Demographic and clinical characteristics of patients.
| Feature | All Patients, n = 99 | Patients with SpA, n = 36 | Patients with Low Back Pain (suspected SpA), n = 63 | p |
|---|---|---|---|---|
| Male, n (%) | 61 (61.6) | 30 (83) | 31 (49) | 0.001 |
| Age, yrs, mean (SD) | 39.8 (11.3) | 42.7 (13.9) | 38.2 (9.3) | 0.0622 |
| Disease duration, mos, median (IQR) | 24 (12–84) | 24 (12–120) | 30 (6–60) | 0.622 |
| HLA-B27, n/tested (%) | 25/88 (28.4) | 12/32 (37.5) | 13/56 (23) | 0.235 |
| BASDAI, mean (SD) | 4.5 (2.3) | 4.3 (2.3) | 4.7 (2.3) | 0.4351 |
| BASFI, mean (SD) | 3.2 (2.5) | 3.6 (2.7) | 2.9 (2.3) | 0.1999 |
| BASMI, mean (SD) | 2.32 (0.14), n = 95 | 2.95 (0.30), n = 34 | 1.96 (0.12), n = 61 | 0.004 |
| ESR, median (IQR) | 17 (8–34) | 24 (8–38) | 15.5 (8–30) | 0.2723 |
| CRP mg/l, median (IQR) | 2.9 (1–10) | 3.7 (0.8–11) | 2.6 (1–9) | 0.6616 |
| HAQ-A, median (IQR) | 0.62 (0.125–1) | 0.62 (0.25–1.12) | 0.55 (0.18–1) | 0.3686 |
SpA: spondyloarthritis; IQR: interquartile range; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; BASFI: Bath Ankylosing Spondylitis Functional Index; BASMI: Bath Ankylosing Spondylitis Metrology Index; HAQ-A: Health Assessment Questionnaire–Argentine version.