Clinical and demographical characteristics of the subjects included in the study.

HC = healthy controls; SAP = seropositive arthralgia patients; RA = rheumatoid arthritis; SpA = spondyloarthropathy; CRP = C-reactive protein; ESR = erythrocyte sedimentation rate; DAS28 = disease activity score 28; RF = rheumatoid factor; anti-CCP = anti-cyclic citrullinated proteins antibodies; BASDAI = bath ankylosing spondylitis disease activity index; ASDAS = ankylosing spondylitis disease activity score; nd = not defined; na = not applicable. Clinical and demographical characteristics of the subjects included in the study.