Patient characteristics comparing those included in LCA to those not (SPACE cohort)
| All (n=748) | Included in LCA (n=465) | NOT included in LCA (n=283) | P value | |
| Age at baseline (years) | 31 (8) | 31 (8) | 30 (8) | 0.35 |
| Male gender | 287 (39) | 161 (35) | 126 (45) | 0.01 |
| Symptom duration (years) | 2 (2) | 2 (2) | 2 (2) | 0.93 |
| Inflammatory back pain | 513 (69) | 308 (66) | 205 (74) | 0.027 |
| ASAS axSpA criteria | 308 (42) | 172 (37) | 133 (52) | <0.01 |
| ASAS pSpA criteria | 281 (39) | 182 (39) | 99 (39) | 0.93 |
| ASAS SpA criteria† | 412 (57) | 249 (54) | 163 (64) | 0.01 |
| axSpA according to Rheumatologist* | 255 (35) | 136 (30) | 119 (45) | <0.01 |
| HLA-B27 | 328 (44) | 172 (37) | 156 (57) | <0.01 |
| Dactylitis ever | 41 (6) | 23 (5) | 18 (6) | 0.39 |
| Uveitis ever | 60 (8) | 33 (7) | 27 (10) | 0.21 |
| Family history of SpA | 317 (43) | 194 (42) | 123 (44) | 0.50 |
| Inflammatory bowel disease ever | 51 (7) | 35 (8) | 16 (6) | 0.34 |
| Psoriasis ever | 95 (13) | 54 (12) | 41 (15) | 0.23 |
| Peripheral arthritis ever | 117 (16) | 76 (16) | 41 (15) | 0.56 |
| Heel enthesitis ever | 146 (20) | 91 (20) | 55 (20) | 0.96 |
| Current arthritis / any enthesitis / dactylitis | 475 (64) | 317 (68) | 158 (58) | <0.01 |
| Elevated CRP (≥6 mg/L) | 182 (25) | 118 (25) | 64 (24) | 0.57 |
| Good response to NSAIDs ever | 327 (45) | 189 (41) | 138 (53) | <0.01 |
| Number of SpA features (0–9)‡ | 2 (1) | 2 (1) | 2 (1) | 0.35 |
| Radiographic sacroiliitis (mNY) | 55 (9) | 38 (8) | 17 (11) | 0.26 |
| Sacroiliitis on MRI-SIJ (ASAS) | 106 (18) | 64 (14) | 42 (30) | <0.01 |
| BME on MRI-spine (≥5 lesions) | 25 (4) | 21 (5) | 4 (3) | 0.42 |
| ≥1 syndesmophyte on X-spine | 20 (4) | 15 (3) | 5 (9) | 0.06 |