| Variables | Baseline | 3 Months | 6 Months |
| Males (number, %) | 40 (76) | ||
| Age (years) | 41 (11) | ||
| Caucasian (number, %) | 45 (85) | ||
| BMI | 25 (4.4) | ||
| HLA B27 + (number, %) | 44 (88) | ||
| Peripheral arthritis (number, %) | 28 (53) | ||
| BASDAI | 6.4 (1.3) | 3.1 (2.0)* | 2.5 (1.7)* |
| Patient Global Disease Activity score | 7.2 (1.9) | 3.2 (2.4)* | 2.5 (2.1)* |
| BASFI | 6.2 (2.1) | 4.1 (2.5)* | 3.5 (2.5)* |
| ESR (median, range) | 22 (1–114) | 5 (1–58)* | 4 (1–33)* |
| CRP (median, range) | 17 (1–92) | 4 (1–44)* | 4 (1–74)* |
| Serum etanercept levels | 0 | 2.7 (1.2) | 3.0 (1.0) |
| Antibodies to etanercept | 0 | 0 | 0 |
Except where indicated otherwise, the values are the mean (SD). Mean serum etanercept and antibodies to etanercept levels are in mg/litre. Normal CRP <8.0 mg/litre; normal ESR <10 mm/h.
*Significance level: p<0.001.
BASDAI, Bath Ankylosing Spondylitis Disease Activity Index (0–10); BASFI, Bath Ankylosing Spondylitis Functional Index (0–10); BMI, body mass index; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; HLA B27, human leukocyte antigen B27.