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Low grade radiographic sacroiliitis as prognostic factor in patients with undifferentiated spondyloarthritis fulfilling diagnostic criteria for ankylosing spondylitis throughout follow up
  1. G Huerta-Sil1,
  2. J C Casasola-Vargas1,
  3. J D Londoño2,
  4. R Rivas-Ruíz3,
  5. J Chavez4,
  6. C Pacheco-Tena5,
  7. M H Cardiel6,
  8. G Vargas-Alarcón7,
  9. R Burgos-Vargas8
  1. 1Department of Rheumatology, Hospital General de México, Mexico City, Mexico
  2. 2Department of Rheumatology, Clinica Universitaria Teleton, University of la Sabana, Bogotá, Colombia
  3. 3Department of Paediatrics, Paediatric Hospital, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social. México City, México
  4. 4Department of Rheumatology, Hospital E Rebagliati, Lima, Perú
  5. 5Facultad de Medicina, Universidad Autónoma de Chihuahua, Chihuahua, México
  6. 6Department of Research Mario Alvizour, Hospital General Dr Miguel Silva. Morelia, México
  7. 7Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico
  8. 8Department of Rheumatology, Hospital General de México, Universidad Nacional Autónoma de México. Mexico City, Mexico
  1. Correspondence to:
    Dr Rubén Burgos-Vargas
    Hospital General de México, Dr Balmis 148, Mexico DF 06726; burgosv{at}; burgosv{at}


Objective: To determine the rate and factors associated with ankylosing spondylitis in a cohort of patients with undifferentiated spondyloarthritides (SpA).

Methods: 62 consecutive patients with undifferentiated SpA seen between 1998 and 1999 underwent clinical and imaging evaluations throughout follow up. The main outcome measure was a diagnosis of ankylosing spondylitis.

Results: 50 patients with peripheral arthritis (n = 35) and inflammatory back pain (n = 24) (26 male; mean (SD) age at onset, 20.4 (8.8) years; disease duration 5.4 (5.7) years) were followed up for 3–5 years. At baseline, >90% of patients had axial and peripheral disease, while 38% had radiographic sacroiliitis below the cut off level for a diagnosis of ankylosing spondylitis (BASDAI 3.9, BASFI 2.9). At the most recent evaluation, 21 patients (42%) had ankylosing spondylitis. Two factors were associated with a diagnosis of ankylosing spondylitis in multivariate analysis: radiographic sacroiliitis grade <2 bilateral, or grade <3 unilateral (odds ratio (OR) = 11.18 (95% confidence interval, 2.59 to 48.16), p = 0.001), particularly grade 1 bilateral (OR = 12.58 (1.33 to 119.09), p = 0.027), and previous uveitis (OR = 19.25 (1.72 to 214.39), p = 0.001). Acute phase reactant levels, juvenile onset, and HLA-B27 showed a trend to linkage with ankylosing spondylitis (NS).

Conclusions: Low grade radiographic sacroiliitis is a prognostic factor for ankylosing spondylitis in patients originally classified as having undifferentiated SpA. Low grade radiographic sacroiliitis should be regarded as indicative of early ankylosing spondylitis in patients with undifferentiated SpA.

  • BASDAI, Bath ankylosing spondylitis disease activity index
  • BASFI, Bath ankylosing spondylitis functional index
  • ESSG, European Spondyloarthropathy Study Group
  • IBP, inflammatory back pain
  • SpA, spondyloarthritis
  • ankylosing spondylitis
  • spondyloarthritis
  • sacroiliitis
  • HLA-B27

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  • Published Online First 11 October 2005