Table 1.
Baseline characteristics and SpA features of chronic back pain patients included in the SPACE cohort (n = 719)
| Characteristic | Value |
|---|---|
| Male gender, n (%) | 275 (38) |
| Age at CBP onset (years), mean (SD) | 29.0 (8.0) |
| Duration of CBP (months), mean (SD) | 13.2 (6.9) |
| Alternating buttock pain, n (%) (N = 454a) | 225 (55) |
| IBP, n (%) | 499 (70) |
| Response to NSAIDs, n (%) | 316 (45) |
| Family history of SpA, n (%) | 305 (43) |
| Peripheral arthritis, n (%) | 111 (15) |
| Heel enthesitis, n (%) | 142 (20) |
| Dactylitis, n (%) | 39 (5) |
| Uveitis, n (%) | 58 (8) |
| Psoriasis, n (%) | 88 (12) |
| IBD, n (%) | 48 (6) |
| HLA-B27+, n (%) | 315 (44) |
| Elevated CRP/ESR, n (%) | 217 (30) |
| MRI-SIJ+, n (%) | 234 (32) |
| X-SIJ+, n (%) | 91 (12) |
| Any positive imaging,b n (%) | 250 (34) |
SpA spondyloarthritis, SPACE SPondyloArthritis Caught Early, CBP chronic back pain, IBP inflammatory back pain, NSAID non-steroidal anti-inflammatory drug, IBD inflammatory bowel disease, HLA human leukocyte antigen, CRP C-reactive protein, ESR erythrocyte sedimentation rate, MRI-SIJ magnetic resonance imaging of sacroiliac joints, X-SIJ plain radiograph of sacroiliac joints
aMissing data < 5% unless otherwise indicated
bMRI-SIJ+ and/or X-SIJ+