Definition of radiographic progression in patients with ankylosing spondylitis. Stratification to different groups of progression rates is according to change of mSASSS or development of new syndesmophytes within a 2-year period.
| Definition of Progression | mSASSS Change | Development of New Syndesmophytes |
|---|---|---|
| Slow | < 2 mSASSS units within 2 yrs | Not more than 1 syndesmophyte within 2 yrs |
| Moderate | 2.0–5.0 mSASSS units within 2 yrs | Not more than 2 syndesmophytes within 2 yrs |
| Fast | > 5 mSASSS units within 2 yrs | More than 2 syndesmophytes within 2 yrs |
mSASSS: modified Stoke Ankylosing Spondylitis Spine Score.