Table 1 The seven domains and 12 items that were selected after the Delphi exercise for inclusion in the analysis to derive a disease activity index in ankylosing spondylitis

Domain	Item
Pain	Patient overall pain assessment of back, neck and hips (BASDAI question 2)
	Patient total spinal pain assessment (pain spine)
	Patient peripheral pain assessment (BASDAI question 3)
Inflammation	Patient back pain at night
Inflammation	Duration of morning stiffness (BASDAI question 6)
Function*	BASFI
Laboratory tests	CRP
Laboratory tests	ESR
Patient global	Global disease activity (by patient self-assessment)
Peripheral signs	Swollen joint count
Peripheral signs	Tender enthesis count
Fatigue	Fatigue level self-assessment (BASDAI question 1)

*BASFI was excluded after discussion among the ASAS members (see text).
ASAS, Assessment of SpondyloArthritis international Society; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate.