Table 5 Formulae for the four draft ASDAS
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.