Table 2.
Characteristics of patients with axSpA with early disease and established disease at start of first TNF inhibitor
| Parameter | All patients diagnosed as having axSpA (main analysis; N=1124) |
Patients fulfilling the ASAS classification criteria (sensitivity analysis; N=816) |
||||||||
| N | Early disease (≤2 years) N=250 |
N | Established disease (>2 years) N=874 |
P value | N | Early disease (≤2 years) N=160 |
N | Established disease (>2 years) N=656 |
P value | |
| Male sex, N (%) | 250 | 127 (50.8) | 874 | 447 (51.1) | 0.98 | 160 | 86 (53.8) | 656 | 362 (55.2) | 0.81 |
| Age, years | 250 | 38.4 (12.9) | 874 | 43.6 (12.3) | <0.001 | 160 | 33.3 (9.7) | 656 | 40.9 (11.5) | <0.001 |
| Symptom duration, years, median (IQR) | 248 | 1.4 (0.8–2.4) | 867 | 10.8 (5.9–19.7) | <0.001 | 159 | 1.4 (0.8–2.6) | 651 | 11.2 (6.1–20.3) | <0.001 |
| Axial symptom duration, years, median (IQR) | 250 | 0.8 (0.5–1.3) | 874 | 10.2 (5.3–19.0) | <0.001 | 160 | 0.8 (0.5–1.3) | 656 | 10.4 (5.5–19.3) | <0.001 |
| Time since diagnosis, years, median (IQR) | 249 | 0.4 (0.2–0.9) | 864 | 2.6 (0.5–8.9) | <0.001 | 160 | 0.3 (0.2–0.8) | 649 | 2.8 (0.5–9.3) | <0.001 |
| HLA-B27 positive, N (%) | 223 | 123 (55.2) | 804 | 533 (66.3) | 0.003 | 140 | 97 (69.3) | 613 | 467 (76.2) | 0.11 |
| Family history axSpA, N (%) | 231 | 42 (18.2) | 812 | 185 (22.8) | 0.16 | 151 | 30 (19.9) | 616 | 159 (25.8) | 0.16 |
| Body mass index | 224 | 25.1 (4.5) | 807 | 25.8 (4.6) | 0.02 | 142 | 24.8 (4.7) | 614 | 25.6 (4.6) | 0.02 |
| Current smoking | 230 | 77 (33.5) | 804 | 266 (33.1) | 0.32 | 146 | 52 (35.6) | 602 | 210 (34.9) | 0.04 |
| Education | 203 | 721 | 0.39 | 133 | 0.83 | |||||
|
31 (15.8) | 124 (17.2) | 22 (16.5) | 87 (16.0) | ||||||
|
124 (61.1) | 402 (55.8) | 77 (57.9) | 303 (55.8) | ||||||
|
47 (23.2) | 195 (27.0) | 34 (25.6) | 153 (28.2) | ||||||
| Back pain due to axSpA* ≥3 months, N (%) | 250 | 250 (100.0) | 874 | 874 (100.0) | N/A | 160 | 160 (100.0) | 656 | 656 (100.0) | N/A |
| Inflammatory back pain, N (%) | 236 | 173 (73.3) | 816 | 689 (84.4) | <0.001 | 160 | 122 (76.2) | 652 | 572 (87.7) | <0.001 |
| Sacroiliitis ever* | ||||||||||
|
226 | 149 (65.9) | 766 | 522 (68.1) | 0.59 | 151 | 112 (74.2) | 615 | 435 (70.7) | 0.46 |
|
229 | 40 (17.5) | 773 | 203 (26.3) | 0.01 | 154 | 31 (20.1) | 621 | 181 (29.1) | 0.03 |
|
226 | 132 (58.4) | 766 | 345 (45.0) | 0.001 | 151 | 108 (71.5) | 615 | 317 (51.5) | <0.001 |
| Spine involvement ever* | ||||||||||
|
227 | 148 (65.2) | 770 | 533 (69.2) | 0.29 | 152 | 99 (65.1) | 619 | 434 (70.1) | 0.27 |
|
227 | 13 (5.7) | 770 | 104 (13.5) | 0.002 | 152 | 8 (5.3) | 619 | 89 (14.4) | 0.004 |
|
227 | 80 (35.2) | 770 | 222 (28.8) | 0.08 | 152 | 48 (31.6) | 619 | 186 (30.0) | 0.79 |
| ASAS classification criteria, N (%) | 212 | 160 (75.5) | 743 | 656 (88.3) | <0.001 | 160 | 656 | 0.01 | ||
|
N/A | N/A | 27 (16.9) | 145 (22.1) | ||||||
|
