Table 1.
Baseline characteristics of patients with spondyloarthritis or chronic low back pain
| Spondyloarthritis (n = 37) | Low back pain (n = 17) | Total (n = 54) | p value | |
|---|---|---|---|---|
| Age* (years) | 35.8 ± 10.7 | 40.8 ± 9.7 | 37.5 ± 10.6 | 0.09 |
| Gender** (female) | 25 (67.6) | 8 (47.1) | 33 (61) | NS |
| Ethnicity** (Caucasian) | 26 (70.3) | 12 (70.6) | 38 (70.4) | NS |
| Family history of SpA** | 14 (37.8) | 1 (5.9) | 15 (27.8) | 0.015 |
| HLA-B27 (+)** | 21 (56.7) | 3 (17.7) | 24 (44.4) | 0.007 |
| Enthesitis** | 16 (43.2) | 3 (17.7) | 19 (35.2) | 0.067 |
| Arthritis** | 11 (29.7) | 1 (5.9) | 12 (22.2) | 0.05 |
| Uveitis** | 3 (8.1) | 1 (5.9) | 4 (7.4) | NS |
| Psoriasis** | 4 (10.8) | 1 (5.9) | 5 (9.3) | NS |
| IBD ** | 2 (5.4) | 0 (0.0) | 2 (3.7) | NS |
| Previous infections** | 3 (8.1) | 0 (0.0) | 3 (5.6) | NS |
| Sacroiliitis MRI** | 22 (59.5) | 0 (0.0) | 22 (40.7) | <0.001 |
| Sacroiliitis X-ray** | 12 (33.3) | 0 (0.0) | 12 (22.2) | NS |
| BASDAI* | 40.5 ± 23.1 | 36.4 ± 22.9 | 39.4 ± 22.7 | NS |
| BASFI*** | 29 [12–45] | 25.5 [11–50] | 26 [12–45] | NS |
| CRP (mg/dl) * | 0.99 ± 2.3 | 0.2 ± 0.25 | 0.7 ± 0.2 | 0.048 |
| ESR (mm/h)* | 23.3 ± 18.8 | 15.6 ± 13.0 | 21.0 ± 17.5 | 0.082 |
| ALP (U/l)* | 62.8 ± 19.4 | 67.2 ± 18.2 | 64.2 ± 18.9 | NS |
| Hb (g/dl)* | 13.2 ± 2.4 | 14.6 ± 1.3 | 13.6 ± 2.2 | 0.023 |
| VIP (pg/ml)*** | 250 [209 – 280] | 292 [230–337] | 251 [212–303] | NS |
Data are shown as the mean ± standard deviation (SD), frequency n (%), or median and [interquartile range]
IBD inflammatory bowel disease, MRI magnetic resonance imaging, BASDAI Bath Ankylosing Spondylitis Disease Activity Index, BASFI Bath Ankylosing Spondylitis Functional Index, CRP C-reactive protein, ESR erythrocyte sedimentation rate, ALP alkaline phosphatase, Hb hemoglobin, VIP vasoactive intestinal peptide, NS non-significant
Statistical significance was established by * Student’s t test, **χ2 or ***Kruskal-Wallis test for a p value <0.05