Table 1.
Characteristics of non-radiographic axial SpA in Asia versus non-Asian regions
| Variables | Asia | Non-Asian regions | P value |
| n | 112 | 486 | |
| Age at disease diagnosis, years | 27.2 (21.1, 39.6) | 34.5 (27.7, 41.7) | <0.001 |
| Age at disease onset, years | 22.8 (18.5, 31.0) | 27.8 (20. 5, 34.8) | 0.007 |
| Age at enrollment, years | 33.9 (24.9, 44.0) | 39.4 (31.5, 47.9) | <0.001 |
| Diagnostic delay*, years | 1.9 (0.27, 5.56) | 2.9 (0.59, 9.58) | 0.01 |
| Male (%) | 85 (75.9) | 229 (47.1) | <0.001 |
| Body mass index, kg/m2 | 23.5 (20.7, 26.6) | 25.2 (22.8, 28.2) | <0.001 |
| Smoking status | |||
| Never (%) | 67 (59.8) | 270 (55.6) | 0.48 |
| Past (%) | 17 (15.2) | 100 (20.6) | 0.24 |
| Current (%) | 28 (25.0) | 116 (23.9) | 0.90 |
| Family history of SpA (%) | 36 (32.1) | 199 (40.9) | 0.11 |
| Meeting ASAS axial SpA criteria | |||
| Imaging arm only (%) | 19 (17.0) | 219 (45.1) | <0.001 |
| Clinical arm only (%) | 63 (56.2) | 145 (29.8) | <0.001 |
| Both (%) | 30 (26.8) | 122 (25.1) | 0.80 |
| MRI tested (%) | 73 (65.2) | 415 (85.4) | <0.001 |
| Sacroiliitis among MRI tested (%) | 49 (67.1) | 341 (82.2) | 0.005 |
| HLA B27 measured (%) | 106 (94.6) | 441 (90.7) | 0.26 |
| HLA B27 positivity among measured (%) | 96 (90.6) | 273 (61.9) | <0.001 |
| Inflammatory back pain (%) | 107 (95.5) | 478 (98.4) | 0.08 |
| Arthritis, enthesitis, or dactylitis (%) | 60 (53.6) | 322 (66.3) | 0.02 |
| Peripheral arthritis (%) | 53 (47.3) | 257 (52.9) | 0.34 |
| Heel enthesitis (%) | 33 (29.5) | 160 (32.9) | 0.55 |
| Peripheral enthesitis (%) | 38 (33.9) | 202 (41.6) | 0.17 |
| Dactylitis (%) | 2 (1.8) | 63 (13.0) | 0.001 |
| Psoriasis (%) | 12 (10.7) | 82 (16.9) | 0.14 |
| CASPAR criteria (%) | 6 (5.4) | 27 (5.6) | 1 |
| Uveitis (%) | 20 (17.9) | 81 (16.7) | 0.87 |
| Inflammatory bowel disease (%) | 5 (4.5) | 27 (5.6) | 0.82 |
| Erythrocyte sedimentation rate, mm/hour | 10.0 (5.0, 19.0) | 11.0 (5.0, 23.0) | 0.11 |
| C reactive protein (CRP) level, mg/dL | 0.50 (0.30, 1.33) | 0.50 (0.10, 1.70) | 0.55 |
| Elevated CRP (%) | 37 (33.0) | 213 (43.8) | 0.05 |
| Physician global assessment (0–10) | 2.0 (1.0, 5.0) | 2.0 (1.0, 4.0) | 0.74 |
| Patient global assessment (0–10) | 3.0 (1.0, 6.0) | 4.0 (2.0, 6.0) | 0.01 |
| ASDAS-CRP | 1.40 (0.95, 2.08) | 1.97 (1.21, 2.78) | <0.001 |
| BASDAI | 2.8 (1.5, 4.2) | 4.1 (2.0, 6.3) | <0.001 |
| BASFI | 0.8(0.1, 2.7) | 2.9(0.8, 5.6) | <0.001 |
| Presence of bamboo spine (%) | 0 (0.0) | 2 (0.4) | 1 |
| History of SpA-related surgeries (%) | 0 (0.0) | 18 (3.7) | 0.03 |
| Treatment | |||
| NSAIDs use since onset (%) | 103 (92.0) | 430 (88.5) | 0.37 |
| COX-2 selective NSAIDs among user (ever) (%) | 32 (31.1) | 127 (29.5) | 0.853 |
| % days with intake ≧50% among user (ever) (%) | 68 (66.0) | 329 (76.5) | 0.039 |
| Good response to NSAIDs (%) | 80 (71.4) | 272 (56.0) | 0.004 |
| Current glucocorticoid use (%) | 10 (8.9) | 59 (12.1) | 0.43 |
| Conventional synthetic DMARDs use (%) | 60 (53.6) | 266 (54.7) | 0.91 |
| Methotrexate use (%) | 18 (16.1) | 134 (27.6) | 0.02 |
| Sulfasalazine use (%) | 51 (45.5) | 205 (42.2) | 0.59 |
| Biological DMARDs (TNF antagonists) use (%) | 27 (24.1) | 191 (39.3) | 0.004 |
| Comorbidities | |||
| Obesity (%) | 24 (21.4) | 91 (19.0) | 0.65 |
| Hypertension (%) | 15 (13.4) | 61 (12.6) | 0.93 |
| Diabetes (%) (%) | 2 (1.8) | 20 (4.1) | 0.40 |
| Dyslipidaemia (%) | 11 (9.8) | 50 (10.3) | 1 |
| Ischaemic heart disease or stroke (%) | 1 (0.9) | 8 (1.6) | 1 |
| Vertebral or fragility fractures (%) | 2 (1.8) | 7 (1.4) | 0.68 |
Values are expressed as n (%) or median (IQR) unless otherwise indicated.
*Diagnostic delay: the difference between the date of the diagnosis and the date of the first symptom.
ASAS, Assessment of SpondyloArthritis International Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; CASPAR, ClASsification for Psoriatic ARthritis; DMARD, disease-modifying antirheumatic drug; HLA, human leucocyte antigens; NSAID, non-steroidal anti-inflammatory drug; SpA, spondyloarthritis; TNF, Tumor Necrosis Factor.