUND
  Despite its wide use in clinical outcome measurement, there is yet no validated German language version of the AOFAS-AHS available. After finishing cross-cultural adaption of the AOFAS-AHS according to the AAOS guidelines, an analysis of agreement was carried out.
  
  
  METHODS
  This was done by means of the 18-item Foot Function Index in its validated German translation by Naal et al. (FFI-D). The results of 91 orthopedic patients as well as healthy persons in both scores were then compared intraindividually. The cohort consisted of 46 individuals with hindfoot disorders and 45 persons without any hindfoot complaints. The FFI-D-Score was linearly transformed in the range 0-100 points of the AOFAS.
  
  
  RESULTS
  Encouraging correlation was then found for the patients with hindfoot disorders (Spearman's correlation 0.73 (95% CI 0.52-0.85); a median deviation of -2 points (interquartile range -13 points; +13 points) in patients with hindfoot disorders implied good median intraindividual score concordance. However, with 30 of these 46 patients showing score deviations beyond or below a pre-specified ±10 points range of clinically tolerable deviations, the scores cannot be considered exchangeable.
  
  
  CONCLUSIONS
  Although the agreement analysis was performed for the German translation of the two questionnaires, analogous results can be expected also for other languages. It should be noted that the results do not allow for judging which of the scores is better suited to give a valid statement on patient outcome in treatment of hindfoot disorders. To verify which of these two scores is better suited to represent hindfoot-dysfunction a subsequent study using instrumental gait analysis and surface EMG is being carried out.
authors.affiliation: Institute for Medical Biometry and Epidemiology (IMBE), University of Witten/Herdecke, Alfred-Herrhausen-Straße, 50, 58448, Witten, Germany, tanja.kostuj@t-online.de.
authors.forename: Tanja
authors.initials: T
authors.lastname: Kostuj
authors.forename: Frank
authors.initials: F
authors.lastname: Krummenauer
authors.forename: Katharina
authors.initials: K
authors.lastname: Schaper
authors.forename: Felix
authors.initials: F
authors.lastname: Stief
authors.forename: Kirsten
authors.initials: K
authors.lastname: Zettersten
authors.forename: Mike H
authors.initials: MH
authors.lastname: Baums
authors.forename: Andrea
authors.initials: A
authors.lastname: Meurer
authors.forename: Sebastian
authors.initials: S
authors.lastname: Lieske
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D005528:Foot / Q000503:physiopathology*; D005534:Foot Diseases / Q000175:diagnosis* / Q000503:physiopathology; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D009985:Orthopedics; D010003:Osteoarthritis / Q000175:diagnosis / Q000503:physiopathology; D012955:Societies, Medical; D011795:Surveys and Questionnaires; D014175:Translating; D014481:United States