Baseline demographic and disease characteristics
| Baseline characteristics | IFX+NPX | PBO+NPX |
|---|---|---|
| Demographic characteristics | N=105 | N=51 |
| Gender (male), n (%) | 72 (68.6) | 40 (78.4) |
| Age (years), mean (SD) | 31.7 (8.51) | 30.7 (7.34) |
| Race, n (%) | ||
| White | 91 (86.7) | 45 (88.2) |
| Asian | 14 (13.3) | 5 (9.8) |
| Multiracial | 0 | 1 (2.0) |
| Body mass index (kg/m2), mean (SD) | 24.1 (4.35) | 24.1 (3.40) |
| Clinical characteristics | N=106 | N=52 |
| Years since diagnosis of axial SpA, mean (SD) | 0.84 (0.814) | 0.69 (0.647) |
| Years since onset of axial SpA symptoms, mean (SD) | 1.76 (0.896) | 1.91 (1.439) |
| Number of SpA manifestations, mean (SD) | 3.8 (1.4) | 4.0 (1.23) |
| Inflammatory back pain, n (%) | 95 (89.6) | 48 (92.3) |
| Arthritis, n (%) | 48 (45.3) | 14 (26.9) |
| Dactylitis, n (%) | 3 (2.8) | 1 (1.9) |
| Psoriasis, n (%) | 6 (5.7) | 2 (3.8) |
| Family history of SpA, n (%) | 16 (15.1) | 11 (21.2) |
| Uveitis, n (%) | 6 (5.7) | 6 (11.5) |
| History of CD/UC, n (%) | 0 | 0 |
| Enthesitis (heel), n (%) | 15 (14.2) | 10 (19.2) |
| ASDAS, n (%) | n=105 | n=51 |
| Inactive disease: <1.3 | 0 | 0 |
| Moderate disease activity: 1.3 to <2.1 | 3 (2.9) | 0 |
| High disease activity: 2.1 to ≤3.5 | 34 (32.4) | 15 (29.4) |
| Very high disease activity: >3.5 | 63 (60.0) | 34 (66.7) |
| HLA-B27–positive status, n (%) | 87 (82.1) | 47 (90.4) |
| X-ray sacroiliitis, according to the modified New York criteria* n (%) | 61 (57.5) | 33 (63.5) |
| Previous good response to NSAIDs, n (%) | 73 (68.9) | 36 (69.2) |
| Patients who had prior NSAID treatment, n (%) | 100 (94.3) | 44 (84.6) |
*Bilateral ≥grade 2 or unilateral ≥grade 3, as assessed by the local investigator.
ASDAS, Ankylosing Spondylitis Disease Activity Score; CD, Crohn's disease; HLA-B27, human leukocyte antigen-B27; IFX, infliximab; NPX, naproxen; NSAIDs, nonsteroidal anti-inflammatory drugs; PBO, placebo; SI, sacroiliac; SpA, spondyloarthritis; UC, ulcerative colitis.