Epidemiological characteristics and disease phenotype of peripheral spondyloarthritis (SpA) and psoriatic arthritis (PsA) sine psoriase
| Peripheral SpA | PsA sine psoriase | |
| Prevalence | 22.8%–28.5% of all SpA (in studies with overlapping SpA subtypes) 9.7%–14% of all SpA (in studies without overlapping SpA subtypes) | 13.5%–24.6% of all PsA 3.1%–5.5% of all SpA (in studies without overlapping SpA subtypes) |
| Mean age of onset | 32.8–42.2 years | 30–44 years |
| Gender | 46.9%–62.8% | 20%–55% |
| Arthritis | 79%–98% | 75%–85.7% |
| Enthesitis* | 41%–63% | 35%–55% |
| Dactylitis* | 12%–49% | 62%–75% |
| Type of joint involved* | Large joints of the lower limbs (51.2%) | Distal Interphalangeal Joints of the hands (40%–70%) |
| No of joint involved | ||
| Oligoarthritis | 45% | 40% |
| Oligoarthritis Polyarthritis | 44% | 35% |
| Axial involvement (Inflammatory Back Pain) | 12%–55% | 12%–35% |
| Sacroiliitis on MRI | 30–35% | |
| Uveitis | 1.2%–17% | 2%–25% |
| Inflammatory Bowel Disease | 4%–17% | N/A |
| ESR mm* | 7–18 | 36 |
| CRP mg/L | 7–13.9 | N/A |
| HLA-B27* | 27%–62% | 18% |
*Features where differences between peripheral SpA and PsA sine psoriase are observed.
CRP, C reactive protein; ESR, erythrocyte sedimentation rate; HLA-B27, Human Leucocyte Antigen-B27; N/A, not available.