title: The prevalence of diffuse idiopathic skeletal hyperostosis in Japan - the first report of measurement by CT and review of the literature.
abstract: BACKGROUND
  Diffuse idiopathic skeletal hyperostosis (DISH) is prone to be accompanied by a spinal column fracture which is resistant to conservative therapy. This major characteristic of DISH is not recognized adequately by physicians, because the disease's detailed pathological condition has not yet been investigated. Therefore, the purposes of this study were to investigate the prevalence of DISH using computed tomography (CT), and to validate the reliability of CT interpretation.
  
  
  METHODS
  Subjects were 558 patients (300 male and 258 female) who underwent both CT of chest to pelvis and x-ray of chest and abdomen from August 2011 to July 2012 at any department other than orthopedic surgery in our institution. The definition of DISH based on x-ray as well as CT was the presence of consecutive fused vertebral bodies according to Resnick's criteria. The prevalence of DISH based on both modalities was calculated in all subjects. For 107 subjects extracted at random, intra- (Cohen kappa) and inter-observer error (Fleiss kappa) were calculated and the levels of fused segments were investigated.
  
  
  RESULTS
  Ninety-eight of 558 subjects (17.6%) were diagnosed as DISH by x-ray, and 152 (27.2%) by CT. Among males, 70 of 300 subjects (23.3%) were diagnosed by x-ray, and 116 (38.7%) by CT. Among females, 28 of 258 subjects (10.9%) were diagnosed by x-ray and 36 (14.0%) by CT. The levels of fused segments were presented from thoracic spine to lumbar spine, especially the middle and lower thoracic spine. Cohen kappa of x-ray was 0.587, and that of CT was 0.825. Fleiss kappa of x-ray was 0.552, and that of CT was 0.643.
  
  
  CONCLUSIONS
  The prevalence of DISH based on CT was 27.1%, which was higher than that of x-ray. In addition, intra- and inter-observer error by review of CT was less than that of x-ray. CT evaluation would be a better method for precise understanding of the state of DISH.
authors.affiliation: Departments of Spine Center, Aichi Medical University, Nagakute, Aichi Pref., Japan.
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Hirasawa
authors.affiliation: Departments of Spine Center, Aichi Medical University, Nagakute, Aichi Pref., Japan. Electronic address: nwakao2009@yahoo.co.jp.
authors.forename: Norimitsu
authors.initials: N
authors.lastname: Wakao
authors.affiliation: Departments of Spine Center, Aichi Medical University, Nagakute, Aichi Pref., Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kamiya
authors.affiliation: Departments of Spine Center, Aichi Medical University, Nagakute, Aichi Pref., Japan.
authors.forename: Mikinobu
authors.initials: M
authors.lastname: Takeuchi
authors.affiliation: Departments of Orthopaedic Surgery, Aichi Medical University, Nagakute, Aichi Pref., Japan.
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Kawanami
authors.affiliation: Division of Biostatistics, Clinical Research Center, Aichi Medical University, Nagakute, Aichi Pref., Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Murotani
authors.affiliation: Departments of Orthopaedic Surgery, Aichi Medical University, Nagakute, Aichi Pref., Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Matsuo
authors.affiliation: Departments of Orthopaedic Surgery, Aichi Medical University, Nagakute, Aichi Pref., Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Deie
mesh_terms: D017677:Age Distribution; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D004057:Hyperostosis, Diffuse Idiopathic Skeletal / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000503:physiopathology; D007564:Japan; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015995:Prevalence; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D013904:Thoracic Vertebrae / Q000254:growth & development / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods*