title: The influence of patient characteristics, disease variables, and HLA alleles on the development of radiographically evident sacroiliitis in juvenile idiopathic arthritis.
abstract: OBJECTIVE
  To assess the frequency of sacroiliitis and the radiographic and clinical outcome in juvenile idiopathic arthritis (JIA) and determine patient characteristics, early disease variables, and genetic markers that predict development of sacroiliitis.
  
  
  METHODS
  We performed a retrospective cohort study of 314 (79%) of the 400 JIA patients first admitted to the hospital between 1980 and 1985. The participants were examined after a median disease duration of 14.9 years (range 11.7-25.1). Radiographs of the sacroiliac joints, hips, ankles, and tarsi were obtained and studied in a blinded manner by 2 radiologists. The presence of HLA-DRB1 and DPB1 alleles was determined by genotyping and that of HLA-B27 by serologic testing. Variables relating to the onset and course of the disease were obtained by chart reviews.
  
  
  RESULTS
  Twenty (6%) of the JIA patients developed radiographic sacroiliitis according to the New York criteria. In 9 patients (45%), sacroiliitis had not been demonstrated before the followup examination. At followup, spinal flexion (lateral and anterior) was reduced in 70-75% of patients with sacroiliitis and in 30-35% of those without sacroiliitis. Compared with the JIA patients without sacroiliitis, those with sacroiliitis more frequently had inflammatory back pain, enthesitis, radiographic changes in the hips and calcanei, erosions of any peripheral joint, and uveitis. Predictors of sacroiliitis were HLA-B27, absence of DPB1*02, hip joint involvement within the first 6 months, and disease onset after age 8 years. The following factors were more common among patients in whom sacroiliitis developed than in other JIA patients: DRB1*04, male sex, family history of ankylosing spondylitis, psoriasis, inflammatory back pain, and enthesitis within the first 6 months.
  
  
  CONCLUSIONS
  In the current study, radiographically evident sacroiliitis had developed in 6% of JIA patients after a median disease duration of 14.9 years. HLA-B27, absence of DPB1*02, late onset of disease, and early hip involvement were predictors of sacroiliitis.
authors.affiliation: Center for Rheumatic Diseases, Rikshospitalet University Hospital, Oslo, Norway. berit.flato@rikshospitalet.no
authors.forename: Berit
authors.initials: B
authors.lastname: Flatø
authors.forename: Anna
authors.initials: A
authors.lastname: Smerdel
authors.forename: Virginia
authors.initials: V
authors.lastname: Johnston
authors.forename: Gunhild
authors.initials: G
authors.lastname: Lien
authors.forename: Knut
authors.initials: K
authors.lastname: Dale
authors.forename: Odd
authors.initials: O
authors.lastname: Vinje
authors.forename: Thore
authors.initials: T
authors.lastname: Egeland
authors.forename: Dag
authors.initials: D
authors.lastname: Sørskaar
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Førre
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D001171:Arthritis, Juvenile / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000235:genetics*; D002648:Child; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005819:Genetic Markers; D015796:HLA-B27 Antigen / Q000235:genetics*; D006684:HLA-DR Antigens / Q000235:genetics*; D059811:HLA-DRB1 Chains; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D015995:Prevalence; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging* / Q000473:pathology
chemical_list: D005819:Genetic Markers; D015796:HLA-B27 Antigen; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains