Table 1.
Differential diagnosis of psoriatic arthritis (PsA) versus other rheumatic disease conditions [8, 73–81]
| Clinical feature | PsA | Osteoarthritis | Fibromyalgia | Gout | Ankylosing spondylitis |
|---|---|---|---|---|---|
| Psoriasis | + | − | − | − | − |
| Nail dystrophy | + | − | − | − | − |
| Enthesitis | + | − | + | + | Less often |
| Dactylitis | + | − | − | + | Less often |
| Peripheral joint | + | + | + | + | − |
| Axial joint/spondylitis | + | − | + | +, less often | + |
| Stiffness | + | +, with mobility | + | + | + |
| Rheumatoid factor positivea | − | − | − | − | − |
aThe diagnostic utility of rheumatoid factor alone is limited because a proportion of healthy individuals can be rheumatoid factor positive and, infrequently, rheumatoid factor can be positive in patients with PsA. Therefore, detection of rheumatoid factor should not be used alone in diagnosis of these conditions but used in conjunction with other clinical and assessment factors [73, 74, 90, 201]