title: Genuine ankylosing spondylitis in children: a case-control study of patients with early definite disease according to adult onset criteria.
abstract: OBJECTIVE
  To describe a group of children with spinal and sacroiliac (SI) joint involvement since the initial year of disease, who fulfilled current adult onset ankylosing spondylitis (AS) diagnostic criteria within 3 years of onset.
  
  
  METHODS
  We conducted a case-control study of 44 patients with juvenile onset definite AS. 14 cases (Group A) and 30 controls (Group B) were studied; groups were matched by age at onset (age < or = 16 years), duration of disease at the time of admission to our clinic (< or = 1 year), diagnostic criteria (New York criteria), and period of observation. We compare demographic characteristics, as well as peripheral joint disease 6 and 12 months after onset, and analyze Group A at time of diagnosis. In contrast to Group A, patients in Group B had a syndrome of peripheral arthritis and enthesitis (SEA syndrome), but no axial symptoms or definite diagnosis of AS in the first 5 years of disease.
  
  
  RESULTS
  Patients in Group A were HLA-B27 positive boys with peripheral arthritis and enthesitis who differed from those in Group B in the frequency of pauciarthritis and polyarthritis at one year of disease (0 vs 36.7% and 100.0 vs 63.3%; p = 0.008) and age at diagnosis (9.03 +/- 1.13 vs 16.5 +/- 3.3 years; p > 0.0001). Six patients in Group A had lumbar pain and 3 SI joint pain 6 months after onset; at the end of the first year, the number increased to 10 and 6 patients, respectively. At time of diagnosis (2.36 +/- 0.72 yrs after onset), all patients in Group A had radiographic sacroiliitis and spinal, SI, and/or costosternal pain, 11 reduced anterior spinal flexion, and 6 reduced chest expansion.
  
  
  CONCLUSIONS
  There is a less common subgroup of adult-like juvenile onset AS who develop clinical and radiographic evidence of disease affecting the axial skeleton earlier than children progressing from SEA syndrome to AS 5 to 10 years after onset.
authors.affiliation: Rheumatology Unit, Hospital General de México, Universidad Nacional Autónoma de México Faculty of Medicine, México City.
authors.forename: R
authors.initials: R
authors.lastname: Burgos-Vargas
authors.forename: J
authors.initials: J
authors.lastname: Vázquez-Mellado
authors.forename: N
authors.initials: N
authors.lastname: Cassis
authors.forename: C
authors.initials: C
authors.lastname: Duarte
authors.forename: J
authors.initials: J
authors.lastname: Casarín
authors.forename: M
authors.initials: M
authors.lastname: Cifuentes
authors.forename: L
authors.initials: L
authors.lastname: Lino
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D016022:Case-Control Studies; D002648:Child; D015796:HLA-B27 Antigen / Q000032:analysis; D006801:Humans; D008297:Male; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000276:immunology; D014057:Tomography, X-Ray Computed
chemical_list: D015796:HLA-B27 Antigen