Fig. 1.

ASAS classification criteria for axial and peripheral spondyloarthritis

(A) ASAS classification criteria for axial spondyloarthritis; (B) ASAS classification criteria for peripheral spondyloarthritis. *Sacroiliitis on imaging refers to definite radiographic sacroiliitis according to the modified New York criteria or active sacroiliitis on MRI according to the ASAS definition. **Peripheral arthritis: usually predominantly lower limbs and/or asymmetric arthritis; enthesitis: clinically assessed; dactylitis: clinically assessed. SpA: spondyloarthritis.