Table 1

Characteristics of patients and controls included in the final analysis

CharacteristicDiscovery cohortConfirmatory cohort
SpA
(n=49)
HC
(n=18)
RA
(n=17)
SpA
(n=38)
HC
(n=51)
RA
(n=11)
Age in years, mean±SD48±1337±10.465.5±11.653±9.854±8.656±19.5
Disease duration in years, mean±SD22.1±12.0N/A19.9±12.829.3±11.2N/A2±2.2
Sex ratio, % of men455018473327
BMI, mean±SDNDNDND25.2±3.925.6±4.924±4.9
HLA-B27 positivity, %67NDND97.445ND
Disease activity*, mean±SD3.9±2.2N/A3±1.43.6±2.2N/A4±1
Radiographic sacroiliitis†, %33NDND683.6ND
Classification criteria fulfilment
 Modified New York AS, %33006800
 ASAS axial SpA, %80009700
 ASAS peripheral SpA, %2000300
 ACR/EULAR RA, %0010000100
Extra-articular manifestations
 Uveitis, %33062900
 Psoriasis, %490016139
 Inflammatory bowel disease, %12.2005.300
Treatments of interest
 Any, %65.3094.176.39.863.6
 NSAIDs, %51035.360.57.845
 Corticosteroids %12.2082 .42.600
 DMARDs, %4053000
 Biotherapy, %30.6070.62600
 Antiacid, %30.6070.644.7227.3
  • The registered manifestations correspond to those present at the time of examination, or retrieved from medical history.

  • *Refers to BASDAI (SpA) or DAS28 (RA).

  • †Refers to radiographic sacroiliitis ≥grade II bilateral or grade III unilateral.

  • ACR, American College of Rheumatology; AS, ankylosing spondylitis; ASAS, Assessment of SpondyloArthritis Iinternational Society; BMI, body mass index; DMARD, disease-modifying drug (ie, methotrexate or sulfasalazine); EULAR, European League Against Rheumatism; HCs, healthy controls; N/A, not applicable; ND, not done; NSAIDs, non-steroidal anti-inflammatory drugs; RA, rheumatoid arthritis; SpA, spondyloarthritis.