| ASDAS A | = | 0.122×Back pain | + | 0.061×Duration morning stiffness | + | 0.119×Patient global | + | 0.210×√(ESR) | + | 0.383×Ln (CRP+1) |
| ASDAS B | = | 0.079×Back pain | + | 0.069×Duration morning stiffness | + | 0.113×Patient global | + | 0.086×Peripheral pain/swelling | + | 0.293×√(ESR) |
| ASDAS C | = | 0.121×Back pain | + | 0.058×Duration morning stiffness | + | 0.110×Patient global | + | 0.073×Peripheral pain/swelling | + | 0.579×Ln (CRP+1) |
| ASDAS D | = | 0.152×Back pain | + | 0.069×Duration morning stiffness | + | 0.078×Fatigue | + | 0.224×√(ESR) | + | 0.400×Ln (CRP+1) |
Back pain, patient global, duration of morning stiffness, peripheral pain/swelling and fatigue are all assessed on a visual analogue scale (from 0 to 10 cm) or on a numerical rating scale (from 0 to 10).
Back pain: BASDAI question 2 (cm); duration of morning stiffness: BASDAI question 6 (cm); fatigue: BASDAI question 1 (cm); peripheral pain/swelling: BASDAI question 3 (cm).
ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; √(ESR), Square root of the erythrocyte sedimentation rate; Ln (CRP+1), natural logarithm of the C-reactive protein (mg/l) +1.