Table 1

Main study characteristics

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  • For longitudinal studies, the baseline characteristics are shown. Characteristics are referring to patients with SpA according to the rheumatologist, except for the studies by van den Berg et al7 (according to ASAS axSpA criteria) and Strand et al10 (SpA and no-SpA).

  • *According to the rheumatologist's diagnosis (in the study by van den Berg et al,7 prevalence of pSpA was calculated considering the 302 patients included in the analysis (prevalence in entire cohort: 76/2011=3.8%).

  • †Typical signs of active inflammation (no formal definition).

  • §Median (IQR).

  • ‡Number of patients used in the analysis from a total of 2011 patients included in the cohort.

  • ¶ASAS/Outcome Measures in Rheumatology (OMERACT) definition.

  • **In the absence of IBP or arthralgia only (without arthritis), one additional SpA feature required: psoriasis, inflammatory bowel disease, uveitis, radiographic sacroiliitis, positivity for HLA-B27 or a family history of SpA.

  • ††And, ≥1 of the following: HLA-B27 positivity, current IBP and prior imaging (MRI or radiographic) evidence of sacroiliitis.

  • ASAS, Assessment of SpondyloArthritis international Society; axSpA, axial spondyloarthritis; CBP, chronic back pain; EAC, Early Arthritis Clinic; IBP, inflammatory back pain; mNY, modified New York criteria; NA, not applicable; NR, not reported; PROSpA, prevalence of axial SpA; pSpA, peripheral spondyloarthritis; SI, sacroiliitis; SpA, spondyloarthritis; SPACE, SpondyloArthritis Caught Early.