Summary of variables related to drug use and disease assessment in intervals
| Continuous variables | Total intervals | On TNFi n=1281 | Off TNFi n=1083 |
| Duration of intervals, mean (SD), day | 439.1 (646.7) | 633.0 (721.0) | 209.8 (448.6) |
| ESR at start, mean (SD), mm/hour | 20.84 (23.75) | 23.67 (26.37) | 17.46 (19.66) |
| CRP at start, mean (SD), mg/dL | 1.47 (1.67) | 1.67 (1.96) | 1.23 (1.21) |
| BASDAI at start, mean (SD) | 3.52 (2.44) | 4.00 (2.69) | 2.95 (1.96) |
| mSASSS change per year (SD) | 0.85 (1.59) | 0.82 (1.53) | 0.89 (1.66) |
| cDMARDs* (%) | 165 (7.0) | 103 (8.0) | 62 (5.7) |
| NSAIDs* (%) | 516 (21.8) | 379 (29.6) | 137 (12.7) |
| Glucocorticoids* (%) | 48 (2.0) | 26 (2.0) | 22 (2.0) |
*Number of intervals prescribed with drugs for >50% of the interval period.
AS, ankylosing spondylitis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; cDMARDs, conventional disease-modifying anti-rheumatic drugs; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; mSASSS, modified Stoke Ankylosing Spondylitis Spinal Score; NSAIDs, non-steroidal anti-inflammatory drugs.