Baseline demographics according to classification criteria at baseline (start of the first TNFi treatment course) for nr-axSpA, AS, and unspecified axSpA. Data are medians (interquartile ranges) unless otherwise stated.
| No. Pts. with Available Data, n | All Pts. | Nr-axSpA | AS | Unspecified AxSpA# | p* | |
|---|---|---|---|---|---|---|
| N | 1250 | 362 | 622 | 266 | ||
| Age, yrs | 1250 | 40 (31–49) | 38 (30–46) | 42 (33–52) | 38 (29–46) | < 0.001 |
| Male, n (%) | 1250 | 792 (63) | 183 (51) | 455 (73) | 154 (58) | < 0.0001 |
| HLA-B27–positive, n (%) | 1045 | 811 (65) | 253 (70) | 395 (83) | 163 (61) | 0.005 |
| BMI, kg/cm2 | 728 | 25 (23–29) | 25 (22–30) | 26 (23–29) | 24 (23–28) | 0.4 |
| MTX, yes, n (%) | 1250 | 222 (18) | 59 (16) | 129 (21) | 34 (13) | 0.09 |
| Manifestations ever, n (%) | ||||||
| Inflammatory back pain | 1177 | 1131 (91) | 326 (90) | 562 (90) | 243 (91) | 0.07 |
| Family disposition | 885 | 199 (16) | 67 (19) | 98 (16) | 34 (13) | 0.9 |
| Peripheral arthritis | 1119 | 441 (35) | 146 (40) | 190 (31) | 105 (39) | 0.05 |
| Enthesitis | 909 | 218 (17) | 72 (20) | 95 (15) | 51 (19) | 0.5 |
| Uveitis | 1042 | 249 (20) | 67 (19) | 145 (23) | 37 (14) | 0.02 |
| Psoriasis | 1018 | 75 (6) | 31 (9) | 35 (6) | 9 (3) | 0.2 |
| Dactylitis | 871 | 40 (3) | 21 (6) | 9 (1) | 10 (4) | < 0.0001 |
| IBD | 1031 | 104 (8) | 31 (9) | 42 (7) | 31 (12) | 0.5 |
| NSAID response | 876 | 614 (49) | 179 (49) | 310 (49) | 125 (47) | 0.9 |
| Elevated CRP | 1093 | 575 (46) | 164 (45) | 307 (49) | 104 (39) | 0.003 |
| Symptom duration, yrs | 1040 | 9 (3–18) | 6 (3–13) | 13 (6–23) | 5 (2–11) | < 0.0001 |
| Disease duration, yrs | 1155 | 1 (0–6) | 1 (0–3) | 3 (1–12) | 1 (0–3) | < 0.0001 |
| Smoking status, n (%) | 976 | |||||
| Current | 377(30) | 97 (27) | 216 (41) | 64 (24) | ||
| Previous | 177 (14) | 42 (12) | 103 (20) | 32 (12) | 0.2 | |
| Never | 422 (33) | 119 (33) | 204 (39) | 99 (37) | ||
| First TNFi drug, n (%) | 1250 | |||||
| Adalimumab | 519 (41) | 151 (42) | 258 (41) | 110 (41) | < 0.0001 | |
| Certolizumab pegol | 8 (1) | 5 (1) | 2 (0) | 1 (0) | ||
| Etanercept | 183 (15) | 53 (14) | 100 (16) | 30 (11) | ||
| Golimumab | 246 (20) | 85 (23) | 88 (14) | 73 (27) | ||
| Infliximab | 294 (24) | 68 (19) | 174 (28) | 52 (20) | ||
| First TNFi start yr, n (%) | 1250 | |||||
| 2005–2008 | 376 (30) | 79 (21) | 259 (41) | 38 (14) | < 0.0001 | |
| 2009–2011 | 442 (35) | 132 (36) | 194 (31) | 116 (45) | ||
| 2012–2014 | 432 (34) | 151 (41) | 169 (27) | 112 (42) | ||
| CRP, mg/l | 964 | 9 (3–20) | 7 (3–17) | 11 (5–22) | 6 (2–16) | < 0.0001 |
| BASDAI, mm | 1012 | 61 (49–73) | 64 (54–77) | 59 (46–71 | 63 (51–74) | < 0.0001 |
| BASDAI, question 5, mm | 783 | 73 (52–86) | 75 (55–91) | 71 (51–84) | 74 (54–86) | 0.02 |
| BASDAI, question 6, mm | 785 | 60 (36–86) | 68 (39–90) | 56 (32–83) | 59 (39–86) | 0.02 |
| BASFI, mm | 980 | 50 (34–68) | 52 (33–69) | 49 (34–67) | 51 (31–67) | 0.7 |
| PGA, mm | 676 | 37 (22–51) | 38 (22–53) | 38 (22–53) | 35 (22–45) | 0.6 |
| BASMI | 848 | 30 (10–40) | 20 (10–40) | 40 (20–50) | 20 (10–40) | < 0.0001 |
| PtGA, mm | 938 | 72 (53–85) | 76 (62–88) | 68 (50–80) | 74 (59–88) | < 0.0001 |
| Pain, mm | 937 | 67 (50–80) | 72 (55–84) | 65 (48–77) | 68 (50–81) | < 0.0001 |
| Fatigue, mm | 846 | 70 (52–83) | 74 (55–85) | 67 (50–80) | 72 (54–85) | 0.001 |
↵# No baseline radiograph of sacroiliac joints available.
↵* Nr-axSpA versus AS. Chi square or nonparametric testing (Mann-Whitney U test) for continuous data. TNFi: tumor necrosis factor inhibitor; AS: ankylosing spondylitis; axSpA: axial spondyloarthritis; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; BASFI: Bath Ankylosing Spondylitis Function Index; BASMI: Bath Ankylosing Spondylitis Metrology Index; BMI: body mass index; MTX: methotrexate; CRP: C-reactive protein; IBD: inflammatory bowel disease; NSAID: nonsteroidal antiinflammatory response; nr-axSpA: nonradiographic axSpA; VAS: visual analog scale; PGA: physician’s global assessment; PtGA: patient’s global assessment.