title: Interphalangeal Osteoarthritis Radiographic Simplified (iOARS) score: a radiographic method to detect osteoarthritis of the interphalangeal finger joints based on its histopathological alterations.
abstract: OBJECTIVE
  To develop a radiographic score for assessment of hand osteoarthritis (OA) that is based on histopathological alterations of the distal (DIP) and proximal (PIP) interphalangeal joints.
  
  
  METHODS
  DIP and PIP joints were obtained from corpses (n=40). Plain radiographies of these joints were taken. Joint samples were prepared for histological analysis; cartilage damage was graded according to the Mankin scoring system. A 2×2 Fisher's exact test was applied to define those radiographic features most likely to be associated with histological alterations. Receiver operating characteristic curves were analysed to determine radiographic thresholds. Intraclass correlation coefficients (ICC) estimated intra- and inter-reader variability. Spearman's correlation was applied to examine the relationship between our score and histopathological changes. Differences between groups were determined by a Student's t test.
  
  
  RESULTS
  The Interphalangeal Osteoarthritis Radiographic Simplified (iOARS) score is presented. The score is based on histopathological changes of DIP and PIP joints and follows a simple dichotomy whether OA is present or not. The iOARS score relies on three equally ranked radiographic features (osteophytes, joint space narrowing and subchondral sclerosis). For both DIP and PIP joints, the presence of one x-ray features reflects interphalangeal OA. Sensitivity and specificity for DIP joints were 92.3% and 90.9%, respectively, and 75% and 100% for PIP joints. All readers were able to reproduce their own readings in DIP and PIP joints after 4 weeks. The overall agreement between the three readers was good; ICCs ranged from 0.945 to 0.586. Additionally, outcomes of the iOARS score in a hand OA cohort revealed a higher prevalence of interphalangeal joint OA compared with the Kellgren and Lawrence score.
  
  
  CONCLUSIONS
  The iOARS score is uniquely based on histopathological alterations of the interphalangeal joints in order to reliably determine OA of the DIP and PIP joints radiographically. Its high specificity and sensitivity together with the dichotomous approach renders the iOARS score reliable, fast to perform and easy to apply. This tool may not only be valuable in daily clinical practice but also in clinical and epidemiological trials.
authors.affiliation: Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Ilse-Gerlinde
authors.initials: IG
authors.lastname: Sunk
authors.affiliation: Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Love
authors.initials: L
authors.lastname: Amoyo-Minar
authors.affiliation: Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Tanja
authors.initials: T
authors.lastname: Stamm
authors.affiliation: Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Haider
authors.affiliation: Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Niederreiter
authors.affiliation: Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Supp
authors.affiliation: Department of Pathology, Medical University of Vienna, Vienna, Austria.
authors.forename: Afschin
authors.initials: A
authors.lastname: Soleiman
authors.affiliation: Department of Radiology and Osteology, Medical University of Vienna, Vienna, Austria.
authors.forename: Franz
authors.initials: F
authors.lastname: Kainberger
authors.affiliation: Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Josef S
authors.initials: JS
authors.lastname: Smolen
authors.affiliation: Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Klaus
authors.initials: K
authors.lastname: Bobacz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005384:Finger Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000473:pathology; D054850:Osteophyte / Q000473:pathology; D011859:Radiography; D015203:Reproducibility of Results; D012720:Severity of Illness Index
keywords: Chondrocytes; Hand Osteoarthritis; Osteoarthritis