Incidence of extra-articular manifestations in ankylosing spondylitis, psoriatic arthritis and undifferentiated spondyloarthritis : Results from a national register-based cohort study
Objectives: To estimate the incidence and strength of association of extra-articular manifestations [EAMs, here: anterior uveitis (AU), IBD and psoriasis] in patients with AS, undifferentiated SpA (uSpA) and PsA, compared with controls. Methods: Three mutually exclusive cohorts of patients aged 18-69 years with AS (n = 8517), uSpA (n = 10 245) and PsA (n = 22 667) were identified in the Swedish Na