Background ASAS classification criteria have been developed and validated to make an early classification of patients presenting with symptoms of spondyloarthritis (SpA), and to better distinguish between patients with predominantly axial SpA (axSpA) and predominantly peripheral SpA (pSpA).
Objectives To investigate the performance of the criteria sets for SpA in a clinical cohort, according to the different available criteria sets (ASAS, ESSG, and Amor) and to assess how the ASAS classification criteria perform in daily clinical practice.
Methods The cohort was established before the development of the ASAS SpA classification criteria, implying that there could not be selection towards the application of these criteria Patients with a clinical diagnosis of SpA attending a specialized rheumatology outpatient clinic were retrospectively classified. The group of patients who met all three criteria sets was compared to the group of patients who met neither.
Results In total, 83.3% of the patients in the cohort (n=581) could be classified as SpA according to the ASAS criteria, 74.1% according to ESSG criteria and 53.1% according to Amor criteria (figure 1). Thirty four percent of patients had predominantly peripheral SpA. A high level of overlap between criteria sets was found and 46.8% (n= 272) of the patients fulfilled all three criteria sets. Those fulfilling the three criteria sets were older (p=0.047), had more SpA features (p=<0.001) and had more frequently a history and presence of back pain, inflammatory back pain, enthesitis, and buttock pain (p=<0.001). Characteristics such as the presence of inflammatory back pain, more SpA features and lower levels of C reactive protein (CRP), lead rheumatologist request an MRI of the SI joints and/or HLA-B27 testing.
Conclusions ASAS criteria are more sensitive classifying patients as having SpA and perform better than the ESSG or Amor criteria with the rheumatologists’ diagnosis as external standard. ASAS criteria perform well in clinical practice allowing physicians to make an early classification.
Rudwaleit M, Ann Rheum Dis 2009;68:777-83
Rudwaleit M, Ann Rheum Dis 2011;70:25-31
Disclosure of Interest None Declared