The 2 ASDAS formulas selected by the ASAS membership: ASDAS-CRP, the [preferred version, and ASDAS-ESR, the alternative version. Back pain, patient global, duration of morning stiffness and peripheral pain/swelling are all assessed on a visual analog scale (0 to 10 cm) or on a numerical rating scale (0 to 10); back pain, BASDAI question 2; duration of morning stiffness, BASDAI question 6; peripheral pain/swelling, BASDAI question 3.
| ASDAS-CRP | 0.12 × back pain + 0.06 × duration of morning stiffness + 0.11 × patient global + 0.07 × peripheral pain/swelling + 0.58 × Ln (CRP + 1) |
| ASDAS-ESR | 0.08 × back pain + 0.07 × duration of morning stiffness + 0.11 × patient global + 0.09 × peripheral pain/swelling + 0.29 ×√ (ESR) |
ASDAS: Ankylosing Spondylitis Disease Activity Score; √ (ESR): square root of the erythrocyte sedimentation rate (mm/h); Ln (CRP + 1): natural logarithm of the C-reactive protein (mg/l) + 1; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index.