Table 1.

Patients' characteristics

	Controls (n = 64)	Ankylosing spondylitis (n = 65)	Psoriatic arthritis (n = 25)	Rheumatoid arthritis (n = 72)
Age (years)	49.2 ± 12.4	43.1 ± 10.9	52.2 ± 12	57.9 ± 11
Gender (% female)	50.8	28.4	45.8	75.6
Rheumatoid factor positivity (%)	0.0	n.d.	n.d.	77.8
CCP-Ab positivity (%)	0.0	n.d.	n.d.	80.5
HLA-B27 positivity (%)	n.d.	78.6	31.3	n.d.
Axial involvement (% positive)	0.0	100.0	48.0	0.0
Erythrocyte sedimentation rate >15 mm/hour (% positive)	0.0	62.7	88.2	86.2
C-reactive protein >0.7 μg/dl (% positive)	0.0	26.1	41.7	46.8

CCP-Ab, antibodies directed against cyclic citrullinated peptides; n.d., not determined.