title: Low back pain, sacroiliitis, and the relationship with HLA-B27 in Crohn's disease.
abstract: OBJECTIVE
  To determine the prevalence of sacroiliitis in patients who have back pain in Crohn's disease (CD) using computed tomography (CT); and to reassess the association of sacroiliitis in CD with HLA-B27.
  
  
  METHODS
  A total of 134 consecutive patients with CD completed a questionnaire about musculoskeletal symptoms. Those reporting low back pain were assessed, including plain radiographs and CT of the sacroiliac joints. HLA-B27 status was determined in patients with and without back pain.
  
  
  RESULTS
  There were 70 (52%) patients with low back pain, of whom 31 (45%) had CT evidence of sacroiliitis. These were characterized by more frequent morning spinal stiffness and positive sacroiliac compression tests even when sacroiliitis was not suspected. Nine had previously recognized radiological and clinical ankylosing spondylitis (AS), and of these 78% were HLA-B27 positive. Of those with newly identified sacroiliitis, 14% were HLA-B27 positive. This frequency was not statistically dissimilar to the 9% HLA-B27 positivity of those without back pain.
  
  
  CONCLUSIONS
  Sacroiliitis defined by CT is a common cause of low back pain in CD. A relationship of sacroiliitis and HLA-B27 could be confirmed only for those with classical AS. Our results accord with the possibility that sacroiliitis in CD is an isolated phenomenon, which is unrelated to HLA-B27 and which may evolve into classical spinal ankylosis in genetically susceptible subjects.
authors.affiliation: Guy's and St. Thomas' Hospitals NHS Trust, London, UK.
authors.forename: Sophia
authors.initials: S
authors.lastname: Steer
authors.forename: Hugh
authors.initials: H
authors.lastname: Jones
authors.forename: Jane
authors.initials: J
authors.lastname: Hibbert
authors.forename: Elli
authors.initials: E
authors.lastname: Kondeatis
authors.forename: Robert
authors.initials: R
authors.lastname: Vaughan
authors.forename: Jeremy
authors.initials: J
authors.lastname: Sanderson
authors.forename: Terence
authors.initials: T
authors.lastname: Gibson
mesh_terms: D000328:Adult; D003424:Crohn Disease / Q000453:epidemiology* / Q000276:immunology; D005260:Female; D015796:HLA-B27 Antigen / Q000032:analysis*; D006650:Histocompatibility Testing; D006801:Humans; D017116:Low Back Pain / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012446:Sacroiliac Joint; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000276:immunology; D014057:Tomography, X-Ray Computed
chemical_list: D015796:HLA-B27 Antigen