Comparison of patients with AS and nr-axSpA. BASDAI inflammation refers to the mean of BASDAI questions 5 and 6. BASDAI fatigue, spinal pain, arthralgia, and enthesitis refer to the questions 1, 2, 3, and 4, respectively. Total severe fatigue is defined for patients who have total FSS ≥ 4 or BASDAI fatigue ≥ 5. For continuous variables, data are expressed as median (interquartile range). Other data are % unless otherwise specified.
| Variables | AS, n = 615 | nr-axSpA, n = 66 | p |
|---|---|---|---|
| Age, yrs | 41 (31–52) | 39 (27.5–48.5) | 0.07 |
| Male | 74.5 | 47.5 | < 0.0001 |
| Disease duration, yrs | 8 (4–17) | 4 (2–8) | < 0.0001 |
| Enthesitis | 6.5 | 7.6 | 0.79 |
| Arthritis | 43 | 47.6 | 0.51 |
| IBD | 11.3 | 9.5 | 0.83 |
| Uveitis | 25.5 | 21.5 | 0.55 |
| HLA-B27 | 78.5 | 70 | 0.14 |
| FSS | 4.7 (2.6–7.4) | 4.7 (2.6–7.5) | 0.77 |
| Severe fatigue according to FSS | 58.9 | 54.5 | 0.51 |
| BASDAI fatigue | 5 (2–7) | 5.5 (2–8) | 0.54 |
| Severe fatigue according to BASDAI fatigue | 54.1 | 62.1 | 0.24 |
| Total severe fatigue | 67.2 | 68.2 | 1 |
| CRP, mg/l | 3 (3–11) | 3 (3–3) | < 0.0001 |
| ESR, mm/h | 7 (3–15) | 5 (3–10) | 0.06 |
| BASDAI | 4.1 (2–6.4) | 4.3 (2.4–6.3) | 0.68 |
| ASDAS-CRP | 2.5 (1.7–3.5) | 2.5 (1.9–3.1) | 0.43 |
| BASDAI inflammation | 4 (1.5–6.5) | 4.5 (1.5–7.1) | 0.42 |
| BASDAI spinal pain | 5 (2–7) | 6 (3–7) | 0.32 |
| BASDAI arthralgia | 3 (1–6) | 3 (1–6) | 0.73 |
| BASDAI enthesitis | 3 (1–7) | 3 (0–6.3) | 0.42 |
| BASFI | 2.8 (1–5.6) | 2.7 (0.7–4.6) | 0.32 |
| Biologic use | 48.7 | 43.5 | 0.51 |
| NSAID use | 69.6 | 73 | 0.67 |
| HAQ | 0.5 (0.1–1) | 0.5 (0.1–0.9) | 0.79 |
| ASQoL | 6 (1–12) | 6 (2–12.5) | 0.79 |
| EQ-5D | 0.8 (0.6–0.8) | 0.8 (0.5–0.8) | 0.42 |
| SF-36 MCS | 49 (37.2–56.3) | 48 (36–56) | 0.64 |
| SF-36 PCS | 38.7 (30.7–48.9) | 37 (29.6–48.7) | 0.55 |
AS: ankylosing spondylitis; nr-axSpA: nonradiographic axial spondyloarthritis; BASDAI: Bath AS Disease Activity Index; FSS: Fatigue Severity Scale; IBD: inflammatory bowel disease; CRP: C-reactive protein; ESR: erythrocyte sedimentation rate; ASDAS: AS Disease Activity Score; BASFI: Bath AS Functional Index; NSAID: nonsteroidal antiinflammatory drugs; HAQ: Health Assessment Questionnaire; ASQoL: AS quality of life; SF-36: Medical Outcomes Study Short Form-36; MCS: mental component summary; PCS: physical component summary.