Fig. 1.

Characteristics of joint involvement of patients in PARWCH. a Classification of subtypes in patients with PsA; b ultrasonic changes of peripheral joints; c ten most frequent anatomical sites with tenderness in patients with peripheral arthritis (n = 252, 91.6%); d ten most frequent anatomical sites with swelling in patients with peripheral arthritis (n = 252, 91.6%); e proportion of sites involved in axial arthritis (n = 140, 50.9%); PARWCH the Psoriatic Arthritis cohort of West China Hospital, MCP metacarpophalangeal joints, PIP proximal interphalangeal joints, DIP distal interphalangeal joints, MTP metatarsophalangeal joints