N/A | N/A | 68 (42.5) | 200 (30.5) | ||||||
|
N/A | N/A | 65 (40.6) | 311 (47.4) | ||||||
| Ever peripheral arthritis, N (%) | 238 | 103 (43.3) | 815 | 352 (43.2) | 1.00 | 160 | 67 (41.9) | 652 | 259 (39.7) | 0.68 |
| Ever enthesitis, N (%) | 236 | 163 (69.1) | 804 | 577 (71.8) | 0.47 | 158 | 109 (69.0) | 644 | 453 (70.3) | 0.81 |
| Ever uveitis, N (%) | 190 | 18 (9.5) | 642 | 101 (15.7) | 0.04 | 125 | 14 (11.2) | 517 | 87 (16.8) | 0.16 |
| Ever psoriasis, N (%) | 189 | 23 (12.2) | 624 | 73 (11.7) | 0.96 | 124 | 13 (10.5) | 502 | 52 (10.4) | 1.00 |
| Ever inflammatory bowel disease, N (%) | 181 | 17 (9.4) | 614 | 55 (9.0) | 0.98 | 121 | 12 (9.9) | 497 | 38 (7.6) | 0.53 |
| Physician global disease activity | 214 | 5.0 (1.9) | 730 | 4.7 (1.8) | 0.06 | 145 | 5.1 (2.0) | 581 | 4.7 (1.9) | 0.08 |
| Patient global disease activity | 180 | 6.1 (2.3) | 627 | 6.1 (2.4) | 0.48 | 122 | 6.0 (2.3) | 498 | 6.1 (2.5) | 0.31 |
| BASDAI | 172 | 5.6 (2.0) | 612 | 5.4 (2.0) | 0.28 | 118 | 5.6 (2.0) | 483 | 5.3 (2.0) | 0.11 |
| ASDAS | 157 | 3.3 (0.9) | 549 | 3.3 (0.9) | 0.48 | 109 | 3.3 (0.9) | 440 | 3.3 (0.9) | 0.25 |
| ASDAS ≥2.1 | 157 | 143 (91.1) | 549 | 498 (90.7) | 1.00 | 109 | 99 (90.8) | 440 | 399 (90.7) | 1.00 |
| Elevated CRP, N (%) | 208 | 113 (54.3) | 703 | 391 (55.6) | 0.80 | 141 | 69 (48.9) | 561 | 264 (47.1) | 0.76 |
| CRP (mg/L), median (IQR) | 209 | 5.9 (2.0–14.0) | 704 | 6.0 (2.0–13.0) | 0.87 | 141 | 6.0 (2.0–14.0) | 562 | 6.5 (2.0–14.0) | 0.94 |
| BASFI | 170 | 3.7 (2.4) | 598 | 3.7 (2.4) | 0.88 | 118 | 3.8 (2.6) | 474 | 3.6 (2.4) | 0.57 |
| BASMI | 186 | 1.4 (1.3) | 657 | 2.1 (1.9) | <0.001 | 128 | 1.3 (1.3) | 524 | 2.0 (1.9) | <0.001 |
| EQ-5D | 167 | 56.2 (20.6) | 586 | 58.6 (20.7) | 0.13 | 116 | 56.7 (20.8) | 465 | 59.5 (20.8) | 0.16 |
| SF-12, physical component summary score | 153 | 35.4 (9.4) | 543 | 36.1 (9.1) | 0.41 | 107 | 36.0 (9.7) | 434 | 36.8 (9.2) | 0.37 |
| SF-12, mental component summary score | 153 | 40.9 (10.0) | 543 | 42.3 (11.1) | 0.19 | 107 | 40.2 (9.7) | 434 | 42.2 (11.2) | 0.10 |
| Non-steroidal antirheumatic drugs, N (%) | 150 | 144 (96.0) | 515 | 488 (94.8) | 0.69 | 98 | 96 (98.0) | 411 | 391 (95.1) | 0.34 |
| Conventional synthetic DMARDs, N (%) | 250 | 34 (13.6) | 873 | 108 (12.4) | 0.68 | 160 | 21 (13.1) | 655 | 67 (10.2) | 0.36 |
Except where indicated otherwise, values represent the mean and SD.
*Information provided by the local rheumatologist with unknown total number of patients with imaging performed.
ASAS, Assessment of SpondyloArthritis international Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; axSpA, axial spondyloarthritis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C reactive protein; DMARDs, disease-modifying antirheumatic drugs; EQ-5D, European Quality of Life 5-domains Questionnaire; HLA-B27, human leucocyte antigen-B27; N/A, not applicable; SF-12, Short Form Questionnaire with 12 questions; TNF, tumour necrosis factor.