Table 1

 Patients and disease characteristics

AS, ankylosing spondylitis; DIP, distal interphalangeal joint; DMARD, disease modifying anti-rheumatic drug; IBD, inflammatory bowel disease; PsA, psoriatic arthritis.
Demographic features
Sex (male/female ratio)111/81
Mean age (years) (range)47 (16 to 78)
Mean disease duration (years) (range)10 (0 to 47)
Familial psoriasis77/192 (40%)
Familial IBD, PsA, or AS27/192 (14%)
Actual use of DMARDs163/192
Clinical features
Skin involvement172/192 (90%)
Nail involvement105/192 (55%)
Inflammatory low back pain76/192 (40%)
DIP involvement75/192 (39 %)
Enthesitis84/192 (44%)
Dactylitis78/192 (41%)
Peripheral arthritis187/192 (97%)
Persistent asymmetrical mono- or oligoarticular disease, predominantly of the lower limbs43/192 (22%)
Radiological features
Erosive disease64/139 (46%)
Typical radiographic features23/139 (16%)
Sacroiliitis42/149 (28%)
Number of patients with at least one feature helpful in discriminating psoriatic arthritis from rheumatoid arthritis.1177/192 (92%)