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THU0382 Development of SPA-Features in Patients with Chronic Back Pain over A One-Year Course: Data from The Spondyloarthritis Caught Early (Space)-Cohort
  1. Z. Ez-Zaitouni1,
  2. M. van Lunteren1,
  3. P. Bakker1,
  4. M. Reijnierse2,
  5. I.J. Berg3,
  6. R. Landewé4,
  7. M. van Oosterhout5,
  8. A. Ortolan6,
  9. D. van der Heijde1,
  10. F. van Gaalen1
  1. 1Rheumatology
  2. 2Radiology, LUMC, Leiden, Netherlands
  3. 3Rheumatology, Diakonhjemmet Hospital, Oslo, Norway
  4. 4Rheumatology, AMC, Amsterdam
  5. 5Rheumatology, GHZ, Gouda, Netherlands
  6. 6Rheumatology, University of Padova, Padova, Italy

Abstract

Background Little is known on the development of SpA-features over time in patients with recent onset chronic back pain (CBP).

Objectives To explore whether patients with suspicion of axial spondyloarthritis (axSpA) develop spondyloarthritis (SpA)-features over time in the SPACE-cohort, and to study the effect of gaining features on the clinical diagnosis and classification according to the Assessment of SpondyloArthritis international Society (ASAS)-criteria for axSpA.

Methods SPACE is an inception cohort study in which CBP pts (≥3 months, ≤2 years, onset <45 years) from various rheumatology centres across Europe are included. Baseline (BL) and one-year (FU) data were used for this study. Pts underwent a full diagnostic work-up consisting of MRI and radiographs of the sacroiliac joints (MRI-SI and X-SI), acute phase reactants, HLA-B27, and assessment of all other SpA-features. For the purpose of this study positive SpA-features were accumulated according to the principle of “once a feature always a feature” meaning pts were not able to “lose” features over time. Total number of SpA-features was calculated excluding sacroiliac imaging and HLA-B27 status. Clinical diagnosis (axSpA yes/no) of pts was provided by the treating rheumatologist with use of local reading and the ASAS-criteria for axSpA (based on central scoring and agreement of 2/3 readers) were used for classification.

Results A total of 270 pts with CBP with both baseline and one-year follow-up visits were included: 36.7% were male, mean age (SD) at inclusion was 31.2 (8.0) years, mean number of SpA-features (SD) at BL and one-year FU were 2.8 (1.5) and 3.5 (1.6), respectively. After one year 49.3% of pts had gained one or more features. Most common features were IBP (BL: 77.0%, FU: 88.2%), good response to NSAIDs (BL: 48.5%, FU: 70.6%), elevated CRP/ESR (BL: 29.5%, FU: 43.3%), and positive family history for SpA (BL: 48.9%, FU: 52.6%).

For 16 out of the 270 pts information on diagnosis at either BL or FU was missing. In the remaining 254 patients, rheumatologists diagnosed 150 (59.1%) and 66 (26.0%) patients with axSpA and no axSpA at both time points, respectively. In 15.0% (38/254) of patients the diagnosis changed; 16 patients with no axSpA diagnosis at BL were diagnosed with axSpA at FU of which 11/16 (68.8%) had acquired one or more features. In 22 patients with axSpA at BL rheumatologists reconsidered their diagnosis at FU. In the 150 patients diagnosed with axSpA, 108/150 (72%) of patients already fulfilled the ASAS-criteria at BL and 79 (52.7%) patients gained a minimum of one feature, which led to a new the axSpA classification for 9 patients at FU.

Conclusions In patients with CBP of short duration almost half developed at least one new SpA-feature within one year, however the impact on diagnosis and classification was limited.

Disclosure of Interest None declared

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