Characteristic | PsA | RA |
Clinical | ||
Psoriasis | +++ | − |
Symmetric joint involvement | + | +++ |
Asymmetric joint involvement | ++ | + |
Polyarthritis | ++ | +++ |
Oligoarthritis/monarthritis | + | + |
Distal interphalangeal joint involvement | +++ | − |
Metacarpophalangeal and wrist involvement | +++ | +++ |
Metatarsophalangeal joint involvement | +++ | +++ |
Axial spine involvement | +++ | − |
Cervical spine involvement | + | +++ |
Enthesitis | +++ | − |
Dactylitis | +++ | + |
Synovitis | ++ | +++ |
Tenosynovitis | ++ | +++ |
Nail dystrophy | +++ | − |
Arthritis mutilans | + | − |
Interstitial lung disease | − | ++ |
Serological | ||
Rheumatoid factor | − | +++ |
Cyclic citrullinated peptide antibodies | −* | +++ |
C reactive protein | ++ | +++ |
Erythrocyte sedimentation rate | ++ | +++ |
Th17 cell upregulation | ++ | − |
TNF-α-driven | +++ | +++ |
IL-17A-driven | +++ | − |
IL-12/23-driven | +++ | − |
IL-6-driven | − | +++ |
Imaging | ||
Pencil-in-cup deformity | ++ | − |
Ankylosis | ++ | − |
Subluxation | ++ | ++ |
Bone proliferation | +++ | − |
Number of erosions | + | +++ |
Bone erosion | + | +++ |
Synovitis | ++ | +++ |
Tenosynovitis | ++ | +++ |
Distal interphalangeal joint involvement | +++ | − |
Genetic | ||
HLA-B27 alleles | ++ | − |
HLA-DRB1 alleles | − | ++ |
The greater number of symbols (+, ++, +++) indicates a more common characteristic. The dash (–) indicates the characteristic is not common.
*Approximately 5% of patients with PsA have seropositive findings for anticyclic citrullinated peptide antibodies.71
HLA, human leucocyte antigen; IL, interleukin; PsA, psoriatic arthritis; RA, rheumatoid arthritis; Th17, T helper 17; TNF, tumournecrosis factor.