title: Validity of the ankylosing spondylitis disease activity score (ASDAS) in patients with early spondyloarthritis from the Esperanza programme.
abstract: OBJECTIVE
  To evaluate the validity of the Ankylosing Spondylitis Disease Activity Score (ASDAS) in early spondyloarthritis (SpA) in comparison with conventional clinical measures of disease activity.
  
  
  METHODS
  Six hundred and seventy-six incident cases of early SpA from the Esperanza programme were included. Patients were categorised into high and low disease activity states based on patient and physician global assessment scores and on the physician's decision to start treatment with a disease-modifying antirheumatic drug or tumour necrosis factor blocker. The discriminant ability of ASDAS-C-reactive protein (CRP) and ASDAS-erythrocyte sedimentation rate (ESR) was tested using standardised mean differences between patients with high and low disease activity. Convergent validity was tested by Pearson correlation between ASDAS versions and other measures of disease activity.
  
  
  RESULTS
  ASDAS-ESR and ASDAS-CRP showed good correlation with BASDAI (r=0.79 and 0.74, respectively). Both indices correlated well with the patient global assessment (r=0.70 in both indices) and moderately with the physician global score (r=0.46 and 0.47, respectively). CRP and ESR showed poor correlation with patient- and physician-derived measures. ASDAS performed similarly across the global SpA sample, ankylosing spondylitis (AS), non-radiographic axial SpA and peripheral SpA.
  
  
  CONCLUSIONS
  ASDAS performed as a valid activity score even being slightly better than the Bath Ankylosing Spondylitis Disease Activity Index in its ability to discriminate between high and low disease activity in early SpA. ASDAS performed similarly in AS, early forms of SpA, non-radiographic axial SpA and peripheral SpA.
authors.affiliation: Rheumatology Department, Hospital Universitario de Móstoles, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Fernández-Espartero
authors.affiliation: Rheumatology Department, Hospital Universitario de la Paz, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: de Miguel
authors.affiliation: Institute for Musculoskeletal Health, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Loza
authors.affiliation: Rheumatology Department, Hospital Universitario de la Princesa, Instituto de Investigación La Princesa, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Tomero
authors.affiliation: Research Unit, Fundación Española de Reumatología, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Gobbo
authors.affiliation: Research Unit, Fundación Española de Reumatología, Madrid, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Descalzo
authors.affiliation: Rheumatology Department, Hospital Universitario Reina Sofía, Instituto Mainónides de Investigación Biomédica de Córdoba, Universidad de Córdoba, Córdoba, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Collantes-Estévez
authors.affiliation: Rheumatology Department, Hospital Universitario de Puerta de Hierro-Majadahonda, Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Mulero
authors.affiliation: Rheumatology Department, Hospital Universitario Infanta Sofía, Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Muñoz-Fernández
authors.affiliation: Rheumatology Department, Hospital Universitario Fundación Alcorcón, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Zarco
authors.affiliation: Institute for Musculoskeletal Health, Madrid, Spain Universidad Camilo José Cela, Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Carmona
mesh_terms: D000328:Adult; D001416:Back Pain / Q000175:diagnosis; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D002097:C-Reactive Protein
keywords: Disease Activity; Outcomes research; Spondyloarthritis